LHC starting up again

[AFTT47]

Okay so if it's that simple, why are the experts coming up with these elaborate hypothesis?

[Anomalocaris]

Because gas pressure and radiant pressure can be explained by convincing theory of their operating mechanisms which can predict accurately how these pressures are observed to work.

Not yet so with vacumn pressure.   We see evidence it exists, we have some observations of how it works, but we have no good explanation of its operating mechanism, other than an somewhat unsatisfactory "it is the property of space and excert a relative pressure proportional to amount of space measured over".

[AFTT47]

So another words, it's an educated guess. I suppose that's not much different from the dark matter/dark energy hypothesis. It just seems that that should occur to the professionals as well. So why are they promoting these ideas which seemingly violate Occam's Razor?

[Anomalocaris]

The existence of the vacumn pressure is not an educated guess.   It was when Einstein proposed it, and he guessed it for the wrong reasons.    But it is a validated fact now.   How it works is still an educated guess.   Occum's razer say since it clearly works, some explanation of how it works would be true.   so guessing specifically how it works so one could test these guesses individually does not violate occum's razor.

[Alex K]

All I can say is that if you embed the standard model into general relativity in the obvious most simpleminded fashion, any vacuum energy from the particles and fields looks like a contribution to Einstein's cosmological constant, which makes vacuum pressure.

Now, this construction breaks down near the planck energy, which is why we need more elaborate ideas about quantum gravity. But this doesn't seem to entirely negate the fact that the vacuum energy of the standard model looks like cosmological constant. One could argue that moving away from this picture would be more of a violation of occams razor more the other way around. That it seems far fetched that new phenomena coming in near the planck energy would precisely compensate the contributions to the cosmoligical constant.

But - since we do not know what precisely the complete picture of quantum gravity looks like, this entire argument might be spurious, and we'll only know for certain once we know how quantum gravity really works. However, in superstring theory, this line of argument holds and the huge contributions to the cosmological constant is indeed there.

[AFTT47]

All I can say is that if you embed the standard model into general relativity in the obvious most simpleminded fashion, any vacuum energy from the particles and fields looks like a contribution to Einstein's cosmological constant, which makes vacuum pressure. Now, this construction breaks down near the planck energy, which is why we need more elaborate ideas about quantum gravity. But this doesn't seem to entirely negate the fact that the vacuum energy of the standard model looks like cosmological constant. Moving away from this picture would be a more of a violation of occams razor more the other way around.

It sounds like you're saying that the whole dark matter/dark energy thing is an over-complication, failing to account for known things. It looks like that to me too although I'm just a layman. I'm just having a hard time imagining that the major players in the physics community wouldn't see this too if that is the case. 

[Alex K]

I don't see why you would say that, can you elaborate? I probably failed to express myself clearly, bc that's not what I wanted to get across.

We have observational evidence for DM and indirect observational evidence for DE.

Once this is established, you look at the theory side and realize that DM is easy to add in form of a new particle, and DE seems to be present automatically, but way too plentiful by default. That's it.

My statements above were probably obscuring this relatively simple summary of the status quo.

[Anomalocaris]

All I can say is that if you embed the standard model into general relativity in the obvious most simpleminded fashion, any vacuum energy from the particles and fields looks like a contribution to Einstein's cosmological constant, which makes vacuum pressure. Now, this construction breaks down near the planck energy, which is why we need more elaborate ideas about quantum gravity. But this doesn't seem to entirely negate the fact that the vacuum energy of the standard model looks like cosmological constant. Moving away from this picture would be a more of a violation of occams razor more the other way around.

It sounds like you're saying that the whole dark matter/dark energy thing is an over-complication, failing to account for known things. It looks like that to me too although I'm just a layman. I'm just having a hard time imagining that the major players in the physics community wouldn't see this too if that is the case. 

hmmm,  "genius is seeing the obvious before everyone else", not because that is illuminating, but because it seems awfully erudite without requiring any erudition.

[AFTT47]

I don't see why you would say that, can you elaborate? We have observational evidence for DM and indirect observational evidence for DE.

We have observational evidence for something we clearly don't understand. The very fact that they are called, "dark matter" and "dark energy" are red flags for me. Might as well call them "enchanted earth" and "mystic fire." You don't use terminology like that for something you understand. You pointed out yourself that dark matter could be explained by neutrino mass + the mass of an unknown particle. You and Chuck suggest that vacuum energy could constitute dark energy. Those sound simpler (and thus a lot more believable) than some exotic and unknown state of matter and a mysterious energy field which is fundamentally different from anything we know.

I thought that was what you were saying yourself.

[Alex K]

The names are just for historical reasons, they are almost meaningless. They stand for a collection of phenomena (missing mass in galaxies and clusters, missing mass in CMB observations, accelerated expansion of the universe, flatness of the universe ) which are most easily explained by a small vacuum energy (cosmo constant) and a new neutral massive particle.

The monicker dark is because the missing mass doesn't radiate or absorb photons, nor does the vacuum energy, and "matter" because DM seems to behave like massive particles with an equation of state like pressureless dust, and "energy" because DE has an equation of state of a constant energy density