Time Travel

[AngloScot]

Has anybody ever made a serious attempt to buid a time machine?

[the freak]

I have.It worked.Now I have a tribe of cavemen hidden under my bed. Ssh! I shouldn't have told you that.

[ll_billym]

http://www.physics.uconn.edu/~mallett/

[Hippy]

I've seen this question before!

[delapeyre64]

In the biggining there was nothing then the big bang, So from nothing came everything. Which means everything is posible including time travel!

[Phantaxus]

actually one answer to the where are all the time travellers question is that you would not be able to use a time machine to travel back beyond the point of its own creation. So the bookies are safe for a while!

[delapeyre64]

Love the answers! what a delema, Most of the visable stars we see at night arent actually the way we perceive them as you all know light is relativly slow in getting to us. So we are perceiving the past right now!

[QmunkE]

You might be able to build some sort of dimension hopping machine a-la "Sliders". In theory, there exist an infinite number of universes due to the different paths that events could unfold along. So, there should be an infinite number of identical universes to our own, each at an infinitesimally different point in time. Unfortunately, there are also an infinite number of different universes that are completely different.

Have fun sorting them out.

[QmunkE]

For travelling backwards in time, you would have to assume that all history is predetermined:

You travel back in time. This means that from the point of view of the time you travel back to, the future has already occurred, hence the future is already written.

Travelling forwards in time is "easy" enough - if you can withstand travelling at very near the speed of light, once you slow down the rest of the universe will have experienced more time than you, due to special relativity.

[PunkDaddy]

To travel back in time the future doesn't have to be predetermined, it just has to have possibilities. If I get my wife pregnant, the possibility is she will have a baby, if I don't she won't (hopefully, or we'll be having words). Every action has a possible reaction or several possible reactions.

[QmunkE]

Say you travel back in time to see your great-great-grandfather. To him, the future must have already happened, otherwise how could you be there? And if following your arrival he attempted to change the future to prevent your birth, this would result in your not travelling back in time to see him, which would result in him never trying to change the future...

Unless of course, you aren't actually travelling in time, only in dimensions, in which case if you return to your own dimension you won't notice any change in the causality series.

[Backdrifter]

QmunkE, not to mention the fact that if someone tried to prevent your birth in the past you would never had made the journey back in the 1st place. Or something.

[QmunkE]

I did mention that, in fact.

[dunlop]

how can everything come from nothing?? surely if there were ever nothing then there would still be nothing now! you cant make something out of nothing!