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Time changes in gravity field.

  1. Dec 29, 2003 #1
    Gravity is supposed to slow time down. Going fast is supposed to do the same thing. Increasing gravity is the equivalent of accelerating greatly. However, if I only accelerate a little, I feel the equivalent of, say, the moons gravity, but I will still eventually reach sub-light speeds and experience relative slowing of time. Why isn't standing on the Earth and experiencing acceleration in space such that you experience earths gravity the same in that in space you're time slows down as you reach higher speeds, relative to an observer, but on Earth nothing changes? Many thanks.
     
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  3. Dec 29, 2003 #2
    When you personally are moving at high speed it is not your own time which is slowing down. Its the time as measured in a clock which is moving relative to you. When you're standing on the Earth then you're not moving relative to your wristwatch so you'll never see your wristwatch slow down. Also, when speaking of reaching higher and higher speeds its only meaningful when you say with respect to what. For example: Standing on Earth you are not moving with respect to the Earth's surface. However if there is a in free-fall in the Earth's gravitational field then it will speed up relative to you. It is in an inertial frame and that inertial frame is accelerating relative to you. It is the stone's "clock" which is now moving slower.
     
  4. Dec 29, 2003 #3
    I was trying to explain to you about Einstein’s 1911 gravitational redshift theory, but the thread censor keeps removing my posts. Anyway, you can find the theory in “The Principle of Relativity”, Dover Publications Inc. Apparently only certain people are allowed to talk about that theory around this place, and since they aren’t talking about it, I suppose they’ve never read it, so they delete my posts about it.
     
  5. Dec 29, 2003 #4

    Janus

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    Re: Re: Time changes in gravity field.

    You are free to discuss your personal interpretation in the Theory Development forum. But in this forum we will stick to the accepted modern interpretation.
     
  6. Dec 30, 2003 #5

    As I was saying, in Einstein’s 1911 theory, a single atom was his “elementary light-generator”. It’s “vibration-number” was its internal harmonic oscillation rate, and that was assumed by most physicists at the time to be very steady or even absolutely steady. He could have gotten his basic idea for an “atomic clock” from Maxwell’s 1873 book, “A Treatise on Electricity and Magnetism, Vol. 1”, in which Maxwell said:

    “In the present state of science the most universal standard of length which we could assume would be the wave length in vacuum of a particular kind of light, emitted by some widely diffused substance such as sodium, which has well-defined lines in its spectrum.

    In astronomy a year is sometimes used as a unit of time. A more universal unit of time might be found by taking the periodic time of vibration of the particular kind of light whose wave length is the unit of length.”

    So, Einstein’s “elementary light-generator” in the 1911 theory was a single atom of an “element”, and in the paper he deduced how the large gravitational potential at the surface of a massive body like the sun could cause the “vibration number” of an atom to be reduced, and how the atom would be forced to emit light of a lower frequency and wavelength, than when that same atom is vibrating and emitting light at the surface of the earth. This is known as his “gravitational redshift” theory, because in the theory the gravitational field of the sun (or any massive body) reduces the “vibration number” of an “elementary light-generator”, ie, and “atom”. Thus, it emits “redshifted light” when compared to the same kind of atom emitting light on earth, while resting inside a weaker gravitational field.

    This was what Einstein said in the theory. I don’t know how Janus thinks about the theory. I don’t even know if he has read it or not. Evidently he hasn’t read both the 1911 theory and the 1873 Maxwell book, since he doesn’t seem to understand why Einstein thought of a single atom as an “elementary light-generator”.

    This is a problem with modern physics in America. Too few people are trying to control the “official” interpretations of the main theories. That is why we are importing so many physicists and scientists from other countries, from Japan, from China, from Indian, and from many other countries where the theorists and scientists aren’t censored and aren’t restricted to “official” interpretations
     
  7. Dec 30, 2003 #6
    Re: Re: Time changes in gravity field.

    What "stone" are you talking about? Why would a "stone's clock" move slower than mine? What do you mean by the "stone's clock"? Are you talking about it atomic vibration rates or its molecular vibration rates? Are you talking about its temperature? What are you talking about? Where do you get this baloney, and why does it not get censored while my posts do?
     
  8. Dec 30, 2003 #7
    Re: Re: Re: Time changes in gravity field.

    I never said that an observer measures time to slow down on his own clock. The doppler effect has nothing to do with this. In fact it would be a bad idea to use Doppler to try to measure time dilation since it will give you the wrong results.
     
  9. Dec 30, 2003 #8
    Re: Re: Re: Time changes in gravity field.

    It isn't wise to moderate something like that out. In fact it can only server to propage any misunderstanding of his. I.e. we can't see what he thinks about redshift and as such we can't explain to him why he's wrong. Moderation should never be about censoring ideas. It should only be limited to keeping conversations on topic and civil.
     
  10. Dec 30, 2003 #9

    Janus

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    Re: Re: Re: Re: Time changes in gravity field.

    As I said. he is perfectly welcome to discuss his ideas in the TD forum (Which by the way he has). Otherwise threads like this which start out as a simple question by someone wishing to learn gets hign-jacked by argument which in most cases merely confuses the initial poster.
     
  11. Dec 30, 2003 #10

    Janus

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    Re: Re: Time changes in gravity field.

    No, this is not what Einstein said. He never implied that local Gravitatational intensity would affect the vibration of an atom. He said that an observer viewing this atom from a higher point of gravitational potential would observe the atom as vibrating slower. This is totally different because it relys purely on Relative position in the field an not on any physical effect gravity has locally. This is the modern interpretaion of Relativity.
     
  12. Dec 30, 2003 #11

    Janus

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    Re: Re: Re: Re: Time changes in gravity field.

    As I said. he is perfectly welcome to discuss his ideas in the TD forum (Which by the way he has). Otherwise threads like this which start out as a simple question by someone wishing to learn gets hign-jacked by argument which in most cases merely confuses the initial poster.
     
  13. Dec 30, 2003 #12
    Re: Re: Re: Re: Re: Time changes in gravity field.

    He's refering to Einstein's 1911 paper on gravitational redshift and that paper is not entirely wrong. In fact its quite accurate in flat spacetime.
     
  14. Dec 30, 2003 #13
    Re: Re: Re: Re: Re: Re: Time changes in gravity field.

    Right, that's exactly what I was talking about.
     
  15. Dec 30, 2003 #14
    Re: Re: Re: Re: Re: Time changes in gravity field.


    I’m not trying to high-jack any thread. As you might know, there are differing opinions about a lot of physics and cosmology subjects. I was trying to explain to Vosh that Einstein was specific in the 1911 paper about gravity slowing atomic clocks down, but not necessarily other kinds of clocks.

    I told Vosh that pendulum clocks speed up in stronger gravity, and that has been known in physics for the past 500 years, but you censored that comment of mine because you didn’t want Vosh to know it.

    There was no reason to censor that comment, since Newton and many other physicists discussed it, and in fact geologists used pendulum clocks in the 19th Century to measure altitude. Perhaps you didn’t know that. If you censor every fact that you don’t know, then we won’t have a thread at all.
     
  16. Dec 30, 2003 #15
    Re: Re: Time changes in gravity field.


    Hi,

    What I was referring to about your “relative motion” comment, is that in 1918 Einstein added a gravitational field to the K’ frame of the Kinematical part of “On the Electrodynamics of Moving Bodies”, specifically to add a “force” that would physically slow down the K’ frame clock, because he realized there was a clock paradox problem with his “peculiar consequence” thought experiment, since in the original 1905 theory he had a clock slowing down due only to “relative motion”, with no “force” being applied to it at all, thereby violating Newton’s First Law of Motion. So, according to Einstein, as of 1918, “relative motion” can’t cause the clock in the K’ frame in the 1905 theory to “slow down”, since in that theory, no “force” is placed on the clock. But this information is not generally known today, since his original 1905 theory, and his 1916 book, say that “relative motion” can cause a clock to slow down, and these books are much more available to the general public than his comments about the gravitational field he added, retroactively, to the 1905 paper, in his 1918 paper.

    If you would like to see a comment about this and about Einstein’s change of opinion, as mentioned by W. Pauli in his 1921 book, “Theory of Relativity”, I’ll be happy to dig the quote out of my files. The Pauli book is now in reprint and available from Dover.
     
  17. Jan 8, 2004 #16
    David - I would like to see the quote to which you refer and the context as well - since SR is a measuration formalism as between moving observers - there are no absolutes as would be the case if accelerations and velocities with respect to space brought about actual changes. While I am not saying that SR is any better or worse than other theories that predict results consistent with the experiments, it may be that you are misreading, misinterpreting, or misapplying Einstein's statement as it applies to SR per se.
     
  18. Jan 11, 2004 #17
    Sorry for the delay in responding to you. Here is the quote from Pauli. He received a Nobel Prize in Physics in 1945. Here is what he said in his book in 1921:

    ”Equation (392) has the following physical meaning: Consider two equal, originally synchronous, clocks at rest and let one of them be placed in a gravitational field for a certain length of time. Afterwards they will no longer be synchronous; the clock which had been placed in the gravitational field will have lost. As mentioned by Einstein [in Naturwissenschaften, 6 (1918) 697], this is the basis of the explanation for the clock paradox described in section #5 [of this book]. In the coordinate system K’ in which the clock C2 is permanently at rest, a gravitational field exists during the time in which its motion is retarded, and the observer in K’ can regard this field as causing the clock C2 to lose.”

    He also said this paradox problem was discussed by “Langevin (1911), Laue (1912), and Lorentz (1914)”. And he says, just as I have said, that the only “solution” to the paradox is to place the K’ frame resting inside a gravitational field.

    In another chapter of his book, Pauli says:

    “Let us describe the process in terms of a reference system K’, always at rest with respect to C2. Clock C1 will then move relative to K’ in the same way as C2 moves relative to K. Yet, at the end of the motion, Clock C2 will have lost compared with C1, i.e. C1 will have gained compared with C2. The paradox is resolved by observing that the coordinate system K’ is not a Galilean reference system and that in such a system the effect of acceleration cannot be neglected, since the acceleration is not produced by an external force, but, in the terminology of Newtonian mechanics, by an inertial force.”

    Just a few weeks ago I learned that Einstein’s 1918 paperof Naturwissenschaften, 6 (1918) 697, is contained in Volume 7 of The Collected Papers of Albert Einstein. I’ve ordered a copy.
     
  19. Jan 11, 2004 #18
    The problem seems to be that very few people know about Einstein’s 1918 “patch” to his 1905 theory. So the rumor has gone around for years that only “relative motion” causes the “time dilation”. But that’s just not true.

    There are two theories at work in the 1905 paper, the first part, the Kinematical part, which is Einstein’s, and the second part, the Electrodynamical part, which is from Lorentz relativity theory.

    Ok, it was Lorentz who first said that a clock could slow down DUE TO MOTION THROUGH FIELDS. These can be the electric field, the magnetic field, or the gravitational field. This puts an actual physical “force” on the clocks, especially atomic clocks, ie “atoms”.

    In 1911, Einstein deduced that atomic clocks could slow down inside a gravitational field, and due to motion related acceleration, and perhaps also due to motion through a strong gravitational field.

    So, the “SR” part of the Hafele-Keating flying clocks experiment was NOT due to “relative motion”, it was due to the motion of the clocks through the earth’s field(s), probably the gravitational field. If it was just due to “relative motion”, the Eastbound and Westbound clocks would have both lost time, but the Westbound clocks actually gained a lot of time. What this probably means is, their speed through the earth’s radiating gravitational field was much slower than that of the Eastbound clocks.

    Since it is believed that the earth “radiates” its gravitational field at about the speed of light, as the earth turns, rotates, it rotates inside its own gravitational field. When a mountain at the equator moves about 1/4 mile, at about 1,000 mph, the “radiated gravitational field” of that mountain has moved out into space about 186,000 miles.

    This is, assuming all these theories are correct.

    Anyway, keep this in mind: Lorentz theory = atomic clock slow down due to motion through fields, Einstein GR = atomic clock slow down due to strong gravitational field and motion-acceleration.

    But NO clock slow down due only to “relative motion”. That is the error in the 1905 theory that Einstein corrected in 1918.

    Now that his 1918 paper is available again, all students will be taught this information within the next 50 years. Yours will be one of the few generations that was incorrectly taught that “relative motion” alone could cause clocks to slow down.
     
  20. Jan 12, 2004 #19
    Hi David

    I am aware of the proposition that clocks actually slow down relative to motion wrt space (you refer to the substantive stuff as fields - but the idea is the same) And as it turns out, one can explain most relativistic effects in terms of actual clock slowing as per Lorentz.
    But most relativistic phenomena can also be explained using traditional SR (totally kinematic). SR struggles with the triplet problem which all SR adherents claim to be non paradoxical.. that is, so they say, "if you really understand SR" - but the reasoning is convoluted, and always leaves me with the feeling that resolution is postulated rather than derived - on the other hand, Lorentz Ether requires actual physical contraction - which to my way of thinking creates serious conceptual problems - and it requires adherence to a different belief system which is for me just as hard to accept.

    Anyway - I am still not convinced from your post that Einstein ever went so far as to endorse a physical mechanism to explain Gravitational time dilation - as I read his works and the many interpretations thereof, I cannot find a foundational underpinning for a physical cause in the Special or General theory per se.

    I Assume you are familiar with the various spatial "inflow" theories.
    They do a good job of tying gravitational time dilation to the effective escape velocity (the rate of inflow determines the escape velocity and this rate corresponds to the time dilation due to this velocity vis a vis SR). Tom Martin has published several papers dealing with experiments that - if performed, will either validate GR and falsify Spatial inflow - or vice versa.

    Regards
     
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