1. Subscribersonhouse
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    07 Mar '09 13:28
    Here is a possible breakthrough in the understanding of quantum physics and possibly combining Relativity and quantum physics in one grand theory, not quite there yet but this seems to be a big step to that end:
    http://www.newscientist.com/article/mg19726391.500-is-time-an-illusion.html?full=true
  2. Standard memberDeepThought
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    07 Mar '09 17:02
    I don´t see what´s new there. There has to be a fourth coordinate for things to be measured on (time axis) and we already know that our perception of time passing is caused by the one way nature of thermal systems. I´ve only read the article you linked to and none of the original papers, the journalist may not be doing them justice, but really I think all they´ve done is rediscovered the law of increase of entropy.
  3. Germany
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    07 Mar '09 17:46
    Interesting article.
  4. Standard memberpatauro
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    08 Mar '09 00:11
    I am just finishing a book on the very subject of time as it relates to physics. The End Of Time by the well respected Julian Barbour. Very fascinating.
  5. Subscribersonhouse
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    08 Mar '09 05:03
    Originally posted by patauro
    I am just finishing a book on the very subject of time as it relates to physics. The End Of Time by the well respected Julian Barbour. Very fascinating.
    It still remains to be seen if they can pull it all off and make predictions that can be verified with experiments, even if it is in subtle details of the MBR.
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    08 Mar '09 23:30
    Could Time Just Be Caused By Mass ???

    If we take the first approximation of Einstein's rate of time dilation caused by gravity we get

    t=t0*(1+G*M/c^2/r)

    t is the equivalent time of an event at "infinity" of length t0
    G is the gravitational constant
    c is the speed of light
    r is the distance from a big mass M

    Now it can be shown that the sum for all the masses in the universe

    sum(G*M(i)/c^2/r(i)) = 1

    It would be logical that we could replace the 1 with this to include all the masses in the universe

    t=t0*sum(G*M(i)/c^2/r(i))

    For the nearest mass this equation would be the same as the first equation above, and as the effect is a 1/r effect far away masses should also do something.

    Therefore if there was no mass in a universe the time would be infinitely fast.The past and the future would all be at the present now.

    On the other hand on a black hold time would stop. Time is somehow bound to the fact that there is mass. Without mass the whole concept of time would disappear.
  7. Standard memberDeepThought
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    09 Mar '09 07:43
    Originally posted by tony4
    Now it can be shown that the sum for all the masses in the universe

    sum(G*M(i)/c^2/r(i)) = 1
    Can it? I´d like to see a proof of this.
  8. Germany
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    09 Mar '09 09:46
    That's a little ambiguous notation with the 2 divisor signs...
  9. Standard memberDeepThought
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    09 Mar '09 09:592 edits
    Originally posted by tony4
    Could Time Just Be Caused By Mass ???

    If we take the first approximation of Einstein's rate of time dilation caused by gravity we get

    t=t0*(1+G*M/c^2/r)

    t is the equivalent time of an event at "infinity" of length t0
    G is the gravitational constant
    c is the speed of light
    r is the distance from a big mass M

    Now it can be shown that the sum for ...[text shortened]... bound to the fact that there is mass. Without mass the whole concept of time would disappear.
    Your first equation is incorrect. Assuming everything is static it should read:

    t = t_0 (1- a/r),

    where a = 2GM/c² (the Schwartzschild radius).

    Your second equation makes no sense. What is r(i) and why are you summing over masses. In the Newtonian approximation what you can do is write the potential energy of two point particles labelled i and j with masses M_i and M_j at r_i and r_j as:

    V_i_j = - G M_i M_j / |r_i - r_j|

    So that the total potential energy involves a double sum over i and j over the two particle potentials:

    V = sum(i) sum(j < i) V_i_j

    I have heard the statement that total field energy balances total mass/kinetic energy before. This is not a prediction of any theory I know of but based on observation.

    When you replaced 1 with the dynamic term equal to one, you dropped the second term. You then write your third equation down and state that if the mass is zero then t = 0. True, but you´ve already relied on that sum being equal to 1 so you can´t then set it equal to zero.

    Also your eventual conclusion is wrong. If there were no mass in the universe then in the General theory of Relativity time would pass at the same rate for all observers - it would not stop nor would it become infinitely fast.

    At the Schwartzschild radius of a (static uncharged) black hole the completely time-like component of the metric vanishes. But that means that a clock at that radius takes an infinite amount of time to tick once when measured by an asymptotic observer - the observer at the Schwartzschild radius doesn´t notice anything unusual.
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    09 Mar '09 10:48
    An universe without mass, is this possible?
    An universe without time, is this possible?
  11. Standard memberDeepThought
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    09 Mar '09 11:34
    Originally posted by DeepThought
    If there were no mass in the universe then in the General theory of Relativity time would pass at the same rate for all observers.
    Subject to them being in the same inertial reference frame.
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    10 Mar '09 19:07
    Originally posted by DeepThought
    Can it? I´d like to see a proof of this.
    Here is a proof ;

    If we assume a uniform density for the whole universe.

    sum= m*integrate(G/c^2*(4*%pi*Density_Universe*r^2)/r,r,0,Radius_Of_Universe)

    Taking

    radius of universe as 7e26m
    and density of universe 9.9 e-27 kg/m^3

    We get

    G/c^2*integrate((4*%pi*Density_Universe*r^2)/r,r,0,Radius_Of_Universe)=23


    Using other values for the density and radius of the universe we get .78

    The true value is exactly 1 so that f=m*a
  13. Standard memberDeepThought
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    10 Mar '09 19:143 edits
    Originally posted by tony4

    sum= m*integrate(G/c^2*(4*%pi*Density_Universe*r^2)/r,r,0,Radius_Of_Universe)
    What is the justification for doing this integration in the first place? The integral is formally divergent so you are relying on the universe having a finite volume.
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    11 Mar '09 22:44
    Originally posted by DeepThought
    What is the justification for doing this integration in the first place? The integral is formally divergent so you are relying on the universe having a finite volume.
    Wikipedia http://en.wikipedia.org/wiki/Universe gives a radius of the universe as 8.80 ×10^26 with a density of 9.9 × 10^&#8722;30 grams per cubic centimeter. Most theories about the universe give it a radius.I was also very surprised when I first did the integration that the sum was about 1.
  15. Standard memberDeepThought
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    12 Mar '09 08:35
    Originally posted by tony4
    Wikipedia http://en.wikipedia.org/wiki/Universe gives a radius of the universe as 8.80 ×10^26 with a density of 9.9 × 10^&#8722;30 grams per cubic centimeter. Most theories about the universe give it a radius.I was also very surprised when I first did the integration that the sum was about 1.
    That figure for the radius comes out at 73 billion light years. It is based on a lower bound of the actual radius of the universe - the true figure could be far higher. The observable radius is around 43 billion light years. What the radius of the space is depends on the density of matter in the universe. It is thought to be close to the so called critical density - which is the figure you quoted. This tips the universe between finite and infinite extent.

    Your integral finds the potential energy of the whole of the rest of the universe due to a gravitating mass at the origin. I doubt it´s terribly meaningful as GR effects dominate at such vast distance scales. However what you would then have shown is that the total field energy is equal to the total mass energy of the source at the origin.

    In any case material outside the observable universe is not causally connected to us so cannot gravitationally influence matter here. You should use the radius of the observable universe for this calculation.
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