Carrock

For the same reason you can't consider the universe as having a temp of 1.95K - the cosmic neutrino background temperature. The CMBR now has the spectrum of black body radiation from a source at 2.7K. It ceased to be in equilibrium at its time of last scattering when its temperature was about 3000K at 380000 years after BB. The CNBR now has the spectrum of black body radiation from a source at 1.95K. It ceased to be in equilibrium at its time of last scattering when its temperature was a few million K at around 1 second after BB. [neutrino interactions are complicated and this description may not be very accurate.] So the universe is not in equilibrium. 'spatially homogeneous and isotropic' need not and in this case does not mean in equilibrium. The CNBR does not have much current effect so it can often be ignored in calculations (but not in calculating critical density). However it has had a major effect and cosmological models have to take it into account. Strange has addressed the other points you've made. This post is simply an expansion of what I've previously written. I've learned a fair amount about cosmology in this topic. You now have four temperatures to choose from....

"That does mess me up. I thought each portion was finite. Or infinite." - Carrock Infinity/infinity or infinity-infinity is basically not defined - I was being (too) informal. Addition and multiplication of infinities is well defined. Using e.g. the denumerable infinity aleph-null, aleph-null = n+(aleph-null) = n*(aleph-null) =(aleph-null)^n where n (I'm being overcautious) is a finite positive integer and definitely not infinite. So a spatially infinite universe can be considered to be e.g. aleph-null units of finite space or aleph-null units of space each of volume aleph-null units.

I was referring to this and the fact that the CMBR at 2.7K and the CNBR at 1.95K are not now and never again will be in equilibrium with themselves or each other. Black body radiation is generated by a body in thermal equilibrium. Once the radiation leaves or is decoupled it is no longer in equilibrium. You're avoiding the question of whether you think the universe is a black body at 2.7K or 1.95K or neither.

I'd update CERN to the diameter of the earth. I predict that inflation induced by building it will ensure that there's never enough money to bring it up to full power.

Which cosmic background radiation do you think is relevant? The neutrino background at 1.95K or the microwave background at 2.7K? IIRC the neutrino time of last scattering was about one second after BB and the photon(microwave) time of scattering 300 thousand years. Expansion lowered their temperature after last scattering but these particles were never again in equilibrium. Perturbations and blocking after last scattering will never be smoothed out. Again these photons are no longer in thermal equilibrium when they've left the sun. The sun heats one side of objects on earth, but not the other. The black body radiation you're referring to here is radiation from a black body, not radiation inside a black body.

There's an analogy used in this thread that I feel has been stretched to breaking point, with some posters confused by its departure from actual cosmology. This is the analogy with a classical container whose gaseous contents remain in thermal equilibrium and cool as it expands, and that the CMBR is the same as the equilibrium radiation associated with a temperature of 2.7K. After the time of last coupling, if the universe doubles in size, the energy of each photon is halved since the wavelength has doubled due to the expansion of space and its energy is hc/wavelength i.e. its energy is inversely proportional to the size of the universe. Non relativistic matter has kinetic energy= (1/2)mv^2. If the universe doubles in size each particle has its velocity halved since it travels twice the distance in unit time. However because of the v^2 term its energy is quartered i.e. its energy is inversely proportional to the square of the size of the universe. Other interactions e.g. gravitational soon swamp the effect of expansion on non relativistic matter. There is an exception, the neutrino, which is ordinary matter travelling at relativistic speed, which complicates things. The temperature of the cosmic neutrino background radiation (with similar caveats as above) is estimated to be about 1.95K. https://en.wikipedia.org/wiki/Cosmic_neutrino_background provides interesting info. The CMBR at 2.7K and the CNBR at 1.95K are not in equilibrium in the sense that there is negligible interaction to even out any perturbation induced since the time of last coupling. While these temperatures, especially the CMBR, are very useful in calculations, neither is applicable in some calculations involving equilibrium thermodynamics.

I don't see it that way. Consider a volume of space (finite or countably infinite i.e. at most aleph-null finite spatial elements) which expands exponentially for aleph-null years i.e. for infinite time. During that time it will double in size aleph-null times i.e. its volume will be 2^(aleph-null) finite spatial elements. 2^(aleph-null) finite spatial elements is equal to aleph-one finite spatial elements, whose number is equal to the number of irrational numbers, or the number of points in aleph-null units of space. So space must contain aleph-one finite units of space. There cannot be a one to one correspondence between the non-denumerable set of points (aleph-one) in space and the set of all finite non overlapping spatial elements. This is an argument by contradiction, showing that there cannot be aleph-one finite units of space. Informally, you cannot store a finite volume of space in a point. I don't think it's necessarily impossible to have eternal expansion, but I don't think it's acceptable to say 'but the universe does not really give a damn about our limited intuition' so infinite expansion must be possible. There's a lot more to this of course but I'll just refer you to http://www.jstor.org/discover/10.2307/186708 and International Journal of Theoretical Physics, Vol. 12, No. 3 (1975), pp. 217-223 Cosmological Models and Non-Denumerable Singularities RICHARD SCHLEGEL My link to this has died.

Opinions aside, you have written little inconsistent with what I've said. "Again I see the fact that the concept of infinity itself is the problem." - Cantor developed a very rigorous mathematics of transfinite numbers; what is the problem? "So why then cannot an infinite universe not expand or stretch if you will?" - it can. "According to the BB, the universe is all there is...it is expanding into nothing, just as it has no borders or edges." - ambiguous. "An infinite universe still expanding/stretching, may seem to be against our intuition, but the universe does not really give a damn about our limited intuition." - my limited intuition is that the universe, infinite or not, is expanding locally, perhaps everywhere, but that is not in itself proof that the universe is not expanding. You're describing a universe which only expands exponentially for finite time, where I was describing one which expands for infinite time. If you want a full response from me, claim something inconsistent with my earlier posts, rather than repeating some of it and saying what I wrote 'does not compute.'

The data, or most of it, is not erased and can be recovered. Only permanently erasing data necessitates increased entropy. Overwriting and destroying data increases entropy; the increase in entropy has just been delayed until the original data is destroyed.

Interesting quote from Kashlinsky, but the link to the original is dead, so I'll reserve judgement...

Depends what you mean by steady state. Non cosmologists use a definition like this: https://en.wikipedia.org/wiki/Steady_state_(electronics) The steady state theory of Bondi and Gold was disproved mathematically and the steady state theory of Hoyle was disproved observationally. These are the only theories that most cosmologists would describe as steady state. Basic lambda-cdm (and some theories modified for dark energy) predict that startup transients such as the cmbr and stars and cosmologists will eventually become unimportant as the universe continues expanding, becoming colder and emptier and approaching an unchanging state. No cosmologist will ever describe that as steady state for historical reasons. An implication of my previous post is that that unchanging state must end after limited or unlimited time. An infinite universe whose volume does not eternally increase or decrease exponentially is the only one which can exist for infinite time and be topologically consistent with current physics. A non cosmologist might describe that as 'steady state.'

Exponential expansion can continue for unlimited but finite time. A/the universe has finite or infinite (i.e. aleph-null) units of volume. If this universe doubles in size an infinite number of times in infinite time it contains 2^(aleph-null) units of volume. This is equal to aleph-one units of volume (assuming the continuum hypothesis). That is, there would be as many units of volume in this universe as there are dimensionless points. This is topologically inconsistent with current physics. Philosophy of Science Vol. 32, No. 1 (Jan., 1965), pp. 21-31 has a good description of this. (The article was very aggressively peer reviewed but some on this forum are convinced it is too old to be correct.) Of course the universe is not constrained by what seems to be (im)possible....

Figure skaters moving their arms closer to the body requires work to be done by the arms. External energy input could used for a similar result.

No. But erasing low entropy data increases overall entropy. The necessity of discarding data gives a theoretical limit to the efficiency of computers. The effect has been observed.

The non bolded points have conveniently been dealt with while I took a break. The finite observable universe originated (probably) in a volume smaller than a proton but because of the lack of observable edge effects the big bang is either spatially infinite or too large to measure. 'Originates' here really means 'this is the earliest time when plausible physics can be invoked.' Inflation is an explanation of why the observable universe is so smooth but I doubt anyone will ever come up with a remotely plausible smoothing mechanism to ensure the big bang was of infinite extent. So while the universe may or may not be infinite in time and/or space I believe the big bang was finite in space. If the universe is spatially infinite I'd expect an infinite number of big bangs.

Take one infinite multiverse. Chop it in two (rather difficult in practice) and you have two infinite universes. You can repeat this an unlimited (but not necessarily infinite) number of times for as many universes as you want. Alternatively, simply say that the (infinite) multiverse is twice as big as the (infinite) multiverse or infinitely many times as big. This is a verbal description of perfectly valid maths. See e.g. http://gizmodo.com/5809689/a-brief-introduction-to-infinity

K-J-U was too late. They've been employed by D Trump as military advisors.

That does mess me up. I thought each portion was finite. Or infinite.

The possibility of pre-emptive defence by USA etc is unfortunately a very good reason for non nuclear countries to acquire nuclear weapons. Once there are viable ICBMs in North Korea the possibility they would be protected against EMP ( or just stored underground) would discourage the above as North Korea would likely launch them, confusing pre-emptive defence with an act of war.

Many theories predict something critical becoming infinite (or zero) in certain situations e.g. inside a black hole. This is usually described as a singularity. The definition of singularity is a bit vague, but it generally means that the theory is useless in that situation, and unknown physics or a new theory is required.

Gone. Someone at arjonline reads this forum.

I thought it best in my previous post to indicate nothing I said was inconsistent with rangerx's posts. Your omission of "Note: this is consistent with the previous post" in your quote of me so that you could claim I disagreed with rangerx is an unscientific but very effective way of ensuring that you won't be taken seriously. I won't waste my time with any of your future posts.

That view hasn't changed significantly. The main damage from these pollutants is on land and freshwater lakes. Locally,SO2 and NOx pollution swamps the effects of increased CO2 in the atmosphere. Unlike CO2 , these pollutants would soon return to preindustrial levels in the atmosphere if the polluting industries were shut down. Note: this is consistent with the previous post.

IIRC Robert Heinlein in "The man who sold the moon" came up with a similar idea in the 1940s or 1950s, to eliminate the first stage in a manned lunar spacecraft.

An investment with no return for 600 years. Ten years with no return maybe.