Do you think it's possible?
>>132-134
all motion is relative, only acceleration is relevant in this case. also, it's quite possible that earth's gravitational field might cause the time machine to follow earth.
Well,... Time travel could be seen as a form of acceleration in space-time. In which case some of this acceleration might result in the problems mentioned... Or not.
>>132
That is very interesting. If you think of time like a space dimension, then jumping forward or backward in time faster than the rate we are going now, is like traveling faster than light. So a time machine is an FTL drive. Cool.
And FTL drives are like time machines? And time travel is full of paradox, so it is impossible. Therefore faster than light travel is not possible...so much for humanity taking over the galaxy.
Actually come to think of it again...we can assume that time travel into the past is impossible and so warp drives would be like going forward in time really fast. Fini.
>>warp drives would be like going forward in time really fast. Fini.
lolwut
srsly, ever heard of the theory of relativity?
>>138
Theory of relativity only deals with sub-light travel. I can make up whatever the hell I want to wrt faster than light travel.
Anyway, I don't know what you are talking about. Explain please.
It's hard enough to get <i>to</i> the speed of light, let alone past it. From the Usenet Physics FAQ:
It is a consequence of relativity that the energy of a particle of rest mass m moving with speed v is given by
E = mc^2/sqrt(1 - v^2/c^2) As the speed approaches the speed of light the energy approaches infinity. Hence is should be impossible to accelerate an object with rest mass to the speed of light and particles with zero rest mass must always go at exactly the speed of light otherwise they would have no energy.
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html
However, none of that explains why time only flows in one direction
>>140
As I said, that only deals with sub-light stuff and using actual down-to-Einstenian-mechanics forces. You can't just use good old classic mechanics when talking about time travel and say oh noes, FTL (faster than light) is impossible.
There could well be a way to "jump" to FTL space and skip the whole energy going to infinity problem. And what I said before was compare going jumping forward (or whatever direction) in space faster than light to jumping forward in time, oh, faster than the current pace time is going. I just never thought of it like that before.
>>141
Time paradox.
it is possible. If i get a plane to somewhere far away, i'll find myself in tomorow or yesterday, lol.
>Time paradox.
That's no answer,... You could imagine a boatload of Space paradoxes (ubiquity, or several objects at the same place), none none prevent you from moving in all directions of space.
>>As I said, that only deals with sub-light stuff
>>that only deals with sub-light stuff
>>sub-light
PROTIP: Star Trek is fantasy.
I'm not sure that you can just turn around and move in the opposite direction through time.
Even though time is a dimension, the arrow of time is a consequence of thermodynamics. Since entropy must always increase,
there is an entropy gradient from 'past' to 'future' across the time dimension. Any information-processing device (such as your brain) is subject to the same physical laws as every other object, and increases the total entropy of the universe every time it it performs an operation. So any information-processor must perceive a total increase in entropy through time in one direction only.
This does not preclude the possibility of closed timelike curves.
>>145
PROTOP: This is a thread of time travel.
>>146
You bring up the classic point of linking time and entropy. Thats fine with me, except for two things:
We use entropy to the issue because it's one of the rare physical laws which is not symmetric, and could thus explain the perceived irreversibility of time.
However you don't know for instance which one is the consequence of the other, or if they are both the consequence of a third unknown factor, or if they have nothing to do, but are both instances of irreversible effects.
Also, if bidirectional time travel exists, then it would increase entropy in the past, which in turn would increase entropy in the future. If so, there would be no obvious break in the second thermodynamic law when you time travel.
Finally, and as you hint, you must take into account the whole system, when you assay the increase in entropy, and thus local time jumps would be possible at the expence of entropy increase somewhere else in the system. Basically, we don't know the link between irreversibility of time and entropy, so it's a bit difficult to explain one with the other. But it's a good starting point for speculation,...
>>141
How do you know time only flows in one direction, or at all?
>>148
How would local reversal of time work though? I tried imagining it and I just can't come up with anything that makes sense.
One, you can't just hop into a time machine and watch the world outside reverse itself. The world is huge and it will take an immense amount of energy...if it's even remotely possible, what with all the tiny atoms and energy and stuff.
You can have an isolated system though, and forward and reverse the stuff inside from the outside (now idea how, but it makes sense).
But let's say we have a bit of space where time is going in reverse. If you throw a rock (or yourself) in there, how is it going to interact with the space?
We have trouble understanding time, because we spend all our life immersed in it. It's a bit like air: in the past people did not realised that air is not just space between objects, it's something in itself. Of course there were hints (water/air interface forming bubbles, winds). Nowadays it's much easier to understand air, because we see all the time applications of our knowledge of it (airplanes, etc).
I have no knowledge of reverse-time physics, but it's not a problem in this case, because all your questions equally apply to time flow variations: as you may know, the flow of time you're in depends on the mass surrounding you and on your speed.
So if you are travelling at close to the speed of light, your time will be very different from all surrounding objects which travel at a slower speed. As you can see, you can induce a local variation in the flow of time without requiring infinite amounts of energy. One could extend the reasoning and assume that you can vary the local flow of time to such an extent, that you might locally revert it. The conceptual difficulties are the same in both cases.
As for your question with the rock, you just have to think about black holes. In a black hole the mass is infinite, and the flow of time is ripped apart (and I think nobody knows what's going on inside a blackhole). So if you throw a rock into the black hole, as the rock travels space, the flow of time it is subjected to will slow down until it reaches singularity, and then it's anyone's guess. Some people have even suggested that matter could emerge in other points of space or time through white holes (it's not only time which is ripped apart, but space too).
Oops, I meant to say 'In a black hole the mass DENSITY is infinite,...'
>>151
In my previous post, I was thinking of time as a consequence of the movement of matter and energy but that's not the case obviously, space-time and all that. So you wouldn't need infinite energy to change your perception of time outside you (or your frame of reference). You need to somehow change your frame of reference so that the outside world is reversing to you. Argh, I need to properly understand special relativity to actually begin to make a guess at this.
>>152
Not necessarily. In order for it to be defined as a black hole, the mass density need only be sufficient that light cannot escape.
We are both right, but at different time points,... You are right that mass density does not need to be infinite to CREATE a black hole (otherwise you'd need infinite amounts of matter and there would be no black holes). What really counts is the amount of matter bound by the gravity well. If this amount is enough to cause collapse and a singularity to occur (a black hole), then the mass density will become infinite. This is why it's called a singularity: all the mass collapsed to a single point in space, the singularity, hence mass density is infinite.
All black holes have the same mass density (infinite), what differs is the amount of mass contained within the singularity. The higher the amount of mass, the wider the event horizon (distance from which light cannot escape the black hole).
Special relativity won't get you much. You need general relativity, and that actually intuitively understanding that may require being insane.
On the topic of time and entropy, though, I recently saw the suggestion made that maybe time itself is only a macroscopic property. That would go some way towards explaining why it's so incredibly hard to define a direction of time from the microscopic theories.
What exactly that would mean in practice sure is food for thought, but without a functioning quantum theory of gravity it may be impossible to even speculate.
>On the topic of time and entropy, though, I recently saw the suggestion made that maybe time itself is only a macroscopic property.
Hard to accept that,... Gravity does not play a role at microscopic scales, but space and time do. Particle accelerators show relativistic effects on time affecting the particles. So it seems it's sleight of hand to suddently consider time a macroscopic property.
>>157
That, and also many kinds of subatomic particles have measurable half-lives which are extended by relativistic travel. This seems to contradict the idea that time is a macroscopic property only.
I think that was more specifically the direction of time being a macroscopic effect, or the flow of time.
I don't see why direction would be macroscopic, while flow remains microscopic. That sounds like a heap of ad hoc contrived postulates,...
ITT we get confused because we used English instead of maths.
Why would you say time has a direction, or flow?
Space does not have direction or flow.
> Why would you say time has a direction, or flow?
Direction: from pas to future
Flow: as your speed/mass increases, your times slows down compared to other objects.
> Space does not have direction or flow.
Direction: space has three (proven) directions, that's why we speak of 3D, three dimensions.
Flow: actually space seems to have a flow, since the universe is expanding. According to latest discoveries, this expansion (called inflation) could eventually lead to disintegration of galaxies, stars, etc,...
CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY CAUSALITY
Loud but short of arguments,...
Newtonian physics causality is independent of time direction. If time started going reverse, it would work equally well.
ITT we are wholly unfamiliar with Feynman diagrams.
>>169
No, I am talking specifically about Feynman diagrams, with time as one axis and space as the other, in which one can see plots of wonderfully counterintuitive ideas like an electron bouncing back and forth in time, turning into a positron when it's traveling backwards, and annihilating itself in a flash of gamma rays, which become an electron-positron pair that is the original electron/positron.
>>164,165
I would say time doesn't have a 'flow', because like we move through space, we move through time (if this perspective is not just a product of a weak three-dimensional brain interpreting the world the only way it can).
Unprovable philosophy and nitpicking semantics, I know, but this thread is about time travel. Complete speculation.
> space has three (proven) directions, that's why we speak of 3D, three dimensions.
Whoa, whoa -- slow down, egghead!
Wouldn't time travel backward require undoing entropy?
Not if you increase entropy as you move backwards in time,... this has already been discussed ITT
My bad... just asking.
Scientists still believe in time to such a degree that they suggest it is possible to travel through it, just because they've discovered it's just illusional.
Time and travel is the exact same thing, "time travel" is a pleonasm.
You may create such circumstances, through a variety of ways, that you may percieve you're travelling into the "future", sleeping is an easy and natural way to do this. However you cannot travel into the past because there is no such thing, there is only now, and memories of what we're doing in it in different places and other circumstances. Everything is happening at the same time everywhere, but at different locations, being observed at different places. Things are moving through distance, you're observing it through distance. You get a mental image of what you're looking at now, things move and it changes but it is still now, not in the future, and what you just saw wasn't in the past. You call that time, it's more like movement. The sun setting is movement, the universe expanding is movement, you getting older is movement. Within the limit of what speed things may travel, things may happen "faster or slower", but in the end it all comes down to how we percieve it, which is linked to the functions of our brain. It gives us an illusion of time, just as it gives illusions of colours and sounds, other things that do not actually exist.
You're all just musing over a fictional concept with your fractured apprehension of what is real.
> Scientists ... time ... discovered it's just illusional.
> illusions of colours and sounds, other things that do not actually exist.
'Scientists' have also discovered the phenomenon of your mother being so morbidly obese, the only method by which you could theoretically have escaped her reproductive organs is through thermal radiation with a black body spectrum.
>>176
lol
I guess that's your way of saying, that you think I'm wrong. Why not try to convince me instead?
If time is "illusional" then space is too. So find the frequency of the illusional vibration, put it into a computer and wire someone with it. Hop, a time/space machine. :)
See http://en.wikipedia.org/wiki/Montauk_Project
>>178
nooooo!!!
The frequency of the illusion would be a non-physical energy frequency, there probably is no physical frequency. The only way to do it is to master astral pojection, probably. Very scientific.
>>179
Well, if the person can master astral projections, then he can view the past using the Akashic Records.
http://en.wikipedia.org/wiki/Akashic_records
He would have no need for a time machine.
that was my point. Akashic records, or, just find the past, and go hang out in it, lol. Probably just going to the past would be a better idea... you're not really supposed to use the akashic records for entertainment.
Forgot to add-
The thing that had me interested was the possibility of there being an identifiable energy frequency... if someone could find that, it would maybe be a much more accurate way to time travel astrally, instead of just trying to do it, or ending up in the past somewhat randomly. Though then it seems likely that this frequency is alreadfy tied to the akashic records.... hmmm. Anyway, it sounds like something well worth looking into, for real scientists and astral projectors alike.
Hey guys, what do you think of this? Time travel is like a feedback loop connect back through a second dimension of time. And all the changes and paradoxes can be explained by changes that happen in the feedback loop until it stabilizes.
this is fucking idiotic
"The Cambridge physicist Professor Stephen Hawking spent much of his career attempting to prove that time travel is impossible. If it were possible, he reasoned, why have we not been visited by voyagers from the future? But he was forced to conclude that there is actually nothing in the laws of physics that prevents moving in time.
"He changed his mind about 10 years ago," said Kaku, "There was no way to ban time travel from happening. So now he says that time travel is possible, but not practical."
The way it might work would be to take a trip through a worm hole connecting one point in space and time with another. The laws of physics suggest that the intense gravity of a black hole is enough to rip the fabric of space and time, making a worm hole possible.
"What we physicists want to do is create our own wormhole so that if you walk through the looking glass you may go backwards in time," said Kaku. Stabilising a black hole would require large amounts of an exotic form of energy called negative energy, thought to be impossible. "But we can now make it in the laboratory," said Kaku."
http://www.guardian.co.uk/science/2008/apr/02/sciencenews.physicalsciences
Time doesn't actually exist, it's just a social construction to measure change. Of course time travel is not possible. Assuming the laws of the universe holds true and applies that is.
Space doesn't actually exist, it's just a social construction to measure change. Of course space travel is not possible. Assuming the laws of the universe holds true and applies that is.
>>189
Physics is just a social construction. We don't really know what is going on beyond this superficial socially constructed mathematical model for what we perceive our physical universe to be.
Time is just a concept made up by us to explain changes that happen around us. It doesn't really exist; it's just change. Causality. Which is just a concept constructed by humans. It's just a mathematical model to explain cause and effect. Therefore, time doesn't actually exist.
You're just spouting philosophical rhetoric.
Which is just a concept constructed by humans.
>>190 is just a social construction. We don't really know what is going on beyond this superficial socially constructed mathematical model for what we perceive this message board to be.
4-ch is just a concept made up by us for the lulz. It doesn't really exist; it's just change. Causality. Which is just a concept constructed by humans. It's just a mathematical model to explain cause and effect. Therefore, >>190 doesn't actually exist.
>>191
No I am not. What I am saying is the truth.
>>192
Of course I exist. I can think and I can see me, so I know I exist and I can see everything around me, so I know they exist. But physics is just mathematics which is socially constructed and not real. So you can't just say time is real by using physics as proof of it. I can't see time. I can't measure time; clocks only measure themselves, not time itself. So it really doesn't exist, it's just causality.
> I can't measure time; clocks only measure themselves, not time itself. So it really doesn't exist, it's just causality.
You can change time. That alone should give you a hint that it exists.
But you can't change causality. Thus, time and causality are distinct concepts.
It's possible.
> I can see me, so I know I exist and I can see everything around me, so I know they exist.
False. You are solely a brain suspended in a vat of fluid. Everything your experience with your senses is merely your brainself being probed with electrical charges.
I'm going to be visiting earlier in this thread to prove it's possible. Just thought you should know!
Oh, Titor! Choice performance, my friend! Choice performance indeed!
>>196
That still = the person and their surroundings existing. Simply in a different form and context than what was percieved, doesn't cancel out the existence. That's similar to saying that because people a few hundred years ago thought the world was flat, that their world didn't exist. It sure wasn't flat, but it definitely existed.
>>It sure wasn't flat, but it definitely existed.
No it didn't, it was just a social construction.
social constructions exist, duh.
Could my dong be this huge if reality was fake?
Roses are red
Violets are blue
Your dong's a social construction
And so are you
Could my dong be this huge if time travel was impossible?
it's possible, so, shoo, shoo! all of you am powtaytowes.
Is anyone here an actual time traveler?
Yes. We all are traveling in time.