Back To The Past?

[MrPresident]

Welcome to the world of the paradox. Is time travel possible? If I go back in time and kill my grandfather then I don't exist so I couldn't go back and kill my grandfather but then I do exist and so on. So can people go back in time (or even forward in time)? What do you think?

 

[Arioch]

Clearly time-travel is not possible within one 'reality'. For any Pratchett readers please consider the 'trousers of time' - as an event occured in one reality the time-traveler would shift to the alternate reality and so on.

I'm sure there are some proper physics theories to deal with this but I suck at physics.

 

[nixon]

No, it's not possible. I don't know how the so-called scientists have gotten the idea that this is possible.

 

[Padma]

Originally posted by nixon
No, it's not possible. I don't know how the so-called scientists have gotten the idea that this is possible.

Mathematically it is definitely possible. I don't claim to be any sort of high-powered mathametician, but in my reading on the subject of Einstein's theories, as well as quantum mechanics, and other more recent theories, the solutions for some equations indicate that time travel, if not necessarily required is certainly not disallowed. This has been understood for decades.

Of course, in the heady world of theoretical physics, just because the equations balance when you add time travel it doesn't mean that there are any practical applications for it. What if only "non-physical" particles can travel through time? What if the only time-travel "direction" is forward? And so on.

 

[stormerne]

Strictly speaking, we already travel in time, in one direction and at a fixed rate. Nevertheless what I think the questioner is asking is "Can we change that direction of our time travel?" and what he should be including too is "Can we change the rate of our time travel?"

It is theoretically possible to effectively travel in time by accelerating towards the speed of light (you don't actually have to reach it or even come close). However this is time perception for the speedy time appears to pass at a different rate to static people, as measured by their respective watches.

Forget the paradox. The old adage says it's impossible to travel backwards in time because otherwise we would have had records of people from the future travelling back to see us. However, if it were possible to travel forwards in time but not backwards, we'd never know would we - at least not until that one-way transport had been invented.

 

[Hitro]

Originally posted by stormerne
The old adage says it's impossible to travel backwards in time because otherwise we would have had records of people from the future travelling back to see us.

I also believe it's not possible to travel backwards for that reason.
But there's one uncertainty about that. It's not possible for us now and if we exterminate ourselves in the next years we will never come to the point of developing a technology for it, even if it was possible. That could explain the missing visitors from the future.

 

[G-Man]

I once read a theory saying it's possible and whatever you do in the past can't affect the future. That is, you might go to the past but you won't be able to find your grandfather or you'll be too scared to kill him. All distruptions caused by what you do in the past will slowly disappear untill the time you were launched from, as at that time they won't have any affect at all. Interesting theory. I think there's an adventure book about such a thing.

 

[G-Man]

Originally posted by stormerne
The old adage says it's impossible to travel backwards in time because otherwise we would have had records of people from the future travelling back to see us. However, if it were possible to travel forwards in time but not backwards, we'd never know would we - at least not until that one-way transport had been invented.

I think if someone from the future would come here he would've been smart enough (or atleast instructed enough) not to come to us and tell us something like "Hey, my name is Bill and I'm from the 25th century". And if you do believe people who say that, you can find a lot of them, Right next to those abducted by aliens

 

[IceBlaZe]

I heard/read/shepherd 2 interesting theories:

1. If you travel by time, you will end up in a different dimension. Therfor you won't see any people, you will reach an "Empty" world, where nothing occures, or where everything is different.

2. Time travel is possible with black holes. There is this theory that a black hole is shaped like a funnel, and that in the end of the funnel there is an exit that is in the width of one atom. The theory says, that since a black hole vacuums everything with its enormous gravitation, the only thing that can hold it is a virtual "cage" made by anti-matter. When you get a hold of anti-matter, and you "cage" the black hole in it, you move it untill it's end connects to the end of another black hole creating a time-warp passage that is as wide as one atom. Now, to expand it, you must pass anti-matter through it, and expand it to the correct size. When you do that, it becomes wide enough to pass through, and you reach a different point in time, or a very far spot in the universe.

But I am too stupid to fully understand all this ****.

 

[IceBlaZe]

Here it is: http://www.popsci.com/popsci/science/article/0,12543,211498-1,00.html

 

[Switch625]

Time travel makes for a good story, but, other than relativistic effects, it is not possible in any practical way. That is, other than in esoteric mathematical theories. Time travel = not possible.

 

[amadeus]

Time travel is possible in the neurological sense. If you can alter the brain waves to believe you are at a certain point in time, I'm certain it's possible. A kind of "Total Recall" type of thing, only without the immense screwings-up

 

[CornMaster]

Oh yeah......it can happen.

And many people think the US did in 1946 (or something) with the Philidelpha Experiment. Where two people went to the year 1984 (or 1982) and were dropped off near a lab. Then they remember seeing the IBM computers and mainframes, etc....

Then they were given radition suits and sent back through time (don't recall how) and they appeared back on the ship when the initial experiment too place. They claim everyone else on the ship had gone insane. (due to the huge radition that was given off)

I watched it on TNN's Conspirory Zone show. Interesting....but I don't think so.

It's easy to say you saw IBM laptops in 1984 in 2002!!! But not at the time. Of course this was a government experiment and they say it was all covered up. Anyway....that's the reason there were no copper pennies minted in 1946.

 

[Rodgers]

Time travel is definately possible - simply catch a train to Barnsley and - hey presto! - you have returned to the middle ages

 

[insurgent]

4 dimensions.
3 dimensions: the dimensions of length and space; width, height, depth.
The fourth dimension is time.
We can travel in three of the dimensions, so logically we would also be able to travel in the fourth.
But with the moderns science it is, of course, not possible. Some day we might learn it. But I'm not sure about the implications...

 

[philippe]

hmm then it would be a matter to make anti-matter
i think it would be fun to travel in time but it will NEVER be possible.NEVER.

 

[amadeus]

I'd be somewhat afraid of going through time...what if you went through time and ended up stuck in the middle of a wall, or something? What about having your head appear in a urinal somewhere?

 

[philippe]

or in the stumach of a whale....

 

[VoodooAce]

Originally posted by rmsharpe
I'd be somewhat afraid of going through time...what if you went through time and ended up stuck in the middle of a wall, or something? What about having your head appear in a urinal somewhere?

Or in the 70's!!

 

[knowltok2]

Originally posted by CornMaster
....that's the reason there were no copper pennies minted in 1946.

Actually it was 1943, and had something to do with a conflict, or fight, or some such thingy on the other side of the oceans.

I don't think time travel is possible. However, if it was:

I believe that you cannot create a paradox. If you tried to shoot your grandfather, something would cause it not to happen. You either wouldn't find him, he would kill you first, you would get hit by a bus, etc.

I have not decided on whether time is divergent or convergent. I suspect convergent, but I also think you could make some pretty big ripples before things smoothed back out.