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Thread: What is Time?

  1. #1 What is Time? 
    Forum Freshman vistotutti's Avatar
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    I'm still learning of relativity, so this is in part a question in the form of a series of statements.

    1) Light does not deserve it's own frame of reference, unlike any other observer in the universe.
    2) Light travels always a C, no matter who observes it.
    3) Time/space will alter in order for 1) and 2) to remain true.

    If light cannot be said to be (nearly) stationary in relation to "Bob", who has attained the speed of light (minus a little bit) in the same direction as the light, then does light inhabit the time dimension at all?

    The reason I ask this is because; Bob and Jane inhabit a 4 dimensional space, and as Bob moves past Jane in the "across" dimension at near C speed. Jane is not sure if she is not moving at near C speed in the opposite direction.

    The only way I can see for a light beam/particle to be exempt from the same principle is if light does not inhabit a four dimensional world as do Bob and Jane.

    Let me explain...

    If light is not involved in the time dimension, then it would be exempt from the distance/time rule. Without time, there is just instantaneous distance.
    Speed being distance traveled over time, after all.
    Bob and Jane, both, see time, and they see distance traveled over that time.

    Can we deny the existence of distance? we can distort it, but it's still there.
    So that leaves Time...

    What is time ... I dont know!

    Does light travel from the big bang to the end of the universe with only distance as a measure, with time not in the equation?

    Does light bounce back from the end of the universe and interfere with itself on the way back to the beginning, in a quantum wave kind of way?

    I'm not sure the English language is up to the task of explaining the concepts I'm grappling with here, but comments in the same flawed language are welcome.
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  3. #2 Re: What is Time? 
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    Quote Originally Posted by vistotutti
    I'm still learning of relativity, so this is in part a question in the form of a series of statements.

    1) Light does not deserve it's own frame of reference, unlike any other observer in the universe.
    2) Light travels always a C, no matter who observes it.
    3) Time/space will alter in order for 1) and 2) to remain true.

    If light cannot be said to be (nearly) stationary in relation to "Bob", who has attained the speed of light (minus a little bit) in the same direction as the light, then does light inhabit the time dimension at all?

    The reason I ask this is because; Bob and Jane inhabit a 4 dimensional space, and as Bob moves past Jane in the "across" dimension at near C speed. Jane is not sure if she is not moving at near C speed in the opposite direction.

    The only way I can see for a light beam/particle to be exempt from the same principle is if light does not inhabit a four dimensional world as do Bob and Jane.

    Let me explain...

    If light is not involved in the time dimension, then it would be exempt from the distance/time rule. Without time, there is just instantaneous distance.
    Speed being distance traveled over time, after all.
    Bob and Jane, both, see time, and they see distance traveled over that time.

    Can we deny the existence of distance? we can distort it, but it's still there.
    So that leaves Time...

    What is time ... I dont know!

    Does light travel from the big bang to the end of the universe with only distance as a measure, with time not in the equation?

    Does light bounce back from the end of the universe and interfere with itself on the way back to the beginning, in a quantum wave kind of way?

    I'm not sure the English language is up to the task of explaining the concepts I'm grappling with here, but comments in the same flawed language are welcome.
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    You need to phrase your question or conjecture in terms of the relevant mathematics in order to make it clear. I think if you do that you will probably answer your own question. See what happens with the Lorentz transformation when you try to apply it to a photon.


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  4. #3  
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    try german, worked for einstein and bohr =)
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  5. #4  
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    Sorry, but German isn't the language of mathematics, and while Einstein spoke and wrote in German, his math was written in math...
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  6. #5 Time and the speed of light 
    Forum Freshman vistotutti's Avatar
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    I'm still reading Einsteinian physics, and trying to come to terms with it.
    I can understand how no-one in the universe has a privileged perspective in regard to location or velocity, but I'm still struggling with the (perceived) privileged perspective of light.

    Observer Bob sees a single photon traveling at C coming toward him.
    Observer Jane sees a single photon traveling at C coming toward her.
    But Bob and Jane have a difference of almost C in velocities, and in different directions!

    I find it difficult to reconcile the two perspectives and say that the speed of light, and hence the speed of said photon is always constant.

    ...unless, and this is where I veer off into wild speculation (with the hope of learning from the error)

    Unless, time is a dimension that photons do not interact with. If the photon only interacts with up, down, left, right, then there is no conflict.

    It is only Jane and Bob that count the seconds of time, and it is only they that get their heads in a knot about how many metres per second a photon passed them by at.

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    P.S. Excuse the dangling infinitive, but in my defense, I leave you with the words of Winston Churchhill
    "this is the sort of English, up with which I will not put!"
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  7. #6  
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    Everything always exists in all dimensions. You can't have something that doesn't "inhabit" the time dimension.

    However, you are somewhat correct, photons do not experience any time whatsoever. A photon that came from the big bang and hasn't reacted with anything, will be exactly zero seconds old.

    So instead of saying that "time is a dimension that photons don't interact with" just say that photons do not move in the time dimension... provided that time even really can be considered a dimension.
    The question of "what is time" is a VERY good one, and it is a question that no one know the answer to. All we can be sure of is that our everyday definitions of time are absolutely wrong.
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  8. #7  
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    TIME is what keeps everything from happening all at once.
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  9. #8  
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    Time causes all matter that exists in spatial dimensions to change and interact. Yet it is also intertwinned with space itself, so any change in space is a change in time and vice versa.

    Time isn't linear and neither is it a constant universal entity. Its just something that works relative. Time for stars and distant objects in the night sky is way off than to ours, but even then me saying that is a non-relative assumption.

    Time is like a big ball of wibbly, wobbly timey wimey... Stuff. It wibbles and it wobbles, it tipples and it topples. Its like different colours of Jelly. Imagine 5 colours of Jelly and 10 people around it. The colour of that Jelly is different from wherever an observor is standing and the angle they are looking. So yeah.... Time is like Jelly... Maybe...
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  10. #9  
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    Some clear influence from doctor who, but a reasonable explanation of time, maybe, in a way.

    I would add that it cannot be directly measured, nor are its effects clear. We notice a change in time only by our method of measuring it; is time actually affected?

    An atomic clock measures changes in electron energy; not time.
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  11. #10  
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    I just want to ask, if all possible observations show that time has changed, what's the difference in saying that time actually did (or did not) change?
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  12. #11  
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    Look just forget what time is. Does it matter? I mean its not as if any of you are going to revolutionize time and create time travel. Not that you could even navigate time's time anyway so leave it to the Time Lord's please...
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  13. #12  
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    As I have previously mentioned, time travel violates fundamental laws of physics. Assuming that these laws are fundamental, time cannot exist except as a concept, and neither can time travel, without violating them.

    did that make sense to anyone?
    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
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  14. #13  
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    Perfect sense. To a Third + fourth dimensional being such as myself....
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  15. #14  
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    [Crazy stuff that respectable scientists think]
    In Einsteinian physics, people often talk of Time as one of the four dimensions that we inhabit.
    This may be just a way of discussing things, or it may have a basis in reality.
    In Quantum physics, theorists often talk of extra dimensions beyond the four we know and experience.
    These extra dimensions are small, curled-up smaller than a Planck-length. These extra curled-up dimensions make space lumpy and act like a three dimensional grid.

    (Let's call the smallest cube of space a Planck)

    As a consequence of the small size of these dimensions, only objects of very small size, less than a single Planck can ever move in them, and hence experience them.
    It is theorized that during the Big-Bang a period of hyper-inflation expanded the four dimension we know, but did not expand the other, now tiny dimensions.

    [Now The truly crazy stuff]
    Suppose that the Time dimension is still expanding today. While the other three large dimensions have slowed their pace of expansion; presumable due to the force of gravity.

    What would be the consequence of this expansion?
    Well, an object embedded in the four dimensional space-time matrix, even when at rest, would be carried along in the time dimension as it expanded.
    Also, the weave of space-time would be getting coarser in the Time dimension.
    Imagine a grid; now stretch that grid so that it gets bigger, the squares of the grid grow coarser.
    If the Time dimension were to grow large enough, then the three dimensions of space could fit inside a single division of the Time dimension.

    (Let's call the smallest unit of the Time dimension a Stein)

    Just as the small dimensions of Quantum mechanics fit inside a single Planck of space, the three space dimensions could fit inside a single Stein of Time.

    In this scenario, something as small as the Universe that we know, would not experience movement in this enormous Time dimension; apart from the expansion of the Time dimension itself. only truly enormous objects spanning many Stein of Time would experience true movement in the Time dimension.
    Just as a sub-atomic object bound to the small Quantum dimensions would not experience the three large space dimensions if it spent it's whole existence inside a single Planck.
    So too the Universe we know and love spends it's entire existence inside a single Stein of Time.

    ..and then again, maybe I've had one too many Stein of lager.
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  16. #15  
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    Quote Originally Posted by drowsy turtle
    As I have previously mentioned, time travel violates fundamental laws of physics. Assuming that these laws are fundamental, time cannot exist except as a concept, and neither can time travel, without violating them.

    did that make sense to anyone?
    No it doesn't.

    Particles can travel forwards in time.

    FACT.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

    www.leohopkins.com
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  17. #16  
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    Wow, we're being pedantic. When I refer to time travel, I mean jumping from one time to another without passing through the time in between. Better?
    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
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  18. #17 Another hypothesis bites the dust 
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    Quote Originally Posted by leohopkins
    Quote Originally Posted by drowsy turtle
    As I have previously mentioned, time travel violates fundamental laws of physics. Assuming that these laws are fundamental, time cannot exist except as a concept, and neither can time travel, without violating them.

    did that make sense to anyone?
    No it doesn't.

    Particles can travel forwards in time.

    FACT.
    It only takes one measurement to ruin a perfectly good hypothesis.
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  19. #18  
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    Quote Originally Posted by drowsy turtle
    As I have previously mentioned, time travel violates fundamental laws of physics. Assuming that these laws are fundamental, time cannot exist except as a concept, and neither can time travel, without violating them.

    did that make sense to anyone?
    Which laws were those?
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  20. #19  
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    Conservation of energy, conservation of lepton number, etc.
    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
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  21. #20  
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    Quote Originally Posted by drowsy turtle
    As I have previously mentioned, time travel violates fundamental laws of physics. Assuming that these laws are fundamental, time cannot exist except as a concept, and neither can time travel, without violating them.

    did that make sense to anyone?
    Given that time dilation is an accepted scientific fact this would seem to suggest that time travel (at least into the future) is possible. In other words time travel becomes a very difficult problem in the fields of technology/engineering and not a concept that "violates fundamental laws of physics".
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  22. #21  
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    You can imagine 3D space as moving along an axis of time. Consider a ball moving in spacetime. now if you click on any point on the time axis (imagine) consider that a new window opens on your "browser" shownig the position of the ball in space at that point on the time axis. Now, you can click on such infinite points on the time axis and you will be able to see where the ball is in space at any point in time. Suppose you create a movie on the time axis you will see the ball move as in normal life. I consider that as TIME.
    Beyond Equations,

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  23. #22  
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    Quote Originally Posted by Street_Physicist
    The question of "what is time" is a VERY good one, and it is a question that no one knows the answer to. All we can be sure of is that our everyday definitions of time are absolutely wrong.
    Agreed!
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  24. #23  
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    Quote Originally Posted by drowsy turtle
    Conservation of energy, conservation of lepton number, etc.
    How does time travel, in general, violate those laws? Sure, the instantly-appear-elsewhen, trasporter-like method would, but what about other methods?

    Not only that, but it doesn't seem like Conservation of Lepton Number is really so fundamental.
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  25. #24  
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    Overall lepton number is still conserved. But that's a different issue.

    I am in fact only thinking of moving from one time to another. Speeding up time or slowing down time would perhaps not cause this violation.

    Time travel back in time would always cause this though.
    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
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  26. #25  
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    Well, it might not, depending on the exact details of the method used. One hypothetical possibility is simply moving some equivalent chunk of stuff back the other way.
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  27. #26  
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    Time Travel violates a lot of laws. (Well backwards anyway). But the laws it violates aren't constant in every circumstance in the universe. AKA Black holes. Alternate non-minkowski space, early universe, relative spacetime etc.

    It is possible, but it is not understood well. If you travel back in time, the furthur away you go from what I call your 'cause and effect universe'. In which imagine it like this.

    Imagine time as we know it as a line, and our universe as a line (think of a grid here). Now alternate cause and effect universes are next to us in this same grid but going the other way (left to right). When one travels forwards one goes 'in a straight line'. But when you go back, you go diagonally backwards. As in you now enter alternate cause and effect universes. If you went back say a million years and then forwards you would have gone back diagonally A LONG WAY. So when you come forward on the same line then time will be totally different to where you were, or rather when you were.

    Its even more a lot more complicated by that but I thought I'd share that with you. Time isn't linear, and neither are its laws that prohibit it.

    Time travel violates 3 dimensional + 1 of time dimensional laws and thus all our attributed laws like baryoness, momentum violation etc. But time travel to the past is not a 4 dimensional concept, its a 5 dimensional concept (its not even that and its more complicated but its how you would understand it more or less). You see, the momentum and the baryoness is conserved because the time travelling object is going to another cause and effect universe and not the one they are leaving, unlike going forwards in time...

    Even if you human beings master time travel. You're still going to have to explain why it's never the same as you left... :P
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  28. #27  
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    You could actually argue that travelling back in time BOTH violates fundamental laws AND is possible.

    Violating laws doesn't necessarily indicate something is impossible but rather could indicate consequences. The fundamental laws we speak of essentially describe the way the universe works as a model. If you broke those laws you would now be outside of the model...that's the only way I can think of travelling back in time being possible.

    It's the same as actually being able to travel fast enough to supposedly travel back in time, ie. faster than c. This in itself is a violation of certain laws and it should technically be impossible for any particle with mass to even reach c, let alone break it. For anything to break c and stay within the confines of the laws it would have to have negative mass, and even that's just an assumption based upon what we're able to model so far. Anything that actually has positive mass would need to "break" that rule.

    I personally don't see how it would be possible for anything besides information to travel through time in such a way. Time dilation is different from the generic concept of "time travel" - it is more a manipulation of the rate of time rather than mastery of it.

    Note:

    And personally, the way I interpret the relationship between time and c is not that somehow c is the determining factor but more that it is a coincidental upper echelon of speed that is reached by "timeless" particles. I may be wrong but for me, the fact that time dilation becomes more prominent on object as they tend towards c is more to do with a change of nature of that object than its speed. Thats just my personal opinion though.

    On the actual topic (lol): For me, time is the very fabric of the nature of this universe - you could call it the system within it. It governs cause and effect, and the myriad of subsystems within the universe. Manipulating time would be tantamount to manipulating the universe itself.
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