Mass of the Universe: Dark Energy, Inflation & Observations

[Mordred]

Obviously, the Hawking radiation with a temperature which is proportional to its surface gravity on the event horizoncan give some insight on the deep relationship between gravity and thermodynamics. Indeed, the thermodynamics of black hole has already been constructed with the Bekenstein entropy of a black hole [3–6]. Note that, the Hawking radiation is usually investigated from the eventhorizon of a stationary black hole. In fact, it can also be obtained from the cosmological horizon of a spacetime such as the cosmological horizon of de Sitter spacetime.



Therefore, Hawking radiation may also exist in a FRW universe. By considering that the FRW universe is also a spherical symmetric spacetime and with an apparent horizon, therefore, the above discussion on the apparent horizon of dynamic spherical symmetric black hole spacetime can be generalized to the FRW universe.

the above is two quotes from the Hawking radiation in an FRW universe. The paper later shows the tunnelling via the cosmological horizon.

 

[timmdeeg]

This account misses the mark for at least two reasons. First the particle anti particle separation at a boundary is not a mathematically based phenomena...

I agree and don't remember that I said something different. The particle separation correlating to tidal forces is a picture, which Bojowald and others are using.

Secondly, there is no matter within the event horizon ['towards the singularity']...and even if there were, nothing inside can get outside where we might observe it.

I am not sure about your point. Do you say there is no pair production inside the event horizon?

Of course, matter/radiation can't escape.

 

[Naty1]

My post #17


timedeeg posts

Martin Bojowald says inflation produces matter (pair production) analogously to black holes. But I am not sure whether this is mainstream physics.

my reply

Particle production DOES seem to be accepted as mainstream physics when event horizons are present...as in black holes, Hawking radiation, Unruh radiation, whether all that is actually correct is of course a theoretical question so far. Different observers will see different quantum states and thus different vacua...different particle counts...

Similarly, cosmological expansion also results in particle production...

I should have clarified that the particle production a/w event horizons does NOT involve matter/anti matter particle separation...As stated elsewhere that is a heuristic non mathematical 'intuitive' explanation.

A better way to think about it is this: [These are from several prior discussions, quotes from various experts here, that I put together to form a bigger perspective

There is not a definite line differentiating virtual particles from real particles — the equations of physics just describe particles (which includes both equally). The amplitude that a virtual particle exists interferes with the amplitude for its non-existence; whereas for a real particle the cases of existence and non-existence cease to be coherent with each other and do not interfere any more. In the quantum field theory view, "real particles" are viewed as being detectable excitations of underlying quantum fields

..The expansion of geometry itself, especially inflation, can produce matter.
Other theoretical cases of geometric circumstances create real (not virtual) particles, like Hawking radiation at a BH horizon and Unruh radiation caused by an accelerating observer. With the Unruh effect, it is theorized that two adjacent observers, one inertial and one accelerating will measure different temperatures and make different counts of particles. In other discussions in these forums, there are theories that at the Hubble radius the accelerating Hubble Horizon is sufficient for the production of particles.

[Apparently Hubble and event horizon coincide for exponential inflation.]

Quantum fluctuations in the inflationary vacuum become quanta [particles]
at super horizon scales. ...The evolution of quantum fluctuations, from their birth [at Planck Scale] in the inflationary vacuum and their subsequent journey out to superhorizon scales where they become real life perturbations, is perhaps my favorite calculation in physics.

Here is how those last two circumstances can be thought to produce particles, without particle/aniparticle separation:

An unbounded quantum ['particle'] perturbation is not detectable as a real particle...it is a wave, a field, everywhere to infinity... The emergence of an event horizon bounds that perturbation and causes a detectable particle to emerge...one of finite wavelength...only certain frequencies/wavelengths are allowed...analogous to a loosely waving string...fix the ends and you can create detectable excitations...sounds...Or via quantum mechanics, put a particle in a box...or a potential well...and decrease the size of the container or change the potential of the well... new excitations emerge...frequencies are 'confined' via harmonic oscillations according to the potential or box size...make the container smaller
and Heisenberg uncertainty causes momentum increases...