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Do quantum fluctuation particles create gravitational effect?

  1. Dec 12, 2014 #1
    Do particles popping in and out of existence due to quantum vacuum fluctuations create a gravitational effect? My thought is yes If so, considering all the quantum particles in existence at one time at a given moment in the universe, added to the mass of the universe as well as the mass of dark matter and energy, what is the total mass of the universe, including the mass of the quantum particles? The reason I ask is that I was wondering what the escape velocity of the universe would be with all the mass in it and I am not sure that the quantum particle gravitational effects are significant or not, though I believe they would be.
     
    Last edited: Dec 12, 2014
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  3. Dec 13, 2014 #2

    Chalnoth

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    Can't be calculated at present. When you try, you get an absurd number that is ##10^{120}## times larger than the observed value of the cosmological constant.

    Maybe quantum vacuum fluctuations have some impact on the value of the cosmological constant, but the link is not obvious and we don't know how to estimate it at present.
     
  4. Dec 13, 2014 #3

    Drakkith

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    There is no escape velocity for the universe. Where would you escape to? The universe, as currently understood, is everything that exists. There is zero evidence of multi-verses at this time.
     
  5. Dec 13, 2014 #4
    Oh last year I worked with fluctuations.
     
  6. Dec 13, 2014 #5
    If you were in a black hole you might not think there was a 'beyond' to it either, using data that you gather from inside of it and based on the physics and principles you see around you while you are inside of it. If the universe had enough mass to be a black hole, then I personally believe that a lot of what we see would be more easily explained. For example, a photon traveling out from a point would never escape, and with the exception of those photons that were traveling away from the mass center of the black hole that would red shift to wavelength zero and cease to exist, the other photons depending on their original path would take varying amounts of time (depending on radius of said black hole) to be bent back around and thus appear to be coming from some distant source. A fire for example, would have photons continuously leaving and returning, some of those photons would have taken a much longer path and so you would see the fire when first lighted, those photons taking a shorter path (more curvature) would be from the fire when it was going strong. In a black hole 'universe' the "farther" one looked out the more galaxies one would see. Photons entering from 'beyond' the black hole would experience an extreme blue shift possibly pushing them into the cosmic ray wavelengths. I haven't ever seen anything that says that the universe itself couldn't be a black hole or that black holes as large as the universe can't exist.
     
  7. Dec 13, 2014 #6

    Drakkith

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    Indeed I've heard of theories that say we live in a black hole. But I don't think these theories are very widely accepted.
     
  8. Dec 13, 2014 #7
    I'm not needing the theory to be true or not. I have no preference, really. I do think it is a possiblity but I am interested in proving or disproving it. It would be nice to see some actual debate on it and reasons for it either being possible or not and if possible what effects would be manifest in our universe that may match up with it being true; or if untrue, what we know, have observed or have measured in our universe so far that may disprove it. Of course that could be difficult because we don't really know all that much yet about black holes either, in my opinion. And who knows, the process of examining and debating something ridiculous like this can even result in an unforeseen understanding of ... who knows what.
     
  9. Dec 14, 2014 #8
    Well, the universe doesn't even need to be a black hole to make some interesting phenomenon happen. If the mass of our universe is extremely high, then any photons floating around in the voidness (or whatever it was) in the same local region that the big bang had occurred, as they became influenced by the gravitational field of a suddenly existent universe would have the same effect I think as approaching a black hole, namely a very pronounced blue-shift. Perhaps enough to become a cosmic ray?
     
  10. Dec 15, 2014 #9

    Drakkith

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    There were no photons drifting around in some "voidness". The big bang was not a local phenomenon that happened in a pre-existing universe. The big bang, as we know it, wasn't even an "event", or an explosion, or a sudden bursting of matter and energy into existence. According to the big bang theory, the universe at the very earliest times we can extrapolate back to was filled with an extremely hot, extremely dense plasma of particles and high-energy radiation. For some reason, we don't know why yet, the universe expanded, with this plasma gradually cooling off and becoming less dense over time until, billions of years later, we have our current universe, which is clumpy, but overall cold and sparse. This expansion took place everywhere in the universe.

    A key aspect here is that there is no point in time that we can point to and say, "That's it. There was nothing prior to this". Instead, as we extrapolate back further and further in time, we reach a point where our current laws of nature stop working correctly. We start getting infinities in the math, a sure sign that our knowledge of physics at the energy and density scale of the early universe is incomplete.
     
  11. Dec 18, 2014 #10
    From the perspective of the Hubble sphere as a containment manifold, the escape velocity is approximately c at the Hubble distance. Of course the Hubble sphere is not a real surface and therefore the whole idea only makes sense from a metaphorical perspective. As such, nonetheless, the concept is useful as a measuring apparatus, ..... the mass and size of the Hubble closely approximates a black hole - in particular the total mass comports with the radius 4(pi)R^2 ... if ordinary mass is spread uniformly over the Hubble manifold, the surface density is very close to one kgm per square meter. If such relationships are purely coincidental, that is, a peculiarity of the present age of the universe, it would be surprising - on the other hand, if the relationship holds for all eras, there is much remodeling required to make the physics fit the facts in the sense of what we have come to think of as constants.
     
  12. Dec 18, 2014 #11

    PeterDonis

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    Can you show an explicit calculation of this? Or give a reference to one?
     
  13. Dec 18, 2014 #12
    Hi Peter, the two sphere mass based upon one kgm/meter^2 comes out as 2.1 x 10^43 kgm for a Hubble scale 1.3 x 10^26 meters ...a bit high for the best estimates which seem center around 1.5 x 10^53 kgm However, the real Hubble sphere is approximated by a uniform density 3 sphere, so in order for the 3 sphere to have the same energy and size as the two sphere shell, the corresponding mass would be less by a factor of 5/6 and G would be greater by the same factor. This results in a total ordinary mass as energy = 1.75 X 10^53 kgm, which is within the range of estimates.
     
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