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Thread: would gravitons have a velocity greater then photons?

  1. #1 would gravitons have a velocity greater then photons? 
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    the universe is expanding right and the further away from us the higher the velocity. So there would have to be a distance where the galaxies in that space have an outward velocity greater than the velocity of light so that their light would never reach us ( and we could possibly be living in a singularity ). But doesn't their gravity effect us ( gravity IS conservative isn't it) This would mean that the gravitons have to travel faster than the speed of light to reach us. Could anyone please enlighten me on this issue and try not to resort to hyperspace please.


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    For any particle to move faster than light, in all frames of reference, it would need to have negetive mass, this would also result in the particle moving backwards in time.

    Gravitons, which at this point remain theoretical, have no mass. ie. 0.
    we do not feel gravitational effects instantaniously. say the mass of the sun was taken away the planets would not notice a deviation from there orbits until the light hits them. there for i would say that the speed of gravity is the same as the speed of light.


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    Quote Originally Posted by wallaby
    For any particle to move faster than light, in all frames of reference, it would need to have negetive mass, this would also result in the particle moving backwards in time.

    Gravitons, which at this point remain theoretical, have no mass. ie. 0.
    we do not feel gravitational effects instantaniously. say the mass of the sun was taken away the planets would not notice a deviation from there orbits until the light hits them. there for i would say that the speed of gravity is the same as the speed of light.
    Well, yes and no. E=mc<sup>2</sup> is of course based on the speed of light. If there is something faster then light that we simply don't know about then this formula no longer becomes valid. The math is still valid, just the results become invalid. We bank a lot on this formula and in all reality it may be accurate enough that it works for all the things we have used it for so far. To outright deny that anything can travel faster then the speed of light because of this formula (based on the speed of light) is a bit foolish. It's also impossible to move backwards in time. Time of course being just a measurement of movement. So far nobody has proved otherwise.
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    the equation for electric field of an electromagnetic wave is
    E=Emax sin(kx +or- wt)
    this allows both retarded and advanced waves to emit from say an excited state electron. The retarded waves travel forward through time and the advanced waves travel backwards through time. Would it be fair to say that the gravitational wave may be the advanced wave arriving from the future just that its properties are altered? Sorry i can't be bothered thinking this through.
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    Quote Originally Posted by phephiphophum
    the equation for electric field of an electromagnetic wave is
    E=Emax sin(kx +or- wt)
    this allows both retarded and advanced waves to emit from say an excited state electron. The retarded waves travel forward through time and the advanced waves travel backwards through time. Would it be fair to say that the gravitational wave may be the advanced wave arriving from the future just that its properties are altered? Sorry i can't be bothered thinking this through.
    Good luck with that backwards through time It's completely impossible by all laws known and all forms of logic. It does make for nice theory and tons of wasted words by people trying to talk about it. This is not directed to you at all, just a general observation.
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    Quote Originally Posted by (In)Sanity
    Quote Originally Posted by wallaby
    For any particle to move faster than light, in all frames of reference, it would need to have negetive mass, this would also result in the particle moving backwards in time.

    Gravitons, which at this point remain theoretical, have no mass. ie. 0.
    we do not feel gravitational effects instantaniously. say the mass of the sun was taken away the planets would not notice a deviation from there orbits until the light hits them. there for i would say that the speed of gravity is the same as the speed of light.
    Well, yes and no. E=mc<sup>2</sup> is of course based on the speed of light. If there is something faster then light that we simply don't know about then this formula no longer becomes valid. The math is still valid, just the results become invalid. We bank a lot on this formula and in all reality it may be accurate enough that it works for all the things we have used it for so far. To outright deny that anything can travel faster then the speed of light because of this formula (based on the speed of light) is a bit foolish. It's also impossible to move backwards in time. Time of course being just a measurement of movement. So far nobody has proved otherwise.
    of course...thats one of the reasons why we havn't detected FTL particles but if such particles did exist that would be one of the requirements, negetive energy...which seems highly improbable.

    but my main point however was that gravity does not react instantaneously and has a finite traveling time, from the Quantum point of view anyway from General Relativity point of view there would just be wave or ripples in spacetime.
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    phephiphophum,

    The upshot is that you are correct that at some point cosmological expansion exceeds the speed of light and carries objects outside of our Hubble Horizon (as it's called). And while there is no unambiguous direct measurement of the speed of gravity, there are lots of good theoretical reasons for it to also travel at 'c'. So that the effects of mass beyond the HH do not affect us.
    Huh?
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  9. #8  
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    the futures goin to be all cold and lonely
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    Yes wallaby, it is. Sad. It looks like your avatar senses this ultimate sadness.
    Huh?
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    And it's doing it's best to warn people.

    while trying to warm himself up.
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    even richard feynman speculated about advanced waves so has einstein always using maxwell's equations as an example
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  13. #12  
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    Quote Originally Posted by wallaby
    .....negetive energy...which seems highly improbable.
    You've never had a teenage son then?
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  14. #13  
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by wallaby
    .....negetive energy...which seems highly improbable.
    You've never had a teenage son then?
    don't need one.
    being a teenager myself.
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  15. #14 Re: would gravitons have a velocity greater then photons? 
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    Quote Originally Posted by phephiphophum
    the universe is expanding right and the further away from us the higher the velocity. So there would have to be a distance where the galaxies in that space have an outward velocity greater than the velocity of light
    Do you think that space extends infinitely? There is no requirement that there be sufficient extension of space such that this is true.

    so that their light would never reach us
    This is quite reasonable. It is very probable that parts of the unvierse are so far from us that their light does not yet reach us.


    But doesn't their gravity effect us
    No. Not if their light does not reach us.

    This would mean that the gravitons have to travel faster than the speed of light to reach us.
    Which is not meaningful and so should be discarded in favor of searching for a better model.
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    As stated above, gravitons, if they exist have zero rest mass, like photons, ergo they travel at the speed of light.

    HOWEVER, light can be slowed down by passing through interviening matter, so theoretically (I believe) gravitons can reach us before light, but usually they would arrive at the same time.

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  17. #16  
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    Quote Originally Posted by jgmaynard
    HOWEVER, light can be slowed down by passing through interviening matter, so theoretically (I believe) gravitons can reach us before light, but usually they would arrive at the same time.
    Are we so sure that gravitons wont be slowed by passing through intervening matter?
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    Gravitons are firmly believed in by today's scientists to be bosons with zero mass and a spin of 2. These are present in all the versions of String theory which are thought of as promising, while those with tachyons are rejected outright. But we don't have any direct evidence of gravitons nor do we even have a working theory of gravitons, for that would be a quantum theory of gravity which we certainly do not have.

    The working theory of gravity that we have today is General relativity and there are no gravitons in it. The working theory of particles we have today is called the Standard Model and the force of gravity is not included. General relativity can be rewritten in 5 dimensions instead of 4 and it will automatically include Maxwell's equations of electromagnetism (see the theory of Kaluza and Klein), which is a classical (non quantized - non particle) theory of the electromagnetism. A theory which includes all the forces (gravity, electromagnetism, weak and strong nuclear forces) does not yet exist. Scientist dream and expect to have a unified field or quantum theory of gravity someday, and it may be a string theory or brane theory, but not yet.
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  19. #18 Gravitons and Cee 
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    Ophiolite, one recalls a report within the last year which purported to measure the speed of gravitational propagation and showed that it was light speed as well. I'm sorry I can't recall the reference, but it was out there in the scientific websites some months back.

    Nothing FTL has yet been seen, altho there is some suggestion/report that quantum tunnelling can go FTL. But it has not yet been confirmed. Another related issue is that if Hawking's hypothesis that black holes evaporate because some photons/particles temporarily exceed cee, then black holes can disappear due to the statistical, QM fluctuations of particles' velocities.

    One suggestion is that if quantum tunneling can show a small, but significant effect which exceeds cee, then it could be a local confirmation of Hawking's supposition on black hole evaporation. However, not being a physicist, I'm in no position to evaluate the reports coming out on quantum tunneling.
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    I forgot to add this conclusion. But if gravitons exist and are zero mass bosons as physicists believe then they certainly travel at the speed of light as do all zero mass particles.

    Scientist do not believe that anything causal can travel faster than light. The only quantum effects that travel faster than light are not causal but purely random.

    The effect which can travel faster than light are correlations between particles linked by a common wave function so that when one is measured (obtaining a random result) then the linked particle which may be far away is automatically known to be in the complimentary state. Since the result of the measurement is random there is no way this can be used to transmit any information or causal effect faster than light.

    Quantum tunneling does not involve any faster than light travel. Quantum tunelling occurs when a the wave function of a particle expands beyond some barrier creating a small chance that the particle can be found on the other side of the barrier. If you imagine a wave function expanding to a very large size then there is a chance the particle may be found a long distance away. But this does not in any way constitute faster than light travel because a wave function cannot expand faster than the speed of light. In conclusion there is no sense in which the particle undergoing quantum tunneling can be said to have traveled faster than light.
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  21. #20 FTL evaporation of black hole 
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    Hawkings himself states that FTL travel by photons and particles out of a black hole can take place, because that is what causes the evaporation of the black hole. This has not been observed, altho it is consistent with the statistical nature of QM.

    Experiments are ongoing to show whether or not quantum tunnelling proceeds at light speed, or if in fact, light speed is exceeded in some cases.

    As nothing can escape a black hole, only a process exceeding the speed of light can escape. So if black holes evaporate, this violation of the light speed barrier must be taking place.
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  22. #21 Re: FTL evaporation of black hole 
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    Quote Originally Posted by steve
    Hawkings himself states that FTL travel by photons and particles out of a black hole can take place, because that is what causes the evaporation of the black hole. This has not been observed, altho it is consistent with the statistical nature of QM.
    You need to supply a reference for this one. I must say this his a highly suspicious statement by Hawkings, possibly out context, misinterpreted or whimsical on his part. It certatainly does not jibe with his theory of quantum hole vaporation as I have understood it. Futhermore black hole physics is such an extreme circumstance, high theoretical and where so much normal physics breaks down that any claims like this really does not prove anything.
    Quote Originally Posted by steve
    Experiments are ongoing to show whether or not quantum tunnelling proceeds at light speed, or if in fact, light speed is exceeded in some cases.
    I will examine a reference if you have one but this one is even more suspicious. Nothing in basic theory of quantum tunneling would have anything to do with faster than light travel, as I explained. Often the enthusiasm of the media exceeds its understanding of physics. This is no more believable than numerous claims of perpetual motion machines.
    Quote Originally Posted by steve
    As nothing can escape a black hole, only a process exceeding the speed of light can escape. So if black holes evaporate, this violation of the light speed barrier must be taking place.
    No this process of Hawking radiation does not describe anything actually traveling out of the Schwartschild radius. It is a quantum effect created by the extreme gravity in a region outside the Schwartschild radius where light can escape.
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  23. #22 Re: Gravitons and Cee 
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    Quote Originally Posted by steve
    Ophiolite, one recalls a report within the last year which purported to measure the speed of gravitational propagation and showed that it was light speed as well.
    Thanks Steve. I was puzzled when I saw your reply as to why I had asked the question. On reviewing the thread I see I was trying to nudge JGmaynard towards recognising a potential contradiction in his post.
    I am comfortable that the consensus view is that gravity travels at light speed: no faster, no slower. The consensus view suits me in those areas where my expertise level is that of interested bystander.
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  24. #23 exceeding light speed 
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    The point being that if in quantum tunneling light speed is exceeded, then a precedent is set such that other events would have to be tested to see if it's a statistical event as well. Doing an advanced google.com search on quantum tunneling and light speed, there was one report that Q tunneling HAD exceeded light speed, but as the effect was unexpected, it's being tested again. The answers are not yet in on this one.

    That nothing can escape a black hole, even light, is the basis of the black hole. However, if the BH does evaporate, then it must be thru quantum tunnelling or the statistics of QM, which temporily allow photons or other particles to exceed light speed.

    As written before, if NOTHING can exceed light speed, then black holes cannot evaporate. As it's believed, generally that they do, esp. the smaller ones, then the same kind of quantum tunnelling which is responsible for radioactive decay, is also a process involving black hole evaporations. One cannot have both. Either light speed can be temporarily exceeded in black hole evaporation & quantum tunnelling effects can exceed light speed, or black holes cannot evaporate.

    Look into the Specifics as to how black holes evaporate, theoretically, and then you'll see the point.

    If light speed in certain processes CAN be exceeded, then gravitons, under certain processes, as they are bosons, can ALSO have a statistically significant chance of exceeding light speed. Altho it's highly likely that most gravitons do travel at cee, meaning gravity propagates at Cee.

    This is the point being made.
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    This ref gives the report in its first paragraph, about the light speed violation in quantum tunneling. From my reading on the issue, it's not yet resolved.

    www.npl.washington.edu/av/altfw75.html

    The second is Hawking radiation, which is a theoretical entity from black holes. If Hawking radiation from BH can be observed, then it, de facto means that quantum tunneling is allowing particles and photons to temporarily exceed light speed. It has not yet been observed. But if, under certain circumstances, there is a statistically significant probability that Q tunneling CAN exceed light speed, it would probably be a verification of Hawking radiation, as it's the same process.

    And if under some circumstances photons can exceed light speed, then so can gravitons. Altho that does not mean all graviton exceed light speed. Just some.
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  26. #25  
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    I'm pleased nobody is making light of this weighty matter.
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  27. #26  
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    Quote Originally Posted by steve
    This ref gives the report in its first paragraph, about the light speed violation in quantum tunneling. From my reading on the issue, it's not yet resolved.
    www.npl.washington.edu/av/altfw75.html
    page cannot be found
    Quote Originally Posted by steve
    The second is Hawking radiation, which is a theoretical entity from black holes. If Hawking radiation from BH can be observed, then it, de facto means that quantum tunneling is allowing particles and photons to temporarily exceed light speed.
    Wrong! It is not particles which are escaping from the black hole but only energy. This is not a case of tunneling. The particles which escape did not exist previously but are one of a pair of virtual particles. You cannot even say that energy is exceeding the speed of light because the energy which is escaping is the from the gravitational field around the black hole! You cannot say that mass is traveling faster than the speed of light because the energy of the gravitational field in the region outside the Schwartschild radius has the mass required or the Hawking radiation would not occur.
    Quote Originally Posted by steve
    It has not yet been observed. But if, under certain circumstances, there is a statistically significant probability that Q tunneling CAN exceed light speed, it would probably be a verification of Hawking radiation, as it's the same process.
    No! I would challenge you to show me the mathematics to prove this statistically significant probability, but it doesn't even make any sense. You cannot have quantum tunneling without the spread of a wave function and wave functions do not spread faster than the speed of light. Hawking radiation is not quantum tunneling.
    Quote Originally Posted by steve
    And if under some circumstances photons can exceed light speed, then so can gravitons. Altho that does not mean all graviton exceed light speed. Just some.
    No if there are gravitons they would not exceed the speed of light. There is no room in theory for anything that could be called a particle to exceed the speed of light. However we do not know that gravitons exist. We have no quantum theory of gravity. Maybe there is none. Maybe the unified field theory that will describes gravity will have something (not a particle) that accounts for the force of gravity and travels faster than the speed of light, but 99.9% of the physics community would not give this idea a minute of consideration.
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    My reading indicates that particles as well can escape. IN one case, an electron/positron pair escapes and the one falls back in and the other continues out.

    If nothing can exceed light speed, then how does the black hole evaporate? If it escapes a black hole, then by definition, it has exceeded light speed.

    You are not dealing with this problem here. Not at all.

    Regarding your math demand, I demand your answers be written in ancient Chinese of the Han Dynasty. It's not the language of the response, which is important, but the truth of the answer. A logical point which seems to have escaped you, once again.

    Link is www.npl.washington.edu/av/altvw75.html Sorry about the typo.
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    Quote Originally Posted by steve
    My reading indicates that particles as well can escape. IN one case, an electron/positron pair escapes and the one falls back in and the other continues out.
    But this happens outside the Schwarzschild radius.
    Quote Originally Posted by steve
    If nothing can exceed light speed, then how does the black hole evaporate? If it escapes a black hole, then by definition, it has exceeded light speed.
    By whose definitiion? I do not think any physicist would ever say such a thing.
    Quote Originally Posted by steve
    You are not dealing with this problem here. Not at all.
    Look, if you are trying to say that Hawking radiation implies something non-local about the energy of a black hole, then you are right But that is the most that you can say.

    The energy of the gravitational field outside the Schwarzschild radius is responsponsible for the Hawking radiation and this does ultimately represent a flow of energy from the black hole. But no particle of any kind is actually traveling from inside the Schwarzschild radius to the outside. That is impossible. It would contradict the theory of black holes and General Relativity.

    There are no space time paths which pass out through the Schwarzschild radius and it is not a matter of surmounting an energy barrier like in quantum tunneling. It makes more sense to say that space and time as we know it unravels at the Schwarzschild radius so that all paths point into the singularity, as wierd and hard to imagine as that may be.
    Quote Originally Posted by steve
    Regarding your math demand, I demand your answers be written in ancient Chinese of the Han Dynasty. It's not the language of the response, which is important, but the truth of the answer. A logical point which seems to have escaped you, once again.
    Any kind of reference to the statistics you were refering to would be sufficient.
    Quote Originally Posted by steve
    Link is www.npl.washington.edu/av/altvw75.html Sorry about the typo.
    Thanks. I already started responding before I saw this and this will take time to look through and check up on. It is interesting. So far from what I have read I would point to the controversy it is generating in the scientific community. But let me take my time looking into this seriously and I will get back to you on it.
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    Quote Originally Posted by steve
    My reading indicates that particles as well can escape. IN one case, an electron/positron pair escapes and the one falls back in and the other continues out.

    This ref gives the report in its first paragraph, about the light speed violation in quantum tunneling. From my reading on the issue, it's not yet resolved.
    Link is www.npl.washington.edu/av/altvw75.html Sorry about the typo.
    Your reference is to a science fiction magazine article. So I investigated and found that a group of scientists checked up on the claim by Gunther Nimtz and found that the speed was less than light. Here is a link the their report.
    http://www.phy.duke.edu/research/pho...04/NLO2004.pdf
    The thing about science is that any scientist can make any crazy claim they like but if it does not stand up to scrutiny then it is not accepted.

    The effect which can travel faster than light are correlations between particles linked by a common wave function so that when one is measured (obtaining a random result) then the linked particle which may be far away is automatically known to be in the complimentary state. Since the result of the measurement is random there is no way this can be used to transmit any information or causal effect faster than light.
    This cannot be even be used to send a signal because the measure of one particle does not cause any event at the other end which can be detected. It simply means that when they perform the measurement it will be consistent with the measurement at the other end. And that is overstating it quite a bit. It is hard to do these pairs of measurements reliably because the measurements only have to agree if nothing interacts with either of the two particles before they are measured. So the realistic result is simply going to be if you perform many of these pairs of measurements then more will be in agreement than would be expected if the two measurements were independent.
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    I just read a book called "Alpha and Omega" which states that particles can and do exceed c for small peroids of time (then fall back below c) and that it is only the average velocity which must remain at c or less.
    We do know that particles create what are called "closed time-like loops" where they go backwards and then forwards through time. That may be connected. I'm not sure.
    I'm not saying it's proof, but it was an interesting concept.

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    Quote Originally Posted by jgmaynard
    I just read a book called "Alpha and Omega" which states that particles can and do exceed c for small peroids of time (then fall back below c) and that it is only the average velocity which must remain at c or less.
    We do know that particles create what are called "closed time-like loops" where they go backwards and then forwards through time. That may be connected. I'm not sure.
    I'm not saying it's proof, but it was an interesting concept.

    JM
    Just how small a period of time are we talking about here?

    On the one hand, I am inclined to believe that anything is possible when quantum intervals of space and time are involved. On the other hand, my scientific training makes me seriously doubt the claim in your book. I suspect that there is a misterpretation of physics involved here. In other words, I would argue the point but I would lose nothing in the main issue at hand even if I am wrong. I see quantum physics as describing the limit of physics itself. So anything under the cover of quantum indeterminacy is outside of physics anyway.

    I have looked at an Amazon.com cover for a book of that name by Charles Seife. It looks like a history of cosmology. It does not look like a reliable source for the information you are telling me. Perhaps a quote what he says exactly would be informative.
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  33. #32  
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    Yes, it is the Seife book. It covers both the history of cosmology as well as some of the science involved. He is mainly a reporter, but the science seems to be pretty good when I cross-referenced claims.
    I feel the same way...... I have a BS in physics, chemistry and history and have been studying this sort of stuff all my life.
    http://www.msnbc.msn.com/id/9868020/
    So, I'm not suprised at anything that may happen at the quantum level, and I believe the times involved were around the plank time. However, I'm being a good little Sagan-devotee and treating it with an open, yet skeptical mind.

    JM
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  34. #33 just a question 
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    So how much of this is true science (actually observed, repeatable, etc) and how much is theory? (i'm not trying to slight theories. I know they have their place). Just wondering. I have seen theories snowball into some serious scientific "issues". Can any of you qualify your thoughts with proof, observations, or experimentation?

    again just wondering : )
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  35. #34 Re: would gravitons have a velocity greater then photons? 
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    ="Dontboreme"
    So how much of this is true science (actually observed, repeatable, etc) and how much is theory? (i'm not trying to slight theories. I know they have their place). Just wondering. I have seen theories snowball into some serious scientific "issues". Can any of you qualify your thoughts with proof, observations, or experimentation?
    Are you talking about the the first post?

    All cosmology is borderline physics and phephiphophum's ideas here are even more so. The theory may describe what is supposed to have happened in the past but it is developed to explain the results of repeatable measurements. The prime datum here is the nearly uniform 4 degree background microwave radiation and the increase of the average redshift of other galaxies with distance. The best mathematical tool for describing this is General relativity in which it is natural to describe the big bang senario which explains this datum. There are also a lot of little things like the agreement of the observed abundances of elements with those predicted by quantum field theory models of the early period of the universe in a state consistent with the big bang idea.
    Quote Originally Posted by phephiphophum
    the universe is expanding right and the further away from us the higher the velocity. So there would have to be a distance where the galaxies in that space have an outward velocity greater than the velocity of light so that their light would never reach us ( and we could possibly be living in a singularity ). But doesn't their gravity effect us ( gravity IS conservative isn't it) This would mean that the gravitons have to travel faster than the speed of light to reach us. Could anyone please enlighten me on this issue and try not to resort to hyperspace please.
    Although the inflation theories talk of a superluminal expansion during the early universe I don't think the acceleration of universe expansion means that the speed of recession will exceed the speed of light. However because of that early superluminal expansion there may be galaxies whose light has not reached us. In this case the only gravitational influence on us by the mass of these galaxies would have come from before that superluminal expansion as part of the overall curvature of space time.

    Gravity is a conservative force, which means that like a spring work done against it stores up potential energy, but this has nothing to do with whether the gravity from such distant galaxies effect us.

    hyperspace?????? That's science fiction.
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  36. #35 Re: would gravitons have a velocity greater then photons? 
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    Quote Originally Posted by phephiphophum
    the universe is expanding right and the further away from us the higher the velocity. So there would have to be a distance where the galaxies in that space have an outward velocity greater than the velocity of light so that their light would never reach us ( and we could possibly be living in a singularity ). But doesn't their gravity effect us ( gravity IS conservative isn't it) This would mean that the gravitons have to travel faster than the speed of light to reach us. Could anyone please enlighten me on this issue and try not to resort to hyperspace please.
    Oh? Why does it *have* to have a recessional velocity greater than light?

    An object possessing mass - in this case a hypothetical, early, receding Galaxy - would *never* achieve C. What occurs is a simple asymptotic relationship. It would approach C fractionally closer and closer, but never achieve it.
    *Welcome, my friends, to the show that never ends*
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  37. #36 Re: would gravitons have a velocity greater then photons? 
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    Quote Originally Posted by mitchellmckain
    Although the inflation theories talk of a superluminal expansion during the early universe I don't think the acceleration of universe expansion means that the speed of recession will exceed the speed of light.
    Are you sure about this Mitchell? I have tended to avoid cosmology, since I find the fairy stories I was told as a child generally more convincing and more firmly rooted in fact. That said, I was under the impression that the superluminal expansion was postulated to have occured faster than light - the clue is in the name: superluminal. Can you comment please.
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  38. #37 Re: would gravitons have a velocity greater then photons? 
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by mitchellmckain
    Although the inflation theories talk of a superluminal expansion during the early universe I don't think the acceleration of universe expansion means that the speed of recession will exceed the speed of light.
    Are you sure about this Mitchell? I have tended to avoid cosmology, since I find the fairy stories I was told as a child generally more convincing and more firmly rooted in fact. That said, I was under the impression that the superluminal expansion was postulated to have occured faster than light - the clue is in the name: superluminal. Can you comment please.
    I know what superluminal means, which is why I called the inflation theory superluminal. But the inflation theory was a special event in the early part of the expansion of the universe. The idea was to explain the uniformity of the universe on a large scale, which could be explained if space-time expanded faster than light during this early period, not giving gravity time to work. But this superluminal inflation was due to some extra-ordinary physics like a decay of a false vacuum (possibly creating matter in the process). This is no longer occuring and the expansion is no longer superluminal. In other words, although the expansion of the universe is accelerating right now, it was not always accelerating. The expansion came to a relative halt after inflation, which is when the galaxies and stars could start to form by the action of gravity.

    However, in doing a little reading I found that apparently recession of distant galaxies can indeed exceed the speed of light, because this is not really a velocity and has nothing to do with special relativity. Apparently this creates what they call a Hubble Horizon. Galaxies past this horizon can no longer send light to us which we will recieve. Which means will only see light from their past until they fade from view in a very long time from now. What do you know, learn something new everyday.
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  39. #38 Re: would gravitons have a velocity greater then photons? 
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    [quote="Galaxies past this horizon can no longer send light to us which we will recieve. Which means will only see light from their past until they fade from view in a very long time from now. What do you know, learn something new everyday.[/quote]

    My first quote : P hope i did it right.

    If the distances you claim are correct then don't we see only "historical" light from any star? Every single star in the galaxy could simultaneously explode (not ours just theirs) and we wouldn't know for about 400 years. Then to our perspective we would see them one by one pop like bubbles from the closest to the furthest away?

    Without a fixed point of reference (i.e. we can with certainty measure a mile with a laser because we confirmed that the distance to target is indeed a mile.) can we really say stars are that far away with certainty. That being the case how can we with a certainty know how far it actually is to the nearest, let alone the farthest star. I know your immediate response is something like... We measure microwaves that originate from the star and wavelengths of light and etc etc etc. But my question is without actually observing the distance is there any way to confirm that the measurements are correct. Is it possible that we are wrong? Even Exponentially wrong?

    Back to the original question. Wouldn't we also cease to see the stars on the outer rim as they accelerate past "c" as the light emitted by them is still retreating from our perspective after being emitted? In the same arguement "gravatons" would suffer the same fate They would be only headed away from us. It is like a rock being thrown in a rushing river. If the waves don't outrun the current the effects never travel upstream. (where earth, our perspective = upstream). Even if gravitons traveled faster than "c" if acceleration continues then stars would eventually be leaving faster than the gravity they emit.

    When we get down to it. Do we really even understand what gravity is?
    "Graviton - The messenger particle of gravity, believed to travel at the speed of light ( http://library.thinkquest.org/25715/glossary/ ). As specific as we get is messenger particle? Do they grab onto us and yank us back on a subatomic level? If so what pulls the gravitons back after they hit us, grab us, push us? We study the effect of gravity trying to figure out what it is and what causes it but do we really know?

    Theoretically. Can we say that gravity is able to travel the same distance as light and with anykind of similarity in decay? Gravity weakens much faster than does light. Just ask the astronauts. So if the light that reaches us from "distant" stars gets here as weak as it is would gravitons reach us at all?

    Still a more basic question? IF your in a car going 50 MPH and throw a baseball in the opposite direction at 30 mph to a third party observer the ball would still be going in the same direction at 20 mph. If those stars (the car) are moving away at advanced rates of speed why does the light from them (the ball) continue to hit us at the speed of light? Why do stars traveling in all those different directions at all those different speeds send light that hits us at the same exact speed? The equation doesn't balance.

    I don't think we know as much as we think we do

    LRS Georgia


    PS I do try to learn something new everyday: ) Hook me up with the knowledge !!!
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  40. #39  
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    figures i'd mess up the quote thing : P
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  41. #40 didn't mean to kill the thread 
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    anyone..... (crickets crirping)
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  42. #41  
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    Quote Originally Posted by Dontboreme
    Without a fixed point of reference (i.e. we can with certainty measure a mile with a laser because we confirmed that the distance to target is indeed a mile.) can we really say stars are that far away with certainty. That being the case how can we with a certainty know how far it actually is to the nearest, let alone the farthest star. I know your immediate response is something like... We measure microwaves that originate from the star and wavelengths of light and etc etc etc. But my question is without actually observing the distance is there any way to confirm that the measurements are correct. Is it possible that we are wrong? Even Exponentially wrong?
    Distances are very difficult to get a handle on but there are some techniques that work well in some cases. For close by stars we actually get a stereoptic effect over the full year, because we see them from slightly different angles as the earth moves around the sun. This is the parallax method. Examine a close examples of a type of variable star called Cephid variables we know that they have a period which is directly related to their innate brightness this allows us to get a rough estimate of the distance to other galaxies by finding a Cephid variable in that galaxy and measuring the period of its brightness we know how bright it really is so when we compare that with its apparent brightness we know how far it must be. But the error boundaries on both methods are often pretty big and when comparing calculations from both methods I have found large disagreements.

    When we get down to it. Do we really even understand what gravity is?
    "Graviton - The messenger particle of gravity, believed to travel at the speed of light ( http://library.thinkquest.org/25715/glossary/ ). As specific as we get is messenger particle? Do they grab onto us and yank us back on a subatomic level? If so what pulls the gravitons back after they hit us, grab us, push us? We study the effect of gravity trying to figure out what it is and what causes it but do we really know?
    Gravitons are a theoretical particle supposedly responsible for gravity but we have no operational theory for such particles and no real evidence that they exist. If they do, they work the same as photons in electrical force, except that they interact with all energy (or the mass equivalent) rather than electric charge. We do have a non-particle theory of gravity that works very well called the General theory of relativity. In that theory gravity is merely an effect of the curvature of space-time on mass and energy.

    Still a more basic question? IF your in a car going 50 MPH and throw a baseball in the opposite direction at 30 mph to a third party observer the ball would still be going in the same direction at 20 mph. If those stars (the car) are moving away at advanced rates of speed why does the light from them (the ball) continue to hit us at the speed of light? Why do stars traveling in all those different directions at all those different speeds send light that hits us at the same exact speed? The equation doesn't balance.
    This is the essence of the special theory of relativity, which is a big topic, so I will cover only one point of it for now. There is a formula for adding or subtracting velocities. So like in your example if v1=50 mph and v2=30mph then the difference between the two velocities is not given by simple subtraction but by the following formula:
    v1 - v2
    ----------------
    1 - (v1/c)(v2/c)
    For the velocities v1=50mph and v2=30mph v1/c and v2/c are so small that the result is basically the same as v1 - v2, but for velocities close to the speed of light it would be very different. For example v1 = 75% of the speed of light and v2 = 50% of the speed of light, we would have v1/c = .75 and v2/c = .5, then 1 - (.75)(.5) = .625 and the result of subtracting the two velocities is not 25% of the speed of light but 40% of the speed of light. So even though the ball was thrown toward the stationary observer at 50% of the speed of light it ends up traveling away from the stationary observer not at 25% of the speed of light but much faster, 40% of the speed of light.

    One result of this formula is that if v1 is the speed of light (so v1/c = 1) you will find out that no matter what velocity you subtract (as long as it is less than the speed of light) the result you get is still the speed of light. (c - v)/(1 - v/c) = c. If both are the speed of light the result is undefined because you get a zero in the denominator. There is no contradiction because you cannot have observers or flashlights traveling at the speed of light.

    For addition the formula would is:
    v1 + v2
    ----------------
    1 + (v1/c)(v2/c)
    If v1 and v2 are both less than the speed of light the result of adding them in this way is also less than the speed of light but if one of them (or both) is the speed of light then adding them will always result in the speed of light.

    So you see it does balance. It is just a different equation than you thought (and different than what common sense would seem to dictate).
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  43. #42 hypothetically.. 
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    Acording to popular accepted science the nearest star (set) is Alpha Centauri, clockin' in at a whopping 4.36 light years away. "A light-year equals 5.88 million million miles (9.46 million million kilometers). This is the distance light travels in one year at a speed of 186,282 miles per
    second" (from hypertextbook.com). lets get rid of the exponents...

    186282 MPS
    1year = 31556926 seconds

    so a light year = 5,878,487,289,132 Trillion miles

    the distance from the sun averages 93,000,000 miles so that would be the radius Diameter is 186,000,000 miles

    So if we are to triangulate a position to find the distance we are still working with a nearly impossible ratio. It would be likened to triangulating the distance to a flarget in montana if you were in miami and only had a width of 200 feet as your base. (forgetting the curvature of the earth and such). Now you probably have no idea what a flarget is as I just made it up. (back to my original point) Isn't possible that stars aren't suns. I won't offer up a "what are they" guess at this point. I just want to see if people are willing to concede that the assumption built upon (stars = suns) through testing could yeild incorrect data. And if that is incorrect having never been any closer to the nearest flarget than 25277495349267.6 miles (4.3 lightyears) and no way to really tell with a decent degree of accuracy what they actually are, could they be much closer and smaller?

    could we be exponentially wrong.

    1000 + 3000 = 4000

    as does 1 + 3 = 4

    If we add zeros to a problem it doesn't make the equation false. It just changes the values. Could we be looking at the entire universe in the wrong manner.

    We used to think the world was flat. Couldn't we be significantly wrong about space too?

    I gotta run coach a ball game. I'll be back with more thoughts or a reply if warrented soon.

    hugs
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    Yes parallax is usually measured in milli arc seconds and is usually given with error bounds. So for example the parallax for upsilon Andromeda is measured to be 74.25 mili arc seconds with an error of .72 mili arc seconds. So this star is between 3260/74.97 = 43.48 light years and 3260/73.53 = 44.34 light years distant. This star is interesting because it is now believed to have three planets in orbit around it. The closest to the star orbits only 29.44 light seconds away, which means that this is an arc separation that is only 1/17 the parallax. Yet that is not what we detect. We usually detect these extra-solar planets due to how their orbit makes the star wobble which is a far far smaller measurement.

    So if you find the measurement of the distances incredible then I am afraid you are getting behind the times because these are nothing compared to the whoppers which the atronomers are telling us these days.
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  45. #44  
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    I haven't really read this entire thread so forgive me if I'm missing a point somewhere, but this is a quick response to Dontboreme's last post, regarding parallax and how it could be in error.
    We only use parallax to estimate the distances of the closest of objects. For farther objects, we use a number of other methods - Cepheid variables and other standard candles come to mind.
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    I was using the closest just to make a point. It comes back to the basic question/statement/conundrum. If we have never been that far away, how can we be certain our measurements are right? Isn't it at least possible that our model of the universe is wrong?

    The "truths" we are using as a foudation for "factual science" are theories being applied and accepted as truth. While that type of science is valid for reseach we shouldn't forget that if the theory is partially or totally incorrect our result data is invalid either partially or wholly.

    simple question.
    How do you know for sure????
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  47. #46  
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    Quote Originally Posted by Dontboreme
    I was using the closest just to make a point. It comes back to the basic question/statement/conundrum. If we have never been that far away, how can we be certain our measurements are right? Isn't it at least possible that our model of the universe is wrong?

    The "truths" we are using as a foudation for "factual science" are theories being applied and accepted as truth. While that type of science is valid for reseach we shouldn't forget that if the theory is partially or totally incorrect our result data is invalid either partially or wholly.

    simple question.
    How do you know for sure????
    I will tell you what I told a biology PHD whose project was aimed at tearing out some pillars of modern day evolution theory. You can poke all the holes you want but you are wasting your time if you cannot propose a better theory that explains facts better than the current theory. The current theory is always accepted as the best explanation of the facts. It is never claimed to explain everything. Until a better theory is proposed it is assumed that unknown details of an insignificant nature will eventually explains all such inadequacies. But regardless, until a better theory comes a long, scientists will continue to use the best one they have.
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  48. #47  
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    Quote Originally Posted by Dontboreme
    I was using the closest just to make a point. It comes back to the basic question/statement/conundrum. If we have never been that far away, how can we be certain our measurements are right? Isn't it at least possible that our model of the universe is wrong?
    Who cares if we don't know for sure? If we find new information, we update our theories. What's the big deal about actually being "that far away" anyway? We observe light up close, or observe light from a distance. We're still dissecting the same stuff to gather our information.
    Mitchell makes a good point too - we use the best theory we have available. It's not touted as "fact", but as the best current explanation.
    Some theories, though, are so well-established that it's hard to think of them as anything but fact.
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    I agree with Mitchell to a degree, but I don't think poking holes in a theory is a waste of time. It is a neccesary step in the revision of theories. If enough holes are poked I think the basis of the theory should be questioned. Have you ever argued with someone who just had to be right? No matter what you say they always have a reason or exuse. When engaging in that type of discussion with that personality type there is the danger of forgetting "true science" and argueing pure speculation as fact in an effort to be correct or win the arguement. I'm not suggesting all scientists are that way by any means. I am simply saying alot of people think they know alot of stuff because what they think simply" makes sense" If you can prove enough of a theory wrong I think it should be scrapped even if there isn't a better one. You don't have to know the right answer to know an answer is wrong.

    Its not really a "big deal" but it is the basis of a theory I have been toying with. Is it possible that the stars aren't really suns. That they are much smaller and closer than we think. Though they have similar characteristics could they be a "different animal". But because of general acceptance we just assumed "bright light in the sky = sun". Now I know this seems to be in conflict with dozens upon dozens of accepted theories. And I admit that this idea is going to be hit with major criticism. I know some of the accepted measuring techniques directly refute this theory. But my question is could we be significantly wrong with our universal model? In nature this similarity in different creatures is obvious. Humans, pigs, frogs, animals in general have hearts, lungs, livers, etc etc etc. Is it possible that stars might exibit the same characteristics as our sun but be significantly different?

    Neutrino said," We observe light up close, or observe light from a distance. We're still dissecting the same stuff to gather our information."

    We attribute the the "weakness" of the light, Wavelength sprawl, etc to distance as opposed to a significantly weaker source. Couldn't a small "sun" produce the type of light we have been observing?

    Just a thought at the tip of the iceberg ; P
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    Quote Originally Posted by Dontboreme
    I agree with Mitchell to a degree, but I don't think poking holes in a theory is a waste of time. ....
    I am glad you explained this point so I don't have to, since you are correct of course. However, you should expect it to be a bit of a thankless job since its significance will not surface until a new theory is developed.

    Quote Originally Posted by Dontboreme
    Is it possible that the stars aren't really suns.
    ....
    As for this, I will give you this faint encouragement. All the great inovators will always be crackpots. The establishment is necessary to provide stability and this is one part of the formula for progress, for without it there is only a chaos of incoherent ideas. And yet the conservativism of the establishment does have its blind spots and so there is a need for innovators who bring radical changes. So it is the reality of progress that it is neccessary that these innovators endure identification with the crackpots until the value of their ideas can win recognition, often long after their death. On the other hand, it behooves us to offer some minimal respect to all the crackpots, ... just in case.
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