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Oct
15
comment Could gravitational pressure act as dark energy?
Well I'm just trying to find a Newtonian explanation for the $p=-\rho c^2/3$ equation of state of the linear cosmological solution of the FRW equations with $\rho \sim 1/a^2$. This exercise should be valid whether or not the Universe actually obeys $\rho \sim 1/a^2$.
Oct
15
revised Could gravitational pressure act as dark energy?
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Oct
15
revised Could gravitational pressure act as dark energy?
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Oct
15
revised Could gravitational pressure act as dark energy?
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Oct
15
revised Could gravitational pressure act as dark energy?
added 72 characters in body
Oct
15
comment Could gravitational pressure act as dark energy?
I'm trying to see whether I can derive an expression for "gravitational pressure", $p$, in a Newtonian cosmological model. If the model is linear (with mass density $\rho \sim 1/a^2$) then one can in fact derive a dark energy type equation of state $p \sim -\rho$ using this gravitational pressure. I realise the concept of gravitational pressure is heretical in GR but maybe one can think of it as "graviton pressure" in an interaction theory of gravitation. I just thought such a negative pressure might be an example of a repulsive dark energy in a particular cosmological model.
Oct
14
revised Could gravitational pressure act as dark energy?
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Oct
14
comment Could gravitational pressure act as dark energy?
See hyperphysics.phy-astr.gsu.edu/hbase/astro/expuni.html#c1
Oct
14
comment Could gravitational pressure act as dark energy?
$r$ is the radius of a spherical shell of mass, centered at the observer, which is expanding with the Universe. $M(r)$ is the mass enclosed by the shell.
Oct
14
asked Could gravitational pressure act as dark energy?
Oct
6
asked Newtonian potential defines size of Universe?
Oct
3
awarded  Good Question
Sep
26
revised Could Dust Equation of State have some negative pressure?
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Sep
26
asked Could Dust Equation of State have some negative pressure?
Sep
4
comment Maximum voltage on metal sphere?
Ok - Thanks John
Sep
4
asked Maximum voltage on metal sphere?
Aug
28
awarded  Notable Question
Aug
27
accepted Do massive particles exchange Higgs bosons?
Aug
27
asked Do massive particles exchange Higgs bosons?
Jul
15
comment Friedmann Equations with varying G?
Could G remain constant but the definition of energy changes globally with cosmological time? In that case G itself would not have an explicit time dependence - only the energy units themselves change.