Is time travel really impossible?

Maybe some don’t dare to believe that time travel is possible, but this view is changing! The understanding of the science behind time travel is improving

Is it or isn’t it…who really knows?

Most of us probably don’t dare to believe that time travel is possible, but I think this is changing! The understanding of the science behind time travel is getting better understood, and an increasing number of scientists are now finding ways which one day might unlock the mystery of the time machine blueprint. The hard study and the calculations continue.

But even if we don’t know how to travel in time now…that doesn’t mean it’s impossible…does it?

Why isn’t time travel impossible?

There are so many paradoxes associated with time travel that you could well be forgiven for thinking that time travel is not possible. The “grandfather paradox” – where you go back in time and kill your grandfather (why would you do that?!) thus preventing your own existence to go back and kill him in the first place is perhaps the most famous of these paradoxes.

Or if time travel was possible, surely we would have met time travelers who have come to our time from another time by now?

Grandfather paradox? It’s all relative!

So on the face of it, it would seem that the idea of time travel is just that…an idea. It has certainly captured the attention of many science fiction authors, and even poets. And recently…scientists. Yes, there have already been many eminent scientists who have gained funding for looking into the possibility of time travel – and to find a way to make it happen. They do this by turning to Einstein’s theory of relativity.

Einstein’s theory of relativity is used to describe our understanding of time and space. Actually, time and space are so heavily intertwined that they are referred to collectively as “timespace” as one affects the other. By studying the theory of relativity, scientists hope to discover a solution to its equations which permit time travel. So has there been any success?

Interestingly, success has been found in the opposite sense…that is to say that nothing has been found which forbids time travel. So that is good news for those of us who would like to travel in time – though we are still no closer in finding out how we can do this. Or are we?

Time dilation

The theory of relativity describes “time dilation”. Time dilation refers to how a second of time can take longer in some situations than in others. This is slightly different to the perception of time which Einstein himself has been quoted as saying “When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That’s relativity.”

Here’s an example of time dilation. There are 2 identical clocks. Let’s call then clock A and clock B. Clock A is put on a jet plane, whilst clock B stays on the ground at the airport. The jet plane takes off, travels at high velocity around the world and lands back at the airport. The times on the two clocks are compared…clock A (the clock which was on the plane) shows that less time has elapsed than shown by clock B at the airport. Why? Because travelling at speed causes time to slow down. That is time dilation.

Another example of time dilation is seen in the satellites used in GPS navigation. In this case, there are two causes of time dilation. The first is the high speed relative to the Earth at which the satellites travel, and the second is the decrease in gravitational potential the satellites experience in orbit. The clocks on board the GPS satellites actually need to be corrected for the effect of time dilation!

The existence and reproducibility of time dilation is a good step towards realising the possibility of time travel. But are we any closer to making our time machine?

Faster than light

Perhaps. Experiments have been conducted which have shown that faster than light speed travel might be possible with some sub atomic particles and arguably this is a step in the right direction for moving on towards building a time machine. However, the energy input required is astronomical, and to reiterate…this was only a sub atomic particle! Perhaps the understanding of an alternative theory of timespace would show a solution to time travel where the energy requirement is not a practical limitation.

Conclusion: the answer is…

Having said that the subject of time travel is now receiving more attention from scientists, that is not to say that all scientists are in support of the existence of time travel. Many scientists have discredited the idea entirely, and it is clear that the question of whether time travel exists or not is still a topic of hot discussion.

So is time travel possible?

I think that presently, it is not possible in the way that we would like it to be – the days of the fabled time machine are far away. I do hope that one day in the future we will be able to travel back to the past, or into the future and experience other times just as we can experience and enjoy the present, though at the same time I am cautious about the possible dangers. Many of us are still not able to navigate safely through space (just think of all of those road accidents…) and I’m sure that navigating through time is a much more complex issue.

And we still don’t know about those time travel paradoxes…

Thankfully, even if real life time travel doesn’t exist, we can still read about it in science fiction!

For a more detailed look on the possibility of time travel (and how), take a look at my time travel 101 main page. If you have time! 😉

Author: Paul Wandason

I love astronomy and science fiction, but I love my family more. So I love time travel too!

17 thoughts on “Is time travel really impossible?”

  1. Help! I think I have come up with a reason time travel would be impossible. If I understand things correctly energy can neither be created nor destroyed. Having taken that as a fact, I postulate that the amount of energy in the universe at any one time is a constant and is equal at all points in time. If that is the case then if I take the energy that I, or anything, consists of and I move it to another time then the amount of energy in that time now becomes E + E(chris) which is more than the amount of energy that existed at that point in time before. Furthermore the amount of energy in the universe at the moment I start to travel through time becomes E – E(chris). I’d very much like to go back and change at least one thing so please help me realise that this conjecture had no merit.


    1. The only problem with your theory is that conservation of energy is only true for a closed system. Time travel opens the system allowing energy and mass to transfer from the future to the past.
      Your suggestion is essentially that since energy must be preserved you cannot step from the kitchen to the living room, since to do so would steal your mass from the kitchen and mysteriously add it to the living room.
      Worm holes and closed-time-like loops of space time all potentially open that door between the living room of the past and kitchen of the future. Although I’m not saying its an easy door to open…

      1. The problem with your rebuttal is that I wouldn’t be in the kitchen and the living room at the same time therefore I’m not changing the total amount of energy there is in the universe by moving through time normally as I move from the living room to the kitchen. In my original post I stated that when I move through time the amount of energy at the point I leave would become E – E(chris) if that’s true then there is a possibility that at some point the whole thing can balance out at some point. A good thing hopefully but the more I think about it if I go back in time from the point I enter the past the amount of energy in the universe become E + E(chris) from that point forward including the point I left from and all future points would be E + E(chris). What would make that extra energy just disappear when I got to my departure point? Nothing I can think of which is even worse for my chances of making time travel work. As for it being a closed system that’s not my rule that’s the rule that says energy cannot be created something I’m pretty sure at this point had been established as a law of nature. Trust me like I said if balancing out over the entire lifespan of the universe was a caveat I’d be happy to take it.

  2. If someone can find a way for me to be in the kitchen and living room at the same time let me know not only would that allow for time travel but it would also let me get snacks without missing part of my program….Lol

    1. You’ve missed the point of my example, since I was trying to demonstrate that the two Seperated locations in space-time are separate. By stating that you can’t be in both the kitchen and living room at the same time you are suggesting that you can’t be in the future and past “at the same time”. Well, of course you can that’s the nature of the beast.

      And as you pointed out as you across the whole universe as a closed system in space-time, it would balance out anyway, the deficit in local energy could be easily balanced through the quantum fluctuations of virtual particles as occurs around black holes.

      There is no law that states energy cannot be created or destroyed, without the caveat of within a closed/isolated system. see the first line of .In fact the whole big-bang event is obviously a breach of energy conservation unless it is actually arriving from the future of the universe, possibly from the matter that falls into black holes, or from a collision with another universe (as in brane theory). Either way it breaks your model of energy conservation.

      1. Thank you for your thoughtful responses. It had indeed made me think more about it and I am willing to accept that energy from the point I am traveling to swaps places with the energy I consist of and also the the energy will manifest itself in the present at the point in space where the earth is in the time I am traveling to hence avoiding the blowing up the planet issue. Btw if you are a time traveler and you are reading this I would really appreciate a trip to a specific point in time and/or to send a message to myself in the past. Contact me. 🙂

  3. Trust me I’m the guy that says if UFOs exist they are way more likely to be people from the future visiting now than aliens from another part of the universe. I appreciate any suggests that would dissuade me from the notion that energy cannot be created or that time travel isn’t the same thing as creating energy. Simply saying time travel opens the system isn’t going to convince me. How does it open the system? Even worse if you try to balance the equation by saying energy from the time I travel to simply swaps with energy from the time I left what from would that energy take? Would the matter I’m composed of transfer to the point I left as energy and say maybe blow up the whole planet?

    1. Hehe.. I literally wrote a book on UFOs being from the future… 3 of them in fact.

      Hmm, you need to understand that law about energy not being created or destroyed a little better, I’m afraid.

      With relativity you can already appear to have mass and energy appearing and disappearing depending on the reference frame you are measuring in. It was one of the reasons people didn’t immediately subscribe to Einstein’s theories. However, when you measure within the appropriate reference frame this missing energy is found again and conservation is valid.

      In the same way with time travel you have to consider the passage of the object through time as its reference frame. As far as the time-traveller is concerned the past is their present, they got there from the universe’s future which is actually their own past. For them, no energy is created or destroyed, they are never duplicated, just displaced along a time-like curve (which is essentially time that ‘flows’ with a different vector to normal space-time).

      By considering that the energy is created at some point in the past (rather than just arriving) you are suggesting the universe at that moment in time is isolated, but the time portal belies that hypothesis, the fact it exists opens your closed system and allows time-travel to occur without invoking any paradox through mass-energy conservation.

      In short, you can open the door and step from the kitchen to living room and back, because along your reference frame energy is conserved.

  4. Having accepted your argument that the energy swap idea would allow for my displacement in time that makes me wonder if time travel isn’t just a matter of reorganizing the particles that I’m made up of now into me in the past hence I could indeed be in two places at once since the particles that make me up are in constant flux except it’s likely those would be the same particles that would be swapped out to make the time travel possible in the first place. Hhhmmm

      1. OK maybe swap was a bad choice of word but if I displace my energy into past by one sec then energy from one sec in the past would have to be displaced to the point at which I left would it not in order for the equation to balance? Hence the choice of swap. I can see an energy flow going both ways through the wormhole or whatever conduit ends up being the mechanism. And again thanks for taking the time to carry on this discussion. I find it interesting and hardly every find anyone willing to discuss the things I find interesting. I should have become an astrophysicist when it was suggested to me but no that’s not the thing I want to change but hey if I’m changing stuff….lol

  5. I’ll accept that I’m thinking about it incorrectly and that it would probably take more of your time to explain it to me than it would to actually figure out how to go back in time. lol But if you do then drop the info on me and we can avoid this whole conversation.

  6. What is time? The most usual answer is that it is the 4th dimension. So, what is a dimension?
    A dimension is a measurement from one point to another. This can be done along 3 different axes so we say there are 3 dimensions; forward/backwards, up/down and sideways. These dimensions measure the distance between points. The distance between 2 points is the SPACE between 2 points. Time does not measure SPACE so it is NOT a dimension like the other 3. Time is the description of a change of relationship between objects in Space. The Earth (an object in Space) goes once around the Sun (another object in Space) and we call that a Year, That is, we describe the change in relationship between those 2 objects as one Year – we say that a period of time, namely one year has passed.
    Time is not a dimension. Time is not a thing. Time cannot be travelled thru.

    1. Hi Leo, This is true – I think it was HG Wells who first described time as a dimension and based his novel on the concept that you could travel through time as you could travel through the spatial dimensions. Although it’s a black box time travel method, he proposed a ‘twisting’ of the dimensions so that the temporal dimension of time mapped itself onto the spatial dimensions which allows travel through time as one might travel through space.

      Perhaps we could then ask what is a dimension? Wikipedia defines a dimension as “the minimum number of coordinates needed to specify any point within it”. Admittedly this does sound as though it limits the concept of a dimension to space, but the page goes on to argue that the temporal dimension of time can be used as a descriptor and a measure of physical change.

      I do concede though that the difference between a dimension and an adjective is somewhat fuzzy! As for what time is – now that’s a very difficult question in both physics and philosophy!

      1. Time is often referred to as the “fourth dimension” for this reason, but that is not to imply that it is a spatial dimension. A temporal dimension is one way to measure physical change. It is perceived differently from the three spatial dimensions in that there is only one of it, and that we cannot move freely in time but subjectively move in one direction – Wikipedia,

      2. “and that we cannot move freely in time but subjectively move in one direction” Ah yes. I’d overlooked that bit…

        Perhaps then, this is the case as it stands now; the arrow of time is one way. But much like the sound barrier, for example, couldn’t be broken a hundred years ago (there was no technology to facilitate such speeds), it is possible now. So could time travel be possible in the future, as supersonic speeds are today? I guess maybe not. It was a technological barrier which needed to be broken first, not a thermodynamic law of physics.

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