Science > Physics > Vacuum Energy Density, or How Can Nothing Weigh Something?
| Topic: |
Science > Physics |
| User: |
"Sam Wormley" |
| Date: |
26 Oct 2005 12:50:18 PM |
| Object: |
Vacuum Energy Density, or How Can Nothing Weigh Something? |
Vacuum Energy Density, or How Can Nothing Weigh Something?
http://www.astro.ucla.edu/~wright/cosmo_constant.html
The equations of quantum field theory describing interacting
particles and anti-particles of mass M are very hard to solve
exactly. With a large amount of mathematical work it is possible to
prove that the ground state of this system has an energy that is less
than infinity. But there is no obvious reason why the energy of this
ground state should be zero. One expects roughly one particle in
every volume equal to the Compton wavelength of the particle cubed,
which gives a vacuum density of
rho(vacuum) = M^4c^3/h^3 = 10^13 [M/proton mass]^4 gm/cc
For the highest reasonable elementary particle mass, the Planck mass
of 20 micrograms, this density is more than 1091 gm/cc. So there must
be a suppression mechanism at work now that reduces the vacuum energy
density by at least 120 orders of magnitude.
See: http://www.astro.ucla.edu/~wright/cosmo_constant.html
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| User: "" |
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| Title: Re: Vacuum Energy Density, or How Can Nothing Weigh Something? |
26 Oct 2005 05:23:52 PM |
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In article <ulP7f.472691$x96.288374@attbi_s72>, Sam Wormley <swormley1@mchsi.com> writes:
Vacuum Energy Density, or How Can Nothing Weigh Something?
http://www.astro.ucla.edu/~wright/cosmo_constant.html
The equations of quantum field theory describing interacting
particles and anti-particles of mass M are very hard to solve
exactly. With a large amount of mathematical work it is possible to
prove that the ground state of this system has an energy that is less
than infinity. But there is no obvious reason why the energy of this
ground state should be zero. One expects roughly one particle in
every volume equal to the Compton wavelength of the particle cubed,
which gives a vacuum density of
rho(vacuum) = M^4c^3/h^3 = 10^13 [M/proton mass]^4 gm/cc
For the highest reasonable elementary particle mass, the Planck mass
of 20 micrograms, this density is more than 1091 gm/cc. So there must
be a suppression mechanism at work now that reduces the vacuum energy
density by at least 120 orders of magnitude.
See: http://www.astro.ucla.edu/~wright/cosmo_constant.html
Gotta love the chain of logic in the above.
1) Starting from "there is no obvious reason why the energy ...
should be zero", which is doubtless true but quite vacuous.
2) Continuing through "One expects roughly one particle in every volume
equal to the Compton wavelength of the particle cubed" which really
doesn't follow from anything other than "hey, having no idea what it
may be, we can try this value>
3) Then through "For the highest reasonable elementary particle mass,
the Planck mass of 20 micrograms" which again is not based on
anything.
4) One reaches "So there *must* (emphasis mine) be a suppression
mechanism..."
Pretty impressive, arriving at such strong conclusion based on such
dubious reasoning.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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