Gravitational waves (split from Wave-Particle Duality)

[MJ kihara]

15 hours ago, Mordred said:

I should add gravity waves only  result from anisotropic conditions.

What are the least possible requirements of such conditions?

[Mordred]

1 hour ago, Genady said:

I think it is a convention, because in the last 15 or so years since I started to study this part of physics, I don't remember seeing a different use of these concepts.

If it is its a good one,  as a physical wavelength doesn't involve any probability so it's handy being able to readily distinguish between the two types of waveforms. (Physical vs probability).

 

22 minutes ago, MJ kihara said:

What are the least possible requirements of such conditions?

That honestly depends on the system being described  for example the Earth due to rotation and Mountains (non uniform mass distribution) can generate GW waves. However the effect is incredibly miniscule. Any non symmetric spinning object can do so. However a symmetric sphere won't regardless of how fast it spins. 

In the case of inflation you get regions where the expansion rate may vary from other local regions. Though on a global average its roughly uniform. It is those local regions of non uniform expansion rates that can generate GW waves.

At \(10^{-43}\) the universe would incredibly uniform in mass/energy density that no GW waves could result. Likely the earliest feasible GW waves would generate via electroweak symmetry breaking and inflation.

[MJ kihara]

16 minutes ago, Mordred said:

However a symmetric sphere won't regardless of how fast it spins. 

Is there anything like a purely symmetric sphere in the universe? given π=3.14.....to infinitiy...and given that it's used in derivation of 10^-43, at such a point, we can say that gravitational waves were present.... maybe they were infinitely strong such that their wave length were infinitely small..that is, what led to expansion rate varying in other local place during inflation...we can say that anisotropy in this case begins with π not terminating,as long as, it's presently known...hope my thinking on this is not mistaken.

[Mordred]

Not really considering the temperature at the same time is roughly 10^19 GeV which when you convert to Kelvin isn't far off Planck temperature. Using the Bose Einstein statistics that equates to roughly the equivalent to 10^90 photons squeezed into a single Planckian volume. Good luck finding anistropy distribution under those conditions. (Also a symmetric state as all particles are in thermal equilibrium).

[MigL]

I remember discussing this years ago, on this forum, Mordred.

Consider a large star going supernova.
It is a spherically symmetric event, yet the 'change in gravity' front from the near end will reach us much sooner than the wave front from the back end.
At the very least, the two wave fronts will be out of phase.

So can a symmetric event, under the right conditions, lead to gravitational waves, or am I confusing myself by picturing it ( in my head ) in three dimensions without taking the quadrupole effect of GWs into account ?

[Mordred]

1 hour ago, MigL said:

I remember discussing this years ago, on this forum, Mordred.

Consider a large star going supernova.
It is a spherically symmetric event, yet the 'change in gravity' front from the near end will reach us much sooner than the wave front from the back end.
At the very least, the two wave fronts will be out of phase.

So can a symmetric event, under the right conditions, lead to gravitational waves, or am I confusing myself by picturing it ( in my head ) in three dimensions without taking the quadrupole effect of GWs into account ?

Interesting thought experiment, I  would like to think about this scenario a bit in terms of the stress energy momentum tensor and how it will correlate to the permutation tensor \(H_{ij}\). I will also have to dig into just how symmetric a supernova would be. 

The answer is yes regardless of how symmetric the core collapse occurs one other factor is that acceleration can also generate GW waves. Though a supernova collapse is never likely to stay symmetric. One simple reason being the typical bulge at the equator of rotation. That's not getting into details such temperature anistropies of the plasma etc. 

The Shockwaves themselves  are sources of GW waves

Edited June 27, 2023 by Mordred

[MJ kihara]

4 hours ago, Mordred said:

Using the Bose Einstein statistics that equates to roughly the equivalent to 10^90 photons squeezed into a single Planckian volume.

Does the number of photon varies as the universe expand?

[Mordred]

21 minutes ago, MJ kihara said:

Does the number of photon varies as the universe expand?

The answer to that will depend on if the conservation laws of thermodynamics applies to the Universe. Under the LCDM (BB) model the universe is treated as conserved and expansion under thermodynamics is treated as an isentropic and adiabatic expansion. In essence a closed system.

So under the LCDM model of the BB the photons become redshifted the density decreases but the total number of photons remain constant.

A neat trick results from this mathematically. One can estimate the blackbody temperature at any given value of Z by using the inverse of the scale factor 

Edited June 28, 2023 by Mordred

[MJ kihara]

I

4 hours ago, Mordred said:

The answer to that will depend on if the conservation laws of thermodynamics applies to the Universe. Under the LCDM (BB) model the universe is treated as conserved and expansion under thermodynamics is treated as an isentropic and adiabatic expansion. In essence a closed system.

So under the LCDM model of the BB the photons become redshifted the density decreases but the total number of photons remain constant.

A neat trick results from this mathematically. One can estimate the blackbody temperature at any given value of Z by using the inverse of the scale factor

When calculating the number of photons...is zero point energy and dark energy taken into consideration?

[Mordred]

Yes provided you use Maxwell Boltzmann statistics for mixed states or its QFT equivalent.

http://arxiv.org/pdf/hep-th/0503203.pdf "Particle Physics and Inflationary Cosmology" by Andrei Linde
http://www.wiese.itp.unibe.ch/lectures/universe.pdf:" Particle Physics of the Early universe" by Uwe-Jens Wiese Thermodynamics, Big bang Nucleosynthesis

you can find further details in these two Introductory level articles. Both articles will provide an excellent overview of the major equations used in modern Cosmology.

Edited June 28, 2023 by Mordred

[MJ kihara]

https://www.google.com/url?q=https://en.wikipedia.org/wiki/Zero-point_energy&sa=U&ved=2ahUKEwjwm8Tzyuv_AhWWVqQEHSG2DWIQFnoECAQQAg&usg=AOvVaw1ys9e3P9SVsLKg64lOVYAR

 

In the words of Dirac:^[55]

The light-quantum has the peculiarity that it apparently ceases to exist when it is in one of its stationary states, namely, the zero state, in which its momentum and therefore also its energy, are zero. When a light-quantum is absorbed it can be considered to jump into this zero state, and when one is emitted it can be considered to jump from the zero state to one in which it is physically in evidence, so that it appears to have been created. Since there is no limit to the number of light-quanta that may be created in this way, we must suppose that there are an infinite number of light quanta in the zero state...

......an infinite number of light quanta in zero state.

 

[swansont]

Yes, you can have as many nonexistent photons as you want. Dirac’s quote is from 1927, so it’s not like the whole idea of bosons had been developed very much.