Energy

[Butch]

Is our universe a closed system? In another thread I put forth speculation that the energy feeding the accelerating expansion of our universe was coming from an outside source (a black hole in another universe). Wow there is a lot of unknown concerning energy! So... Let us discuss!

Hmm, 9 views and no feedback... 

Ok, in my speculation, the expansion is absolute, that is to say it includes fields and matter. Such an expansion (seeing as we are a part of it) could only be detected by our observation as red shift.

[Mordred]

The thermodynamic term your looking for is adiabatic.

 In our Universe regardless if closed or open there is no net inflow or outflow of heat or energy.

 Energy is the ability to perform work, it is a result of system conditions. There is no need to create energy as per se, as it is a property of a system not a thing unto itself.  There is two primary types of energy in terms of cosmology applications. Pay close attention to the following definitions and memorize them. They are of primary importance.

Kinetic energy: energy due to an object or particles motion.

Potential energy: Energy due to to position relative to otber positions/coordinates.

 In the latter it is the anistropic variations of a field within itself that gives rise to the potential differences from one locale to another. (just like potential differences is electromagnetic fields.)

 The greater the differences from one locale to another in field strength etc the greater the potential energy between those two coordinates 

Edited April 19, 2018 by Mordred

[studiot]

5 hours ago, Mordred said:

The thermodynamic term your looking for is adiabatic.

Adiabatic solely restricts heat transfer, not a general energy transfer.

Wiki will do for this.

Quote

Wikipedia

In thermodynamics, an adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings. In an adiabatic process, energy is transferred to its surroundings only as work.

Note they say without transfer of heat or matter, but specifying matter is unneccessary as you can't transfer matter without bringing in some heat with it.

Edited April 19, 2018 by studiot

[Mordred]

correct for the classical usage but now consider the mass/energy density terms in cosmology applications.

Here is an example article 

" then obtain for the time change of the entropy
[latex] kTd(sR^3) = d(pR3^) + pdR&3,[/latex] where R is the radius of the universe as it appears in the
Robertson-Walker metric. The vanishing of Eq. 2.2 express that the evolution is adiabatic"

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.pnas.org/content/pnas/83/17/6245.full.pdf&ved=2ahUKEwj2n8mf-sXaAhXoslQKHQP1BjM4ChAWMAN6BAgAEAE&usg=AOvVaw0WnKtpy7_8BFZXcg6jL_ud

Some literature use entropy other literature uses energy in the above. Ie via 

"For a system at equilibrium the entropy density, energy density and pressure can be written as
functions only of the temperature, ρ = ρ(T), s = s(T), P = P(T). Since ds and dρ are intensive
quantities proportional to dT, the coefficients of the dT and dV terms must separately be zero (for
example under a volume change at constant temperature the dV term must be zero). For the dV
coefficient we get an expression for the entropy density"

https://www.google.com/url?sa=t&source=web&rct=j&url=http://cosmologist.info/teaching/EU/notes_EU1_thermo.pdf&ved=2ahUKEwi2ro-e_8XaAhWO0J8KHZjuAkc4HhAWMAN6BAgEEAE&usg=AOvVaw0T1BASBIvgzb2FpZSOBPW6

 

Edited April 19, 2018 by Mordred

[Butch]

Great discussion! But is our universe at equilibrium? Certainly measured by our observation it is, however we are part of the system. Is redshift a function of the age of a proton? The CMB was predicted as evidence of the Big Bang, and certainly I agree with that, however does the Big Bang have a beginning? Is it possible that if we could travel back to the beginning of the Big Bang might we find the universe pretty much as it is now? Time is ultimately physical relationships, if those relationships remained the same when the universe(to an outside observer) was much smaller would we as part of that universe still determine that a Big Bang started about 3.7 billion years previous?

12 hours ago, Mordred said:

The thermodynamic term your looking for is adiabatic.

 In our Universe regardless if closed or open there is no net inflow or outflow of heat or energy.

 Energy is the ability to perform work, it is a result of system conditions. There is no need to create energy as per se, as it is a property of a system not a thing unto itself.  There is two primary types of energy in terms of cosmology applications. Pay close attention to the following definitions and memorize them. They are of primary importance.

Kinetic energy: energy due to an object or particles motion.

Potential energy: Energy due to to position relative to otber positions/coordinates.

 In the latter it is the anistropic variations of a field within itself that gives rise to the potential differences from one locale to another. (just like potential differences is electromagnetic fields.)

 The greater the differences from one locale to another in field strength etc the greater the potential energy between those two coordinates 

You might say that we are trapped in the time/space of this universe, it seems unimportant that we should be able to escape that... and really it is rather unimportant I suppose, as is the concept of how the universe " began".

If the Big Bang does have a beginning it might have some importance in many billions of years... However if it is steady state, it really does lack importance I suppose... Unless of course, we find it possible to travel through a black hole, certainly a one way trip.

It is interesting to discuss, and maybe Hoyle should have received his prize, I suppose however in reality we are trapped here and now and must live with it.

Perhaps a better term for this speculative inflow to our universe is cosmic flux or something of that order. The thought that occurs to me however relates to gravity. Fields and thus particles would be absorbing this "flux" and would be doing so at rates that maintain relativity. If we consider tensors in fields produced by this activity, massive bodies would tend to attract. In the case of bodies in contact, they would undergo acceleration due to expansion of the bodies.

Edited April 19, 2018 by Butch