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Relativity and The Big Bang.

  1. Jan 15, 2006 #1
    Hi - Im new here. Here goes.
    Has anyone ever considered the fact that our "rate of second elapse" is created by our speed through spacetime as provided to our planet/solar system/galaxy by the big bang?
    Am I of the opinion that the time we inherit is gathered from the speed we at which we are moving.
    All rotational motion is taken into consideration - such as our speed around the sun, our speed around the hub of the Milky Way and back to earth our own rotation.
    If we were to stop all of these movements - then am I correct in thinking that our seconds would elapse instantaneoulsy? (Given that STOP is as far away from the speed of light as is possible? And that seconds last longer at the speed of light.)
    Thanks
     
  2. jcsd
  3. Jan 15, 2006 #2

    pervect

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    What do you mean by the "rate of second elapse", and how do you measure it?

    For that matter, what is the "speed through spacetime", and how do you measure it?

    Are you any relation to the poster known as "trepeidation" who seems to have similar ill-defined ideas? (He didn't explain himself, apparently he just did a hit-and-run posting).
     
  4. Jan 15, 2006 #3
    Wouldn't this be

    [tex]U^\mu U_\mu = \eta_{\mu\nu}\frac{dx^\mu}{d\tau}\frac{dx^\nu}{d\tau}[/tex]

    which is basically equal to 1, or c in SI units?
     
  5. Jan 15, 2006 #4

    pervect

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    It's hard to say, unless we hear more from the O.P. (original poster). I'm still waiting to see if he's going to show up, or whether this is yet another "hit and run" posting.
     
  6. Jan 15, 2006 #5
    You can't determine your speed in relation to anything without having a non moving point of reference, but how do you find such a point anyway. For all I know everything is moving at C and C is just 2C. To us it's C of course I think that's what's important.
     
  7. Jan 15, 2006 #6
    "rate of second elapse"
    As I understand it - a second elapses at a slower rate as we approach the speed of light. Its measured with atomic clocks.
    Is this not true?
    "Hit and run poster" - I guess youve had a prob??? Dont worry - I own 300 + domains and run many many boards on the net (its my living) - I aint here to hit n run or cause a prob.
    I was just pondering on the concept of time dialation - and was hoping for a chat about whether or not our own "rate of seconds" (keeping with seconds as a unit) elapse at our percieved rate due to the speed we are moving away from the point of origin - which as I understand things - would be the big bang.
    To clarify - if we were further away from the point of origin now - we would logically be moving faster - and therefore would our seconds take "longer to elapse"?
    Im thinking that you can determine speed by using the initial big bang point of singularity as a point of reference - something which nobody has considered so far as I am aware.
    To me - c - thats just a nice effect in an expanding sphere of matter.
    I would rather see that as we travel back towards the point of origin, that our "rate of second elsapse" would accelerate as we subtract x from our speed of outbound motion from the blast - where x would be our speed measure towards the point of the blast.
    Hey - I dont have all the answers - theres no need for "malformed ideas" and such.
    In summary - is it recognised that our seconds are what they are in terms of rate of elapse due to our speed through the cosmos?
    If we were moving faster - would they take longer to elapse?
    I think they would - but was hoping for other more mathematical minds to confer.
     
    Last edited: Jan 15, 2006
  8. Jan 15, 2006 #7

    ZapperZ

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    No, it isn't. YOu have severely misunderstood time dilation.

    Your time (proper time) never change. Your time, as view BY OTHERS in another inertial frame, is the one that "dilates". So if you view another frame moving, you will see that the time in that frame appears to move slower. But observers in THAT frame sees no difference. They observe their proper time being the same as it should.

    So when "we approach the speed of light", we see no such time dilation of our proper time.

    Zz.
     
  9. Jan 15, 2006 #8
    But in the twins paradox - doesnt the traveller come back less aged than the stationary twin?
    And an atomic clock - after a long flight will show a different time to its stationary partner on the ground?

    Therefore the time taken for a second to elapse for the traveller is longer than that for the none traveller surely ive read this correctly?

    If - in flight - the ground based atomic clock were to be handed to a traveller after a few weeks of flying with his own clock, the traveller himself would read two different times?
     
    Last edited: Jan 15, 2006
  10. Jan 15, 2006 #9

    ZapperZ

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    But THAT involves MORE than just straightforward time dilation due to approaching the speed of light. It involves speeding up, slowing down, i.e. accelerated motion! This isn't what you stated in the beginning. And including such motion is MORE COMPLICATED, something I truly believe you have not understood.

    I strongly suggest you go back and look at elementary description of Special Relativity. Look again the SIMPLEST situation of two moving inertial frame and understand what is meant by time dilation in that situation FIRST. If you do not understand this, you cannot build on more complicated situations, and certainly not something involving accelerated motion.

    Zz.
     
  11. Jan 15, 2006 #10
    K - Im here to learn.

    Ignore acceleration for the moment - I havent mentioned that.

    Am I correct at all when I say that a clock on an object moving close to the speed of light will measure time differently (will run slower) than a clock which is not moving at anywhere near the same speed.

    ?

    Surely thats correct - and is the absolute simplest I can make it?
     
  12. Jan 15, 2006 #11
    albert if your on a rocket that is moving(from your frame of reference)away/towards a space station with a relativisticy velocity any clock on the space station will seem to run slower compared to your clock when you observe them.

    But people on the space station will observe YOUR clock to run slower when THEY observe you.

    So both the space station and you will say "your clock runs slower than mine"

    This is because you can either think of it as the rocket moving and the space station is holding its position. Or the rocket is standing still and the space station is moving. Both are equaliy valid.
     
  13. Jan 15, 2006 #12

    ZapperZ

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    Let's go back to the simplest basics.

    I am in inertial frame A. You are in inertial frame B. I see you moving with velocity v. You see me moving with velocity v, but in opposite direction. Are we OK so far?

    My clock moves "normally". My proper time doesn't do anything "weird". In your frame, you see your clock moving normally. Your proper time also doesn't do anything weird. Are we OK so far here?

    But when I look at YOUR clock, it is slower than mine. But since there's nothing special about my reference frame, there's nothing to say that my reference frame is absolute. You can also argue that in your frame, you seem my clock moving slower than yours.

    NOW do you see what I'm getting at? When you say "clock or time slows down", you HAVE to indicate an observation from WHOSE perspective! You cannot just say "..... a clock on an object moving close to the speed of light will measure time differently (will run slower) .... " without indicating explicitly the observing reference frame, because the observer that is moving with the clock sees NO slowing down.

    Zz.
     
  14. Jan 15, 2006 #13
    Let's not call it a rocket since that implies acceleration. Let's instead just 2 space stations moving apart from each other. That way, it is a symmetric situation since they are both inertial (and therefore equally valid in the SR regime) observers.
     
  15. Jan 15, 2006 #14
    Ok - I am happy with what you are saying here with reference to the observers and the percieved "no slowing" of a traveller watching his own clock - thanks.

    Can I put this question to you.

    There are 3 people on earth - p1, p2, p3.

    p1 and p2 have clocks.

    p3 is a "steward of the experiment".

    Gaining instant and constant speed just below c - p1 goes into space for a period of time measured by p2 of 3 years.

    On p1 arriving at earth (he flew in a circular path (a rather large one at that)) - p1 and p2 hand their clocks over to p3 - the steward.

    P3 looks at the clocks.

    Are they reading different times according to what the steward sees at the instant the clocks are handed over?
     
  16. Jan 15, 2006 #15

    ZapperZ

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    Again, you have introduced an acceleration component. Something moving in a circular path, no matter how big, is in an accelerated frame. Do you really want to do this?

    An observer in an accelerated frame is no longer the same as the one in an inertial frame. The symmetry between the two travellers no longer exists.

    Zz.
     
  17. Jan 15, 2006 #16
    Reworded.

    Ok - I am happy with what you are saying here with reference to the observers and the percieved "no slowing" of a traveller watching his own clock - thanks.

    Can I put this question to you.

    There are 3 people on earth - p1, p2, p3.

    p1 and p2 have clocks.

    p3 is a "steward of the experiment".

    Gaining instant and constant speed just below c - p1 goes into space for a period of time measured by p2 of 3 years.

    On p1 arriving at earth (he flew straight out - and straight back) - p1 and p2 hand their clocks over to p3 - the steward.

    P3 looks at the clocks.

    Are they reading different times according to what the steward sees at the instant the clocks are handed over?
     
  18. Jan 15, 2006 #17

    Garth

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    First welcome to these Forums Albert!

    In your last example p2 and p3 are the same are they not? It's just that p3 hasn't a clock.

    p1 and p2 clocks will read differently, p1 will record less time duration. In that sense time dilation is 'real', it makes a physical difference.

    The twin paradox depends on the fact that, as velocities are relative, p1 might think it was p2 and p3 who went on the journey with the whole Earth, and therefore p2's clock ought to read 'slow', whereas p2/p3 will think it was p1 who made the trip and her clock ought to be 'slow'.

    However, the paradox is resolved by realising that, although velocities are relative, accelerations are not; you can tell whether it was p1 or p2/3 who took a trip, p1 accelerated outwards and then accelerated 'inwards' to get back home again. It is p1's clock that is slow compared to the other two.

    If you want a real 'twin' paradox consider two space travellers who circumnavigate a closed universe. They pass close by each other at high relative speed and synchronise their clocks. Neither accelerate or decelerate, they both remain in inertial frames of reference. After a very long time they pass by each other again, one having circumnavigated the universe, and compare clocks a second time. Which one made the circumnavigation? From the point of view of each both would consider that they had remained stationary and the other accomplished the circumavigation, each would think the other's clock would be 'slow', but which one?

    Garth
     
    Last edited: Jan 15, 2006
  19. Jan 15, 2006 #18

    ZapperZ

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    Again, this requires a slowing down, and then an acceleration in the opposite direction, i.e. ACCELERATION/DECELERATION.

    This is no different than your earlier example which I said contained accelerating frame. You already said you don't want this, so why are you invoking it again?

    Zz.
     
  20. Jan 15, 2006 #19
    ZapperZ
    It assumes instant speed and instant stop and instant change of direction - this is more than sufficient in order to answer the question.

    Would the answer be different if we involved acceleration/deceleration - possibly under certain rates of those - and time travelling close to c.

    Thank you Garth - I'll post again once I get my head around a few matters.
     
  21. Jan 15, 2006 #20

    Janus

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    A change of velocity is an acceleration, even if it is "instant". Instant change of velocity just implies infinite acceleration.
     
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