by Alex Lehner CC BY 2.0

Time travel is possible, but it’s a one-way ticket

Chenoa van den Boogaard, Physics and Astronomy editor

The ability to travel through time, whether it is to fix a mistake in the past or gain insight into the future, has long been embraced by science fiction and debated by theoretical physicists. While the debate continues over whether travelling into the past is possible, physicists have determined that travelling to the future most certainly is. And you don’t need a wormhole or a DeLorean to do it.

Real-life time travel occurs through time dilation, a property of Einstein’s special relativity. Einstein was the first to realize that time is not constant, as previously believed, but instead slows down as you move faster through space.


As part of his theory, Einstein re-envisioned space itself. He coined the phrase “spacetime,” fusing the three dimensions of space and one dimension of time into a single term. Instead of treating space as a flat and rigid place that holds all the objects in the universe, Einstein thought of it as curved and malleable, able to form gravitational dips around masses that pull other objects in, just as a bowling ball placed in the centre of a trampoline would cause any smaller object placed on the trampoline to slide towards the centre.

Courtesy and © of NASA

A computer-generated representation of Einstein’s curved spacetime. The Earth creates a gravitational dip in the fabric of spacetime which is deepest at its core. Courtesy and © of NASA


The closer an object gets to the centre of the dip, the faster it accelerates. The centre of the Earth’s gravitational dip is located at the Earth’s core, where gravitational acceleration is strongest. According to Einstein’s theory, because time moves more slowly as you move faster through space, the closer an object is to the centre of the Earth, the slower time moves for that object.

This effect can be seen in GPS satellites, which orbit 20,200 kilometres above the Earth’s surface. These satellites have highly precise clocks onboard that gain an average of 38 microseconds per day due to time dilation. While this time gain seems insignificant, GPS satellites rely on their onboard clocks to maintain precise global positioning. Running 38 microseconds fast would result in a positioning error of nearly 10 kilometres, an error that would increase daily if the time difference were not constantly corrected.

A more dramatic example of time dilation can be seen in the movie Interstellar when Matthew McConaughey and his crew land on a planet with an extreme gravitational field caused by a nearby black hole. Because of the black hole’s intense gravitational influence, time slows dramatically for the crew on the planet, making one hour on the surface equal to seven years on Earth. This is why, when the crew returns to Earth, Matthew McConaughey’s daughter is an old woman while he appears to be the same age as when he left.

So why hasn’t humanity succeeded in making such drastic leaps forward in time? The answer to this question comes down to velocity. In order for humanity to send a traveller years into the future, we would either have to take advantage of the intense gravitational acceleration caused by black holes or send the traveller rocketing into space at close to the speed of light (about 1 billion km/h). With our current technology, jumping a few microseconds into the future is all humans can manage.

But if technology one day allows us to send a human into the future by travelling close to the speed of light, would there be any way for the traveller to use time dilation to return to the past and report her findings? “Interstellar travel reaching close to the speed of light might be possible,” says Dr. Jaymie Matthews, professor of astrophysics at the University of British Columbia, “[but] this voyage is one way – into the future, not back to the past.”

If we can’t use time dilation to return to the past, does this mean that the past is forever inaccessible? Perhaps not. Einstein proposed that time travel into the past could be achieved through an Einstein-Rosen bridge, a type of wormhole. Wormholes are theoretical areas of spacetime that are warped in a way that connects two distant points in space.

Image by Panzi, CC-BY 3.0

A visualization of a wormhole: The fabric of spacetime curves back upon itself, forming a bridge between two distant locations. Image by Panzi, CC-BY 3.0


Einstein’s equations suggested that this bridge in space could hypothetically connect two points in time instead if it were stable enough. “At the moment, even an Einstein-Rosen bridge cannot [be used to] go back in the past because it doesn’t live long enough – it is not stable,” Matthews explains.

“Even if it was stable, it [requires] other physics, which we don’t have. Hypothetical particles and states of matter that have “exotic” physical properties that would violate known laws of physics, such as a particle having a negative mass. That is why “wormholes” are only science fiction.”


While it would be fascinating to travel back in time to see the dinosaurs or to meet Albert Einstein and show him the reality of time travel, perhaps it is best if the past remains untouched. Travelling to the past invites the possibility of making an alteration that could destroy the future. For example, in Back to the Future, Marty McFly travels to the past and inadvertently prevents his parents from meeting each other, nearly preventing his own existence. But if he had undone his own existence, how could he have travelled back in time in the first place?

Marty’s adventures are a variation of the grandfather paradox: what happens if you go back in time and kill your grandfather before your father is conceived? If you are successful, how is it possible that you’re alive to kill your grandfather in the first place?

A recent study at the University of Queensland may have the answer to this baffling paradox. In this study, the researchers prove mathematically that paradox-free time travel is possible, showing that the universe will self-correct to avoid inconsistencies. If this is true, then even if we could travel back in time, we would never be able to alter events to create a different future.

While these new findings are enlightening, there appears to be more evidence that, although time dilation can allow us to glimpse the future, we will never be able to visit the past. As the late Stephen Hawking said in his book Black Holes and Baby Universes, “The best evidence we have that time travel [into the past] is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”


Banner image by Alex Lehner, CC BY 2.0

104 thoughts on “Time travel is possible, but it’s a one-way ticket

  1. So what if time travel is the reason that we now believe there are other realities in our own world.this could be that a Time traveler we could only go back and couldn’t come back, and on doing so if you do something to change the past in stead make a new reality.making other things are deferent and ours realty stays the same . sometimes reality gets mixed up make the mandela effect that we see today

    • Time in the future it is faster then now. The past is slower so you can travel . It is up to you. One way is to meditate. You can travel and see any body you want right now. You can fly faster then light. That is one way. You go to the future. To go to the past you sleep for a long time. Some time you go to the future or the past. Your heart well stop and your body gets cold. Sometimes you can control it sometimes you can’t.

      • but how do we know that is really true ? i mean i want to figure this out, i want to time travel, but how is it that simple ? so many people have been trying to figure this out for many years and its that simple ?

      • You cant go there in the first place. Dont worry. With current technology, we will only end up messing some few microseconds. Highly doubtful, if we can end up getting the news of travelling hundreds of years in our lifetime.

  2. but how do we know that is really true ? i mean i want to figure this out, i want to time travel, but how is it that simple ? so many people have been trying to figure this out for many years and its that simple ?

    • Time is an illusion based on perceived reality and is only relative to our limitations. Time isn’t what it seems and all things can’t be figured out

        • This is blowing my mind people, then I see the school boy on the post. Great stuff, whoever reads this is already capable of travelling through time. Think about all people who have posted on this thread, now think about who will read mine. Now think of those €opposite trolls $ who never ever bother posting on you tube thread etc. But ONE comment from one of the time travellers who wrote on this thread.
          So that opposite troll is me,I don’t normally post.however because of previous comments I’m posting here. And I love the DMT shit I loved that and lived that one out in real life,,,,another day.

          So my point is ifOne or two threads have made me write this….then what will my post make others write , think…..then I could travel back and not write this…. then what.
          Love the conception of time how can u travel something that doesn’t YOU perceive to be time, like a train can only run on its train tracks, a car can only drive on a road etc
          It’s posibble I know it is. Sometimes when u have fun times moves swift but locked in jail it goes snail pace. U c me. I write letters to myself from past from future. Remember everything that happens in present becomes part the past. But the future is what you hold in your hands. Question is, now you know….what the f are u gonna do about it?..

          Hahahah only realised school boy is named BIG dick pissing myself laughing I gotta go pee. Respect certified

  3. I believe time travel is already possible, however we cannot fix past mistakes without altering future predicaments. Say we stop JFK’s assasination, that would completely change the future from that point forward to one none of us can know/guess or conclude the effects? Other time travel purposes go to the future I think that from now our world will die off before 2096 basdd on overpopulation, global warming & polution as such creating islands of plastic waste in our oceans. The best thing my opinion go back to the garden of Eden, kill that Serpent Satan before he tricks Eve into the forbidden fruit. Then let God raise, enlighten & teach us how to be humanly sustainable on his planet & I guarantee technology & smart phones? Ain’t no part of it!!

    • There is no God. No magical serpent or Garden of Eden ever existed. Basing a scientific theory on archaic stories does no one any good.

      • You choose a hopeless eternity. I choose hope through the promise of salvation through Christ for those who believe. You see, I have child in heaven. Thankfully, have a hopeful reality that I can embrace. There is a God. Our known universe is only 14 or so billion years old… is it mathematically possible that random molecules out of the Big Bang mixed in just the right way from to form a complex cellular organism… with DNA… and result in humans and such diversity of life forms? It’s naive to accept this as a result of chance. Think about it. How is that remotely possible without a creator?

        • Hahaha. You make it seem as tho the big bang happened, and we just popped into existence? Naw it’s called evolution baby, we started out as microscopic organisms, seriously, when did you drop out of school? But that’s like saying a some guy writes a book to explain away natural phenomenons that they were to stupid (un-evolved) to grasp and the concept good and bad and the eternal damnation, And thus, the Bible, and boom, everyone now was made by God, hahaha. When you can prove he/she exists, and that the Bible was a autobiography, and not just some twisted piece of Fiction, that has no real basis in reality, and cannot be proved to be more that a work of Fiction. Rather than being used as the16th Century control tact, ‘be good or you’ll go to hell’. But I guess that’s what they mean when they say ignorance is bliss, (maybe if I was as ignorant as y’all believers I’d believe to). But I can’t see how a ‘GOD’ would ever ask one of its creations to kill another.. Genocide, Crusades, all the ethnic cleansing.. All In the name of God Almighty! Hahahahahhaaa. Aliens are more believable than this shit, and theirs no proof they exist either. Hahahahaha. Fug’n Bible thumpers. ‘Step out side your faith and see the world for what it really is, a complex organism, mad of gravity and dust, quite a unique specimen! And we, yes Bible bangers, this includes you, are destroying it like the bubonic plague.’. ‘The end is coming and it’s our fault’

          • Have you taken the time to read The Old Testament and the prophecies therein that came to be ?.

            How do you explain that ?.

          • You have not had an encounter yet with God. Don’t be so certain on yuour theory of evolution. He came and shook my reality to it’s core. Made thing possibly that no one could ever explain.

          • You have not had an encounter yet with God. Don’t be so certain on yuour theory of evolution. He came and shook my reality to it’s core. Made thing possibly that no one could ever explain.

      • Time travel is very much possible just as you decided to come existence in this century meaning one can decide to be in another time zone . life is all about numbers, you just have to work on numbers

    • Changing the past is impossible, because if we went back into the past, that means we were already there during the time you experienced it.

  4. if it is shown that if something, such as a solution to a particular class of equations, were possible, then two mutually contradictory things would be true, such as a number being both even and odd. The contradiction implies that the original premise is impossible.

    This is called proof by impossibility. Thus if some traveled back in time far enough to kill his grandfather, we have the contradiction and therefore it is impossible.

    You could argue that he would be able to time travel, but not kill his grandfather. However almost anything a person does going back in time would cause the same contradiction, thererfore it is the traveling back in time that is impossible.

    Actually, it probably is possible to travel back in time, however to do so, you would also have to travel so far in space that you cannot see anything that happened before your current time due to the speed of light, because this to could affect the future.

  5. The reason I am here is that, i really want to go back the day when our matriculation exam was just finished. Everything around me is peaceful and happy. Currently, I am living in dire situation. People are dying outside on the streets. Smokes everywhere. Everything is in doom.
    Ah, yeah. I really miss my past. If you are reading this, you can judge me in anyways. I just want to live peacefully and happily.

    • I entirely know what you say and how you feel, Robin. I am totally convinced that future is no promise to offer a better place to live. World is becoming unnecessarily more complex and more horrible and more insecure. Therefore, travelling back in time to a point where things were still far away from such ordeals is what I aspire. But I think if it is possible to travel back in time without the possibility of carrying our lived experiences with us, it will be useless as we will be repeating the same mistakes over and over again. Now, this begs the questions “in what type of physique could we imagine ourselves back there if such time travel becomes possible? That is, becoming younger again in a physical regression (as I said this would be a torture without having learned from all these later years)? Or appearing at our desired times in our present physique and age?
      I believe the most ideal one would be if we appeared at our desired point in time at the same age that we were at that point of time with a good feeling of our later lived experiences.

  6. Mam all u need to do is just run faster as much as u can or visit the black hole because in both condition time just slow it down ….

    • Time travel is simple. If you do happen to travel to the past you create a new time line not affecting the time line you left. In essence you going to the past is now your future. Even if you were able to return you may never know if you remained in your time-line or created a new one. So even if you changed something in your travels it would happen in the future not the past.

      • Changing the past is impossible, because if we went back into the past, that means we were already there during the time you experienced it.

  7. Sorry time traveling is not possible, there is no way you can go into the past or the future ‍♂️. You can only be in the time you are already in.

    • Incorrect. General relativity allows time travel into the future. You need a space ship that can travel extremely fast though, approaching the speed of light, or you need to get close to a supermassive black hole.

      It is travel into the past that there is no known practical way to do, and is probably impossible.

  8. Simple question from a simple mind:

    At what point, when a person says they are from the future, do we stop throwing them in the funny farm and actually start listening??

  9. I don’t believe that “glimpses into the future” could be possible. If it were so, we could glimpse blueprints of the future that we could bring back to the present and build before they were invented. My personal.beleif is in any time frame there is only one active time which is the present. The past no longer exists and the future hasn’t occurred yet, so there is no such thing as ‘time travel’ except for the frame we are in now.

  10. First off time is not real we make time if you travel anywhere all you are doing is beating the Earth speed try this for a mathematical equation the Earth travels a thousand miles per hour you’re not beating human time that is your own equation the Earth travels a thousand miles per hour a space shuttle travel 17,000 mph you can beat time that you made so time is not real you are only beating the Earth speed if you go in a space shuttle and go around the earth 17,000 miles per hour the Earth only travels a thousand miles per hour plus it has all types of gravitational pull from the Moon Earth’s access on the til t you figure out the mathematical equation I cannot time travel is real if you can beat the Earth speed and we can it has nothing to do with its 12:00 it’s 1:00 that’s not real time is made up as a mathematical equation you can beat the Earth speed you can go back into the Earth’s time in a space shuttle but you’re not beating anything except the Earth’s speed think about that one time is not real at all all it is is a mathematical equation think about that one real long

  11. What I’m trying to say is this a space shuttle travel 17,000 mph the Earth travels a thousand you beat it 16 times faster that’s all you did you’re not beating any time you’re not beating 1:00 you’re not beating 3:00 all you’re doing is beating the Earth’s time you can go in reverse around the Earth 17,000 mph okay you can go forward with the Earth’s centrifugal force 17,000 miles per hour you’re not beating anything you’re beating a mathematically equation that we we created astronauts been traveling time for instance for years and haven’t told us because of the space shuttle that does travel 17,000 mph it beats the Earth speed 16 times a boggles my mind you have the Earth access the moon gravitational pull but you can get in a space shuttle and travel 17,000 miles per hour and beat the Earth’s speed 17 times think about it

  12. If any scientist or anybody can actually answer this question how do you set up this equation with the Earth spinning a thousand miles per hour you have the moon pulling gravity the Earth’s access on until I want to know tell me then wondering for a while this equation popped into my head about 2 years ago I’m not a math whiz or anything I just thought about it weird how the mind works I’m not into space or any space stuff at all I’m Samanthas boy friend John antos wrote this

  13. how would any of that stuff be true because e’*34+Em would stop all the forss of vissecs and how would we do it if you now what i mean??? also thanks for the scuff for my project

  14. I would love it if I had a real life time machine here with me now which could take me to anytime I want, the past, present or future. If I had a time machine here with me now, I would go to the past in September 2004 when I was born and give myself to another family that is actually rich and not this horrible family that I have now.

  15. Close but not quite right scientists of the idiotic variety, yes, you don’t want people to travel back in time to mess with their own pasts, of course, but you say it’s impossible, but it’s not, and I’m always ignored with my crazed crackpot theories, so what’s the harm in telling the truth as I see it, while it could be possible to travel to the past, here in lies the problem with rewriting the future, while some believe it’s possible to travel back in time, but it’s very expensive and definitely a one-way trip to the future or to the past. Basically Doc Brown got the mechanism for time travel almost right but the energy out put needs to be quadrupled instead, allowing for the ‘physical item, being or vehicle’ to transport through time without killing the time traveler in question. Wormholes are unpredictable, until warp speed for spaceships are a thing, it is not possible for the space ships to achieve time travel, unless they want to enter a black hole, which I would not recommend. as you need warp speed to survive the emptiness of the black hole, without being ripped to shreds. Say for example, Back to the future 1, the timeline doesn’t erase it continues on without the ‘said time traveler’ in existence basically the Marty from Wimpy George’s timeline did time travel to the past and messed with his parent’s meeting so to speak, but never return to the same timeline therefore Marty A went known as a Missing Child in timeline A, while it continues on without him, however Marty A became Marty B/C, in the Successful George Timeline. So that is what I’m talking about. the timeline changes only for the time traveler themselves the ones who are left behind don’t experience a thing of timeline rewritten-ism, as it would never happen in the first place. The other thing is if you want to mess with your own childhood, to make a better life for the past self, the key thing to remember it’s not really you. It’s an alternative version of you, that you interfered with. creating a parallel timeline to it’s original, yet slightly different. Yes it would be awkward to raise yourself. but as long as you are staying in the past, nothing should happen until the age you traveled back in time, unless of course you touched your past self and suddenly de-aged and merged with your past self, is an option 1, option 2 the future self explodes spreading guts all over the place and therefore the past self, of you became a murderer of your future self, I am more inclined to believe option 1 as option 2 seems a little too out there. Basically you would have two memories one of the former timeline and one of the current different timeline. Still traveling through time is truly a one way trip and if you want to travel through time, you would need some time travel mechanism, the way you scientist talk is basically a dream version, or an OBE version (OUT-OF-BODY-EXPERIENCE) which is basically a vivid/lucid dream which is not true time travel, the true time travel is based on the BTTF Trilogy not the idiotic versions you preach about. I believe I’ve said enough.

    • And that my friend is absolutely what you do not or would not know. Everyone focuses on what they don’t or haven’t had rather than what positives they do have around them. To change the ingredients of a past life only changes the flavour you have in this life, it does not make you happier.

  16. No, travel to the future is not possible. Like, future is unpredictable and always have been so give up on that field

  17. Time travel 101-

    Create a closed loop circuit around a full metal structure, hermetically seal it and bring O2, Use two tesla coils to create north and south poles. (Artificial Magneto sphere.) Make sure to pain the outside in lead to prevent any cosmic rays from penetrating the materials on the inside. (Radiation = bad). Connect a ball made of w/e with wires that alternate the current from the coils to w/e panel on the outside of the structure to make it move via inductive magnetic / electric Lorentzo (Lorentzo = ExMfield = Velocity. = Antigravity) Create Antigravity by using forces from the inside reactor. (Pressurized Mercury, and Tesla Turbine.) Then Move 10-100x faster than light depending on the charged field, Friction will be added to the electric field instead of the craft allowing the G-forces not to crush you inside. The field will take the pressures of outer space, The temperature of space will allow for super conductivity of the structure.

    Eventually you will arrive in the future, if you stay in one place. but account for the movement of earth in your travel log. To see outside you will need a monitor / camera system, as any leaks through a viewing area will cause death by radiation from the cosmic rays from the field you have created.

    The O2 can be used as a backup generator, through air pressure and the tesla turbine.

    There are many different ways to make wormholes, but the curvature of space is really hard to calculate to send a machine far out to the end and create a link with the machine that wants to travel there. And leaving one behind to get back.

    If you can imagine it, it can be done. You just need the knowledge of not dying to complete it.

  18. Until recently, I thought my neighbor was a crackpot until he actually invented a time machine. He utilized an ordinary closet, and showed me the sophisticated (to me) instrumentation he had installed. I was very skeptical at first, until he offered a small demonstration and entered the time coordinates and energized his invention. To my amazement, when I opened the door, the clock on the wall was 30 minutes later than when we stepped into the machine. OMG!!! Destroy this thing before it destroys us!!!.

  19. So happy to have my husband back after 6 months of separation. get any kind of relationship/marriage help you want from….Robinsonbuckler11 @gmail com………………………

    • I find it odd that people say time travel isn’t possible yet… If time travel is possible, it has always existed. Meaning, there is not past present it future, only our perception of time. What we know as past present and future have always been occurring simultaneously, so travel was invited the moment the universe wss formed. Dinosaurs are roaming the earth right now, and forever. A version of me is typing this and has always been typing this, within this perceived moment of “time” and time travel has always happened, whether or not we exist in that reality at the right “time” to observe time travel is the only question.

  20. Thank you so much for compiling these ”Doomsday: 10 Ways the World Will end ”you have covered almost everything. I am also doing kinda same work , please spare some time suggestion me improvement . i am very happy see your growth in google . thanks and regards

  21. I find it odd that people say time travel isn’t possible yet… If time travel is possible, it has always existed. Meaning, there is no past present or future, only our perception of time. What we know as past present and future have always been occurring simultaneously, so travel was invited the moment the universe was formed. Dinosaurs are roaming the earth right now, and forever. A version of me is typing this has always been typing this, within this perceived moment of “time” and time travel has always happened, whether or not we exist in that reality at the right “time” to observe time travel is the only question.

  22. To be fair, even if it is a one way trip into the past, that doesn’t stop machines going back. We could send a machine back and order it to do anything we want and then tell it to meet us at a certain time in the future. We send it back, then go straight to the meeting point we agreed and then we’ll be able to prove if it worked or not.

  23. Time travel is very much possible just as you decided to come existence in this century meaning one can decide to be in another time zone . life is all about numbers, you just have to work on numbers

  24. thx to eleon wont we soon be able to digitize our conscious being, then accelerate that data pass the speed of light some how then download it into some android or something…..i dunno…..just a thought

  25. I want to go to my elementary school again. Someone help me out, I know its Idiotic but stil..
    I am not good at science. As far I understood,
    1) we can trace through time if we travel fast than speed of light.. I think memory os the only thing that is faster than light, Yeah I can go to Paris within 1 sec in my memory but yeah its illustion, i want in real
    2) Through Blackhole – I think its Bermuda triangle

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