# Quick time travel question

1. Mar 6, 2004

### aychamo

Hey guys

I have a quick time travel question. Some people say that we will never be able to travel in time because if we were able to then someone would have already traveled back in time to tell us that it is indeed possible. They say that since this has not happened, then we will never travel in time.

Personally, I think this is poor logic, but it raises a question. It is hard for me to put it into words. Like, say I invented a time machine and travled to the 60s and met Lennon before the Beatles were famous, that would be possible because the 60s have already passed. We are at the leading edge of time. I guess what I'm saying is how do we know that whatever is about to happen has not already happened?

Like whatever happens next is unknown. If there exists a future in front of us, wouldnt that get rid of our "free will"? Like if there is a future that has already passed that contains a time when a time machine is invented, that means that whatever happens immediately next in my life has already passed and I have no control over.

Or it means that our present has already passed. How do we know that we are the first time through whatever has happened?

Argh, this is hard to write. Like, if we use the argument at the beginning of this post, how can we know that there even is a future, that we aren't the first set of whatever to pass through this time. We may be the future that indeed invents the time machine. Do you see what I'm saying?

2. Mar 6, 2004

### AWolf

Time is determined by the movement of particulate energy.
Energy takes an amount of time to move, once it has moved thats it time has elapsed and the energy will move again.

To go backwards in time you would have arrange all the energy into the position it was in at the moment in time you wanted to travel to, but it would not be the past, it would be now with the appearance of the past.
If once you had created this past time you did something to change what happened originally, when you rearranged all the energy again for your present time there would be no record of what you did because you didn't do it then, you did it now.

The same is true of the future. You could only create an appearance of the future.

I hope that makes sense.

3. Mar 6, 2004

### EL

I´m traveling in time every day!=)

4. Mar 6, 2004

### LURCH

Oh, the paradoxes of time travel!

his bit of reasoning:

Has some validity to it, but only limits the possible range of time-travel. If we were to accept this as correct, it would mean that we will only be able to travel through those areas of time in which time-travel exists. Many schemes of time-travel make use of a sending and a recieving station. So one could only travel into the past as far as the invention of the time machine, or there would be no reciever to rematerialize the traveler.

But let's look at this:
Try reversing your point of view. If you were in the '60s, you would still see yourself as being at the "present", and nobody from the 21st cantury coul;d visit you because the 21st century does not yet exist. So this statement:
Holds equally true for somone in what we call "the past" as it does for us. To a traveller from the future, this decade has already passed.