rachel on 11/5/2007 at 16:13
I don't get that "bigger than the universe thing", can you explain?
A machine that protects itself from the effects of time travels effectively excludes itself from the universe for as long as the "travel" lasts. It is not necessarily bigger.
Think of it like a diver's bell. It preserves a bubble of universe outside of that universe, and reestablishes contact at the end of the journey. Its size is irrelevant.
Volca on 11/5/2007 at 16:52
Quote Posted by sparhawk
Yes, but seem my other post. What is this "stuff" that is moving along this axis, to give us the sensation of NOW?
As BR796164 written, better said by himself, it is the perception of change, the comparison of the state with the state remembered. If there would be no change happening, then you could not tell if the time is running or not. For example being closed in a totally dark room, not able to move, you can hardly tell how much time passed. I would think people learn to percept time the same way they learn to see.
Quote Posted by sparhawk
Yes. That was the line of thought that made me thinking what would happen with such a machine, and it lead to my conclusion that such a machine couldn't work, because it would immediately cancel itself out. Even if we could assume a machine that is protected against this effect, then it shouldn't work farther then the machine started to get to the point where the actual time reversing process would start, because I would have to take it with me, to get any further backward in time, but since I'm not protected against this, and the machine is, then it wouldn't work. Now if the machine would also protect me, where does it stop? What about the environment the machine is located in? How much of that would need to be preserved. That goes soon into the "Bigger then the universe" problem again. :)
Yes, the machine would have to be able to isolate itself, like black holes are.
That always suprises me in the movies. Sometimes the machine goes with you, sometimes it's just the human itself that is moved to another time. Same goes with teleports - how does the machine know what I am? Am I only the flesh, or even the clothes I wear, the stuff in my stomach, air around me? Sometimes they solve this by putting the human in a special chamber, and the contents of that chamber are transported.
About the self - canceling effect. It seems you're right about that. If the machine would be linear, not doing direct skip in time. Maybe there is some way of doing this by skipping, not smoothly. I've read somewhere that you could skip back in time if a certain amount of matter vanished from existence very quickly, causing a gravity wave.
Volca on 11/5/2007 at 16:59
Quote Posted by BR796164
Because future people are careful enough not to reveal that fact to inferior previous generations! Proof of inferiority of you folks? You live in naive consumerist society which teaches you from the crib that everything can be eventually bought for entertainment purposes of common masses. Well forget about that! Can you comprehend the importance and sense of time travelling in the future? No. The first law of time travelling is :
Do not interfere!Now that I have revealed this biggest secret in human history to you, they won't let me back to the future!
I am doomed to live with these savages until the rest of my days. Oh drat... :nono:
:) Well, there always is some bad guy, ignoring the rules. Heck, even star-trek captains sometimes interfere with the local life forms :confused:
sparhawk on 11/5/2007 at 18:25
Quote Posted by BR796164
Remove intelligent beings with such ability and you have no time, since there would be nobody to recognize and sophictically define such intangible constant.
I know that there is this anthropocentic unvierse, but this doesn't really work. Chemical reactions happen all the time, even if no intelligent observer is there. Particle interactions also work when there is no observer, otherwise we wouldn't be here in the first place.
sparhawk on 11/5/2007 at 18:52
Quote Posted by raph
I don't get that "bigger than the universe thing", can you explain?
A machine that protects itself from the effects of time travels effectively excludes itself from the universe for as long as the "travel" lasts. It is not necessarily bigger.
Think of it like a diver's bell. It preserves a bubble of universe
outside of that universe, and reestablishes contact at the end of the journey. Its size is irrelevant.
The probloem is the following: IF a machine would reverse time, by decreasing entropy, it means that it has to cause all involved particles and forces to take the route in the reverse order. Suppose we only do this for a local space. What happens to "stuff" that is outside this local space? As long as they are outside, they would move normal in time, but if their trajectory sets them on a course that crosses our local space, then it would be reversed as well. You can not simply exclude such interactions, because they might have an impact. Suppose we have a meteorite impact and we are going back in time before that. Obviously that impact must also be reveresed. So we can not take a small space to reverse time. But if such a meteorite came from deep space, then we would have to include this as well in our reversal. So this goes back and back. Depending on how far exctly and what effects need to be considered. In the end it would mean that the entire universe would have to be rewinded, which would mean that this machine would have to be "bigger" then the universe to do this. :)
If we only move back a local space, then the question would also be, how much of this local space is required? If you only include earth, and you turn back the time about 8 hours ago, then the balance in our solar system might be unbalanced. So this would suggest that at least our solar system would have to be considered as a minimum.
Vivian on 11/5/2007 at 18:57
no BR's got a point. We observe things like chemical reactions happening because we ARE in effect traveling through time - going forwards. Like if you're flying over a country, you see the landscape below you change into lakes, into forest, into cities. If you are stationary, or going in the other direction, you see different things happening, or nothing happening at all. If you are far enough away and have clear enough vision, you see the entire thing and realise that you have just been panning across a landscape, not seeing things trangsmogerify.
SOOO, if an observer with a fixed time-motion is not present you cannot say which direction chemical reactions will happen in, if they will happen at all, if the entire history of every particle involved is just spread out like cosmic silly string.
sparhawk on 11/5/2007 at 20:38
Quote Posted by Volca
As BR796164 written, better said by himself, it is the perception of change, the comparison of the state with the state remembered. If there would be no change happening, then you could not tell if the time is running or not. For example being closed in a totally dark room, not able to move, you can hardly tell how much time passed. I would think people learn to percept time the same way they learn to see.
So we assume that we have this room without anyone being able to look into it. Now we place a particle inside, where we know that it has an average liftime of 1 hour before it decays. So we look into this room after two hours and find it gone. Does this mean that time has passed inside it or not? I don't think that the universe needs an intelligent being to tick. :)
Quote:
That always suprises me in the movies. Sometimes the machine goes with you, sometimes it's just the human itself that is moved to another time. Same goes with teleports - how does the machine know what I am? Am I only the flesh, or even the clothes I wear, the stuff in my stomach, air around me? Sometimes they solve this by putting the human in a special chamber, and the contents of that chamber are transported.
Yes, that's indeed some puzzle. :) Even if it is put into a seperate chamber, then how does the machine know which molecules belong to the chamberwall and which are not? On the molecular level there is not such a clear distinction anymore, to seperate two objects.
Quote:
About the self - canceling effect. It seems you're right about that. If the machine would be linear, not doing direct skip in time. Maybe there is some way of doing this by skipping, not smoothly. I've read somewhere that you could skip back in time if a certain amount of matter vanished from existence very quickly, causing a gravity wave.
Well, but even this would have to take some time. Instant vanishing could mean in that case in planck time, as there is, according to current understanding, no shorter timeintervall possible.
sparhawk on 11/5/2007 at 20:41
Quote Posted by Uncle Bacon
SOOO, if an observer with a fixed time-motion is not present you cannot say which direction chemical reactions will happen in, if they will happen at all, if the entire history of every particle involved is just spread out like cosmic silly string.
Which would lead to theother assumption that I posted in the original thread, having a static universe, where everything, in the future and the past would already be fixed in spacetime, and we macroscopic observers would, so to speak, move over the coordinates of that spacetime.
Martin Karne on 11/5/2007 at 22:33
Sorry I've got no time to waste discussing about time travel, my time travel trip begins in two hours.
SD on 11/5/2007 at 22:52
Everyone's talking over the fundamental issue here; does time travel follow "Terminator rules", "Back to the Future rules" or "Timerider rules"?
