is it true a time machine has never been invented now or in the future?

Question

I was told that a time machine hasn't and will never be invented, because if it had been we would know (e.g. they would have come back and we would be aware of the time travellers existence) the bit I can't get is, say the machine is invented in the year 4000ad, in the future ,so it hasn't been invented yet, how can we know it won't be invented then and go back and change history? If they go back from the year 4000ad and kill Hitler then this would obviously change history so the fact that no historical event ever mentions people from future does this mean it will never happen or just not yet?
Stupid question I know but I can't get mey head round it.

Answer 1

there is a lot we dont know about time travel and there is many thoeries.

But what youe saying is right if someone had come from the future and changed our past then it would alredy be like that to us.

So theoretically someone may have alredy changed our past and we don't know about it.

To all nay-sayers and the comments about linear time, some of us would agree that tomorrow hasn't happend yet,
But imagin that you could go back to last week, to you 'today' is very real, to all around you its 'undecided'
whos to say that we carn't visit a time in the future?

*EDIT*

Not realy an answer to your question but an interesting fact,

Time travel is real and actualy has alredy been done!
Time is relative to each and every person and place, this means between different places time is moving faster or slower (not by much tho) so the top off a mountain being further away from the earth gravitional field would be moving that little bit quicker, (0.000001 of a second).
If you can use that time difference (for example one person stays up there and one on the ground) then that person has time traveled into the future. (because the guy on the mountain has gone fowards a few seconds everyday without doing anything.

Interesting but utterly useless

Answer 2

The point is we don't know if they have changed history, we would never know, because if history changed our past would have changed as well, and our memories, the history books would also change and we wouldn't realize anything had changed, no matter how many times it happened.

If time travel becomes possible, it doesn't mean that the people of that time would be aware of the person from the future, so in this current time there may be millions of school children from the year 310,916, visiting our time for their history lesson, but it is impossible to change the pass, so they can only observe, they cannot change anything.

Hope that clarifies the situation for you.
If history changed we would be unaware of it.
If time travel becomes possible, they may not be able to change history.

In other words we can never know if time travel will ever become possible, or even if it was possible in the past, and is being done today.

It is actually a good question, the person who told you time machines (and therefore time travel) would never be invented, hadn't thought through the problem properly.

If you watched the episode of Doctor who, where he wasn't present for most of the story, and the statues were attacking people and sending them back in time. That made some good points about time travel.

Answer 3

There are two major problems with time travel.

THe first, and most obvious, is the physics side of things. The closest you can possibly get is the slowing of time when a particle acclerates to the speed of light, but the reality is that it's the particles age the changes, not the world around it.

The second is causality. The theory that eerything you do has untold knock on effects.

Imagine this, in the first time span, the time machine is invented. You go back and do something that has repercussion after repercussion. Dont to something like, the scientist who invents it, you meet him, tell him about the invention and it terrifies him. He stops all work and instantenously, you would, in theory, cease to exist because he would never have invented the machine in the first place.

The argument then is that if he never invented the machine, you couldnt have gone back and told him about it, so he would have invented it anyway, at which point you'd back again telling him he invented it, at which point he panics and stop research .... ad infinitum.

You just can't do it.

Answer 4

You cannot invent a time machine, based upon the 1/1 cause-affect ratio in place.

In other words, you can't invent a time machine to travel back and see your birth (for example, and if it is false in one example, it becomes false in every other) because at the time/period of your actual birth, you were being born (an object cannot occupy two places at the same time. Therefore, any 'event' you would travel to would, in fact, be an alternate reality, whose consequences would have no bearing whatsoever upon the main 'reality' from which you came from. In other words, you can't exist in a place you don't exist first.

Theoretically, you can make a time jumping machine, but that is like inventing a dead adult: following the normal processes, you will get to the future anyway. And jumping 1000 years into the future would be as inappropriate as Columbus jumping 1000 years into the future: no such preparation for the world he would be landing in.

Answer 5

It's impossible to change the past, because anything you did when you travelled back to it has already been done. That aside, the actual thinking - given that this topic is highly theoretical and unlikely to ever come to fruition - is that a time machine would have the capacity to transport matter back to any point in time after the machine was turned on. In other words, by turning on the machine, you are defining the very earliest point to which it may take any given object.

This is, however, likely to be replaced by an even stranger hypothesis within the year.

Answer 6

I suppose the simple answer is, if time travel does become possible at some future date and someone did come back and change history, would we know about it because history would be as it is not as it was?

To turn your example on its head supposing Corporal Hitler had died during the first world war and some neo nazi from the future came back and saved him, the history we now know would have been entirely different, but would we be any the wiser?

Having said that I do not believe time travel is possible, certainly not in any physical sense, but then that would also depend on what our concept of time is and how we perceived it.

Answer 7

If the time line is a linear progression then you are right... but if time is linear then the future has not happened yet. If time is non-linear, in that every moment can exist it may be possible to change the past. If the future has yet to happen then we can only go back from now.... but as we don't know whether time is linear or not we'll never know... and it maybe that the folks from the future are so clever we never know if they've changed anything as time for us as individuals seems linear. For all we know Hitler won the war and someone went back in time and changed history so he' d lose.

Answer 8

Let's say someone in the future had a time machine and went back to 1889 and killed Hitler at birth. That would permanently alter the future from that point on. WWII (as we know it) would not occur. So, we would never know that anything changed and that someone in a time machine came back and altered history.

Even so, I don't believe a time machine could really work, because I believe that once time has passed there is no way to physically go back to that exact time.

Answer 9

This will answer all of your questions about time travel: http://en.wikipedia.org/wiki/Time_travel

As regards your specific premise - that the proof that time travel isn't possible is that nobody from our technologically advanced future has played space tourist and popped in to say hi - I believe is a true statement. You explain this away by saying they come back and visit but do so stealthily all the while altering history. I don't think visitors from the future would be able to return to our present without causing a big stir somehow, but that's just my take.

Answer 10

I saw a documentary about a scientist who says he is quite close to inventing some sort of time machine. His research is very interesting, he is currently running experiments to try and send atoms back in time. His theory is that we will only be able to go back as far as the day when the machine was first built and activated, as the machine is a static object, not a mobile teleportation device as such.