Do you think it's possible?
If you have a Delorean
and some plutonium
Yeah and then you just need to accelerate to 88 MPH :D
Ok, I love that movie, in fact Back to the Future is one of my favories.
But my question is somewhat serious.
Imho time travel maybe possible but only for traveling to the past. I think future isn't determined yet so you cannot go there. On the other hand, going to the past and changing only a minor thing can lead to huge effects on the present. Just is you go to the past, you've already changed it.
You know the chaos theory. :)
Anyway wether it is possible or not I think time travel remains in the world of sf for a couple more centuries.
I watched a whole show on this on either Discovery, Learning Channel, or oddly enough, History Channel. Maybe I watched it on Nova back when I was still watching Nova.
Anyway, they talked about Einsteinian physics and said that as far as we understand the universe time travel is inherently possible. Science has accepted that. But, what does that mean? Is it possible to go back in time to kill your grandfather before your father is born? That's the paradox question that comes up every time you get into time travel.
The rest is left up to science fiction because science has no answers.
Once we invent the Flux Capacitor...
>>6 Nah, the flux capacitor is most likely a simple wave generator.
I'm more worried about the 1.21 gigawatts of power needed...
We don't have portable plutonium-powered nuclear reactors currently.
>>8 But Mr. Fusion is in the future... TIME PARADOX!
Back to the topic (oh dear god no!! I didn't mean to)
I don't believe so. I'm too tired to explain it, but I thought about it enough to right a 3 copy page essay on it last year.
Good times ^_^
At least thirty years back, there were some papers published discussing the possiblity. I mean scholarly papers, from physicists, who were looking at the mathematical models in Einstein's theory of relativity and examining them under unnatural, possibly impossible conditions.
Google for "Tipler machine," "Kerr metric space warp," or "closed timelike curve" and you will see some very brilliant stuff.
I don't know whether any of it was ever found to be mathematically inconsistent with relativity, or proven to be mathematically impossible, though the reduction-to-practice aspects are daunting.
A Kerr metric space warp, for instance, would require the mass of a star crammed into a superdense black whole whose core was not in the natural spherical shape that gravity would push it into, but, rather, a torus--a ring, in other words--that was spinning at almost the speed of light. Pass through the center, go into the past. Or something like that. It's a fascinating idea but you can't exactly build one in the garage.
>>10 Time travel is a reality. I'm travelling in time right now. And so do you. At 1x speed.
Your humble opinion is completely wrong. Time travel into the future is very easy. Besides the fact that you're travelling there right now, simple special relativity tells you that if you're in a hurry, you just need to go move very fast and you'll get there quicker. Once you're there, though, you're stuck.
Unless the esoteric relativistic solutions like >>11 mentions ever turn out to be feasible, but that's very uncertain. Those are, however, not exactly "time machines", but something much, much stranger.
Using what I've heard and read of time travel and parallel universes, most likely what would be experienced in time travel is just going to a universe that is however far back as you think you've traveled (say 2006 to 1920s, just 86 years behind ours). Because of this, coming back here will show no know changes because it affected another world entirely.
I'm guessing of course.
>>13 Yeah. There is also gravitational time dilation: for example the GPS satellites we have in orbit have their clocks running behind. I guess one could say that the satellites are time-travelling into the past, by a minute amount.
GPS satellites, as they are orbiting or just falling through the vaccum of space, aren't affected (or very little) of gravity. Somehow matter moves at a slower pace when not under gravity. So clocks on satellites tend to stay behind earth-time and need to become updated in a periodic basis.
I think that beings tend to live a little longer when in weightlesness.
I don't know wether time-travel will ever be possible or not. But I have been experimenting a little bit with myself as of how time shifts according to situations. Whenever I sleep with my music on, I can unconciously hear it (sometimes) and notice a faster beat rate, meaning that the music goes faster than what you are accustomed to hear. Therefore, I can say that my body is moving at a slower rate, because it is in sleep mode, and time moves faster. I remember that I once was listening to music when suddenly the phone rang. And because it is located at the other end of my home, I had to run. Once I hung up I continued to listen to my music, but noticed it was moving slower. It seemed that, under that desperate situation, my body modified its biological clock and made time go slower, hence making the music become slower and have a lower pitch.
Maybe different situations make our body change its biological clock to respond correctly and more efficiently to them.
What do you think?
I think biological clocks have as much to do with time travel as sunglasses with have with nuclear fusion.
>>17 Lol. Good analogy.
Yes, time travel is possible under Einsteinian physics. Unfortunately we have no clue how it works nor how to move backwards through time. Since to move backwards in time forces us to break the speed of light, which also under Einsteinian physics is impossible. Tests have shown however that time travel is possible. We have tested and measured small instances of slowing time, most notably through the use of atomic clocks placed in orbit.
You are technically correct that we have "tested and measured small instances of slowing time", but this really is a bit misleading. Not only are experiments confirming this (by necessity) done every day, but many everyday occurances depend on it - notably, GPS navigation.
Adding to my comment >>15, "time travel into the past", I'm still not sure of my assertion. Is it the GPS clock that moves backward in time, or is it the clock on the ground that moves (fast)forward in time?
I think you're misunderstanding. Both are moving in time at the same speed according to the effects of both gravity and motion. Since according to Einsteinian physics the closer you are to a gravitational center the slower you move in time. Also the faster you travel the slower you move in time.
By moving an object away from the center of gravity (Earth) you are minutely moving it faster through time. But! The effects of being away from the center of the earth is negligable compared to the effects of traveling at high speed that slows it down.
Once one atomic clock is seperated from the other and placed in orbit it begins to move at a different rate through time. It's not much but it is measurable because atomic clocks are amazingly accurate.
So to answer you, neither atomic clock (you call them GPS clocks but I imagine you meant atomic clocks) is moving forward or backward in time. They are both moving forward in time at different rates, the one in orbit moves slightly slower through time then the one on the ground because it's slowing time as it approaches the speed of light.
People... "time" doesnt exist...
its invented by humans to make life a little easier, like: "hey lets meet at 7 ok?"
the so called "ageing" is just a procces off cells breaking down
so how can time traveling be possible is there isnt even time to travel with?
sigh but anyway its getting late and its time to go, see you next time!
>>21 Okay, but which time should a time traveller sync his clock to? I suppose that with the Moon orbiting Earth, they are variations in the atomic clocks on the ground as well. Also planets/the Sun moving closer or away. Don't those ground clocks get out of sync with each other at times? Or not?
Yes, a clock set on the moon will move at a different rate then one on Earth, or the Sun, or Jupiter, or wherever it's placed. It's unavoidable. We do the best we can with what we've got though and right now since Greenich standard time is universal on Earth you can assume that it's universal in the Galaxy (assuming of course that we're all there is in intelligent life). Any clock which gets out of sync presumably would be reset to GMT whenever possible.
Since interstellar travel is still a dream we don't know exactly what happens when people begin traveling through space and colonizing other worlds. Right now it's left to science fiction how to handle clocks in that future.
The basic principle of relativity is that there is no preferred reference frame. That is to say, there is no clock to sync to. All clocks run different, and there's nothing you can do about it, except choose an arbitary one to call your standard time. Even if you do, it won't have anything to do with any deeper aspect of reality, it will just be bookkeeping for yourself.
You should also realize that this goes further than that. The concept of "simultaneity" doesn't exist, either. The concept of two things happening in different place simultaneously is meaningless, because this is also dependent on your reference frame (that is, the speed you're moving at, gravity, and such). Things can only happen at the same time if they also happen in the same place.
This is a pain in the ass to wrap your head around, but unfortunately it's how the universe works.
There is another way of timetravelling into the future that hasn't been mentioned above yet, and that's temperature.
For example, food in the fridge decays slower that in the heat.
So this is yet another factor that could influence an atomic clock, isn't it?
Are those forward-timetravel factors (gravity + speed + cold) cumulative?
> But! The effects of being away from the center of the earth is negligable compared to the effects of traveling at high speed that slows it down.
But! all movement is relative, so it isn't actually moving at all.
Cold only slows down the atoms. I don't believe cold has anything to do with slowing time to any degree. It's used to preserve foods because it keeps bacteria and molds inactive.
No. Lay off the acid.
>>28 Wait, wait... if cold is slowing down the atoms, why has it no influence on an atomic clock?
>>30
No. Lay off the acid.