Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: @drugsworker on 17/09/2011 03:30:01
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@drugsworker asked the Naked Scientists:
I'm just reading the Time Travellers wife great book, could it ever be possible?
What do you think?
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No, even though JP says that the arrow of time can reverse in quantum mechanics.
I think it was Feynman that said this : The abscence of time travelling tourists proves that time travel will never work. [:)]
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Yeah, agree totally Johan, even if we assume that every time traveler would create a 'split' leaving Earth partitioned into two Earths, the one before the time travel and the one after, we should still have noticed it, and I don't see anything hindering it from happening again and again and again and ... Leaving us with billionary amass of worlds, eh, sort of.
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Hi Yor_on,
I really don't trust the results of the quantum experiment that JP was talking about.
What i don't understand is how we can observe the arrow of time directly.
It's like observing what is happening in another dimension.
It seems very strange.
[???]
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I imagine it is possible to travel only forward in time, maybe in a jump. Would not no how to jump to to the right space though. Ending up in deep space.
I open mindedly think if one made a powerful vehicle, one could travel space and time, to the future, without the ability to effect it or be seen, and return to the present, and change the future.
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Are you thinking of time dilations? Johan? Like with those two synchronized atomic clocks ticking, then moving one to the floor and see them desynchronize?
That experiment tells you something very important about time, it's a little like there are two components to it, well, when I think of it :) One indifferent, which express itself in the way that 'clock' never differs for you, as when comparing heartbeats to your wristwatch. They will be the same wherever you are, on the event horizon or on earth, loosely speaking here. Then the way you find all other clocks to change durations depending on where you are and what you do, accelerating for example. If we stop looking at it as 'time' and instead discuss it as 'clocks' it become easier to accept, for me that is :)
The only thing I'm sure of is that all points in this universe have one of those 'clocks' embedded, and that all of them have a direction into the 'future'. None of them ticks backwards. But the 'clocs' all gets their definition from you, measuring them, all except one, your own intrinsic 'clock' that have only one beat to tick too. That beat it's the same as what Einstein used to define relativity, 'c'. 'c' never differs, it is the same whenever you measure it locally, and so is your intrinsic time.
Or if we look at it as 'clocks' solely. Which is the best 'clock' that exist?
Radiation.
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Yes, no one fully understands time, as time is space. Therefore anything is possible because we don't fully understand the dynamics of our Uni/Multiverse especially entities such as Black/White Holes!
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Read in New Scientist last year that quantum physicists reckon they can mathematically perform their calculations correctly and eliminate time altogether from equations.
What now for relativity theories?
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Johnny - not sure which New Scientist article you are talking about - but I do not believe that any one has managed to remove time uncertainty from quantum mechanics. it is inherent in the maths of qm. even if they could; how that would affect relativity is anyone's guess - there is a nobel prize out there for the physicist who can nicely link qm and relativity
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Travel into the future means that the travelling object should disappear today and appear tomorrow.Such cases do not exist. [:-'(]
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These things, as with sci fi, could be governed by previously highly advanced minds of another solar system, or by the intelligence behind the formation of the universe.
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What i don't understand is how we can observe the arrow of time directly.
We can observe the arrow of time directly. A beam of light has a source and a sink.
The other main arrows of time are gravity and entropy.
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No.
Time travel as we understand it in our linear way , is impossible. It really comes down to logic. The first option to assume given' the science fiction of it, is that somehow we would manipulate the entire universe to go backwards into time. That is, those galaxies that we can only conceive of from pictures and vision light years ahead would somehow be forced to go backwards. Not even imaginably possible, is it. There is no known energy on earth that could support a task as to make the entire universe go backwards. Seems ridiculous to even have to say it, but you will see why i felt the need.
now that means that any form of time traveling would have to be environmental or local. I think, that it is safe to assume that there is no way known to make the entire earth go backwards. not even sure that would be a practical course. This can be potentially narrowed down to, say a room. lets say. now, lets say we have a room or for imaginary purpose, a cube of some volume that can be documentation and witnessed by the researchers. they start it up and inside they have the test subject. here is where it gets confusing. the person say is 1 hour slower then us in that cube. lets pretend that he has a cellphone. makes a call to one of the researchers out of the cube. the question is, would the researcher get the call at that time? or would the researcher check the voice mail and find a call from the actual subject one hour from when it was witnessed outside of the cube.
logic suggests it would be an hour beforehand right? well, it wouldn't. it would be at that time it was witnessed. because , for the action to translate into our time reference, it would have to be on par with the universal constant. it is a strange fashion of relativity i figured out when reading about the planes that would claim to have slower clocks and that recent experiment that showed that clocks do go slower. the clocks and the mechanism, be it electrical or mechanical all rely on the physical universe to operate.those laws still apply no matter what. so, it just comes down to relativity. honestly that easy. as for any claim , like that Russian guy, that he has made a time machine. you can be sure that it is bogus. reason is, lets say you go back 200 years, or even further or forward, doesn't really matter which way. the earth still turns. the position would not be in the same spot.because you are affecting that single area . that single spot. remember , we feasibly would only be able to affect say a room or a area space.it remains static.for instance, your chair , where it was physically say four days ago, could be anywhere from a mile to just a few yards away. the earth wobbles and is imperfect in its days. 24 hours being just an average.
lastly, there is no practical reason for going back into time. it wont change anything. this is a big fallacy they seem to forget in movies like terminator. basically if you are an agent from say 3011, and you go to this time. lets say you want all chocolate bars to be free and assessable to all chocolate enthusiasts. so you implement a alternate timeline. when it gets to the exact moment you went back to 2011, in the year 3011, everything goes back to the way it was. nothing changed.because you exist in that universe.
i usually use the fact that Hitler existed as proof. to me, if there was any valid reason to go back and change anything he is certainly one of them. the only real reason i can think of that would sponsor a time regression would be to make use of the free real estate that existed say in the Permian age. as an answer to overpopulation. however, i think space exploration and the ocean have precedence over that. there is of course more logical reasons why, it isn't possible and why even if it is, it wouldn't be practical. i hope i have given some insight.
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No, it is the stuff of fiction. The nearest you get to time travel is viewing the recent past.
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I mostly agree with wiredbadger it is highly unlikely, but anything is possible, for instance we assume the universe is real, this may all be a computer simulation/petri dish of some advanced life form that can reverse the time of everything in our real universe in a few key strokes, or the act of exploring our universe within and without may create it as if the whole universe might be the combined hallucination of everyone's fantastic dream. If we did have a time travel machine, I seriously doubt it would be used for much good.
Something to think about though, what is "time" anyway?
If we were able to freeze a frog or a person someday for 500 years and then reanimate them back to life, would they have traveled forward in time?
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If we were able to freeze a frog or a person someday for 500 years and then reanimate them back to life, would they have traveled forward in time?
Everything travels forward in time. They would be 500 + years old. Time travel is generally thought of as travelling through time to some point in the future or past without your own age altering.
The four dimensions of space-time are intimately connected and just by being stationary you are travelling through space-time. To travel through time you would need to separate the time dimension from the other spacial dimesnions.
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To travel through time you would need to separate the time dimension from the other spacial dimesnions.
Or leave all 4 dimensions and enter them again at other spacetime coordinates..
Time travel is impossible with our current knowledge of physics. But who's to say that there isn't more to it than we know, or that we're completely wrong with our current assumptions..
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Hypothetically, time travel, backward could result in some people not being conceived who presently exist. As a matter of faith, that really can't be.
The Earth splitting into two plots would take a lot of energy, right?
And would Pluto have to split into two as well?
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To travel through time you would need to separate the time dimension from the other spacial dimesnions.
Or leave all 4 dimensions and enter them again at other spacetime coordinates..
Time travel is impossible with our current knowledge of physics. But who's to say that there isn't more to it than we know, or that we're completely wrong with our current assumptions..
Seems to me that would entail leaving and re-entering the Universe and that would be more of a paradox than time travel itself.
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Could time travel be possible?
How about if you were in a spaceship made from antimatter (ignoring the annihilation problem) and matter and antimatter are found to be going different directions in time. Could this take you into the past?
Probably not as any time reversal effect would be cancelled by the overwhelming forward flowing time of the universe.
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Maybe 'time' is 'gravity'?
Gravity is 'space' in my definitions, there is no place without it. Even in a uniform motion there will be gravity involved, as described by earth. If gravity can define a time dilation then gravity contains a 'clock'. All 'clocks' you ever will define have only one motion, into the future, no matter what time dilation you measure them to have. Even those 'standing still' relative you have only one direction to go.
So gravity defines the clocks, relative your measuring, which defines the arrow of time.
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To get it right you need to remember that no matter what you measure another 'clock' to tick/show, it will always be found to have the exact same time/beat as you, when you measure it 'locally'. That is, arriving to that place, being in the same 'frame of reference'.
So time never 'ticks' differently for you. It has the same beat everywhere, and the beat it ticks by is 'c'. Which makes radiation the 'clock' of choice here :)
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So now we have two, gravity and radiation, where radiation is the beat, and gravity is what makes the beat 'dilate'(relative the observer), maybe :)
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Time travel is possible. If it were not possible time would be the same for everyone. Further more, as time travel is possible you can prove its existence. NASA like to call it time transfer and you can read about it here, http://tycho.usno.navy.mil/ptti/ptti2002/paper1.pdf
No one can prove that time travel is not possible, if they could we would not be having this topic discussion [;D]
People orbiting the earth at high speed experience it also. Their clocks are different to ours on the ground. Wether you like it or not that is time travel....... whatever the cause the effect is there for all to observe.
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What I can say is that the arrow, so far, only have one way macroscopically. And that is into the future.
If time travel is you 'conceptually moving' from one 'happening' to another, then it is a causality chain that only points one way, our 'logic' used to define it. That 'logic' comes from our expectations, experiences, and what experiments we have trying to understand 'time'.
We are all 'time travelers' in that motto. But if SpaceTime is consisting of 'clocks' we still have to find one of those going 'backwards'.
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If Yor_on and photon travel by different speeds in the time, then they should be in different times. [;D]
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:)
No, or yes :)
Depends on how you define time. If you define it locally, it has only one beat. That you will find all other 'clocks' to differ from yours is a result of that 'universal beat' being the exact same, ignoring mass and motion. And the description that fits that as a hand in a glove will always be the way radiation acts. Radiation is the universal 'clock' and we all 'tick' by it, as I see it. And from that you will get a 'time dilation'. But only pointing one way, into the future.