information on time travel

Is Time Travel Possible?

We all travel in time! We travel one year in time between birthdays, for example. And we are all traveling in time at approximately the same speed: 1 second per second.

We typically experience time at one second per second. Credit: NASA/JPL-Caltech

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away . It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope, we are seeing what those stars and galaxies looked like a very long time ago.

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second. That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

Image of galaxies, taken by the Hubble Space Telescope.

This image from the Hubble Space Telescope shows galaxies that are very far away as they existed a very long time ago. Credit: NASA, ESA and R. Thompson (Univ. Arizona)

How do we know that time travel is possible?

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Einstein's theory of relativity says that space and time are linked together. Credit: NASA/JPL-Caltech

What does this mean for time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.

For example, there was an experiment that used two clocks set to the exact same time. One clock stayed on Earth, while the other flew in an airplane (going in the same direction Earth rotates).

After the airplane flew around the world, scientists compared the two clocks. The clock on the fast-moving airplane was slightly behind the clock on the ground. So, the clock on the airplane was traveling slightly slower in time than 1 second per second.

Credit: NASA/JPL-Caltech

Can we use time travel in everyday life?

We can't use a time machine to travel hundreds of years into the past or future. That kind of time travel only happens in books and movies. But the math of time travel does affect the things we use every day.

For example, we use GPS satellites to help us figure out how to get to new places. (Check out our video about how GPS satellites work .) NASA scientists also use a high-accuracy version of GPS to keep track of where satellites are in space. But did you know that GPS relies on time-travel calculations to help you get around town?

GPS satellites orbit around Earth very quickly at about 8,700 miles (14,000 kilometers) per hour. This slows down GPS satellite clocks by a small fraction of a second (similar to the airplane example above).

Illustration of GPS satellites orbiting around Earth

GPS satellites orbit around Earth at about 8,700 miles (14,000 kilometers) per hour. Credit: GPS.gov

However, the satellites are also orbiting Earth about 12,550 miles (20,200 km) above the surface. This actually speeds up GPS satellite clocks by a slighter larger fraction of a second.

Here's how: Einstein's theory also says that gravity curves space and time, causing the passage of time to slow down. High up where the satellites orbit, Earth's gravity is much weaker. This causes the clocks on GPS satellites to run faster than clocks on the ground.

The combined result is that the clocks on GPS satellites experience time at a rate slightly faster than 1 second per second. Luckily, scientists can use math to correct these differences in time.

Illustration of a hand holding a phone with a maps application active.

If scientists didn't correct the GPS clocks, there would be big problems. GPS satellites wouldn't be able to correctly calculate their position or yours. The errors would add up to a few miles each day, which is a big deal. GPS maps might think your home is nowhere near where it actually is!

In Summary:

Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

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April 26, 2023

Is Time Travel Possible?

The laws of physics allow time travel. So why haven’t people become chronological hoppers?

By Sarah Scoles

yuanyuan yan/Getty Images

In the movies, time travelers typically step inside a machine and—poof—disappear. They then reappear instantaneously among cowboys, knights or dinosaurs. What these films show is basically time teleportation .

Scientists don’t think this conception is likely in the real world, but they also don’t relegate time travel to the crackpot realm. In fact, the laws of physics might allow chronological hopping, but the devil is in the details.

Time traveling to the near future is easy: you’re doing it right now at a rate of one second per second, and physicists say that rate can change. According to Einstein’s special theory of relativity, time’s flow depends on how fast you’re moving. The quicker you travel, the slower seconds pass. And according to Einstein’s general theory of relativity , gravity also affects clocks: the more forceful the gravity nearby, the slower time goes.

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“Near massive bodies—near the surface of neutron stars or even at the surface of the Earth, although it’s a tiny effect—time runs slower than it does far away,” says Dave Goldberg, a cosmologist at Drexel University.

If a person were to hang out near the edge of a black hole , where gravity is prodigious, Goldberg says, only a few hours might pass for them while 1,000 years went by for someone on Earth. If the person who was near the black hole returned to this planet, they would have effectively traveled to the future. “That is a real effect,” he says. “That is completely uncontroversial.”

Going backward in time gets thorny, though (thornier than getting ripped to shreds inside a black hole). Scientists have come up with a few ways it might be possible, and they have been aware of time travel paradoxes in general relativity for decades. Fabio Costa, a physicist at the Nordic Institute for Theoretical Physics, notes that an early solution with time travel began with a scenario written in the 1920s. That idea involved massive long cylinder that spun fast in the manner of straw rolled between your palms and that twisted spacetime along with it. The understanding that this object could act as a time machine allowing one to travel to the past only happened in the 1970s, a few decades after scientists had discovered a phenomenon called “closed timelike curves.”

“A closed timelike curve describes the trajectory of a hypothetical observer that, while always traveling forward in time from their own perspective, at some point finds themselves at the same place and time where they started, creating a loop,” Costa says. “This is possible in a region of spacetime that, warped by gravity, loops into itself.”

“Einstein read [about closed timelike curves] and was very disturbed by this idea,” he adds. The phenomenon nevertheless spurred later research.

Science began to take time travel seriously in the 1980s. In 1990, for instance, Russian physicist Igor Novikov and American physicist Kip Thorne collaborated on a research paper about closed time-like curves. “They started to study not only how one could try to build a time machine but also how it would work,” Costa says.

Just as importantly, though, they investigated the problems with time travel. What if, for instance, you tossed a billiard ball into a time machine, and it traveled to the past and then collided with its past self in a way that meant its present self could never enter the time machine? “That looks like a paradox,” Costa says.

Since the 1990s, he says, there’s been on-and-off interest in the topic yet no big breakthrough. The field isn’t very active today, in part because every proposed model of a time machine has problems. “It has some attractive features, possibly some potential, but then when one starts to sort of unravel the details, there ends up being some kind of a roadblock,” says Gaurav Khanna of the University of Rhode Island.

For instance, most time travel models require negative mass —and hence negative energy because, as Albert Einstein revealed when he discovered E = mc 2 , mass and energy are one and the same. In theory, at least, just as an electric charge can be positive or negative, so can mass—though no one’s ever found an example of negative mass. Why does time travel depend on such exotic matter? In many cases, it is needed to hold open a wormhole—a tunnel in spacetime predicted by general relativity that connects one point in the cosmos to another.

Without negative mass, gravity would cause this tunnel to collapse. “You can think of it as counteracting the positive mass or energy that wants to traverse the wormhole,” Goldberg says.

Khanna and Goldberg concur that it’s unlikely matter with negative mass even exists, although Khanna notes that some quantum phenomena show promise, for instance, for negative energy on very small scales. But that would be “nowhere close to the scale that would be needed” for a realistic time machine, he says.

These challenges explain why Khanna initially discouraged Caroline Mallary, then his graduate student at the University of Massachusetts Dartmouth, from doing a time travel project. Mallary and Khanna went forward anyway and came up with a theoretical time machine that didn’t require negative mass. In its simplistic form, Mallary’s idea involves two parallel cars, each made of regular matter. If you leave one parked and zoom the other with extreme acceleration, a closed timelike curve will form between them.

Easy, right? But while Mallary’s model gets rid of the need for negative matter, it adds another hurdle: it requires infinite density inside the cars for them to affect spacetime in a way that would be useful for time travel. Infinite density can be found inside a black hole, where gravity is so intense that it squishes matter into a mind-bogglingly small space called a singularity. In the model, each of the cars needs to contain such a singularity. “One of the reasons that there's not a lot of active research on this sort of thing is because of these constraints,” Mallary says.

Other researchers have created models of time travel that involve a wormhole, or a tunnel in spacetime from one point in the cosmos to another. “It's sort of a shortcut through the universe,” Goldberg says. Imagine accelerating one end of the wormhole to near the speed of light and then sending it back to where it came from. “Those two sides are no longer synced,” he says. “One is in the past; one is in the future.” Walk between them, and you’re time traveling.

You could accomplish something similar by moving one end of the wormhole near a big gravitational field—such as a black hole—while keeping the other end near a smaller gravitational force. In that way, time would slow down on the big gravity side, essentially allowing a particle or some other chunk of mass to reside in the past relative to the other side of the wormhole.

Making a wormhole requires pesky negative mass and energy, however. A wormhole created from normal mass would collapse because of gravity. “Most designs tend to have some similar sorts of issues,” Goldberg says. They’re theoretically possible, but there’s currently no feasible way to make them, kind of like a good-tasting pizza with no calories.

And maybe the problem is not just that we don’t know how to make time travel machines but also that it’s not possible to do so except on microscopic scales—a belief held by the late physicist Stephen Hawking. He proposed the chronology protection conjecture: The universe doesn’t allow time travel because it doesn’t allow alterations to the past. “It seems there is a chronology protection agency, which prevents the appearance of closed timelike curves and so makes the universe safe for historians,” Hawking wrote in a 1992 paper in Physical Review D .

Part of his reasoning involved the paradoxes time travel would create such as the aforementioned situation with a billiard ball and its more famous counterpart, the grandfather paradox : If you go back in time and kill your grandfather before he has children, you can’t be born, and therefore you can’t time travel, and therefore you couldn’t have killed your grandfather. And yet there you are.

Those complications are what interests Massachusetts Institute of Technology philosopher Agustin Rayo, however, because the paradoxes don’t just call causality and chronology into question. They also make free will seem suspect. If physics says you can go back in time, then why can’t you kill your grandfather? “What stops you?” he says. Are you not free?

Rayo suspects that time travel is consistent with free will, though. “What’s past is past,” he says. “So if, in fact, my grandfather survived long enough to have children, traveling back in time isn’t going to change that. Why will I fail if I try? I don’t know because I don’t have enough information about the past. What I do know is that I’ll fail somehow.”

If you went to kill your grandfather, in other words, you’d perhaps slip on a banana en route or miss the bus. “It's not like you would find some special force compelling you not to do it,” Costa says. “You would fail to do it for perfectly mundane reasons.”

In 2020 Costa worked with Germain Tobar, then his undergraduate student at the University of Queensland in Australia, on the math that would underlie a similar idea: that time travel is possible without paradoxes and with freedom of choice.

Goldberg agrees with them in a way. “I definitely fall into the category of [thinking that] if there is time travel, it will be constructed in such a way that it produces one self-consistent view of history,” he says. “Because that seems to be the way that all the rest of our physical laws are constructed.”

No one knows what the future of time travel to the past will hold. And so far, no time travelers have come to tell us about it.

Time travel: Is it possible?

Science says time travel is possible, but probably not in the way you're thinking.

time travel graphic illustration of a tunnel with a clock face swirling through the tunnel.

Albert Einstein's theory

General relativity and GPS
Wormhole travel
Alternate theories

Science fiction

Is time travel possible? Short answer: Yes, and you're doing it right now — hurtling into the future at the impressive rate of one second per second.

You're pretty much always moving through time at the same speed, whether you're watching paint dry or wishing you had more hours to visit with a friend from out of town.

But this isn't the kind of time travel that's captivated countless science fiction writers, or spurred a genre so extensive that Wikipedia lists over 400 titles in the category "Movies about Time Travel." In franchises like " Doctor Who ," " Star Trek ," and "Back to the Future" characters climb into some wild vehicle to blast into the past or spin into the future. Once the characters have traveled through time, they grapple with what happens if you change the past or present based on information from the future (which is where time travel stories intersect with the idea of parallel universes or alternate timelines).

Related: The best sci-fi time machines ever

Although many people are fascinated by the idea of changing the past or seeing the future before it's due, no person has ever demonstrated the kind of back-and-forth time travel seen in science fiction or proposed a method of sending a person through significant periods of time that wouldn't destroy them on the way. And, as physicist Stephen Hawking pointed out in his book " Black Holes and Baby Universes" (Bantam, 1994), "The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future."

Science does support some amount of time-bending, though. For example, physicist Albert Einstein 's theory of special relativity proposes that time is an illusion that moves relative to an observer. An observer traveling near the speed of light will experience time, with all its aftereffects (boredom, aging, etc.) much more slowly than an observer at rest. That's why astronaut Scott Kelly aged ever so slightly less over the course of a year in orbit than his twin brother who stayed here on Earth.

Related: Controversially, physicist argues that time is real

There are other scientific theories about time travel, including some weird physics that arise around wormholes , black holes and string theory . For the most part, though, time travel remains the domain of an ever-growing array of science fiction books, movies, television shows, comics, video games and more.

Scott and Mark Kelly sit side by side wearing a blue NASA jacket and jeans

Einstein developed his theory of special relativity in 1905. Along with his later expansion, the theory of general relativity , it has become one of the foundational tenets of modern physics. Special relativity describes the relationship between space and time for objects moving at constant speeds in a straight line.

The short version of the theory is deceptively simple. First, all things are measured in relation to something else — that is to say, there is no "absolute" frame of reference. Second, the speed of light is constant. It stays the same no matter what, and no matter where it's measured from. And third, nothing can go faster than the speed of light.

From those simple tenets unfolds actual, real-life time travel. An observer traveling at high velocity will experience time at a slower rate than an observer who isn't speeding through space.

While we don't accelerate humans to near-light-speed, we do send them swinging around the planet at 17,500 mph (28,160 km/h) aboard the International Space Station . Astronaut Scott Kelly was born after his twin brother, and fellow astronaut, Mark Kelly . Scott Kelly spent 520 days in orbit, while Mark logged 54 days in space. The difference in the speed at which they experienced time over the course of their lifetimes has actually widened the age gap between the two men.

"So, where[as] I used to be just 6 minutes older, now I am 6 minutes and 5 milliseconds older," Mark Kelly said in a panel discussion on July 12, 2020, Space.com previously reported . "Now I've got that over his head."

General relativity and GPS time travel

Graphic showing the path of GPS satellites around Earth at the center of the image.

The difference that low earth orbit makes in an astronaut's life span may be negligible — better suited for jokes among siblings than actual life extension or visiting the distant future — but the dilation in time between people on Earth and GPS satellites flying through space does make a difference.

Can wormholes take us back in time?

General relativity might also provide scenarios that could allow travelers to go back in time, according to NASA . But the physical reality of those time-travel methods is no piece of cake.

Wormholes are theoretical "tunnels" through the fabric of space-time that could connect different moments or locations in reality to others. Also known as Einstein-Rosen bridges or white holes, as opposed to black holes, speculation about wormholes abounds. But despite taking up a lot of space (or space-time) in science fiction, no wormholes of any kind have been identified in real life.

Related: Best time travel movies

"The whole thing is very hypothetical at this point," Stephen Hsu, a professor of theoretical physics at the University of Oregon, told Space.com sister site Live Science . "No one thinks we're going to find a wormhole anytime soon."

Primordial wormholes are predicted to be just 10^-34 inches (10^-33 centimeters) at the tunnel's "mouth". Previously, they were expected to be too unstable for anything to be able to travel through them. However, a study claims that this is not the case, Live Science reported .

The theory, which suggests that wormholes could work as viable space-time shortcuts, was described by physicist Pascal Koiran. As part of the study, Koiran used the Eddington-Finkelstein metric, as opposed to the Schwarzschild metric which has been used in the majority of previous analyses.

In the past, the path of a particle could not be traced through a hypothetical wormhole. However, using the Eddington-Finkelstein metric, the physicist was able to achieve just that.

Koiran's paper was described in October 2021, in the preprint database arXiv , before being published in the Journal of Modern Physics D.

Alternate time travel theories

While Einstein's theories appear to make time travel difficult, some researchers have proposed other solutions that could allow jumps back and forth in time. These alternate theories share one major flaw: As far as scientists can tell, there's no way a person could survive the kind of gravitational pulling and pushing that each solution requires.

Infinite cylinder theory

Astronomer Frank Tipler proposed a mechanism (sometimes known as a Tipler Cylinder ) where one could take matter that is 10 times the sun's mass, then roll it into a very long, but very dense cylinder. The Anderson Institute , a time travel research organization, described the cylinder as "a black hole that has passed through a spaghetti factory."

After spinning this black hole spaghetti a few billion revolutions per minute, a spaceship nearby — following a very precise spiral around the cylinder — could travel backward in time on a "closed, time-like curve," according to the Anderson Institute.

The major problem is that in order for the Tipler Cylinder to become reality, the cylinder would need to be infinitely long or be made of some unknown kind of matter. At least for the foreseeable future, endless interstellar pasta is beyond our reach.

Time donuts

Theoretical physicist Amos Ori at the Technion-Israel Institute of Technology in Haifa, Israel, proposed a model for a time machine made out of curved space-time — a donut-shaped vacuum surrounded by a sphere of normal matter.

"The machine is space-time itself," Ori told Live Science . "If we were to create an area with a warp like this in space that would enable time lines to close on themselves, it might enable future generations to return to visit our time."

Amos Ori is a theoretical physicist at the Technion-Israel Institute of Technology in Haifa, Israel. His research interests and publications span the fields of general relativity, black holes, gravitational waves and closed time lines.

There are a few caveats to Ori's time machine. First, visitors to the past wouldn't be able to travel to times earlier than the invention and construction of the time donut. Second, and more importantly, the invention and construction of this machine would depend on our ability to manipulate gravitational fields at will — a feat that may be theoretically possible but is certainly beyond our immediate reach.

Graphic illustration of the TARDIS (Time and Relative Dimensions in Space) traveling through space, surrounded by stars.

Time travel has long occupied a significant place in fiction. Since as early as the "Mahabharata," an ancient Sanskrit epic poem compiled around 400 B.C., humans have dreamed of warping time, Lisa Yaszek, a professor of science fiction studies at the Georgia Institute of Technology in Atlanta, told Live Science .

Every work of time-travel fiction creates its own version of space-time, glossing over one or more scientific hurdles and paradoxes to achieve its plot requirements.

Some make a nod to research and physics, like " Interstellar ," a 2014 film directed by Christopher Nolan. In the movie, a character played by Matthew McConaughey spends a few hours on a planet orbiting a supermassive black hole, but because of time dilation, observers on Earth experience those hours as a matter of decades.

Others take a more whimsical approach, like the "Doctor Who" television series. The series features the Doctor, an extraterrestrial "Time Lord" who travels in a spaceship resembling a blue British police box. "People assume," the Doctor explained in the show, "that time is a strict progression from cause to effect, but actually from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly-wobbly, timey-wimey stuff."

Long-standing franchises like the "Star Trek" movies and television series, as well as comic universes like DC and Marvel Comics, revisit the idea of time travel over and over.

Related: Marvel movies in order: chronological & release order

Here is an incomplete (and deeply subjective) list of some influential or notable works of time travel fiction:

Books about time travel:

A sketch from the Christmas Carol shows a cloaked figure on the left and a person kneeling and clutching their head with their hands.

Rip Van Winkle (Cornelius S. Van Winkle, 1819) by Washington Irving
A Christmas Carol (Chapman & Hall, 1843) by Charles Dickens
The Time Machine (William Heinemann, 1895) by H. G. Wells
A Connecticut Yankee in King Arthur's Court (Charles L. Webster and Co., 1889) by Mark Twain
The Restaurant at the End of the Universe (Pan Books, 1980) by Douglas Adams
A Tale of Time City (Methuen, 1987) by Diana Wynn Jones
The Outlander series (Delacorte Press, 1991-present) by Diana Gabaldon
Harry Potter and the Prisoner of Azkaban (Bloomsbury/Scholastic, 1999) by J. K. Rowling
Thief of Time (Doubleday, 2001) by Terry Pratchett
The Time Traveler's Wife (MacAdam/Cage, 2003) by Audrey Niffenegger
All You Need is Kill (Shueisha, 2004) by Hiroshi Sakurazaka

Movies about time travel:

Planet of the Apes (1968)
Superman (1978)
Time Bandits (1981)
The Terminator (1984)
Back to the Future series (1985, 1989, 1990)
Star Trek IV: The Voyage Home (1986)
Bill & Ted's Excellent Adventure (1989)
Groundhog Day (1993)
Galaxy Quest (1999)
The Butterfly Effect (2004)
13 Going on 30 (2004)
The Lake House (2006)
Meet the Robinsons (2007)
Hot Tub Time Machine (2010)
Midnight in Paris (2011)
Looper (2012)
X-Men: Days of Future Past (2014)
Edge of Tomorrow (2014)
Interstellar (2014)
Doctor Strange (2016)
A Wrinkle in Time (2018)
The Last Sharknado: It's About Time (2018)
Avengers: Endgame (2019)
Tenet (2020)
Palm Springs (2020)
Zach Snyder's Justice League (2021)
The Tomorrow War (2021)

Television about time travel:

Image of the Star Trek spaceship USS Enterprise

Doctor Who (1963-present)
The Twilight Zone (1959-1964) (multiple episodes)
Star Trek (multiple series, multiple episodes)
Samurai Jack (2001-2004)
Lost (2004-2010)
Phil of the Future (2004-2006)
Steins;Gate (2011)
Outlander (2014-2023)
Loki (2021-present)

Games about time travel:

Chrono Trigger (1995)
TimeSplitters (2000-2005)
Kingdom Hearts (2002-2019)
Prince of Persia: Sands of Time (2003)
God of War II (2007)
Ratchet and Clank Future: A Crack In Time (2009)
Sly Cooper: Thieves in Time (2013)
Dishonored 2 (2016)
Titanfall 2 (2016)
Outer Wilds (2019)

Additional resources

Explore physicist Peter Millington's thoughts about Stephen Hawking's time travel theories at The Conversation . Check out a kid-friendly explanation of real-world time travel from NASA's Space Place . For an overview of time travel in fiction and the collective consciousness, read " Time Travel: A History " (Pantheon, 2016) by James Gleik.

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Vicky Stein is a science writer based in California. She has a bachelor's degree in ecology and evolutionary biology from Dartmouth College and a graduate certificate in science writing from the University of California, Santa Cruz (2018). Afterwards, she worked as a news assistant for PBS NewsHour, and now works as a freelancer covering anything from asteroids to zebras. Follow her most recent work (and most recent pictures of nudibranchs) on Twitter.

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Will it ever be possible for time travel to occur? – Alana C., age 12, Queens, New York

Have you ever dreamed of traveling through time, like characters do in science fiction movies? For centuries, the concept of time travel has captivated people’s imaginations. Time travel is the concept of moving between different points in time, just like you move between different places. In movies, you might have seen characters using special machines, magical devices or even hopping into a futuristic car to travel backward or forward in time.

But is this just a fun idea for movies, or could it really happen?

The question of whether time is reversible remains one of the biggest unresolved questions in science. If the universe follows the laws of thermodynamics , it may not be possible. The second law of thermodynamics states that things in the universe can either remain the same or become more disordered over time.

It’s a bit like saying you can’t unscramble eggs once they’ve been cooked. According to this law, the universe can never go back exactly to how it was before. Time can only go forward, like a one-way street.

Time is relative

However, physicist Albert Einstein’s theory of special relativity suggests that time passes at different rates for different people. Someone speeding along on a spaceship moving close to the speed of light – 671 million miles per hour! – will experience time slower than a person on Earth.

Related: The speed of light, explained

People have yet to build spaceships that can move at speeds anywhere near as fast as light, but astronauts who visit the International Space Station orbit around the Earth at speeds close to 17,500 mph. Astronaut Scott Kelly has spent 520 days at the International Space Station, and as a result has aged a little more slowly than his twin brother – and fellow astronaut – Mark Kelly. Scott used to be 6 minutes younger than his twin brother. Now, because Scott was traveling so much faster than Mark and for so many days, he is 6 minutes and 5 milliseconds younger .

Some scientists are exploring other ideas that could theoretically allow time travel. One concept involves wormholes , or hypothetical tunnels in space that could create shortcuts for journeys across the universe. If someone could build a wormhole and then figure out a way to move one end at close to the speed of light – like the hypothetical spaceship mentioned above – the moving end would age more slowly than the stationary end. Someone who entered the moving end and exited the wormhole through the stationary end would come out in their past.

However, wormholes remain theoretical : Scientists have yet to spot one. It also looks like it would be incredibly challenging to send humans through a wormhole space tunnel.

Time travel paradoxes and failed dinner parties

There are also paradoxes associated with time travel. The famous “ grandfather paradox ” is a hypothetical problem that could arise if someone traveled back in time and accidentally prevented their grandparents from meeting. This would create a paradox where you were never born, which raises the question: How could you have traveled back in time in the first place? It’s a mind-boggling puzzle that adds to the mystery of time travel.

Famously, physicist Stephen Hawking tested the possibility of time travel by throwing a dinner party where invitations noting the date, time and coordinates were not sent out until after it had happened. His hope was that his invitation would be read by someone living in the future, who had capabilities to travel back in time. But no one showed up.

As he pointed out : “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

Telescopes are time machines

Interestingly, astrophysicists armed with powerful telescopes possess a unique form of time travel. As they peer into the vast expanse of the cosmos, they gaze into the past universe. Light from all galaxies and stars takes time to travel, and these beams of light carry information from the distant past. When astrophysicists observe a star or a galaxy through a telescope, they are not seeing it as it is in the present, but as it existed when the light began its journey to Earth millions to billions of years ago.

NASA’s newest space telescope, the James Webb Space Telescope , is peering at galaxies that were formed at the very beginning of the Big Bang, about 13.7 billion years ago.

While we aren’t likely to have time machines like the ones in movies anytime soon, scientists are actively researching and exploring new ideas. But for now, we’ll have to enjoy the idea of time travel in our favorite books, movies and dreams.

This article first appeared on the Conversation. You can read the original here .

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Is time travel possible? Why one scientist says we 'cannot ignore the possibility.'

A common theme in science-fiction media , time travel is captivating. It’s defined by the late philosopher David Lewis in his essay “The Paradoxes of Time Travel” as “[involving] a discrepancy between time and space time. Any traveler departs and then arrives at his destination; the time elapsed from departure to arrival … is the duration of the journey.”

Time travel is usually understood by most as going back to a bygone era or jumping forward to a point far in the future . But how much of the idea is based in reality? Is it possible to travel through time?

Is time travel possible?

According to NASA, time travel is possible , just not in the way you might expect. Albert Einstein’s theory of relativity says time and motion are relative to each other, and nothing can go faster than the speed of light , which is 186,000 miles per second. Time travel happens through what’s called “time dilation.”

Time dilation , according to Live Science, is how one’s perception of time is different to another's, depending on their motion or where they are. Hence, time being relative.

Learn more: Best travel insurance

Dr. Ana Alonso-Serrano, a postdoctoral researcher at the Max Planck Institute for Gravitational Physics in Germany, explained the possibility of time travel and how researchers test theories.

Space and time are not absolute values, Alonso-Serrano said. And what makes this all more complex is that you are able to carve space-time .

“In the moment that you carve the space-time, you can play with that curvature to make the time come in a circle and make a time machine,” Alonso-Serrano told USA TODAY.

She explained how, theoretically, time travel is possible. The mathematics behind creating curvature of space-time are solid, but trying to re-create the strict physical conditions needed to prove these theories can be challenging.

“The tricky point of that is if you can find a physical, realistic, way to do it,” she said.

Alonso-Serrano said wormholes and warp drives are tools that are used to create this curvature. The matter needed to achieve curving space-time via a wormhole is exotic matter , which hasn’t been done successfully. Researchers don’t even know if this type of matter exists, she said.

“It's something that we work on because it's theoretically possible, and because it's a very nice way to test our theory, to look for possible paradoxes,” Alonso-Serrano added.

“I could not say that nothing is possible, but I cannot ignore the possibility,” she said.

She also mentioned the anecdote of Stephen Hawking’s Champagne party for time travelers . Hawking had a GPS-specific location for the party. He didn’t send out invites until the party had already happened, so only people who could travel to the past would be able to attend. No one showed up, and Hawking referred to this event as "experimental evidence" that time travel wasn't possible.

What did Albert Einstein invent?: Discoveries that changed the world

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Is Time Travel Even Possible? An Astrophysicist Explains The Science Behind The Science Fiction

If traveling into the past is possible, one way to do it might be sending people through tunnels in space..

multiple-red-alarm-clocks-drifiting-in-a-spiral-of-cosmic-matter

But is this just a fun idea for movies, or could it really happen?

Time is relative

Time isn’t the same everywhere.

However, wormholes remain theoretical: Scientists have yet to spot one. It also looks like it would be incredibly challenging to send humans through a wormhole space tunnel.

Paradoxes and failed dinner parties

As he pointed out : “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

Telescopes are time machines

NASA’s newest space telescope, the James Webb Space Telescope , is peering at galaxies that were formed at the very beginning of the Big Bang, about 13.7 billion years ago.

Adi Foord is an Assistant Professor of Astronomy and Astrophysics at the University of Maryland, Baltimore County. This article is republished from The Conversation under a Creative Commons license . Read the original article .

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Is time travel even possible? An astrophysicist explains the science behind the science fiction

Assistant Professor of Astronomy and Astrophysics, University of Maryland, Baltimore County

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Adi Foord does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected] .

Will it ever be possible for time travel to occur? – Alana C., age 12, Queens, New York

But is this just a fun idea for movies, or could it really happen?

Time is relative

However, wormholes remain theoretical: Scientists have yet to spot one. It also looks like it would be incredibly challenging to send humans through a wormhole space tunnel.

Paradoxes and failed dinner parties

As he pointed out : “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

Telescopes are time machines

NASA’s newest space telescope, the James Webb Space Telescope , is peering at galaxies that were formed at the very beginning of the Big Bang, about 13.7 billion years ago.

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Is time travel even possible? An astrophysicist explains the science behind the science fiction

Published: Nov 13, 2023

By: Magazine Editor

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Written by Adi Foord , assistant professor of physics , UMBC

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected] .

Will it ever be possible for time travel to occur? – Alana C., age 12, Queens, New York

But is this just a fun idea for movies, or could it really happen?

Time is relative

However, wormholes remain theoretical: Scientists have yet to spot one. It also looks like it would be incredibly challenging to send humans through a wormhole space tunnel.

Paradoxes and failed dinner parties

As he pointed out : “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

Telescopes are time machines

NASA’s newest space telescope, the James Webb Space Telescope , is peering at galaxies that were formed at the very beginning of the Big Bang, about 13.7 billion years ago.

This article is republished from The Conversation under a Creative Commons license. Read the original article and see more than 250 UMBC articles available in The Conversation.

Tags: CNMS , Physics , The Conversation

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Can time travel survive a theory of everything.

It’s complicated. But studying ways to visit the past could help us understand the cosmos

By Tom Siegfried

Contributing Correspondent

September 20, 2019 at 8:00 am

The TARDIS and other fictional time machines make time travel look relatively easy (Peter Capaldi and Jenna Coleman are shown promoting the BBC’s Doctor Who ). But just because it’s permitted by the laws of physics, doesn’t mean it’s practical.

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Time Travel Probably Isn't Possible—Why Do We Wish It Were?

Time travel exerts an irresistible pull on our scientific and storytelling imagination.

Since H.G. Wells imagined that time was a fourth dimension —and Einstein confirmed it—the idea of time travel has captivated us. More than 50 scientific papers are published on time travel each year, and storytellers continually explore it—from Stephen King’s JFK assassination novel 11/22/63 to the steamy Outlander television series to Woody Allen’s comedy Midnight in Paris . What if we could travel back in time, we wonder, and change history? Assassinate Hitler or marry that high school sweetheart who dumped us? What if we could see what the future has in store?

These are some of the ideas that bestselling author James Gleick explores in his thought-provoking new book, Time Travel: A History. Speaking from his home in New York City, he recalls how Stephen Hawking once sent out invitations to a party that had already taken place ; why the Chinese government has branded time travel as “incorrect” and “frivolous” ; and how the idea of time travel is, ultimately, about our desire to defeat death.

Let’s cut right to the chase: What is time?

Oh, no, you didn’t! [ Laughs. ] In A.D. 400, St. Augustine said—and many people have said the same thing since, either quoting him consciously or unconsciously—“What, then, is time? If no one asks me, I know. If I wish to explain it to one that asks, I know not.” I think that is actually not a quip, but quite profound.

The best way to understand time is to recognize that we actually are very sophisticated about it. Over the past century-plus, we’ve learned a great deal. The physicist John Archibald Wheeler said, “Time is nature’s way to keep everything from happening all at once.” If you look it up in a dictionary, you get stuff like, “The general term for the experience of duration.” But that’s just completely punting because what is duration ?

I try to steer away from aphorisms and dictionary definitions, just to say two things. First, that we have a lot of contradictory ways of talking about time. We think of time as something we waste, spend, or save, as if it’s a quantity. We also think of time as a medium we are passing through every day, a river carrying us along. All of these notions are aspects of a complicated subject that has no bumper sticker answer.

When does the idea of time travel first appear in the West? And how did it impact popular culture?

I assumed, as a person who always read sci-fi a lot when I was a kid, that time travel is an obvious idea we’re born knowing and fantasizing about. And that it must always have been part of human culture, that there must be time travel Greek myths and Chinese legends. But there aren’t! Time travel turns out to be a very new idea that essentially starts with H.G. Wells’s 1895 novel, The Time Machine . Before that nobody thought of putting the words time and travel together. The closest you can come before that is people falling asleep, like Rip Van Winkle, or fantasies like Charles Dickens’s A Christmas Carol .

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The beginning of my book is an attempt to answer the question, “Why? Why not before? Why suddenly at the end of the 19 th century was it possible— necessary— for people to dream up this crazy fantasy?” Even though it’s H.G. Wells who does it, people pick up his ball very quickly and run with it. You find it in American science fiction that started appearing in pulp magazines in the 1920s and 1930s, or in the great new modernist literature of Marcel Proust’s In Search of Lost Time , James Joyce, and Virginia Woolf.

All these writers were suddenly making time their explicit subject, twisting time in new ways, inventing new narrative techniques to deal with time, to explore the vagaries of memory or the way our consciousness changes over time.

In 1991, Stephen Hawking wrote a paper called “Chronology Protection Conjecture , ” in which he asked: If time travel is possible, why are we not inundated with tourists from the future? He has a point, doesn’t he?

Yes! He even scheduled a party and sent out an invitation inviting time travelers to come to a party that had taken place in the past. Then he observed that none of them had shown up. [Laughs.] Hawking is one of these physicists who love playing with the idea of time travel. It’s irresistible because it’s so much fun! When he talks about the paradoxes of time travel it’s because he’s reading the same science fiction stories as the rest of us.

The paradoxes started appearing in magazines aimed mostly at young people in the 1920s. Somebody wrote in and said, “Time travel is a weird idea, because what if you go back in time and you kill your grandfather? Then your grandfather never meets your grandmother and you’re never born.” It’s an impossible loop.

Hawking, like other physicists, decided, “Time is my business. What if we take this seriously? Can we express this in physical terms?” I don’t think he succeeded but what he proposed was that the reason these paradoxes can’t happen is because the universe takes care of itself. It can’t happen because it didn’t happen. That’s the simple way of saying what the chronology protection conjecture is.

How have the Internet and other new technologies changed our perception and experience of time?

We are just beginning to see what the Internet is doing to our perception of time. We are living more and more in this networked world in which everything travels at light speed. We are multitasking and experiencing new forms of simultaneity, so the Internet appears to us as a kind of hall of mirrors. It feels as though we’re embedded in an ever expanding present.

Our sense of the past changes because in some ways the past becomes more vivid than ever. We’re looking at the past on our video screens and it’s just as vivid if the movie is about something that happened 20 years ago, as if it is a live stream. We can’t always tell the difference. On the other hand, the past that’s more distant—and isn’t available in video form—starts to seem more remote and fuzzier. Maybe we are forgetting how to visualize the past from reading histories. We’re entering a new period of time confusion, in which we suddenly find ourselves in what looks like an unending present.

In 2011, the Chinese government issued an extraordinary denunciation of the idea of time travel. What was their beef?

They thought it was corrupting and decadent. It’s a reminder that time travel is neither a simple nor innocent idea. It’s very powerful. It enables us to imagine alternative universes, and this is another line that science fiction writers have explored. What if someone was able to go back in time and kill Hitler?

Time travel is also a powerful way of allowing us to imagine what the future might bring. A lot of futurists nowadays tend to be dystopian. Time travel gives us ways of exploring how the worst tendencies of our current societies could grow even worse. That’s what George Orwell did in 1984 . I imagine the Chinese government doesn’t particularly want the equivalent of 1984 to be published in Beijing. [ Laughs. ]

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More than 50 scientific papers a year are now published on the idea of time travel. why are scientists drawn to the subject.

Scientists live in the same science fictional universe as all the rest of us. Time travel is a sexy and romantic idea that appeals to the physicist as much as it appeals to every teenager. I don’t think scientists are ever going to solve the problem of time travel for us but they still love to talk about wormholes and dark matter.

There’s a fascinating coincidence in the early history that when H.G. Wells needed to set the stage for his time machine hurtling into the future, he decided not to just jump right into his story but set the scene with a framing device—his time traveler lecturing a group of friends on the science of time—in order to justify the possibility of a time machine. His lecture introduces the idea that time is nothing more than a fourth dimension, that traveling through time is analogous to traveling through space. Since we have machines that can take us into any of the three special dimensions, including balloons and elevators, why shouldn’t we have a machine able to travel through the fourth dimension?

A decade later, Einstein burst onto the scene with his theory of relativity in which time is a fourth dimension , just like space. Soon after that, Hermann Minkowski pronounced that, henceforth, we were not going to talk about space and time as separate quantities but as a union of the two, spacetime , a four-dimensional continuum in which the future already exists and the past still exists.

I’m not claiming that Einstein read H.G. Wells 10 years before. But there was something in the air that both scientists and imaginative writers were empowered to visualize time in a new way. Today, that’s the way we visualize it. We’re comfortable talking about time as a fourth dimension.

You quote Ursula K. Le Guin , who writes, “Story is our only boat for sailing on the river of time.” Talk about storytelling and its relationship to time.

One of the things that has happened, along with our heightened awareness of time and its possibilities, is that people who invent narratives have learned very clever new techniques. Literal time travel is only one of them. You don’t actually need to send your hero into the future or into the past to write a story that plays with time in clever new ways. Narrative is also how everybody, not just writers, constructs a vision of our own relationship with time. We imagine the future. We remember the past. When we do that, we’re making up stories.

Psychologists are learning something that great storytellers have known for some time, which is that memory is not like computer retrieval. It’s an active process. Every time we remember something we are remembering it a little bit differently. We’re retelling the story to ourselves.

If time travel is impossible, why do we continue to be so fascinated with the idea?

One of the reasons is we want to go back and undo our mistakes. When you ask yourself, “If I had a time machine, what would I do?” sometimes the answer is, “I would go back to this particular day and do that thing over.” I think one of the great time travel movies is Groundhog Day , the Bill Murray movie where he wakes up every morning and has to live the same day over and over again. He gradually realizes that perhaps fate is telling him he needs to do it over, right. Regret is the time traveler’s energy bar. But that’s not the only motivation for time travel. We also have curiosity about the future and interest in our parents and our children. A lot of time travel fiction is a way of asking questions about what our parents were like, or what our children will be like.

At some point during the four years I worked on this book, I also realized that, in one way or another, every time travel story is about death. Death is either explicitly there in the foreground or lurking in the background because time is a bastard, right? Time is brutal. What does time do to us? It kills us. Time travel is our way of flirting with immortality. It’s the closest we’re going to come to it.

This interview was edited for length and clarity.

Simon Worrall curates Book Talk . Follow him on Twitter or at simonworrallauthor.com .

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Where Does the Concept of Time Travel Come From?

Time; he's waiting in the wings.

Wormholes have been proposed as one possible means of traveling through time.

The dream of traveling through time is both ancient and universal. But where did humanity's fascination with time travel begin, and why is the idea so appealing?

The concept of time travel — moving through time the way we move through three-dimensional space — may in fact be hardwired into our perception of time . Linguists have recognized that we are essentially incapable of talking about temporal matters without referencing spatial ones. "In language — any language — no two domains are more intimately linked than space and time," wrote Israeli linguist Guy Deutscher in his 2005 book "The Unfolding of Language." "Even if we are not always aware of it, we invariably speak of time in terms of space, and this reflects the fact that we think of time in terms of space."

Deutscher reminds us that when we plan to meet a friend "around" lunchtime, we are using a metaphor, since lunchtime doesn't have any physical sides. He similarly points out that time can not literally be "long" or "short" like a stick, nor "pass" like a train, or even go "forward" or "backward" any more than it goes sideways, diagonal or down.

Related: Why Does Time Fly When You're Having Fun?

Perhaps because of this connection between space and time, the possibility that time can be experienced in different ways and traveled through has surprisingly early roots. One of the first known examples of time travel appears in the Mahabharata, an ancient Sanskrit epic poem compiled around 400 B.C., Lisa Yaszek, a professor of science fiction studies at the Georgia Institute of Technology in Atlanta, told Live Science

In the Mahabharata is a story about King Kakudmi, who lived millions of years ago and sought a suitable husband for his beautiful and accomplished daughter, Revati. The two travel to the home of the creator god Brahma to ask for advice. But while in Brahma's plane of existence, they must wait as the god listens to a 20-minute song, after which Brahma explains that time moves differently in the heavens than on Earth. It turned out that "27 chatur-yugas" had passed, or more than 116 million years, according to an online summary , and so everyone Kakudmi and Revati had ever known, including family members and potential suitors, was dead. After this shock, the story closes on a somewhat happy ending in that Revati is betrothed to Balarama, twin brother of the deity Krishna.

Time is fleeting

To Yaszek, the tale provides an example of what we now call time dilation , in which different observers measure different lengths of time based on their relative frames of reference, a part of Einstein's theory of relativity.

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Such time-slip stories are widespread throughout the world, Yaszek said, citing a Middle Eastern tale from the first century BCE about a Jewish miracle worker who sleeps beneath a newly-planted carob tree and wakes up 70 years later to find it has now matured and borne fruit (carob trees are notorious for how long they take to produce their first harvest). Another instance can be found in an eighth-century Japanese fable about a fisherman named Urashima Tarō who travels to an undersea palace and falls in love with a princess. Tarō finds that, when he returns home, 100 years have passed, according to a translation of the tale published online by the University of South Florida .

In the early-modern era of the 1700 and 1800s, the sleep-story version of time travel grew more popular, Yaszek said. Examples include the classic tale of Rip Van Winkle, as well as books like Edward Belamy's utopian 1888 novel "Looking Backwards," in which a man wakes up in the year 2000, and the H.G. Wells 1899 novel "The Sleeper Awakes," about a man who slumbers for centuries and wakes to a completely transformed London.

Related: Science Fiction or Fact: Is Time Travel Possible ?

In other stories from this period, people also start to be able to move backward in time. In Mark Twain’s 1889 satire "A Connecticut Yankee in King Arthur's Court," a blow to the head propels an engineer back to the reign of the legendary British monarch. Objects that can send someone through time begin to appear as well, mainly clocks, such as in Edward Page Mitchell's 1881 story "The Clock that Went Backwards" or Lewis Carrol's 1889 children's fantasy "Sylvie and Bruno," where the characters possess a watch that is a type of time machine .

The explosion of such stories during this era might come from the fact that people were "beginning to standardize time, and orient themselves to clocks more frequently," Yaszek said.

Time after time

Wells provided one of the most enduring time-travel plots in his 1895 novella "The Time Machine," which included the innovation of a craft that can move forward and backward through long spans of time. "This is when we’re getting steam engines and trains and the first automobiles," Yaszek said. "I think it’s no surprise that Wells suddenly thinks: 'Hey, maybe we can use a vehicle to travel through time.'"

Because it is such a rich visual icon, many beloved time-travel stories written after this have included a striking time machine, Yaszek said, referencing The Doctor's blue police box — the TARDIS — in the long-running BBC series "Doctor Who," and "Back to the Future"'s silver luxury speedster, the DeLorean .

More recently, time travel has been used to examine our relationship with the past, Yaszek said, in particular in pieces written by women and people of color. Octavia Butler's 1979 novel "Kindred" about a modern woman who visits her pre-Civil-War ancestors is "a marvelous story that really asks us to rethink black and white relations through history," she said. And a contemporary web series called " Send Me " involves an African-American psychic who can guide people back to antebellum times and witness slavery.

"I'm really excited about stories like that," Yaszek said. "They help us re-see history from new perspectives."

Time travel has found a home in a wide variety of genres and media, including comedies such as "Groundhog Day" and "Bill and Ted's Excellent Adventure" as well as video games like Nintendo's "The Legend of Zelda: Majora's Mask" and the indie game "Braid."

Yaszek suggested that this malleability and ubiquity speaks to time travel tales' ability to offer an escape from our normal reality. "They let us imagine that we can break free from the grip of linear time," she said. "And somehow get a new perspective on the human experience, either our own or humanity as a whole, and I think that feels so exciting to us."

That modern people are often drawn to time-machine stories in particular might reflect the fact that we live in a technological world, she added. Yet time travel's appeal certainly has deeper roots, interwoven into the very fabric of our language and appearing in some of our earliest imaginings.

"I think it's a way to make sense of the otherwise intangible and inexplicable, because it's hard to grasp time," Yaszek said. "But this is one of the final frontiers, the frontier of time, of life and death. And we're all moving forward, we're all traveling through time."

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Originally published on Live Science .

Adam Mann is a freelance journalist with over a decade of experience, specializing in astronomy and physics stories. He has a bachelor's degree in astrophysics from UC Berkeley. His work has appeared in the New Yorker, New York Times, National Geographic, Wall Street Journal, Wired, Nature, Science, and many other places. He lives in Oakland, California, where he enjoys riding his bike.

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Exploring the Reality of Time Travel: Science Fact vs. Science Fiction

Will it ever be possible for time travel to occur?

But is this just a fun idea for movies, or could it really happen?

The Science Behind Time Travel

Time Is Relative

Theoretical Possibilities and Challenges

Some scientists are exploring other ideas that could theoretically allow time travel. One concept involves wormholes, or hypothetical tunnels in space that could create shortcuts for journeys across the universe. If someone could build a wormhole and then figure out a way to move one end at close to the speed of light – like the hypothetical spaceship mentioned above – the moving end would age more slowly than the stationary end. Someone who entered the moving end and exited the wormhole through the stationary end would come out in their past.

However, wormholes remain theoretical: Scientists have yet to spot one. It also looks like it would be incredibly challenging to send humans through a wormhole space tunnel.

Paradoxes and Failed Dinner Parties

Famously, physicist Stephen Hawking tested the possibility of time travel by throwing a dinner party where invitations noting the date, time, and coordinates were not sent out until after it had happened. His hope was that his invitation would be read by someone living in the future, who had capabilities to travel back in time. But no one showed up.

As he pointed out : “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

James Webb Space Telescope Artist Conception

Telescopes Are Time Machines

Interestingly, astrophysicists armed with powerful telescopes possess a unique form of time travel . As they peer into the vast expanse of the cosmos, they gaze into the past universe. Light from all galaxies and stars takes time to travel, and these beams of light carry information from the distant past. When astrophysicists observe a star or a galaxy through a telescope, they are not seeing it as it is in the present, but as it existed when the light began its journey to Earth millions to billions of years ago.

NASA’s newest space telescope , the James Webb Space Telescope , is peering at galaxies that were formed at the very beginning of the Big Bang , about 13.7 billion years ago.

Written by Adi Foord, Assistant Professor of Astronomy and Astrophysics, University of Maryland, Baltimore County.

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Until the problem of the second law of thermodynamics(entropy) is solved, the concept of time travel will remain the subject of science fiction. Since this is a basic law of our universe, there is no conceivable way that we know of to do this. The great thing about our knowledge of the universe is that it continues to grow and with that our view of what is possible continues to change. After all, at one time it was believed we could never leave earth!

The 7 planets are soul pollen in the space @ life has been the world has been prepared @ The pollen of the universe is hidden @ Around the axis of the galaxy, the universe is hidden@@ The pollen of the galaxies is a hidden cluster Itis made that we thought about what wisdom is in God’s work and how it is arranged in the form of words.The verse that is made is as follows @@ John, you are in time @ worlds, planets around the axis of the branches of galaxies @@ 8 Prophets, divine prophets, God-aware witnesses @ God’s words of revelation, they are aware @@ 48 What the words of revelation that every prophet has about @ sometimes Sometimes the message of God has become a verbal cliché in the head @@ 62 The message of God was given to every prophet @ The message was made around the power of God @@ 46 The truth of the religions of the cradle of time is said in the world @ Prophets always came for justice in time @@ 62 A warrior became brave in time @ Delaver Ghahrmani Boud Taarani@@ 43 Omar Noah never died, who knows!@ Imransan Is there an unseen world, immortality!?@@ 49 Men’s rights in the sign @ Human rights, the observance of world justice @@ 40 We have God’s love @ A love that is not patched, separation!!!: @@ 39 Take one word from the end of the first and second stanzas to the bottom of these eight verbal verses, and this sentence is made @@ God-aware, the world is born, you know the sign of God @ Agah,the beginning of time, the world, eternity, the world of separation @@ The meaning of this sentence is That God, who before us humans lived on the earth, formed the earth’s crusts with full knowledge, and we humans know the sign of God, which is on the earth, on the continents and countries, and some names have been shown by God for our knowledge since the end of time.In a later video, if I have a lifetime left, I will explain exactly about these poems, God willing @@ The word of the Prophet 17 is the 17th and Muhammad (PBUH) said that the Bedouin Arabs should pray 17 rakats so that theyperform ablution and be clean and not kill and loot.From the caravans, these were all God’s will, and he is good everywhere, in every nation, God does not like evildoers, sinners, and oppressors.Muhammad (PBUH) was God’s last messenger to the Arab people, he was God’s best prophet, and the third verse is because they do not accept Muhammad (PBUH).Some Iranians who were in contact with me, that’s why in the third verse of this surah, he said that his message was given to every prophet, the message is based on divine power, and the word truth, the first two letters of which istruth, is truth, and truth is the 43rd and forty-third word, and the word is time.It is exactly 46, and this song of the Prophets was revealed at the age of 46 ببخشید اگر قبلآ مطالبی فرستادم که به مذاهب مذاهم ارتباط داد شاید به درد شما نمیخورد من در کامنت های بعدی سعی میکنم از نجوم و حیات زمین سخن بگویم این چند بیت را به خارجی انگلیسی که تبدیل کردم معنی آن حیرت انگیز تعغیر کرد گفتم برای شما بفرستم و بداند که این کلام من نبوده کلام خداوند بوده شما نظرتان در مورد خداوند چیست من میگویم خداوند که پدر ومادر انسان بودند قادر به ساختن ما بودند اما آیا آنها قادر به ساختن ستاره ها هم بودند

Your comment has validity to God. But it surely has no place here, it is only fare if the hole comment were in english and has less of a convincing push in a belief a person either believes or not.

It’s too bad physics can’t come to a complete consensus about time, I would like to add some thought about discoveries it has been proven that time travels in only one direction forward, the experiment dealt with light thru glass and how it reacts in the middle and what change happens after light exits the other side, a simple explanation of this experiment. Brings me to theorize and start that time existed before the big bang and is outside of our universes influence, when time is acted on by gravity the ( Form ) of time is changed until the influence no longer has effect, this could go hand in hand with light photons the photon has a influence in the Form that time has. This can not be a observed difference unless we were to see beyond the speed of light. We do agree that physics changes at a subatomic state and also does some strange changing once the speed of light has been exceeded.

The experiment I referred to was posted on IFL in October 2023 headlined ( Solution to complex light problem shows that time can only go Forward ).

One of the problem with travel time is the one people keep forever. And, that is that the earth is always move through space. Matter of fact, the earth is not in the same place that it was 50 years ago. So you will have to move through space as well as time.

Ironically, the only science fiction that seems to handle this is the original story “The Time Machine”.

Time travel is happening now. It has been done since the 1950s. The method satisfies all the requirements. Traveler can’t change the past, but only observe. You can’t go farther back than when the machine was first invented (1950s). There’s one more limitation, you can only observe what the machine was directed. The time machine, the common video camera, and video tape recorder. Now it’s the camera, and file capture computer. Yes, viewing a video tape is effectively going back in time. It’s more than the video, it’s the sound too. There are working versions of smell, and touch which can be recorded too. If you record, and replicate all the senses, you have effectively complete time travel. The most primitive form is the picture. This technology has been around for thousands of years, and is manually intensive. Later many pictures were strung together to make a film. Using a camera to record film was the first example of complete visual time travel (back to when the film was made). Later sound was added, and we have the movies. A way of going back in time that included sight, and sound. Now we have video systems (YouTub) that can play back past events selected by you. Yes, video systems are virtual time travel machines we have now.

How Stellar Cannibalism Illuminates Cosmic Evolution

جزایر فیلیپین دایناسوری که توسط انسان خلق شده در بیش ده ها میلیون سال و بخاطر ریخته شدن دوهزار متر خاک غرق شده بخاطر بالا آمدن آب اقیانوس اما جزایر فیلیپین شبیه دایناسوریست

The address of the above comment on the site about a thief who was trained by a dinosaur bird who was trained by humans tens of millions of years ago and who arrested murderers and robbers.The police were arrested by big birds.don’t the scientists of the world think about this?They were buried in the bed of important cities, they were buried with all the tools and machines, the traces of humans tens of millions of years ago, they had a civilization and a history of hundreds of thousands of years, they built a base underthe earth, from the meteorites that explode from the planets when they hit the sun, and they knew that several thousand meters of soil is poured on the surface of the seas and islands, and they knew that the shapes they made of the islands in thecountry of Papua may go under the ocean, of course, the Philippine islands.The picture is of a baby dinosaur that went under the ocean, but the northern island of Australia, which is Papua, is quite clear.It is a big dinosaur whose tail is towards the east and its mouth is open towards the west.There is the Philippines, but it was more difficult to take the soil to the Philippine islands to create a dinosaur than the island of Papua, that is why the height of the soil in the Philippines is lower, and when the meteorites fell a few kilometerson the surface of the ocean, the image created by humans under the ocean in the shape of a dinosaur is hidden in the American continent The picture is of a bird in the shape of a dinosaur that is flying, and this bird was made to flyby the Indians of the tribe, that bird was talking to people, but its spirit might have heard something from the police because a thief while in the bird’s mouth He was handcuffed by the police and the weapon, which is a machine gun, is fromthe east of the American continent on the coast

The country of Florida is a machine gun.When you continue to New York City, you will reach the mouth of the dinosaur, where a thief is trapped in the mouth of a bird, and the little finger of the police handcuffed the thief’s hand, and a small colt is in the hand ofthe thief, who the police caught in the mouth of the dinosaur.put in the mouth of the bird dinosaur, you can clearly see that the thief fell on the ground and was shot in the head, and it is clear that his forehead was pierced, the bird’s mouth is open in flight, the head of the birdis from the east of the American continent, and a fish is placed in the bird’s mouth in the water of the ocean.The stretched glove of the police, which is in the form of a fist, with a handcuff attached to the left hand of the thief who fell on the ground in the sea and the mouth of the bird, the head of the thief and the killer, is located towards the southwest and west coast of America.All these images were created from the American continent and islands by Humans were created, but they didn’t have enough fuel and time to create more accurate images and meteorites ruined the beauty of the images, but it is clear that all these changes were createdby humans, but you have to consider that two thousand meters of soil from meteorites are fish.And they buried the whales under the beaches, and after a very long time, the bodies of the whales turned into oil under the two thousand meters of soil on the beaches, and on the other hand, the presence of two thousand meters of soil onthe surface of the seas and droughts could not make the created images disappear.

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A history of time travel: the how, the why and the when of turning back the clock

Pop on Aqua's 'Turn Back Time' and settle in

For most of human history, the world didn’t change very quickly. Until the 1700s, kids could largely expect their lives to be similar to their parents, and that their children would have an experience very similar to their own, too. There were obviously changes in how humans lived over longer stretches of time, but nothing that even different generations could easily observe.

My first introduction to science fiction was Valérian and Laureline. I was ten years old. Every Wednesday there was a magazine called Pilote in France, and there was two pages of Valerian every week. It was the first time I’d seen a girl and a guy in space, agents travelling in time and space. That was amazing.

The past is written. The present? We have to deal with it. But the future is a white page. So I don’t understand why people on this white page are putting all this darkness.

God! Let’s have some color! Let’s have some fun! Let’s at least imagine a better world. Maybe we won’t be able to do it, but we have to try.

The industrial revolution changed all of this. For the first time in human history, the pace of technological change was visible within a human lifespan.

It is not a coincidence that it was only after science and technological change became a normal part of the human experience, that time travel became something we dreamed of.

Time travel is actually somewhat unique in science fiction. Many core concepts have their origins earlier in history.

The historical roots of the concept of a 'robot' can be seen in Jewish folklore for example: Golems were anthropomorphic beings sculpted from clay. In Greek mythology, characters would travel to other worlds, and it's no coincidence that The Matrix features a character called Persephone. But time travel is different.

The first real work to envisage travelling in time was The Time Machine by HG Wells, which was published in 1895.

The book tells the story of a scientist who builds a machine that will take him to the year 802,701 - a world in which ape-like Morlocks are evolutionary descendants of humanity, and have regressed to a primitive lifestyle.

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The book was a product of its time - both in terms of the science played upon (Charles Darwin had only published Origin of the Species 35 years earlier), and the racist attitudes: it is speculated that the Morlocks were inspired by the Morlachs, a real ethnic group in the Balkans who were often characterised as “primitive”.

Real science

But of course, this was science fiction - what about science fact? The two have always been closely linked, and during the early days it was no different. In 1907, the physicist Hermann Minkowski first argued that Einstein’s Special Relativity could be expressed in geometric terms as a fourth dimension (to add to our known three) - which is exactly how Wells visualised time travel in his work of fiction.

The development of Special and then General Relativity was significant as it provided the theoretical backbone for how time travel could be conceived in scientific terms. In 1949 Kurt Gödel took Einstein’s work and came up with a solution which as a mathematical necessity included what he called “closed timelike curves” - the idea that if you travel far enough, time will loop back around (like how if you keep flying East, you’ll eventually end up back where you started).

Minkowski's expression of the fourth dimension, no special glasses needed

In other words, using what became known as the Gödel Metric, it is theoretically possible to travel between any one point in time and space and any other.

There was just one problem: for Gödel’s theory to be right, the universe would have to be spinning - and scientists don’t believe that it is. So while the maths might make sense, Gödel’s universe does not appear to be the one we’re actually living in. Though he never gave up hope that he might be right: Apparently even on this deathbed, he would ask if anyone has found evidence of a spinning universe. And if he does ever turn out to be right, it means that time travel can happen, and is actually fairly straightforward (well, as far as physics goes anyway).

Since Gödel, scientists have continued to hypothesise about time travel, with perhaps the best known example being tachyons - or particles that move faster than the speed of light (therefore, effectively travelling in time). So far, despite one false alarm at CERN in 2011, there is no evidence that they actually exist.

Chancers and hoaxes

Of course, the lack of real science when it comes to time travel has not stopped some people from claiming to have done it. With the likes of Marty McFly and Doctor Who on the brain, chancers and hoaxers have realised that time travel is immediately a compelling prospect. Here’s a couple of amusing examples.

At the turn of the millennium, when the internet was still in its infancy, forums were captivated by the story of John Titor. Titor claimed he was from the year 2036, and had been sent back in time by the government to obtain an IBM 5100 computer. The thinking appeared to be that by obtaining the computer, the government could find a solution to the UNIX 2038 bug - in which clocks could be reset, Millennium Bug-style, leading to chaos everywhere.

Posting on the 'Time Travel Institute' forums, Titor went into details on how his time machine worked: It was powered by “two top-spin, dual positive singularities”, and used an X-ray venting system. He also gave a potted history of what humanity could expect: A new American civil war in 2004, and World War III in 2015. He also claimed the “many worlds” interpretation of quantum physics was true, hence why he wasn’t violating the so-called “grandfather paradox”.

Titor claimed he was from the year 2036, and had been sent back in time by the government to obtain an IBM 5100 computer.

Okay, so he probably wasn’t a real time traveller, but in the early days of the internet, when anonymity was more commonplace, he truly captured the imaginations of nerdy early adopters who perhaps, just a little bit, hoped that he might be the real thing.

More recently, in 2013, an Iranian scientist named Ali Razeghi claimed to have invented a time machine of sorts. It was supposedly capable of predicting the next 5-8 years for an individual, with up to 98% accuracy. According to The Telegraph , Razeghi said the invention fits into the size of a standard PC case and “It will not take you into the future, it will bring the future to you”. The idea is that the Iranian government could use it to predict future security threats and military confrontations. So perhaps it is time to check in and see if he managed to predict Donald Trump?

The actual Time Lord, Professor Stephen Hawking

So is this the best we can do? Will we ever manage to crack time travel? Some scientists are still sceptical that it could ever be possible. This includes Stephen Hawking, who proposed the 'Chronology Protection Conjecture' – which is what it sounds like. Essentially, he argues that the laws of physics are as they are to specifically make time travel impossible – on all but “submicroscopic” scales. Essentially, this is to protect how causality works, as if we are suddenly allowed to travel back and kill our grandfathers, it would create massive time paradoxes.

Hawking revealed to Ars Technica in 2012 how he had held a party for time travellers, but only sent out invitations after the date it was held. So did the party support his argument that time travel is impossible? Or did he end up spending the evening in the company of John Titor and Doctor Who?

“I sat there a long time, but no one came”, he said, much to our disappointment.

Huge thanks to Stephen Jorgenson-Murray for walking us through some of the more brain-mangling science for this article.

To celebrate the release of Valerian and the City of a Thousand Planets , Luc Besson is today behind the lens at TechRadar. Here’s what we’ve got in store for you:

Luc Besson presents TechRadar
From Verne to Valerian: how France became the home of sci-fi
Luc Besson talks streaming, viral videos and cinema tech
Star spangled glamour: making space travel cooler than ever before
A history of time travel: the how, the why and the when
20 best sci-fi films on Netflix and Amazon Prime
Amazing future tech from sci-fi films that totally exist now

Valerian and the City of a Thousand Planets is released in UK cinemas August 2nd, and is out now in the US.

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Do you believe in time travel? I’m a skeptic myself — but if these people’s stories about time travel are to be believed, then I am apparently wrong. Who knows? Maybe one day I’ll have to eat my words. In all honesty, that might not be so bad — because the tradeoff for being wrong in that case would be that time travel is real . That would be pretty rad if it were true.

Technically speaking time travel does exist right now — just not in the sci fi kind of way you’re probably thinking. According to a TED-Ed video by Colin Stuart, Russian cosmonaut Sergei Krikalev actually traveled 0.02 seconds into his own future due to time dilation during the time he spent on the International Space Station. For the curious, Krikalev has spent a total of 803 days, nine hours, and 39 minutes in space over the course of his career.

That said, though, many are convinced that time dilation isn’t the only kind of time travel that’s possible; some folks do also believe in time travel as depicted by everything from H. G. Wells’ The Time Machine to Back to the Future . It’s difficult to find stories online that are actual accounts from real people — many of them are either urban legends ( hi there, Philadelphia Experiment ) or stories that center around people that I’ve been unable to verify actually exist — but if you dig hard enough, sincere accounts can be found.

Are the stories true? Are they false? Are they examples of people who believe with all their heart that they’re true, even if they might not actually be? You be the judge. These seven tales are all excellent yarns, at any rate.

1 The Moberly–Jourdain Incident

Paris, France- April 10, 2010: Paris is the center of French economy, politics and cultures and the ...

In 1901, two Englishwomen, Anne Moberly and Eleanor Jourdain , took a vacation to France. While they were there, they visited the Palace of Versailles (because, y’know, that’s what one does when one visits France ). And while they were at Versailles, they visited what’s known as the Petit Trianon — a little chateau on the palace grounds that Louis XVI gave to Marie Antoinette as a private space for her to hang out and do whatever it was that a teenaged queen did when she was relaxing back then.

But while they were there, they claimed, they saw some… odd occurrences. They said they spotted people wearing anachronistic clothing, heard mysterious voices, and saw buildings and other structures that were no longer present — and, indeed, hadn’t existed since the late 1700s. Finally, they said, they caught sight of Marie Antoinette herself , drawing in a sketchbook.

They claimed to have fallen into a “time slip” and been briefly transported back more than 100 years before being jolted back to the present by a tour guide.

Did they really travel back in time? Probably not; various explanations include everything from a folie a deux (basically a joint delusion) to a simple misinterpretation of what they actually saw. But for what it’s worth, in 1911 — roughly 10 years after what they said they had experienced occurred — the two women published a book about the whole thing under the names Elizabeth Morison and Frances Lamont simply called An Adventure. These days, it’s available as The Ghosts of Trianon ; check it out, if you like.

2 The Mystery Of John Titor

John Titor is perhaps the most famous person who claims he’s time traveled; trouble is, no one has heard from him for almost 17 years. Also, he claimed he came from the future.

The story is long and involved, but the short version is this: In a thread begun in the fall of 2000 about time travel paradoxes on the online forum the Time Travel Institute — now known as Curious Cosmos — a user responded to a comment about how a time machine could theoretically be built with the following message:

“Wow! Paul is right on the money. I was just about to give up hope on anyone knowing who Tipler or Kerr was on this worldline.

“By the way, #2 is the correct answer and the basics for time travel start at CERN in about a year and end in 2034 with the first ‘time machine’ built by GE. Too bad we can’t post pictures or I’d show it to you.”

The implication, of course, was that the user, who was going by the name TimeTravel_0, came from a point in the future during which such a machine had already been invented.

Over the course of many messages spanning from that first thread all the way through the early spring of 2001, the user, who became known as John Titor, told his story. He said that he had been sent back to 1975 in order to bring an IBM 5100 computer to his own time; he was just stopping in 2000 for a brief rest on his way back home. The computer, he said, was needed to debug “various legacy computer programs in 2036” in order to combat a known problem similar to Y2K called the Year 2038 Problem . (John didn’t refer to it as such, but he said that UNIX was going to have an issue in 2038 — which is what we thought was going to happen back when the calendar ticked over from 1999 to 2000.)

Opinions are divided on whether John Titor was real ; some folks think he was the only real example of time travel we’ve ever seen, while others think it’s one of the most enduring hoaxes we’ve ever seen. I fall on the side of hoax, but that’s just me.

3 Project Pegasus And The Chrononauts

Close up of golden pocket watch lean on pile of book.

In 2011, Andrew D. Basiago and William Stillings stepped forward, claiming that they were former “chrononauts” who had worked with an alleged DARPA program called Project Pegasus. Project Pegasus, they said, had been developed in the 1970s; in 1980, they were taking a “Mars training class” at a community college in California (the college presumably functioning as a cover for the alleged program) when they were picked to go to Mars. The mode of transport? Teleportation.

It gets better, too. Basiago and Stillings also said that the then- 19-year-old Barack Obama , whom they claimed was going by the name “Barry Soetero” at the time, was also one of the students chosen to go to Mars. They said the teleportation occurred via something called a “jump room.”

The White House has denied that Obama has ever been to Mars . “Only if you count watching Marvin the Martian,” Tommy Vietor, then the spokesman for the National Security Council, told Wired’s Danger Room in 2012.

4 Victor Goddard’s Airfield Time Slip

World War II P-51 Mustang Fighter Airplane

Like Anne Moberly and Eleanor Jourdain, senior Royal Air Force commander Sir Robert Victor Goddard — widely known as Victor Goddard — claimed to have experienced a time slip.

In 1935, Goddard flew over what had been the RAF station Drem in Scotland on his way from Edinburgh to Andover, England. The Drem station was no longer in use; after demobilization efforts following WWI, it had mostly been left to its own devices. And, indeed, that’s what Goddard said he saw as he flew over it: A largely abandoned airfield.

On his return trip, though, things got… weird. He followed the same route he had on the way there, but during the flight, he got waylaid by a storm. As he struggled to regain control of his plane, however, he spotted the Drem airfield through a break in the clouds — and when he got closer to it, the bad weather suddenly dissipated. But the airfield… wasn’t abandoned this time. It was busy, with several planes on the runway and mechanics scurrying about.

Within seconds, though, the storm reappeared, and Goddard had to fight to keep his plane aloft again. He made it home just fine, and went on to live another 50 years — but the incident stuck with him; indeed, in 1975, he wrote a book called Flight Towards Reality which included discussion of the whole thing.

Here’s the really weird bit: In 1939, the Drem airfield was brought back to life. Did Goddard see a peek into the airfield's future via a time slip back in 1935? Who knows.

5 Space Barbie

I’ll be honest: I’m not totally sure what to do with thisone — but I’ll present it to you here, and then you can decide for yourself what you think about it. Here it is:

Valeria Lukyanova has made a name for herself as a “human Barbie doll” (who also has kind of scary opinions about some things ) — but a 2012 short documentary for Vice’s My Life Online series also posits that she believes she’s a time traveling space alien whose purpose on Earth is to aid us in moving “from the role of the ‘human consumer’ to the role of ‘human demi-god.’”

What I can’t quite figure out is whether this whole time traveling space alien thing is, like a piece of performance art created specifically for this Vice doc, or whether it’s what she actually thinks. I don’t believe she’s referenced it in many (or maybe even any) other interviews she’s given; the items I’ve found discussing Lukyanova and time travel specifically all point back to this video.

But, well… do with it all as you will. That’s the documentary up there; give it a watch and see what you think.

6 The Hipster Time Traveler

In the early 2010s, a photograph depicting the 1941 reopening of the South Fork Bridge in Gold Bridge, British Columbia in Canada went viral for seemingly depicting a man that looked… just a bit too modern to have been photographed in 1941. He looks, in fact, like a time traveling hipster : Graphic t-shirt, textured sweater, sunglasses, the works. The photo hadn’t been manipulated; the original can be seen here . So what the heck was going on?

Well, Snopes has plenty of reasonable explanations for the man’s appearance; each item he’s wearing, for example, could very easily have been acquired in 1941. Others have also backed up those facts. But the bottom line is that it’s never been definitively debunked, so the idea that this photograph could depict a man from our time who had traveled back to 1941 persists. What do you think?

7 Father Ernetti’s Chronovisor

According to two at least two books — Catholic priest Father Francois Brune’s 2002 book Le nouveau mystère du Vatican (in English, The Vatican’s New Mystery ) and Peter Krassa’s 2000 book Father Ernetti's Chronovisor : The Creation and Disappearance of the World's First Time Machine — Father Pellegrino Ernetti, who was a Catholic priest like Brune, invented a machine called a “chronovisor” that allowed him to view the past. Ernetti was real; however, the existence of the machine, or even whether he actually claimed to have invented it, has never been proven. Alas, he died in 1994, so we can’t ask him, either. I mean, if we were ever able to find his chronovisor, maybe we could… but at that point, wouldn’t we already have the information we need?

(I’m extremely skeptical of this story, by the way, but both Brune’s and Krassa’s books swear up, down, left, and right that it’s true, so…you be the judge.)

Although I'm fairly certain that these accounts and stories are either misinterpreted information or straight-up falsehoods, they're still entertaining to read about; after all, if you had access to a time machine, wouldn't you at least want to take it for a spin? Here's hoping that one day, science takes the idea from theory to reality. It's a big ol' universe out there.

32 Movies Great Movies About Time Travel With Completely Different Rules

Prepare for some serious stipulations.

Marty McFly and Doc Brown in Back to the Future testing out the time machine

Is there ever a bad time to watch a time travel movie? Some of the best sci-fi movies in history have tackled this frequently explored topic, and new wrinkles in the fabric of the concept have made the subject more exciting over time. So why don’t we take a look at the different rules these flights of fancy have introduced? Should you be stuck in a time loop, we apologize if this list is starting to get old.

Back To The Future

Everyone loves to talk about how Back to the Future’s time travel works , but there’s one aspect we take for granted throughout the whole trilogy. Doc Brown ( Christopher Lloyd ) may have given Marty McFly ( Michael J. Fox ) the keys to travel through the past, present, and future; but you seriously need to consider the exact spot you’re traveling to. Otherwise, you might find yourself altering history in some intriguing ways. R.I.P. Twin Pines Mall.

Time After Time

A novel adventure starring the father of time travel H.G. Wells (Malcolm McDowell), Time After Time actually introduced an interesting mechanic to temporal transport. Let’s just say that if you don’t use the Time Machine properly, you could find yourself stuck in your final destination. Or worse, falling through the time-space continuum, without a way back home.

The Terminator

The Terminator's time travel will forever be a head-scratcher, as the existence of John Connor is the ultimate ontological paradox. How else can you explain Kyle Reese (Michael Biehn) being sent back to the 1980s to save the world…and make sure the person who sent him is born in the first place?

Star Trek IV: The Voyage Home

The oldest method of time travel in the Star Trek movies, 1986’s The Voyage Home saw Captain Kirk ( William Shatner ) and his crew trying to save the whales through a time heist. This wouldn’t have been possible if it wasn’t for the Enterprise crew using a Klingon Bird of Prey, a slingshot orbit around the sun, and a lot of engineering power to do it.

David Sullivan and Shane Carruth in Primer

2004’s Primer is still hotly discussed among time travel aficionados, and it’s not hard to see why. The shenanigans in this test case involve multiple versions of a singular traveler (Shane Carruth) existing in a single timeline, which creates one of the most chaotic timelines ever depicted.

The Adam Project

Story-wise, The Adam Project is pretty cozy when it comes to how it handles time travel. But when it comes to traveling in style, the older Adam Reed ( Ryan Reynolds ) has a Time Jet that’s specifically coded to his DNA! Not many temporal travelers HAVE that, and it prevents so many mistakes other adventures of this sort use for story purposes.

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Avengers: Endgame

How Avengers: Endgame’s time travel works is rather unorthodox, to be honest. Instead of overwriting the past into a more pleasing result, the MCU’s finest are only allowed to use it in the name of stealing/returning the Infinity Stones. Timelines can still create tangent histories, and 2014 Gamora takes over for her slain variant in the films, but you can’t stop “The Snap.”

Lost In Space

If all time travelers had the device Older Will Robinson (Jared Harris) built in 1998’s Lost in Space , they’d have it made. While only one person can travel at a time, exact coordinates in time and space are required; so you can go to a very specific spatial location on the timeline.

The Butterfly Effect

The Butterfly Effect's time travel works on rules similar to that of Quantum Leap . Evan ( Ashton Kutcher ) can indeed change history, but it’s only within his own life’s timeline. Unfortunately, thanks to the multiple trips leading to continued alterations to the fabric of events, it all adds up in terms of severe physical wear and tear.

Hot Tub Time Machine

Hot Tub Time Machine is a very special case when it comes to time travel. To be fair, the comedy ensemble franchise gets points for having its protagonists travel only within their own bodies. As for how one can actually travel with said titular device, apparently you need an energy drink, the right hot tub with the right temperature, and some convenient writing.

Paul Dano and Joseph Gordon Levitt cruising by in a red car in Looper.

Real-time bodily damage. That’s probably one of the most unique additions to Looper’s usage of time travel , as we see people incur damage in the past, only for it to show up on their future selves. Poor Seth ( Paul Dano ) demonstrated that lesson the hard way in Rian Johnson ’s sci-fi masterpiece.

Star Trek: Generations

What if you could wish really hard to create an alternate timeline? Or what if you could send yourself back to your best memory, and never leave? That’s what The Nexus from Star Trek: Generations could do, and both Captains Kirk (William Shatner) and Picard ( Patrick Stewart ) got a taste of that sweet life, before ultimately using their new power to stop the villainous Dr. Soren (Malcolm McDowell).

Bill And Ted’s Excellent Adventure

If you ever want to bring a figure from history home for dinner in the present, do it in the universe of Bill and Ted’s Excellent Adventure . There are little to no consequences, especially when it comes to our heroes (Alex Winter and Keanu Reeves) whisking away two medieval princesses to become betrothed in the 1980s. Seriously, how did that not start a war?

Rachel McAdams and Eric Bana talk while standing in front of a window in The Time Traveller's Wife.

The Time Traveler's Wife

“Chrono Impairment” is a seriously rare affliction, but it’s enough of a headache that it prevents Rachel McAdams and Eric Bana’s clock-crossed lovers from ever enjoying a normal life. Such is the nature of The Time Traveler's Wife , which invented that affliction to send Bana’s character Henry on unpredictable trips at unforeseeable intervals throughout his life.

Harrison Ford and Phoebe Waller-Bridge in Indiana Jones and the Dial of Destiny

Indiana Jones And Dial Of Destiny

For Indiana Jones and the Dial of Destiny's time travel to actually happen, the world of Harrison Ford’s iconic archeologist needed specific hardware. Aided by some very precise calculations to try and take the Nazis to where they were trying to go, it wasn't as simple as jumping into a car and gunning it to 88 miles per hour.

Star Trek: First Contact

For a franchise that uses temporal transit as much as the Star Trek series does, there sure are a lot of different ways to go back in time. And if you’re not satisfied with The Voyage Home’s method of a slingshot orbit around the Sun, then you can always do what Star Trek: First Contact did. While I wouldn’t personally recommend waiting for a Borg invasion to cause a temporal wake you can just hitch a ride on; you do you.

Ok, so technically Tenet’s shenanigans involving time is “time inversion,” rather than time travel. Which only makes the journey, and the resulting reality The Protagonist (John David Washington) lives in all the more complicated. It also makes for some classic Christopher Nolan mind melts.

Paul Walker with a painful expression in Timeline.

Would this really be a sci-fi party if author Michael Crichton didn’t show up? Timeline’s time travel is a lot of fun, if you consider using a “human fax machine” to send yourself to medieval times “fun.” In which case, try not to abuse it too much, as every trip has the chance to leave you with transcription errors in your reassembled DNA. Again, we’re working with a fax machine here.

Somewhere In Time

It’s the moment you’ve been waiting for Christopher Reeve fans! Somewhere in Time just had to be on this list, as it's pretty unique in how it sends a person back through the ages. In the case of Reeve’s playwright Richard, all he needs is a really powerful hypnotic focus to zoom back to 1912.

Chris Pine sits on the bridge with a determined expression in Star Trek.

Star Trek (2009)

It’s kind of fitting that the 2009 Star Trek reboot would use time travel, given that the series has continually danced with that concept on TV and in movies. For this J.J. Abrams-directed venture, the destructive and inexact force of a black hole is what’s used to accidentally alter time so vastly that William Shatner turns into Chris Pine.

Déjà Vu

Tony Scott’s 2006 action-thriller Déjà Vu is a big movie with a relatively limited scope. With intelligence gathering, and ultimately one human transport, that can only go as far back as four and a half days, Denzel Washington’s work was kind of cut out for him on this caper.

The Tomorrow War

The Chris Pratt-starring time travel ensemble adventure The Tomorrow War has some pretty huge stipulations when it comes to recruiting an army for the future. The largest among them was, of course, you had to be dead according to the records of the future hellscape that pitted humanity against some very nasty creatures.

X-Men: Days Of Future Past

Going from here to there in the then and now in X-Men: Days of Future Past requires a serious amount of power. With Wolverine (Hugh Jackman) going back to his past body, the key to how it all happens lies in the phasing abilities of Kitty Pryde (Elliot Page). So this story uses a very physical, and incredibly vulnerable, method to execute its vision.

Out of all the time travel universes we’ve seen on screen, perhaps the one I feel the most sorry for is the one shown in 12 Monkeys . The basic rule of this Bruce Willis epic’s temporal transit is “hope for the best,” thanks to the method of being shot through time and intending to land in the right place going wrong more often than you think.

Midnight In Paris

Reminiscent of many other vehicular-based time travel films like Back to the Future , any character that travels through time in Midnight In Paris just needs to catch the right ride, at just about Midnight. The experience is bespoke to whoever is traveling, as the period of time that suits them best also dictates the method of transportation provided.

The Final Countdown

Dropping an aircraft carrier from the 1980s into the moments before Pearl Harbor, The Final Countdown delivers a moral dilemma plenty of time travelers have tangled with. But the real difference with this underrated sci-fi movie is the fact that the time-traveling storm that is responsible for the trip is inescapable. You’re going home, whether you want to or not.

Domhnall Gleeson and Bill Nighy in About Time

Sharing a similarity with the romantic classic Somewhere In Time , Richard Curtis’ About Time allows any potential traveler to jump into the past with merely intense concentration. However, certain caveats are in play, like the recommendation of not traveling past certain life milestones, or the fact that only the men of the Lake family can actually use this gift.

Donnie Darko

Donnie (Jake Gyllenhaal) can’t exactly travel through time in Donnie Darko , but he does have a special temporal ability that’s kind of funny and kind of sad. With the ability to open a wormhole between the present and the past, Mr. Darko can send objects through time; the skill that gives Richard Kelly’s movie its bittersweet ending.

Kate & Leopold

Kate & Leopold’s usage of a localized time portal is a method as old as time. However, the big difference with this Meg Ryan/Hugh Jackman rom-com is that the journey Leopold (Jackman) takes to the “future” of 2001 robs us all of elevators. Also, there’s a ticking clock on this specific portal’s usage, which only complicates things further.

Groundhog Day

Perhaps the movie that nailed the time loop into the consciousness of the world, Groundhog Day brought us a charming Bill Murray rom-com mixed with a time travel story. Its misanthropic lead needed to change, even as the world around him stayed the same. The rest was sci-fi history in the making.

Happy Death Day

What happens if you make a Groundhog Day-style time loop into a deadly game? You get a movie like Happy Death Day , in which our initially unlikable lead Tree (Jessica Rothe) is being stalked through a single-day time loop. The big kicker in this variant is that, unlike your standard time loop, Tree has a finite number of cycles before she possibly dies for good.

Josh Hutcherson wearing retro futuristic sunglasses in Detention.

Where does one start with director Joseph Kahn’s Detention? Well, how about the fact that the teenagers in play (including a pre- Hunger Games Josh Hutcherson) use a stuffed bear as a time travel capsule? Or the fact that a mother/daughter pair can body swap on a permanent basis, and with no consequences?

And with that, our supreme sampling of time travel trips has come to a close. Which more than likely has left you with a want to watch some of these movies again, or for the first time. That's totally natural, because this is a subgenre that always leaves us with one question: is there ever a bad time to watch a time travel movie?

Mike Reyes is the Senior Movie Contributor at CinemaBlend, though that title’s more of a guideline really. Passionate about entertainment since grade school, the movies have always held a special place in his life, which explains his current occupation. Mike graduated from Drew University with a Bachelor’s Degree in Political Science, but swore off of running for public office a long time ago. Mike's expertise ranges from James Bond to everything Alita, making for a brilliantly eclectic resume. He fights for the user.

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My Travel Tips for Seeing the World’s Best Places

A photograph of a road stretching toward mountains in the distance.

By Nicholas Kristof

Opinion Columnist

’Tis the season for vacations, so let me make my pitch that the best travel is not lounging at a beach resort but rather journeying into a different world. We all need relaxation at times, but nothing beats the thrill of a trip of discovery and the education that comes with it.

Mark Twain once observed that “travel is fatal to prejudice, bigotry and narrow-mindedness.” In that spirit, I’ve long urged young Americans to take gap years before college or junior years abroad . (One high school reader of such an essay, Spencer Cohen , ended up taking a gap year partly in Japan, became an Asia hand and is now a colleague at The Times.)

Still, there are risks, less of violence (the U.S. has more guns than other countries) than of having your passport and credit cards stolen. So I preach both travel and prudence, and on a recent book tour , I found myself often asked about travel advice I had mentioned in my memoir. So let me share a few tips for the vacation season:

1. The most memorable travel often involves encountering something unfamiliar, so consider escaping the herds parading through Paris. Indonesia, Ghana, India, Nepal, Vietnam, Morocco and Bolivia are generally safe, far cheaper than Europe and offer indelible experiences. I’ll never forget venturing deep into the Potosí silver mines in Bolivia, exploring a grim slave castle in Ghana that dispatched prisoners to slavery in America, learning how to use a blowgun while staying with families in their longhouse in Indonesia’s Borneo rainforest. The world awaits us!

2. Some of the places that you find most culturally distant may be right here in the United States. A teenager from an affluent family in the New York or Boston areas would step into a different world by taking a ranch job in Wyoming. And this is the kind of travel that is not only affordable but actually pays for the experience.

3. Be spontaneous. As a law student in 1982, I spent five weeks backpacking through the Middle East and met a couple of Palestinian students on a West Bank bus; I jumped off at their stop and spent a memorable day with them in their refugee camp hearing about their frustrations and dreams (I wrote about reuniting with them last fall). And while on a bus in the Sahara, I accepted an Algerian man’s invitation to visit his village — which turned out to be a warren of underground burrows to protect families from the extreme heat, the most unusual residential architecture I’ve ever seen. In each case, I was with a couple of friends, which made it seem safer to put myself in the company of people I’d just met, and obviously one should be as judicious as one is spontaneous.

4. One occasionally hears that adventurous travel is just for men, but some of the most accomplished foreign correspondents and overseas photographers are women, as are a majority of Peace Corps volunteers. As a man, I don’t face the same risks that women face, but I have seen female travelers — disproportionately from Australia and New Zealand — thriving as they backpack through the most remote places. Some have suggested the purchase of a cheap wedding ring; a $20 band and a fabricated husband can help keep pests away.

5. Carry a decoy wallet. If pickpockets grab it, let them run off — only to discover that it contains just a bit of cash for street purchases, a day pass for the subway and an expired credit card. But do remember to let the pickpockets escape. Years ago, in Lima, Peru, I instinctively jumped a pickpocket who was trying to grab my friend’s decoy wallet, forgetting that he had nothing much in it; next thing I knew we had a melee and a gun was being fired.

6. Carry your passport and valid credit cards and cash in a pouch that loops on your belt and is tucked inside your pants. Travelers often carry travel pouches round their necks under their shirts, but these are visible and sometimes get stolen. While I’ve had bandits make me take off my shoes and socks while searching for cash, nobody has found my pouch in my pants (I dare mention this only because I assume robbers are not big readers of my column).

7. Carry a small cable lock (those for skis are perfect) to lock your bags together so one doesn’t run off while you’re sleeping in a train or on a bench at the train station.

8. Never check a bag for a flight because then it will get lost. That means packing light and taking quick-dry clothes suitable for washing in a hotel sink. I’m fond of travel clothing from a company called Clothing Arts , and I also rely on ultralight backpacking gear such as a tiny Black Diamond or Petzl headlamp that is invaluable when the power goes out.

9. If you’re getting into a taxi or other car in a location that seems at all dubious, use your phone to photograph the license plate before you get in. The driver may wonder if you’ve texted it to a friend. And women can look for female drivers if they exist.

10. My editor doesn’t want me to say anything that might encourage readers to try something dangerous, so I won’t suggest that there is nothing like the view while riding on the top of a train in Sudan . (That was in my dissolute youth, and today I definitely disapprove of riding on top of trains.)

11. People worry about terrorists, but the most likely serious risk is probably a vehicle accident. Motorcycle taxis common in low-income countries can be perilous, while buses and trains are safer (inside trains only!).

12. Now forget all the fears this article has conjured. Go have fun. Travel should be as enjoyable as it is eye-opening. If you take precautions it will be.

The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips . And here’s our email: [email protected] .

Follow the New York Times Opinion section on Facebook , Instagram , TikTok , WhatsApp , X and Threads .

Nicholas Kristof became a columnist for The Times Opinion desk in 2001 and has won two Pulitzer Prizes. His new memoir is “ Chasing Hope: A Reporter's Life .” @ NickKristof

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Air Travel Consumer Report: May 2024 Numbers

WASHINGTON – The U.S. Department of Transportation (DOT) today released its Air Travel Consumer Report (ATCR) on airline operational data compiled for the month of May 2024 for on-time performance, mishandled baggage, and mishandled wheelchairs and scooters. The ATCR is designed to assist consumers with information on the quality of services provided by airlines.

For May 2024, 1.4% of flights were cancelled, higher than the 0.6% cancellation rate for May 2023 and lower than the 2.0% cancellation rate in both 2022 and in pre-pandemic May 2019.

DOT expects that airlines will operate flights as scheduled and that when they do not, airlines will provide consumers the services promised when a flight is cancelled or delayed because of an airline issue. After a two-year DOT push to improve the passenger experience, the 10 largest U.S. airlines now guarantee meals and free rebooking on the same airline and nine guarantee hotel accommodations. Consumer-friendly information regarding airline commitments to their customers is available on the Department’s Airline Customer Service Dashboard at FlightRights.Gov. DOT also pushed the 10 largest U.S. airlines to provide fee-free family seating, rolled out a new family seating dashboard that highlights the airlines that guarantee fee-free family seating and those that don’t, and proposed a rule that would ban junk fees to seat children with their parents when they fly.

Flight Operations

The 640,137 flights operated in May 2024 were 104.46% of the 612,797 flights operated in May 2023. Operated flights in May 2024 were up 4.46% year-over-year from the 612,797 flights operated in May 2023 and up 3.97% month-over-month from 615,715 flights operated in April 2024.

"U.S. Airlines Operated Domestic Flights: May 2022-May 2024. Operated=Scheduled - Canceled"

In May 2024, the 10 marketing network carriers reported 649,428 scheduled domestic flights, 9,291 (1.4%) of which were cancelled. In April 2024, airlines scheduled 619,940 domestic flights, 4,225 (0.7%) of which were cancelled. In May 2023, airlines scheduled 616,630 domestic flights, 3,833 (0.6%) of which were cancelled.

May 2024 On-Time Arrival

In May 2024, reporting marketing carriers posted an on-time arrival rate of 72.6%, down from both 80.4% in April 2024 and 81.2% in May 2023. The year-to-date on-time arrival rate for 2024 is 77.5%.

Highest Marketing Carrier On-Time Arrival Rates May 2024 (ATCR Table 1)

Delta Air Lines Network – 79.8%
Allegiant Air – 78.8%
Alaska Airlines Network – 78.0%

Lowest Marketing Carrier On-Time Arrival Rates May 2024 (ATCR Table 1)

Frontier Airlines – 63.6%
American Airlines Network – 66.3%
Southwest Airlines – 71.4%

May 2024 Flight Cancellations

In May 2024, reporting marketing carriers cancelled 1.4% of their scheduled domestic flights, higher than both the rate of 0.7% in April 2024 and the rate of 0.6% in May 2023. The year-to-date cancellation rate for 2024 is 1.5%.

Lowest Marketing Carrier Rates of Cancelled Flights May 2024 (ATCR Table 6)

Allegiant Air – 0.4%
Delta Air Lines Network – 0.4%
Alaska Airlines Network – 0.4%

Highest Marketing Carrier Rates of Cancelled Flights May 2024 (ATCR Table 6)

American Airlines Network – 2.7%
Frontier Airlines – 2.6%
Hawaiian Airlines – 2.5%

Complaints About Airline Service

Earlier this month, DOT released data on the submissions (complaints, inquiries, and opinions) it received from consumers about air travel for June-December 2023 and the full calendar year 2023. The submissions about air travel in calendar year 2023 are the highest number on record except for calendar year 2020.

The release of the submissions data in the ATCR continues to be delayed primarily because of the high volume of complaints against airlines and ticket agents received by the Office of Aviation Consumer Protection (OACP) and the time needed to review and process these consumer complaints using the Department’s outdated legacy consumer complaint application system. Over the past three years, complaints made up an average of 91% of consumer submissions. DOT plans to release data on the submission received from consumers about air travel for January-May 2024 later this month. .

The Department has been actively working on modernizing its system for handling consumer complaints with the support of a Technology Modernization Fund (TMF) investment to improve the customer experience for the tens of thousands of consumers who use the system each year. The modernization of the system will also enable OACP to engage in oversight of the airline industry more effectively and report complaint data to the public more quickly.

Tarmac Delays

In May 2024, airlines reported 38 tarmac delays of more than three hours on domestic flights, compared to 11 tarmac delays of more than three hours on domestic flights reported in April 2024. In May 2024, airlines reported four tarmac delay of more than four hours on an international flight, compared to one tarmac delay of more than four hours on international flights reported in April 2024.

Airlines are required to have and adhere to assurances that they will not allow aircraft to remain on the tarmac for more than three hours for domestic flights and four hours for international flights without providing passengers the option to deplane, subject to exceptions related to safety, security, and Air Traffic Control related reasons. An exception also exists for departure delays if the airline begins to return the aircraft to a suitable disembarkation point to deplane passengers by those times.

The Department investigates extended tarmac delays.

Mishandled Baggage

In May 2024, reporting marketing carriers handled 43.4 million bags and posted a mishandled baggage rate of 0.58%, higher than the rate of 0.46% in April 2024, and higher than the rate of 0.51% in May 2023.

The Department began displaying the mishandled baggage data as a percentage (i.e., per 100 bags enplaned) in January 2022. This is consistent with the manner that the mishandled wheelchairs and scooters rate is calculated and displayed. In the prior three calendar year reports (2019 to 2021), the Department calculated the mishandled baggage rate based on the number of mishandled bags per 1,000 checked bags.

Mishandled Wheelchairs and Scooters

In May 2024, reporting marketing carriers reported checking 88,281 wheelchairs and scooters and mishandling 1,099 for a rate of 1.24% mishandled wheelchairs and scooters, lower than the rate of 1.27% mishandled in April 2024 and lower than the rate of 1.27% mishandled in May 2023.

To address many of the significant barriers and challenges experienced by passengers who use wheelchairs, the Department has proposed a rulemaking that, if adopted as proposed would make it an automatic violation of the Department’s Air Carrier Access Act regulations for airlines to mishandle a passenger’s wheelchair. This Notice of Proposed Rulemaking would also enhance training requirements for airline personnel who provide hands-on transfer assistance to passengers and handle wheelchairs. The proposal is available at https://www.regulations.gov, docket number DOT-OST-2022-0144.

Bumping/Oversales

Bumping/oversales data, unlike other air carrier data, are reported quarterly rather than monthly. For the first quarter of 2024, the 10 U.S. reporting marketing carriers posted an involuntary denied boarding, or bumping, rate of 0.27 per 10,000 passengers, lower than both the rate of 0.29 in the first quarter of 2023 and higher than the rate of 0.20 in the fourth quarter of 2023.

Incidents Involving Animals

In May 2024, carriers reported two incidents involving the death, injury, or loss of an animal while traveling by air, one death and one injury, higher than the zero reports filed in both April 2024 and in May 2023.

As part of its IT modernization, DOT’s Office of Aviation Consumer Protection (OACP) is improving the options for covered carriers to submit their monthly and annual Reports on Incidents Involving Animals During Air Transport. While the new system is being developed, OACP is permitting covered carriers to delay submission of reports on incidents involving animals during air transport. Annual data on such incidents will be published when DOT receives carriers’ complete submissions of the 2023 data.

Consumers may file air travel consumer or civil rights complaints online at https://secure.dot.gov/air-travel-complaint , or they may mail a complaint to the Office of Aviation Consumer Protection, U.S. Department of Transportation, C-70, W96-432, 1200 New Jersey Avenue, SE, Washington, DC 20590.

The ATCR and other aviation consumer matters of interest to the public can be found at https://www.transportation.gov/airconsumer .

DOT’s Historic Record of Consumer Protection Under the Biden-Harris Administration

DOT has issued a final rule that requires airlines to provide automatic cash refunds to passengers when owed and another final rule to protect consumers from costly surprise airline fees. These rules significantly expand consumer protections in air travel, provide passengers an easier pathway to refunds when owed, and save consumers more than half a billion dollars every year in hidden and surprise junk fees. Provisions of the final rule on airline refunds were fortified through the FAA Reauthorization Act of 2024 (Public Law 118-63) that President Biden signed into law on May 16, 2024. The final rule that DOT issued to protect consumers against costly airline junk fees has been challenged in court by the airline industry and the court has put a temporary hold on implementation of this rule. The Department will continue to defend this rule and notes that nothing in the Court’s decision prevents airlines from voluntarily complying with this common-sense rule.
In addition, DOT is improving transportation for individuals with disabilities. In July 2023, DOT finalized a rule which requires airlines to make lavatories on new, single-aisle aircraft more accessible. Then, in February 2024, DOT issued a proposal to address other barriers that Americans who use a wheelchair encounter when it comes to air travel by, among other things, proposing to mandate enhanced training for airline employees and contractors who physically assist passenger with disabilities and handle passengers’ wheelchairs.
Further, when necessary, DOT takes enforcement action against airlines and ticket agents that fail to comply with the Department’s aviation consumer protection requirements. In 2023, DOT issued the largest fines in the history of the consumer protection office. This includes a $140 million penalty against Southwest Airlines for failing passengers during the 2022 holiday meltdown. That penalty, which was in addition to over $600 million DOT already ensured was refunded by Southwest to passengers, requires Southwest to establish a $90 million compensation system for passengers affected by significant delays and cancellations beginning April 30, 2024 . Additionally, DOT has helped return nearly $4 billion in refunds to travelers since the pandemic began.
In April, DOT announced the launch of the bipartisan Airline Passenger Protection Partnership with 18 state attorneys general to investigate airlines and ticket agents and hold them accountable when they violate aviation consumer protection laws. The partnership significantly expands the Department’s oversight capacity by establishing a new fast-track system prioritizing misconduct cases from state attorneys general who uncover unfair or deceptive airline practices. Through the partnership, DOT will provide state attorneys general with access to the federal complaint database and help ensure that airlines cooperate with state investigations.

How Do Lawyers Bill Their Time?

Understand what is a billable hour and how attorneys bill their time.

Getty Images

The exact method of timekeeping will depend on the software and the attorney’s preferences.

The term “billable hour,” a unit of time used in the legal industry, is common in popular culture but can be misunderstood.

What goes into a billable hour is more than 60 minutes of time, and timekeeping and billing practices differ. Here's a closer look at how attorneys charge for their work .

Billing Increments and Ethics

If attorneys bill clients for time, they may choose to bill in increments of an hour. While some may charge by either the quarter hour (15 minutes) or a half hour (30 minutes), a tenth of an hour (six-minute increments) is becoming an industry standard. In theory, the smaller fractional periods protect clients from being overcharged.

Lawyers round up time to the relevant increment, so a seven-minute call is billed as a tenth of an hour (or a quarter hour, and so on). Beyond that, lawyers are ethically required to only charge for the time they worked for the client, says George Warner of Warner Law, a Minneapolis practice specializing in creditors’ rights.

One notable exception is that some jurisdictions allow attorneys to include in a fee agreement that they bill at least a half hour of time for any client calls received in the evenings or they bill time and a half during the weekend. Attorneys who use these provisions are often family law or criminal defense attorneys, and the intent is to discourage clients from constantly peppering lawyers for new information even after the courts are closed, Warner says.

How Lawyers Keep Track of Their Time

While some lawyers still use paper logs in notebooks or calendars to track their time, many lawyers now rely on law practice management software to inventory their time.

One attorney may track a phone call by using a calendar function to mark the call’s start and end. Another might rely on a phone’s timer to tell them the call’s duration and then enter the time into the application.

Regardless of which technique is used, the result should be the same: The lawyer writes down the relevant amount of time (e.g., 0.4 hours) along with a brief description of what they did during that time.

These time records should be accurate and contemporaneous, Warner says.

What to Look for in a Bill

When a firm first takes on a client, it will typically assign them a client number and then a second number for each matter the firm works on. Thus if a client is assigned “4280,” then 4280.1 is for their lawsuit against Jane Doe while 4280.7 is for work relating to a contract negotiation with Widget Corp. The bill then lists costs for each matter, broken down by task.

Good lawyers send clients a bill that has a description of the services provided on the left and the corresponding amount of time on the right, Warner says.

So a bill might look something like this:

Phone conference call with client regarding Jane Doe litigation 0.5 hour.
Researched bases of liability and defenses for third-party defendant 1.0 hour.
Drafted amended Jane Doe complaint naming third-party defendant 1.1 hours.

Attorneys bill each task separately for two reasons. First, this method is an industry best practice, Warner says.

Secondly, in different fields, parties may be entitled to attorneys’ fees. A prevailing party’s attorney will submit their invoices to the case’s judge, who then reviews the bills and determines how much of the fees the losing party must pay.

“If you don’t have those types of detailed bills, you’re not going to get the award,” Warner says.

How Bigger Institutional Clients Can Get Smaller Bills

Larger institutional clients may approach time differently than individual clients. For example, a Fortune 500 client’s contract may require that partners only bill their full rate when doing work requiring a partner’s level of experience, and associates must bill for associate-level work. Additionally, these clients might refuse to pay for administrative time, such as organizing case files, even if it’s related to their cases, Warner says.

Individual clients don’t necessarily know to ask for those adjustments, and they probably don’t have the bargaining power to get them in their contracts anyway.

Therefore, if the associate had to photocopy documents after the firm’s paralegals had left for the day, individual clients could end up paying an associate’s hourly rate of $200 for the time spent copying. By contrast, the institutional client might demand the firm charge a $25 hourly rate of a law clerk for the associate’s copying, Warner says.

When and Why Lawyers Don’t Charge for Their Time

Lawyers don’t charge for all of the time they spend on a matter for a few reasons.

Attorneys often have phone calls with potential clients to discuss pending cases and may not bill them for such calls. Similarly, attorneys may decide not to charge for the time spent drafting a fee agreement or overhead related to a new client, Warner says.

If an attorney is working on something they don’t normally do, they may write off some time they spent to get the particular knowledge needed to effectively represent their client.

Attorneys may “bill with a lighter hand,” Warner says, and write off a substantial portion of time if they’re representing a new client referred to them by another attorney in hopes that the referrer sends more cases their way.

Attorneys also discount bills for nonprofits or those needing pro bono representation , he says.

Don’t Guess: Ask About the Billing Rate and Policies

Before hiring an attorney, ask about their billing practices, including how they keep time. At the same time, ask for an estimated budget. Experienced attorneys should be able to estimate the amount of time and money that a case will require, Warner says.

Clients can save money by asking what tasks they can do to help their attorney. Being prepared, including having relevant documents ready when an attorney asks for them, can reduce the bill. It can impress the attorney, who may believe the client will be more prepared and forthright during their representation.

So a client who saves money by being organized may be even further rewarded – with a better quality of representation.

Why Attorneys Get Disbarred

Ashley Merryman Jan. 19, 2024

Legal Disclaimer

This content contains general legal information, but any references to the law are subject to changes through ongoing updates in legislation, regulation, and caselaw at the federal and state levels. This content does not constitute legal advice and should not be relied upon as legal advice for any particular situation. Nothing in this content should be interpreted as creating an attorney-client relationship. If you have legal questions, you should consult the advice of an attorney who is licensed to practice in your jurisdiction.

Tags: law , lawsuits , personal budgets , ethics

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