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Thread: Time travel question

  1. #1 Time travel question 
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    Hello, I'm not good at physics at all but I just have a question that will probably seem silly to physicists.


    I've watched a lot of time travel movies, but the time travel movies, but the type of time travel seen a lot is 'do over' time travel. Where time just keeps resetting every day or something. The type of time travel is nicknamed the Time Loop and the most famous movie with it in it is Groundhog Day. I just wanted to know, are time loops possible, even if the chances are small? As they don't make paradoxes like other time travel movies and seem consistent. Or is there some laws of physics that make them impossible?

    Thank you for reading.


     

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    They are possible in general relativity. But, on the other hand, there is no reason to think they can actually exist.

    Possibly a future theory that combines quantum theory and GR will show that they are not possible. (Or, less plausibly, show us how to build a time machine!)


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    Speaking of time, does it expand as the distances between galaxies increase? Does FTL expansion affect time in some way?
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    The problem with the film "Groundhog Day" is that the lead character is (once he realises) consciously aware of the time loop, i.e his mind is working independent of the time frame he exists in. If time loops were possible then I doubt you would be able to be consciously aware of it anyhow. Which means time loops may well exist but its impossible to independently experience them.
     

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    Quote Originally Posted by zinjanthropos View Post
    Speaking of time, does it expand as the distances between galaxies increase? Does FTL expansion affect time in some way?
    What does it mean for time to "expand"? (But I think the answer is "no", anyway.)
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    This wouldn't actually be a loop. It can't be. If Bill Murray litreally went back to the same time and place, he would run into himself.

    This is parallel universes. Each time he goes back, he spawns a new universe that starts off identical to the old one, but events immediately diverge in independent directions.

    Presmably, everybody is acting with free will, even as they repeat the same actions in every universe. Murray though, having memory of the previous universe, acts with that knowledge, changing his actions.
     

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    Quote Originally Posted by DaveC426913 View Post
    This wouldn't actually be a loop. It can't be. If Bill Murray litreally went back to the same time and place, he would run into himself.

    This is parallel universes. Each time he goes back, he spawns a new universe that starts off identical to the old one, but events immediately diverge in independent directions.

    Presmably, everybody is acting with free will, even as they repeat the same actions in every universe. Murray though, having memory of the previous universe, acts with that knowledge, changing his actions.
    If it makes parallel universes, does that mean what Bill Murray went through is possible? Or is there still laws that don't allow it.
     

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    Quote Originally Posted by PhysicallyStupid View Post

    If it makes parallel universes, does that mean what Bill Murray went through is possible? Or is there still laws that don't allow it.
    Well, parallel universes do avoid that particular paradox.
     

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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by PhysicallyStupid View Post

    If it makes parallel universes, does that mean what Bill Murray went through is possible? Or is there still laws that don't allow it.
    Well, parallel universes do avoid that particular paradox.
    Yeah but it doesn't explain what's causing it, like why is he teleporting into parallel universes? It's still time travel either way as he's going back in time. So, wouldn't it still violate certain laws of physics?
     

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    Quote Originally Posted by PhysicallyStupid View Post
    Yeah but it doesn't explain what's causing it, like why is he teleporting into parallel universes?
    Implicitly, it is some supernatural intelligence.

    It becomes apparent that it is happening to him for a reason. He will continue to re-experience that day until he improves himself.
    Thus, some thing is making such a judgement and eventually deems him worthy.

    Quote Originally Posted by PhysicallyStupid View Post
    It's still time travel either way as he's going back in time.
    It's not really time travel if a parallel universe is created anew each time.
    Which seems to be the case, since each new universe is not the one he left - the difference being that his original is not in it when he arrives.

    Quote Originally Posted by PhysicallyStupid View Post
    So, wouldn't it still violate certain laws of physics?
    There is no physical law that says time travel is not possible.

    On the other hand there are solutions to some of Einsteins equations that do permit time travel.
    They could, in theory, be exploited with fantastically-advanced technologies.
    Wormholes, toroidal black holes, and nigh-infinitely long cylinders, all make appearances in some of these designs.
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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by PhysicallyStupid View Post
    Yeah but it doesn't explain what's causing it, like why is he teleporting into parallel universes?
    Implicitly, it is some supernatural intelligence.

    It becomes apparent that it is happening to him for a reason. He will continue to re-experience that day until he improves himself.
    Thus, some thing is making such a judgement and eventually deems him worthy.

    Quote Originally Posted by PhysicallyStupid View Post
    It's still time travel either way as he's going back in time.
    It's not really time travel if a parallel universe is created anew each time.
    Which seems to be the case, since each new universe is not the one he left - the difference being that his original is not in it when he arrives.

    Quote Originally Posted by PhysicallyStupid View Post
    So, wouldn't it still violate certain laws of physics?
    There is no physical law that says time travel is not possible.

    On the other hand there are solutions to some of Einsteins equations that do permit time travel.
    They could, in theory, be exploited with fantastically-advanced technologies.
    Wormholes, toroidal black holes, and nigh-infinitely long cylinders, all make appearances in some of these designs.
    Yeah, so it's basically out of the realm of science then, if it is supernatural. Still a cool plot though.

    Also, doesn't entropy mean time travel is impossible, that and causality.
    Last edited by PhysicallyStupid; February 11th, 2018 at 06:01 PM. Reason: xd
     

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    Oops
    Last edited by PhysicallyStupid; February 11th, 2018 at 06:02 PM.
     

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    Quote Originally Posted by PhysicallyStupid View Post
    Also, doesn't entropy mean time travel is impossible, that and causality.
    Entropy doesn't forbid it.
    You can reduce entropy locally and temporarily. (That's what life does.)
    But a reduction in entropy always increases entropy in the larger, longer context.
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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by PhysicallyStupid View Post
    Also, doesn't entropy mean time travel is impossible, that and causality.
    Entropy doesn't forbid it.
    You can reduce entropy locally and temporarily. (That's what life does.)
    But a reduction in entropy always increases entropy in the larger, longer context.
    Ok. But we can agree that the stuff we were talking about (time loops) are impossible, right. They aren't part of science.
     

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    Quote Originally Posted by PhysicallyStupid View Post
    Ok. But we can agree that the stuff we were talking about (time loops) are impossible, right. They aren't part of science.
    Not?
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    Quote Originally Posted by PhysicallyStupid View Post
    Ok. But we can agree that the stuff we were talking about (time loops) are impossible, right. They aren't part of science.
    I do not agree. Theory supports time travel.

    It does not support Groundhog Day time travel, no.
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    My biggest problem with time travel is what if everyone who travels in time (could be millions) by some device wanted to attend the same event? How would a million people fit on the Titanic (unless they brought their floatation gear to brave the North Atlantic)? That bucket of bolts might sink before it reaches the iceberg or slow down so much that it never hits it? How many people would it take to bring down The Spirit of St Louis if tt's decided to ride along with Lindberg? If tt is possible than there's no doubt in my mind that history changes, there are parallel universes or there's something remarkably weird with the universe we're in.
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    Quote Originally Posted by zinjanthropos View Post
    My biggest problem with time travel is what if everyone who travels in time (could be millions) by some device wanted to attend the same event?
    Ah that’s easy: Laws and restrictions on time-travel predate the birth of time-travel technology (much like Asimov’s laws of Robotics before the “singularity”). Boy it must be stressful being a time-travel controller! I imagine they have a lot of paid leave.
     

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    Quote Originally Posted by Vexspits View Post
    I imagine they have a lot of paid leave.
    How would you even know they went for a coffee break? Maybe returning to their desk looking 10 years older might be a clue.
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    Quote Originally Posted by zinjanthropos View Post
    My biggest problem with time travel is what if everyone who travels in time (could be millions) by some device wanted to attend the same event? How would a million people fit on the Titanic (unless they brought their floatation gear to brave the North Atlantic)?
    Don't envision it as some human-sized door you can step through and close behind yourself. That's TV stuff.

    The examples I listed above (an infinitely long cylinder rotating at near the speed of light, a toroidal black hole, etc.) are (not to put too fine a point on it) rather larger than a cruise ship.

    They require (and thus emit) truly colossal amounts of energy. These things have so much energy, they twist spacetime itself though 90 degree turns. That tends to have some ... collateral influence.

    One should not expect a toroidal black hole to appear in the ship's ballroom without atomizing the ship, the planet, and - indeed - a large chunk of the solar system.
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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by zinjanthropos View Post
    My biggest problem with time travel is what if everyone who travels in time (could be millions) by some device wanted to attend the same event? How would a million people fit on the Titanic (unless they brought their floatation gear to brave the North Atlantic)?
    Don't envision it as some human-sized door you can step through and close behind yourself. That's TV stuff.

    The examples I listed above (an infinitely long cylinder rotating at near the speed of light, a toroidal black hole, etc.) are (not to put too fine a point on it) rather larger than a cruise ship.

    They require (and thus emit) truly colossal amounts of energy. These things have so much energy, they twist spacetime itself though 90 degree turns. That tends to have some ... collateral influence.

    One should not expect a toroidal black hole to appear in the ship's ballroom without atomizing the ship, the planet, and - indeed - a large chunk of the solar system.
    Well then there's really no point discussing tt on a human scale. Apologies for going off course.
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    Quote Originally Posted by zinjanthropos View Post
    Well then there's reallysci no point discussing tt on a human scale. Apologies for going off course.
    No, that's cool. I was just injecting some hard science into the discussion for balance.

    After all, it was originally about a movie.
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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by zinjanthropos View Post
    Well then there's reallysci no point discussing tt on a human scale. Apologies for going off course.
    No, that's cool. I was just injecting some hard science into the discussion for balance.

    After all, it was originally about a movie.
    Alas, I've never watched Groundhog Day in its entirety. Edge of Tomorrow with Tom Cruise was a time loop movie except his character had to be killed in order to go back and start over again, and again, and again..... Might have been a reincarnation (or multiple universe?) movie too because he always maintained the memory of his past repetitive lives..
    Last edited by zinjanthropos; February 17th, 2018 at 08:30 AM.
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    Quote Originally Posted by zinjanthropos View Post
    Edge of Tomorrow with Tom Cruise
    I've never even heard of that, let alone seen it.
    Was it not popular?
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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by zinjanthropos View Post
    Edge of Tomorrow with Tom Cruise
    I've never even heard of that, let alone seen it.
    Was it not popular?
    Not sure if it was popular/box office success, but I saw it at the local Cinema. Not too long ago it was repeatedly shown on the Space Channel here.

    From Wiki: Edge of Tomorrow initiated its theatrical run in several territories on May 28, 2014, and rolled out to a total of 28 territories for its opening weekend of May 30 – June 1, 2014.[55][60] It grossed $20.1 million on its opening weekend.[61] For the second weekend of June 6–8, 2014, it was released in 36 additional territories.[62]Edge of Tomorrow grossed $100.2 million in North America and $270.3 million in other territories for a worldwide total of $370.5 million.[3] After the film's theatrical run, Entertainment Weekly said it had a "lukewarm box-office reception" despite praise from critics.[63]
    Last edited by zinjanthropos; February 17th, 2018 at 10:50 AM.
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    Quote Originally Posted by zinjanthropos View Post

    Not sure if it was popular/box office success, but I saw it at the local Cinema. Not too long ago it was repeatedly shown on the Space Channel here.
    Looked it up on imdb. Vague recollections of it.
    Also vague recollections of not getting interested in it because it looked like time travel was just being used as a vehicle to make two straight hours of combat into a plot.
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    OK, just for fun permit me more questions on objects moving through time & space. Here's a few things I've wondered about (space) time itself. Can I go anywhere in this universe and experience what I call real, true or undistorted space time? Since I am composed of particles with rest mass then my presence anywhere would actually distort space time, no? Even if only in a nearly undetectable way, if space time is distorted by my presence in the universe then might that affect tt for a life form such as ours? Same goes for a mechanical device travelling through time. Could we ever be aware of undistorted space time? Would we require undistorted time or the knowledge of it to even attempt tt?
    Last edited by zinjanthropos; February 18th, 2018 at 12:05 PM. Reason: there was a 'not' in the wrong place
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    Quote Originally Posted by zinjanthropos View Post
    OK, just for fun permit me more questions on objects moving through time & space. Here's a few things I've wondered about (space) time itself. Can I go anywhere in this universe and experience what I call real, true or undistorted space time? Since I am composed of particles with rest mass then my presence anywhere would actually distort space time, no? Even if only in a nearly undetectable way, if space time is distorted by my presence in the universe then might that not affect tt for a life form such as ours? Same goes for a mechanical device travelling through time. Could we ever be aware of undistorted space time? Would we require undistorted time or the knowledge of it to even attempt tt?
    That is how I see it.Distortion is the norm and Euclidean geometry is an idealization but one that is essential to understanding ** and measuring how curvature varies fr one location to another

    Despite curvature I think all the mathematics in GR is actually Euclidean that is "shoehorned" into service.

    Very much subject to correction as usual

    ** which of course I haven't
     

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    Quote Originally Posted by zinjanthropos View Post
    OK, just for fun permit me more questions on objects moving through time & space. Here's a few things I've wondered about (space) time itself. Can I go anywhere in this universe and experience what I call real, true or undistorted space time? Since I am composed of particles with rest mass then my presence anywhere would actually distort space time, no? Even if only in a nearly undetectable way, if space time is distorted by my presence in the universe then might that not affect tt for a life form such as ours? Same goes for a mechanical device travelling through time. Could we ever be aware of undistorted space time? Would we require undistorted time or the knowledge of it to even attempt tt?
    That is how I see it.Distortion is the norm and Euclidean geometry is an idealization but one that is essential to understanding ** and measuring how curvature varies fr one location to another

    Despite curvature I think all the mathematics in GR is actually Euclidean that is "shoehorned" into service.

    Very much subject to correction as usual

    ** which of course I haven't
     

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    Questions I was afraid to ask in the recently trashed rubber sheet analogy thread.... What of space time in a 2D universe, would it be distorted by a 2D object's mass (is 2D mass even a possibility?) or is that impossible and thus 2D space time is undistorted despite the presence of 2D objects? Is a 3rd dimension the minimal requirement for mass to produce a space time distortion?

    My feeling is that before we go wandering through time that perhaps we'll need to know a hell of a lot more about it than we do now.
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    What are your 2 dimensions? 1 Time and 1 Space or do you just mean 2 spatial dimensions (+1 of Time)?
     

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    Quote Originally Posted by geordief View Post
    What are your 2 dimensions? 1 Time and 1 Space or do you just mean 2 spatial dimensions (+1 of Time)?
    2 + 1
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    Are you asking whether objects can exist in only 2 spatial dimensions?

    Have you an example of them doing so?

    I have heard of atoms sandwiched in one atom deep layers of material with their freedom of movement so restricted and they were described as effectively 2 dimensional.

    But that did not convince me.
     

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    Quote Originally Posted by geordief View Post
    Are you asking whether objects can exist in only 2 spatial dimensions?

    Have you an example of them doing so?

    I have heard of atoms sandwiched in one atom deep layers of material with their freedom of movement so restricted and they were described as effectively 2 dimensional.

    But that did not convince me.
    I read this on Reddit:
    However, things that matter is made out of (electrons, quarks, etc) are, as far as we can tell, point particles. These point particles are 0-dimensional objects, as they don't have a size, and they do have mass. So theoretically, you could construct a technically 2-dimensional object out of points, and it would have mass.
    Don't know if science agrees with this. I'm thinking that if 2D objects with mass exist then they must be on a 2D plane where things don't go over or under one another, just go around. I don't see how 2D mass objects could warp time let alone the space they exist in if there's only one plane for the universe. An extra dimension would seem to be necessary to me if space time is to be affected by mass. Remember I'm just a layperson trying to understand so my questions are not worded correctly most times.
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    That is beyond me.I have also heard (and wondered) about "point particles"

    Perhaps dimensions are different in QM?

    If quantum objects move differently then our macro spatial dimensions might not apply.
    Help
    Last edited by geordief; February 18th, 2018 at 08:28 PM.
     

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    Can I go anywhere in this universe and experience [...] undistorted space time?
    No, not if by „undistorted“ you mean flat, Minkowski spacetime. You can only go to regions very far away from sources of gravity (or restrict your attention to very small, local patches), where spacetime is approximately flat.

    Since I am composed of particles with rest mass then my presence anywhere would actually distort space time, no?
    Yes, that too.

    Despite curvature I think all the mathematics in GR is actually Euclidean that is "shoehorned" into service.
    What makes you think that?

    What of space time in a 2D universe, would it be distorted by a 2D object's mass (is 2D mass even a possibility?)
    General Relativity is independent of the number of dimensions, so you can apply the field equations to a 2D universe too. The result is fairly trivial though, because in 2D the Riemann tensor (the object describing curvature) has only one functionally independent component, so everything reduces down to just a single equation. Essentially you get a surface that is completely described by just a scalar curvature. Higher order effects such as gravitational radiation etc do not exist here. In fact, gravity as we observe it needs at least four dimensions to work the way it does.
     

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    Quote Originally Posted by Markus Hanke View Post

    Despite curvature I think all the mathematics in GR is actually Euclidean that is "shoehorned" into service.
    What makes you think that?
    https://www.youtube.com/watch?v=UfThVvBWZxM

    I have been told that this is a good ,video and in I see that normal 180 degrees and "normal" operations are employed at the infinitesimal scale (eg at 17.59 minutes)

    It feels like the tangent is "manually"reset as one moves along the curve ("shoehorning" seemed like an analogy ).

    I was surprised to find plain flat geometry being used at the most local level (even though I had of course been told this before)

    Seeing a geometric animation seemed to bring out that aspect for me

    Maybe I have badly misunderstood or ,more likely badly expressed myself.

    Seems like a good vid to me. I have been told elsewhere to stick with it. (I haven't understood any of the intricacies of it yet ,just perhaps the overview)

    Rereading my post should/could I change "all the mathematics in GR " to some of the fundamental mathematics"?
     

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    [QUOTE=Markus Hanke;613362]
    Can I go anywhere in this universe and experience [...] undistorted space time?
    No, not if by „undistorted“ you mean flat, Minkowski spacetime. You can only go to regions very far away from sources of gravity (or restrict your attention to very small, local patches), where spacetime is approximately flat.

    Since I am composed of particles with rest mass then my presence anywhere would actually distort space time, no?
    Yes, that too.

    Thanks Markus. MY mind is shorting out on this subject so please bear with me and my unprofessional approach....I going to assume that because mass is present in the cosmos that there isn't one part of the universe that doesn't experience time distortion(flattening if you will), even if barely measurable. Does that mean the present, the moment or the instant is not a true time experience but some sort of stretched version of it? If so then wouldn't all observers including mechanical devices experience time differently from one another? What of the universe itself, would it not also experience only a distorted time? If so then it leads me to think of whether or not an undistorted time has ever existed at all but if it has then I'm thinking it had to be before the universe came into being or at least prior to the introduction of mass or an extra dimension suddenly unfolded.

    I'm only farting around with this because if I hopped on a Time Machine tomorrow and if it was distorting time so that it doesn't match mine then how in hell could I calibrate it? One nanosecond difference might see me hurled to the other side of the universe. Once I entered such a machine then my own mass would distort time even more, I think. Is there anyway to make an accurate measurement of undistorted time by accounting for the distortion?
    Last edited by zinjanthropos; February 19th, 2018 at 08:43 AM.
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    I was surprised to find plain flat geometry being used at the most local level
    Yes, locally - i.e. in a small enough region - all curvature is negligible. This is why, when you look out the window at your garden, you don’t notice the curvature of the Earth. The patch is small and local.
     

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    If so then wouldn't all observers including mechanical devices experience time differently from one another?
    No, all observers will experience time the same way within their own frames of reference, but if you were to compare the clocks used by different observers after a while, then yes, you might see discrepancies. Remember that time dilation is a relationship between observers, it’s not something that “happens” locally.

    Curvature to some degree or another is present everywhere in the universe, but in some regions it might be so small as to be negligible.
     

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    Quote Originally Posted by Markus Hanke View Post
    I was surprised to find plain flat geometry being used at the most local level
    Yes, locally - i.e. in a small enough region - all curvature is negligible. This is why, when you look out the window at your garden, you don’t notice the curvature of the Earth. The patch is small and local.
    Doesn't seem to apply to your garden . I can plainly see the curvature in them there hills

    Or is that not a spade you have there ?A sleán ?
     

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    It is possible change the rate of time flow in enclosed space - by creating a kind of chamber, where time flows faster or slower.
    But you can't jump to another point of time. It's impossible, according to QM, as future is undetermined in the case of subatomic particles...
     

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    Quote Originally Posted by AstralTraveler View Post
    It is possible change the rate of time flow in enclosed space - by creating a kind of chamber, where time flows faster or slower.
    Citation needed.
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by AstralTraveler View Post
    It is possible change the rate of time flow in enclosed space - by creating a kind of chamber, where time flows faster or slower.
    Citation needed.
    What citation? Dilation of time is a well known phenomenon. Accelerate the "chamber" close to the speed of light and the flow of time inside of it will be reduced almost to 0...
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    Quote Originally Posted by AstralTraveler View Post
    What citation? Dilation of time is a well known phenomenon. Accelerate the "chamber" close to the speed of light and the flow of time inside of it will be reduced almost to 0...
    Oh ok.
    If that's what you meant then you worded it very badly. (And no, the "flow of time" will NOT be reduced - it will still pass at 1 second per second).
    Please tell me how we get time to flow faster in this "chamber".
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    Quote Originally Posted by AstralTraveler View Post
    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by AstralTraveler View Post
    It is possible change the rate of time flow in enclosed space - by creating a kind of chamber, where time flows faster or slower.
    Citation needed.
    What citation? Dilation of time is a well known phenomenon. Accelerate the "chamber" close to the speed of light and the flow of time inside of it will be reduced almost to 0...
    The chamber and its contents relative to another frame of reference will measure different time lapse. But the contents of the chamber & the chamber will be in the same reference frame and time will tick by just the same, as Dywyddyr said "1sec per sec". The scenario is no different than accelerating a space craft to close to the speed of light then comparing its clock against that of a different reference frame on return, e.g the twin paradox.
     

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    time travel is not frontwards ,its only backwards,and has nothing to do with mathematical equations,it got to do with the less of certain kind of metal on earth which causes unstability on the planet which causes a total distruction to the planet from the inside ,that's when time returns back to the first of its form era
     

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    Quote Originally Posted by tomeliviathan View Post
    time travel is not frontwards ,its only backwards,and has nothing to do with mathematical equations,it got to do with the less of certain kind of metal on earth which causes unstability on the planet which causes a total distruction to the planet from the inside ,that's when time returns back to the first of its form era
    Any evidence (or supporting data) for ANY of that?
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by tomeliviathan View Post
    time travel is not frontwards ,its only backwards,and has nothing to do with mathematical equations,it got to do with the less of certain kind of metal on earth which causes unstability on the planet which causes a total distruction to the planet from the inside ,that's when time returns back to the first of its form era
    Any evidence (or supporting data) for ANY of that?
    I already posted my proof in the pseud section,i don't have a research lab to give u a certified proof.but I know what I talking about
     

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    Quote Originally Posted by tomeliviathan View Post
    I already posted my proof in the pseud section
    No, you didn't.
    Do NOT post in the hard science sub fora in future.

    but I know what I talking about
    Evidently not...
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    Quote Originally Posted by tomeliviathan View Post
    time travel is not frontwards ,its only backwards,and has nothing to do with mathematical equations,it got to do with the less of certain kind of metal on earth which causes unstability on the planet which causes a total distruction to the planet from the inside ,that's when time returns back to the first of its form era
    What?

    This sounds like a nice movie premise.. But it doesn't sound like anything even a bit believable, let alone possible.

    Your claims are.

    - There is a metal on earth that causes instability on the planet. (unbelievable, yet we don't know all materials yet)
    - Instability causes total destruction. (plausible)
    - The destruction is to the planet from the inside. (implausible)
    - This planets destruction will return time back to the first of its form era. (What the actual F***)

    Just to show you where you went wrong with your logic. There is nothing you have you can back up any of your claims.
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    Oh ok.
    If that's what you meant then you worded it very badly. (And no, the "flow of time" will NOT be reduced - it will still pass at 1 second per second).
    Please tell me how we get time to flow faster in this "chamber".
    Acceleration of the chamber will cause the time dilation, so an observer outside the chamber will experience different flow of time, than the one placed inside - however for both 1 second will be the same. You need to compare the clocks from outside and the inside, to see the difference. Again - those are well known scientific facts...

    If acceleration causes the time to flow "slower" inside the accelerating frame, then deceleration should cause opposite effect - but it would be hard, considering, that everything in Universe is moving in some way or other. So maybe it would be easier, to drop the temperature inside to (almost) Absolute 0. But it's rather just my guess, than mainstream science - for now no one didn't check, how the state of Bose-Einstein condensate is related with the apparent flow of time...
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    The chamber and its contents relative to another frame of reference will measure different time lapse. But the contents of the chamber & the chamber will be in the same reference frame and time will tick by just the same, as Dywyddyr said "1sec per sec". The scenario is no different than accelerating a space craft to close to the speed of light then comparing its clock against that of a different reference frame on return, e.g the twin paradox.
    This is exactly the same scenario and you can treat the space craft, as a chamber. Point is, that 1 second inside the accelerated frame won't be the same as 1 second in the "stationary" frame - if you would be able to observe a clock inside an accelerating space ship from the ground, you should be able to notice the difference of apparent time flow.
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    time travel is not frontwards ,its only backwards,and has nothing to do with mathematical equations,it got to do with the less of certain kind of metal on earth which causes unstability on the planet which causes a total distruction to the planet from the inside ,that's when time returns back to the first of its form era
    Woow! And scientists consider me, as a heretic...
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    Quote Originally Posted by AstralTraveler View Post
    If acceleration causes the time to flow "slower" inside the accelerating frame, then deceleration should cause opposite effect
    Don't be stupid.
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by AstralTraveler View Post
    If acceleration causes the time to flow "slower" inside the accelerating frame, then deceleration should cause opposite effect
    Don't be stupid.
    But it's something completely obvious. If for an observer, who's accelerating almost to the speed of light, flow of time gets slower (and stops completely, when the velocity of c is reached), then decelerating from the speed of light will cause the time to flow "faster" inside the decelerating frame.
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    Quote Originally Posted by AstralTraveler View Post
    But it's something completely obvious. If for an observer, who's accelerating almost to the speed of light, flow of time gets slower (and stops completely, when the velocity of c is reached), then decelerating from the speed of light will cause the time to flow "faster" inside the decelerating frame.
    Still wrong.
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    Still wrong.
    You're right, I made a mistake - as the accelerating/decelerating observer won't observe any difference of time flow inside his frame. It's the stationary observer, who will be able to observe the changing rate of time flow inside the accelerating/decelerating frame (just as accelerating/decelerating observer will observe the changing rate of time flow inside the stationary frame). But both stationary and accelerating/decelerating observers won't see no difference of time flow inside their own frames.

    My point was however, that while acceleration from 0 m/s to the velocity of c, makes the time to flow "slower" inside the accelerating frame (compared to a stationary frame), deceleration from the velocity c to 0 will invert this process - time will start flowing faster, until it will reach the same rate, as in the stationary frame. Of course, it doesn't mean, that deceleration from c to 0 will move you back in time - so there still be a difference of measured times for both frames.

    Ok, I hope that I managed to express myself correctly this time...
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    Just a note to AstralTraveler, think about the following.

    Time doesn't stop at c. If it did, traveling at c would pass infinitely fast, and you would be at your destination instantly.

    What i don't understand however. How Gravity, and high speed reaching c, seem to have a similar effect on time. Is it because gravity = acceleration too? Seems logical. But how can being stationary but under acceleration from gravity, have the same effect as being accelerated. One way warps space around you, and the other way makes you go through space. Hope someone can explain a bit.
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
     

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    Just a note to AstralTraveler, think about the following.

    Time doesn't stop at c. If it did, traveling at c would pass infinitely fast, and you would be at your destination instantly.
    I also don't believe, that time stops completely at c. Time dilation has to be proportional for stationary and accelerating/decelerating frames - if acceleated observer experience 2 times slower flow of time, then stationary observer has to experience the time flow, which is 2 times faster, than in the accelerated frame. If at velocity of c there wouldn't be any flow of time, there couldn't be no flow of time in the stationary frame neither - so both observers would agree, that the travel from point A to B with the speed of c was ABSOLUTELY INSTANT (t=0). But since light still needs some time to travel through space, time has to flow inside the frame, which moves with the speed of c.

    Besides, it would also mean, that velocity higher, than c would cause the time to flow in reverse - but this can't be possible due to the causality of all processes...

    However, this is exactly, what mainstream science tells us
    https://en.wikipedia.org/wiki/Time_dilation

    "Special relativity indicates that, for an observer in an inertial frame of reference, a clock that is moving relative to him will be measured to tick slower than a clock that is at rest in his frame of reference. This case is sometimes called special relativistic time dilation. The faster the relative velocity, the greater the time dilation between one another, with the rate of time reaching zero as one approaches the speed of light (299,792,458 m/s). This causes massless particles that travel at the speed of light to be unaffected by the passage of time."\

    But the next sentence shows, how wrong is such statement:
    "Theoretically, time dilation would make it possible for passengers in a fast-moving vehicle to advance further into the future in a short period of their own time."

    There can't be any period of time in a frame, which doesn't experience flow of time...

    What i don't understand however. How Gravity, and high speed reaching c, seem to have a similar effect on time. Is it because gravity = acceleration too? Seems logical. But how can being stationary but under acceleration from gravity, have the same effect as being accelerated. One way warps space around you, and the other way makes you go through space. Hope someone can explain a bit.
    Sorry, but I can't explain it - I'm just an amateur of physics, not professional physicist What makes it even worse, is the fact, that gravity and gravitational time dilation are connected with time-space being curved by energy/mass distribution, while time-space inside accelerated frame remains flat for both accelerated and stationary observers... This is over my head at this moment...
    Last edited by AstralTraveler; March 10th, 2018 at 08:12 PM.
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    Quote Originally Posted by AstralTraveler View Post
    Sorry, but I can't explain it - I'm just an amateur of physics... This is over my head at this moment...
    Evidently - because you persist in making the same false claim (despite it being explained correctly on the Wiki page you linked to).
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    Quote Originally Posted by AstralTraveler View Post
    I also don't believe, that time stops completely at c. Time dilation has to be proportional for stationary and accelerating/decelerating frames - if acceleated observer experience 2 times slower flow of time, then stationary observer has to experience the time flow, which is 2 times faster, than in the accelerated frame. If at velocity of c there wouldn't be any flow of time, there couldn't be no flow of time in the stationary frame neither -
    Which is why c is not a valid reference frame.

    Which is how SR works, and your ideas do not.
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    Which is why c is not a valid reference frame.

    Which is how SR works, and your ideas do not.
    But c is not a reference frame, only a constant value of maximal velocity, which a physical object can reach (if it has no rest mass). Reference frame can be moving through space at the speed of c, relative to some other frame (stationary or moving one).

    Could you explain an amateur, like me, what do you actually mean? I've noticed, that most of you love to make some crucial statements without any elaboration... I don't know everything about physics, although I'm trying to learn - and you don't make it easy in any way...
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    Evidently - because you persist in making the same false claim (despite it being explained correctly on the Wiki page you linked to).
    Which one? I've noticed, that you consider 99% of my claims as false, so I don't know, which one you mean in this case. Besides, you tell, that my claims are false, even when I tell, that I don't know the answer. How not knowing something can be false?

    Not to mention, that Wikipedia doesn't explain at all, what is the general cause of time dilation - everything, what is being said there is: " As a result of the nature of spacetime" - what doesn't explain too much
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    Quote Originally Posted by AstralTraveler View Post
    Reference frame can be moving through space at the speed of c
    Which would make c the reference frame.

    relative to some other frame (stationary or moving one)
    Except that c is c to ALL frames. Ergo it's not a valid frame.

    I don't know anything about physics
    FIFY.
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    Quote Originally Posted by AstralTraveler View Post
    Which one?
    Take a look at what the linked Wiki page says causes time dilation, then look at what YOU persist in claiming does it.

    Besides, you tell, that my claims are false, even when I tell, that I don't know the answer.
    Given that you admit you don't know what you're talking about why do keep making flat statements?
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    Which would make c the reference frame.
    How velocity can be a frame? Velocity is a property of frame - just like temperature, density of matter, volume etc.

    Except that c is c to ALL frames. Ergo it's not a valid frame.
    Yes - and a frame can be stationary or moving one - there's no other option. So, what is the reason of "except" in this case?

    And why exactly a frame, which moves at the speed of c is not "valid"? You can change the properties of light, by polarizing it for example - so photons have to experience flow of time. If they wouldn't be affected by the flow of time, it wouldn't be possible to change any of their properties (as each physical process takes place in some measurable period of time time and follows the cause/effect relation).

    FIFY.
    I don't know the meaning of FIFY. Besides, if you citate me, then do it right - I don't like, when someone changes things, which I said and tells, that those are my exact words....

    Take a look at what the linked Wiki page says causes time dilation, then look at what YOU persist in claiming does it.
    I NEVER told, what is the actual cause of time dilation - except, that it can be caused by difference of velocities or by gravitational fields. Till now I was talking only about observable effects. I don't know, what's the general cause of time dilation.

    Wiki says, that time dilation exists "As a result of the nature of spacetime" - what doesn't explain too much. But I don't argue with that at all...

    Given that you admit you don't know what you're talking about why do keep making flat statements?
    Which are...? I'm not afraid to admit, that I can be wrong, if my statements are inconsistent with observations - example can be seen couple comments above...
    Last edited by AstralTraveler; March 10th, 2018 at 11:35 PM.
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    Quote Originally Posted by AstralTraveler View Post
    And why exactly a frame, which moves at the speed of c is not "valid"?
    A. By definition, one's reference frame is one in which one is stationary.

    B. The second postulate of Special relativity is that light moves at c in all reference frames.

    C. Therefore, to posit a reference frame that moves at the speed of light, you must posit that light is both moving at c relative to you and stationary simultaneously. That is a direct contradiction.

    i.e. the second postulate of SR incontrovertibly forbids the speed of light being a valid reference frame.
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    A. By definition, one's reference frame is one in which one is stationary.
    But I can be moving through space. It might appear to me, that I'm stationary and that it's everything else, what is moving - but it's an subjective effect of relativity... Objective truth is, that it's me, who's moving through stationary space.

    B. The second postulate of Special relativity is that light moves at c in all reference frames.

    C. Therefore, to posit a reference frame that moves at the speed of light, you must posit that light is both moving at c relative to you and stationary simultaneously. That is a direct contradiction.
    But the same goes for the velocity of sound on Earth - speed of sound is constant in the lower atmosphere for stationary and moving observers. You can move with the speed of sound and every sound wave, which you will emit, will still travel with the speed of sound. Similary, a source of light can theoretically move with the speed of light, and the emitted light will still move at velocity of c.

    Difference is, that mass can travel faster, than sound - what is impossible for c.*

    i.e. the second postulate of SR incontrovertibly forbids the speed of light being a valid reference frame.
    If it forbids it, then how anyone can say, that there's no flow of time inside a frame, moving with the velocity of c? You need to compare two frames, to speak about the flow of time, inside of them...

    If a frame, which moves at the speed of c is not valid, then it should be totally incorrect to speak about any physical properties of that frame.

    * Actually object with mass can move faster than light in a dense medium (like ice for example) - this is, how we can detect neutrinos (there's a flash of light, when a neutrino starts to move faster than light in a cube of ice)
    Last edited by AstralTraveler; March 11th, 2018 at 12:09 AM.
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    Quote Originally Posted by AstralTraveler View Post
    How velocity can be a frame? Velocity is a property of frame - just like temperature, density of matter, volume etc.
    And a frame moving at c is...?

    Yes - and a frame can be stationary or moving one - there's no other option. So, what is the reason of "except" in this case?
    If the frame is at c then everything else is also at c (see also DaveC's reply).

    I don't know the meaning of FIFY. Besides, if you citate me, then do it right - I don't like, when someone changes things, which I said and tells, that those are my exact words....
    FIFY = Fixed It For You - i.e. I changed your words to more accurately show the reality.

    Wiki says, that time dilation exists "As a result of the nature of spacetime" - what doesn't explain too much.
    Try reading the very first sentence of the Wiki page.

    Which are...?
    How about the Wiki page (first sentence) and what you claim?
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    Velocity is a property of frame
    That is incorrect, velocity is a relationship between any two frames. If the spacetime that contains these frames is flat, and the frames are inertial ones, then the magnitude of velocity (i.e. speed) is equivalent to a hyperbolic rotation angle in spacetime.
     

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    And a frame moving at c is...?
    A frame, moving at c...?
    If the frame is at c then everything else is also at c (see also DaveC's reply).
    everything else, or everything, what moves slower, than c?
    https://physics.stackexchange.com/qu...le-light-speed
    "In any case, there is no reference-frame moving with either photon, so no operational way to measure relative velocities between them. relative velocities have meaning only from a inertial frame. There are no inertial frames moving with the photon, otherwise this frame would measure that photon to be at rest"

    Besides it's only a subjective effect of relativity - even if from a perspective of a photon, slower frames appear to move at c, it doesn't mean, that they do so objectively...
    Try reading the very first sentence of the Wiki page.
    How about the Wiki page (first sentence) and what you claim?

    1st sentence:
    "
    According to the theory of relativity, time dilation is a difference in the elapsed time measured by two observers, either due to a velocity difference relative to each other, or by being differently situated relative to a gravitational field."

    My claim:
    "I NEVER told, what is the actual cause of time dilation - except, that it can be caused by difference of velocities or by gravitational fields. Till now I was talking only about observable effects. I don't know, what's the general cause of time dilation."

    And...?
    Last edited by AstralTraveler; March 11th, 2018 at 03:38 AM.
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    That is incorrect, velocity is a relationship between any two frames. If the spacetime that contains these frames is flat, and the frames are inertial ones, then the magnitude of velocity (i.e. speed) is equivalent to a hyperbolic rotation angle in spacetime.
    I think, that every property of a frame is a relationship between any two frames - you need to compare some value to other one, to determine it. Frame moves at some velocity, in relation to other frame - just as time inside a frame can flow at some rate, relative to other frame. But it doesn't matter - I just wanted to say, that velocity IS NOT a substitute of the word "frame"
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    Quote Originally Posted by AstralTraveler View Post
    A. By definition, one's reference frame is one in which one is stationary.
    But I can be moving through space. It might appear to me, that I'm stationary and that it's everything else, what is moving - but it's an subjective effect of relativity... Objective truth is, that it's me, who's moving through stationary space.
    This is false.



    Quote Originally Posted by AstralTraveler View Post
    C. Therefore, to posit a reference frame that moves at the speed of light, you must posit that light is both moving at c relative to you and stationary simultaneously. That is a direct contradiction.
    But the same goes for the velocity of sound on Earth - speed of sound is constant in the lower atmosphere for stationary and moving observers. You can move with the speed of sound and every sound wave, which you will emit, will still travel with the speed of sound. Similary, a source of light can theoretically move with the speed of light, and the emitted light will still move at velocity of c.
    No. Sound is a property of the medium it is in: air.
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    I think, that every property of a frame is a relationship between any two frames - you need to compare some value to other one, to determine it.
    No. Some properties are intrinsic to frames, i.e. not defined in relation to something else. Examples are all tensor quantities, such as energy-momentum, or curvature.
     

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    This is false.
    Why? If one can assume, that he is stationary, while the frame is moving, then he can freely assume opposite situation. It doesn't matter - there's no objective frame, except the infinite one.
    No. Sound is a property of the medium it is in: air.
    So is light, but in opposite way - the more dense is the medium, the slower is the light. Neutrinos move faster than light in ice.
    Sounds moves faster, the more dense is the medium - solid matter transmits sound faster, than air.

    Funny qestion: can you hear yourself in a plane, which moves at mach 3...? ...Ha!
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    No. Some properties are intrinsic to frames, i.e. not defined in relation to something else. Examples are all tensor quantities, such as energy-momentum, or curvature.
    And how can one determine, that he is in curved frame, if there's no flat frame to compare with. You need two points of reference, to define a scale - and I don't see any other way. If there's a 1 in space, there has to be a 0 - and infinity is placed between them...

    There's a physical limit of energy/mass density in a single unit of space - which is Planck's mass moving through Planck's lenght at c - which is just as possible, as a photon frozen to absolute 0. It's physicaly impossible to pack more mass/energy in limited space, or make it more "empty".

    Generally, I think that I understand the SR. According to Einstein, it's the dilation of time, what allows the relativistic effect of c to happen. You can move at 99% of c, but light will move at c for you because the rate of time flow in your frame. You need a third observer, to see, how a frame, which moves at c is related to any other frame. From the "perspective" of a distant star, light which it emits, moves at c, but on Earth we can observe, that star is "chasing it's own light" or moving "away from it" - and we can observe it as red- or blue-shift.

    And I think, that I can give you the solution for SR applied to QM. SR makes just one mistake - but it changes a lot. Frame wich moves at c doesn't freeze in time. It becomes a wave function and start to determine the flow of time in any other frame, by defining the Planck's time (time, in which a single photon moves through Planck's lenght)

    You turn into a single 1, which is everywhere and nowhere at the same time...
    Last edited by AstralTraveler; March 11th, 2018 at 01:47 PM.
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    Quote Originally Posted by AstralTraveler View Post
    1st sentence:
    "
    According to the theory of relativity, time dilation is a difference in the elapsed time measured by two observers, either due to a velocity difference relative to each other, or by being differently situated relative to a gravitational field."

    And yet you have persistently stated that acceleration is the cause of time dilation.
    Velocity != acceleration.
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    And yet you have persistently stated that acceleration is the cause of time dilation.
    Velocity != acceleration.
    Acceleration of a stationary frame increases the difference of velocity, between it and a second stationary frame. I don't see no problem here - it's still all about the difference of velocities...

    Effect of time dilation between those 2 frames will be constantly increasing during the acceleration - due to the growing difference of velocities.
    Last edited by AstralTraveler; March 11th, 2018 at 01:58 PM.
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    The air in the plane is moving relative to YOU, the mach 3 outside the plane is irrelevant.

    Please stop spewing idiocy
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    Quote Originally Posted by AstralTraveler View Post
    Acceleration of a stationary frame increases the difference of velocity, between it and a second stationary frame. I don't see no problem here - it's still all about the difference of velocities...

    Effect of time dilation between those 2 frames will be constantly increasing during the acceleration - due to the growing difference of velocities.
    But, as noted, acceleration is not what causes the difference.
    If you can't be precise then we have no idea whether you know what you're talking about (and other posts of yours give the impression that you don't).
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    The air in the plane is moving relative to YOU, the mach 3 outside the plane is irrelevant.

    Please stop spewing idiocy
    The frame inside the plane moves together with you.
    Sound is transferrend also through solid matter - not only by air.
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    But, as noted, acceleration is not what causes the difference.
    Acceleration/deceleration = changing difference of velocity between 2 frames.
    If a stationary frame will start to accelerate in relation to another stationary frame, time dilation will be observed.
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  86. #85  
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    Quote Originally Posted by AstralTraveler View Post
    Acceleration/deceleration = changing difference of velocity between 2 frames.
    If a stationary frame will start to accelerate in relation to another stationary frame, time dilation will be observed.
    Regardless of how much you wriggle your previous assertions were wrong.
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  87. #86  
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    Quote Originally Posted by AstralTraveler View Post
    The air in the plane is moving relative to YOU, the mach 3 outside the plane is irrelevant.

    Please stop spewing idiocy
    The frame inside the plane moves together with you.
    Sound is transferrend also through solid matter - not only by air.
    Irrelevent, still.
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    Quote Originally Posted by AstralTraveler View Post
    No. Sound is a property of the medium it is in: air.
    So is light, but in opposite way - the more dense is the medium, the slower is the light. Neutrinos move faster than light in ice.
    Sounds moves faster, the more dense is the medium - solid matter transmits sound faster, than air.
    Are you asking? Or telling?

    The above is also false. But there's little point in explaining why, since it is becoming clear that pretty much everything you think about physics is wrong.

    If we were to systematically correct every misunderstanding you have, we would be pretty much teaching you science from the ground up, which is beyond the scope of a forum thread.
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    And how can one determine, that he is in curved frame, if there's no flat frame to compare with.
    By checking for tidal gravity.

    And I think, that I can give you the solution for SR applied to QM.
    We have known for a long time how to combine SR and QM - it’s called quantum field theory.
     

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    Irrelevent, still.
    And what about sound in a frame, which is accelerated to 99% of c?
    Last edited by AstralTraveler; March 14th, 2018 at 09:53 AM.
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    By checking for tidal gravity.
    But doesn't gravity need, two interacting frames?

    We have known for a long time how to combine SR and QM - it’s called quantum field theory.
    But is quantum field theory complete, or does it still need improvements?

    For example lack of time flow at c doesn't make too much sense - as you can change the properties of light, so it's obvious, that pjotons have to experience flow of time of some sort...
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    Quote Originally Posted by DaveC426913 View Post
    Quote Originally Posted by AstralTraveler View Post
    No. Sound is a property of the medium it is in: air.
    So is light, but in opposite way - the more dense is the medium, the slower is the light. Neutrinos move faster than light in ice.
    Sounds moves faster, the more dense is the medium - solid matter transmits sound faster, than air.
    Are you asking? Or telling?

    The above is also false. But there's little point in explaining why, since it is becoming clear that pretty much everything you think about physics is wrong.

    If we were to systematically correct every misunderstanding you have, we would be pretty much teaching you science from the ground up, which is beyond the scope of a forum thread.
    No - I'm absolutely correct in this case. Sound DOES travel faster in solid matter, than in gases...

    https://en.wikipedia.org/wiki/Speed_of_sound

    " However, the speed of sound varies from substance to substance: sound travels most slowly in gases; it travels faster in liquids; and faster still in solids."

    And YES - light travel slower in more dense medium (like water) - this is a well known law of physics.
    http://www.emsb.qc.ca/laurenhill/phy...1%20of%202.pdf
    Last edited by AstralTraveler; March 14th, 2018 at 10:21 AM.
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    Quote Originally Posted by AstralTraveler View Post
    But, as noted, acceleration is not what causes the difference.
    Acceleration/deceleration = changing difference of velocity between 2 frames.
    If a stationary frame will start to accelerate in relation to another stationary frame, time dilation will be observed.
    at point x you take a picture of a walking spider. at point y again. you have accelerated. but in the frame of reference i.e. the picture. you're at rest to the spider. but knowing your speed, and the displacement of the spider in both pictures tells you the spiders speed.
     

  94. #93  
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    Quote Originally Posted by AstralTraveler View Post
    No - I'm absolutely correct in this case. Sound DOES travel faster in solid matter, than in gases...
    No you're not.
    You claim was - Sounds moves faster, the more dense is the medium.
    Evidence you're wrong.
    Speed of sound in water: 1433 m/ sec, density of water: 1gm/ cm3.
    Speed of sound in lead: ~1240 m/ sec, density of lead: 11.34gm/ cm3.
    Speed of sound in rubber: ~95 m/ sec, density of rubber: 3.36gm/ cm3.

    You have a habit of making erroneous statements and insisting you're correct. Stop it.
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    But doesn't gravity need, two interacting frames?
    No. Gravity is geodesic deviation, and that doesn’t have anything to do with frames.

    But is quantum field theory complete, or does it still need improvements?
    I don’t know what you mean by “complete” - it is a mathematical framework to describe the interaction of quantum particles in Minkowski spacetime, even when there are changing particle numbers involved (which standard QM also cannot do). It is hence a unification of QM and SR, and as such quite successful, as evidenced in particle accelerator experiments. It is even possible to generalise QFT further, into the domain of curved spacetimes.

    For example lack of time flow at c doesn't make too much sense
    Of course it doesn’t make sense, because there is no such thing as a “lack of time flow at c”. This is a common misunderstanding, which arises when people try to extend the laws of SR outside its domain of applicability. A photon is not a valid frame of reference, and neither is any other particle with zero rest mass, so asking what time a clock co-moving with a photon would record, is physically meaningless, since no clock can move at c. However, the world line of a photon in spacetime still has a well defined geometric length, but to find it you need to parametrise the world line with something other than proper time. When you do this for (e.g.) a photon going from the sun to the Earth, you will find that this world line has a length of approx eight light minutes, and all observers agree on this (geometric world line lengths are relativistic invariants).
     

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    at point x you take a picture of a walking spider. at point y again. you have accelerated. but in the frame of reference i.e. the picture. you're at rest to the spider. but knowing your speed, and the displacement of the spider in both pictures tells you the spiders speed.
    I agree, but still you have to compare the frame of spider to yours (what's funny, is that scale makes in such case the main difference). Besides spider needs to accelerate the frame, to determine it, as the accelerated one, relative to a stationary macroscopic observer. Without acceleration, both frames are stationary - it's something, what's rather obvious to me. But of course, I'm probably wrong as always...
    Last edited by AstralTraveler; March 16th, 2018 at 04:07 PM.
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    No. Gravity is geodesic deviation, and that doesn’t have anything to do with frames.
    Gravity doesn’t have anything to do with frames? Interesting... I thought, that GR and SR have rather a lot to do with relativity of frames. Without a second frame, there's no relativity...

    Of course it doesn’t make sense, because there is no such thing as a “lack of time flow at c”. This is a common misunderstanding, which arises when people try to extend the laws of SR outside its domain of applicability. A photon is not a valid frame of reference, and neither is any other particle with zero rest mass, so asking what time a clock co-moving with a photon would record, is physically meaningless, since no clock can move at c. However, the world line of a photon in spacetime still has a well defined geometric length, but to find it you need to parametrise the world line with something other than proper time. When you do this for (e.g.) a photon going from the sun to the Earth, you will find that this world line has a length of approx eight light minutes, and all observers agree on this (geometric world line lengths are relativistic invariants).
    Actually it's not that hard to guess, what happens with the flow of time at c - you become the flow of time. Time in space is defined by c - both in QM and SR. Light is the only objective frame of reference in physics, so relative to everything, what is accelerated to c, all other frames are stationary. Am I wrong?

    There is nothing in physics, what is not valid. There is nothing, what is theoretically impossible and incorrect. This would be against science.
    Last edited by AstralTraveler; March 16th, 2018 at 04:17 PM.
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    Can someone stop this dick posting in the hard science areas?
     

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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by AstralTraveler View Post
    No - I'm absolutely correct in this case. Sound DOES travel faster in solid matter, than in gases...
    No you're not.
    You claim was - Sounds moves faster, the more dense is the medium.
    Evidence you're wrong.
    Speed of sound in water: 1433 m/ sec, density of water: 1gm/ cm3.
    Speed of sound in lead: ~1240 m/ sec, density of lead: 11.34gm/ cm3.
    Speed of sound in rubber: ~95 m/ sec, density of rubber: 3.36gm/ cm3.

    You have a habit of making erroneous statements and insisting you're correct. Stop it.
    Ok. I was wrong. My point was to say, that density of a medium has a significant influence on the speed of sound - and so does for c.

    There are also many other factors, which determine both velocities - and in the end all is determined by properties and distrubution of matter (like probably everything else). My bad.
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    you didn't get my point i guess. do you think w/o frames there is no time dilation or gravity?
     

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    Quote Originally Posted by AstralTraveler View Post
    There is nothing in physics, what is not valid. There is nothing, what is theoretically impossible and incorrect. This would be against science.
    Since you don't know very much science, you are unqualified to make statements about what is or is not science.

    You need to back away from the keyboard. Now. And don't come back to type until you've actually learned something about the subject. You've gone full-idiot and have become more than a mere annoyance here. Straighten up -- and fast -- or I suspect your time here will be very, very short.
     

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