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Thread: Are we living in perpetual motion?

  1. #1 Are we living in perpetual motion? 
    Lover of Ideas jacate's Avatar
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    This notion came to me after reading someones comment on an article of physicist claiming that time is not a dimension.

    It was a simple comment that stated: "The universe is perpetuity of motions or processes, chemical or otherwise."

    Thus is the universe in perpetual motion or would it stop with entropy?

    So what do you think? Please enlighten me (and no flames please, just a curious thought here)


    Last edited by jacate; August 21st, 2013 at 10:21 AM. Reason: grammar
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  3. #2  
    Brassica oleracea Strange's Avatar
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    Motion can never stop, for many reasons, including the impossibility of reaching absolute zero.

    I don't know what that has to do with time being a dimension. One nice way to think about this in relativity is that a stationary (1) body is moving through time at the maximal rate, when the body moves (2) with a given velocity, then it swaps some of its motion through time for motion through space. This explains time dilation: the Lorentz transform is actually a rotation (3) between the time and space dimensions.


    (1) Obviously, "stationary" is a relative term.
    (2) Obviously, "moves" is a relative term.
    (3) Technically, a hyperbolic rotation.


    ei incumbit probatio qui dicit, non qui negat
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  4. #3  
    Moderator Moderator Markus Hanke's Avatar
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    Yes, it a certain sense one could say that the universe and everything in it is in constant motion.

    Consider, for simplicity, a point-like particle - in space-time, such a particle is a twisting, curving, but static world-line. Now, the thing is that at every point along that world-line one can define what is called a unit tangent-vector; the means we have a 4-vector which is tangent to the world-line at that point, and the components of which are parametrized in terms of the arc-length of the world-line. When you examine the magnitude ( "length" ) of such a vector, you will find that it is always exactly c, i.e. the speed of light, at all points; the direction of the vector will be a combination of "space" and "time" elements. For example, for a particle perceived to be at rest the vector may point only in the time direction ( "ageing" ); for something going very fast it may point a lot more in the "space" directions than it does in the time direction ( "time dilation" ), relative to the first event; and so on. The point is that a case can be made for everything in space-time to have a velocity of exactly c at all times, i.e. for the universe to be in constant motion, based on purely geometric considerations. This works in both flat as well as curved space-times.

    Not sure if that makes sense, but hopefully you get the main idea
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  5. #4  
    ▼▼ dn ʎɐʍ sıɥʇ ▼▼ RedPanda's Avatar
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    Quote Originally Posted by Markus Hanke View Post
    Yes...
    ...and then you lost me.
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  6. #5  
    Theatre Whore babe's Avatar
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    OK.....I kind of think about it as sleeping.......even when you sleep you move.

    You breathe....and that is movement...your eyelids often flutter in sleep patterns.....that is movement.....

    Maybe I am not speaking of what you are referring to, but I don't think we are ever not in motion, in some way.
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  7. #6  
    Moderator Moderator Markus Hanke's Avatar
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    Quote Originally Posted by RedPanda View Post
    Quote Originally Posted by Markus Hanke View Post
    Yes...
    ...and then you lost me.
    Sorry...it's actually really simple, but hard to explain
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  8. #7  
    Lover of Ideas jacate's Avatar
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    Quote Originally Posted by Strange View Post
    Motion can never stop, for many reasons, including the impossibility of reaching absolute zero.

    I don't know what that has to do with time being a dimension. One nice way to think about this in relativity is that a stationary (1) body is moving through time at the maximal rate, when the body moves (2) with a given velocity, then it swaps some of its motion through time for motion through space. This explains time dilation: the Lorentz transform is actually a rotation (3) between the time and space dimensions.


    (1) Obviously, "stationary" is a relative term.
    (2) Obviously, "moves" is a relative term.
    (3) Technically, a hyperbolic rotation.
    So where do we get our energy to continuously be in motion or perhaps even the universe?(not just light accelerating, the whole thing)

    Quote Originally Posted by Markus Hanke View Post
    Yes, it a certain sense one could say that the universe and everything in it is in constant motion.

    Consider, for simplicity, a point-like particle - in space-time, such a particle is a twisting, curving, but static world-line. Now, the thing is that at every point along that world-line one can define what is called a unit tangent-vector; the means we have a 4-vector which is tangent to the world-line at that point, and the components of which are parametrized in terms of the arc-length of the world-line. When you examine the magnitude ( "length" ) of such a vector, you will find that it is always exactly c, i.e. the speed of light, at all points; the direction of the vector will be a combination of "space" and "time" elements. For example, for a particle perceived to be at rest the vector may point only in the time direction ( "ageing" ); for something going very fast it may point a lot more in the "space" directions than it does in the time direction ( "time dilation" ), relative to the first event; and so on. The point is that a case can be made for everything in space-time to have a velocity of exactly c at all times, i.e. for the universe to be in constant motion, based on purely geometric considerations. This works in both flat as well as curved space-times.

    Not sure if that makes sense, but hopefully you get the main idea
    So wait if that is so, by moving in the direction of space would the particle be faster than the speed of light or slower than the speed of light given that the vector is always at C too? Not to mention if every given point is at C, then a body at rest is also moving at C so as strange said thus it can't stop but then why does it become the time direction given that the body is still moving at C?
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  9. #8  
    Anti-Crank AlexG's Avatar
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    So where do we get our energy to continuously be in motion or perhaps even the universe?
    We don't need any energy to be continuously in motion. You just need energy to change that motion.
    babe likes this.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
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  10. #9  
    Theatre Whore babe's Avatar
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    Quote Originally Posted by AlexG View Post
    So where do we get our energy to continuously be in motion or perhaps even the universe?
    We don't need any energy to be continuously in motion. You just need energy to change that motion.
    Thanks I like that answer!!
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  11. #10  
    Lover of Ideas jacate's Avatar
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    Quote Originally Posted by AlexG View Post
    So where do we get our energy to continuously be in motion or perhaps even the universe?
    We don't need any energy to be continuously in motion. You just need energy to change that motion.
    Thank you for that answer =D
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  12. #11  
    Moderator Moderator Markus Hanke's Avatar
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    Quote Originally Posted by jacate View Post
    So wait if that is so, by moving in the direction of space would the particle be faster than the speed of light or slower than the speed of light given that the vector is always at C too?
    A vector has magnitude and direction; the magnitude is always c, but the direction can change. So, for any given event, such a vector might point more in the "time direction", or more in the "space direction"; it is the particular mix of these components which we perceive as the actual speed in our everyday world, or at least this is a simplified way to look at it and visualise it.

    a body at rest is also moving at C so as strange said thus it can't stop but then why does it become the time direction given that the body is still moving at C?
    An object at relative rest does not travel in space; it remains in the same local position. However, it still does age - hence it is travelling through time ( "ageing" ), but not through space. Again, this is a simplification, but it does work as a visualisation tool.
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  13. #12  
    ▼▼ dn ʎɐʍ sıɥʇ ▼▼ RedPanda's Avatar
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    Quote Originally Posted by PhDemon View Post
    Quote Originally Posted by jacate View Post
    Thank you for that answer =D
    He nicked it off Newton
    Well, this Newton fellow sounds quite bright.
    He should get some credit for his work - maybe a small mention on Wikipaedia or something.
    People like that deserve to get some recognition.
    PhDemon, babe and jacate like this.
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  14. #13  
    Lover of Ideas jacate's Avatar
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    Quote Originally Posted by RedPanda View Post
    Quote Originally Posted by PhDemon View Post
    Quote Originally Posted by jacate View Post
    Thank you for that answer =D
    He nicked it off Newton
    Well, this Newton fellow sounds quite bright.
    He should get some credit for his work - maybe a small mention on Wikipaedia or something.
    People like that deserve to get some recognition.
    Agreed!
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  15. #14  
    Anti-Crank AlexG's Avatar
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    Quote Originally Posted by PhDemon View Post
    Quote Originally Posted by jacate View Post
    Quote Originally Posted by AlexG View Post
    So where do we get our energy to continuously be in motion or perhaps even the universe?
    We don't need any energy to be continuously in motion. You just need energy to change that motion.
    Thank you for that answer =D
    He nicked it off Newton
    I stand on the shoulders of giants.
    PhDemon likes this.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
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