Why is there so much Dark Energy?

The calculation for it, like all the rest of the parameters of the big bang, is currently based primarily on analysis of WMAP data. See http://map.gsfc.nasa.gov/ for details. There are other ways to estimate it, such as measuring the acceleration of the expansion directly with supernovae, but that is much less accurate.

The 3/4 refers to the fact that the energy density of dark energy is 3/4 of the critical density required for the universe to be flat. The universe is indeed very close to flatness, the rest of the energy density coming from matter.

It would be inaccurate to call dark energy a "force" in GR, just as attractive gravity between masses is not a force in GR. Both the accelerating expansion and attractive gravity of masses are simply different kinds of curvature of spacetime.

https://en.wikipedia.org/wiki/Friedmann_equations#...

Of course, to write the density parameter you need to have a state equation for each component (radiation, matter, curvature and vacuum).

But because the theory itself doesn't give how much of each of those should exist (thus giving a very strong test to the theory), you have to get the results from observation instead and fit the predicted theoretical scenario to the observations.

Notice the different curves on figure 1 of Perlmutter's 1999 preprint http://arxiv.org/pdf/astro-ph/9812133v1.pdf for the different scenarios; the yellow and red dots are the observations from galaxies, the lines crossing the points are error bars. The model that is picked is that which fits the best with the experimental data (including error bars).

That's where the 3/4 Omega comes from. As to

<QUOTE>Why is there so much Dark Energy? </QUOTE>

... well, that's the million dollar question, baby. As it is, the standard theory doesn't have an explanation to why the universe is the way it is.

The simple answer to much of your question is that we simply don't know. Until the 1990s, very few cosmologists really suspected even that dark energy might exist. It, or something a little like, turned up as a constant of integration in Einstein's General Theory of Relativity, but after playing with it for a while, he arbitrarily set it to zero, and pretty much everyone went along with that. It was not until the 1990s, when the expansion of the universe was found to be accelerating that it was necessary to back to the drawing board. Since then we have used 'Dark Energy' as shorthand for 'there seems to be something out there, but we really haven't a clue what it is'. There are one or two hypotheses, but they are still no more than that.

Measurement of dark energy is based on its effect, prety much like anything else. If you want to measure gravity, you suspend two masses, and measure to what extent they are attracted to each other. In this case, you measure the acceleration of the expansion of the universe. You then make some assumptions, such as the assumption that this force is reasonably constant in time and pervades all of space, and you have your answer. You then compare that answer (using the standard equation for mass-energy equivalence, E=mc^2) with the measured mass of the universe, including Dark Matter (which, as it happens, is also shorthand for 'there seems to be something out there, but we really haven't a clue what it is'). It is the possibility that it pervades all of space which makes DE add up to rather a large number in this comparison. By comparison, space is pretty empty of matter.

Does that answer your question at all?

Dark energy?

Probably it does not even exist.

A problem occurred with the big bang theory.

To account for the discrepancy it was decided to invent an invisible and undetectable thing called dark matter & dark energy.

I'd suggest that there is some other "more plausible" explanation for the discrepancy that does not require dark energy.

We just need to wait until cosmologists re-evaluate the situation.

It is a theoretical entity that just may not exist.

Something new to our media science is the concept that quantum wave particle duality may be the cause of the accelleration in universal expansion.

Since all electromagnetic particles, like light, behave as a wave untill they contact something and apear as particles, the probabillity wave for that particle potentialy encompasses the entire universe where the wave is aligned, these waves are constantly interacting over vast distances. It is suggested that this property is driving the universal expantion by exerting quantum vacuum presure on all the objects in the trejectory of the wave.Since there are so many of these photonic waves ripping through the cosmos in all directions,though the effect is small on a localised level, over the expanse of the universe the cumulative effect is greater than gravity across the vastness of intergalactic spaces and is supplying a constant outward thrust to all the galaxies.

So far that makes more sense than a mysterious non force force driving expansion.

It could also be the result of weak interaction of the multiverses resulting from small perturbations in the dimensional seperations of these coexisting universes we inhabit.

These are realy big questions with realy long and potentialy wrong answeres.Fact is we may never be able to prove any of it since we are locked in our dimentional frame and can't directly observe these co-universii.All we can do is take carefull measurments of lot's of stuff and ponder the implications of the data till something makes sense.

Because you touch yourself at night