The "Big Rip"

[Dr Mordrid]

Story....

New universes will be born from ours

What gruesome fate awaits our universe? Some physicists have argued that it is doomed to be ripped apart by runaway dark energy, while others think it is bouncing through an endless series of big bangs and big crunches. Now these two ideas are being combined to create another option, in which our universe ultimately shatters into billions of pieces, with each shard growing into a whole new universe. The model could solve the mystery of why our early universe was surprisingly well ordered.
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In their model, dark energy becomes very dense and sets the universe expanding at such a rate that it approaches the big rip. The universe tears into small patches that rush away from each other faster than the speed of light. But the destruction is then halted, as the density of dark energy becomes equal to the density of the universe. At this point, each patch crunches in on itself. "All the patches, of which there are a huge number, will separately contract into disparate universes," says Frampton. Each patch will then bounce outwards again, creating a new universe.

Crucially, each patch only contains a fraction of the overall entropy of its parent universe - so each new universe starts out in a low entropy state, as required. The work will appear in Physical Review Letters.
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[Technoid]

uhm....

Wonder what they will come up with if they still fail to detect "dark matter//Energy" ?

[Nowhere]

Don't put dark matter and dark energy in one basket
Two different things...

[Dr Mordrid]

Dark Energy = Einsteins cosmological constant = very likely

Dark Matter = an undefined construct (undiscovered particles? gas? black holes? neutrinos? All of the above?) to explain a problem with galaxies rotational speed = far less likely

Part of the construct for dark matter has been "cold dark matter", and it recently suffered a blow to the gut by way of some recent observations at Keck.

According to the research, the relationship between a galaxy’s mass and a new speed indicator that measures movement of its stars and gas remains the same for all forms of galaxies, from spirals like our own Milky Way, to elliptical galaxies, and even the so-called "train wrecks" left over by galactic mergers.

"Surprisingly, if you use this new speed indicator to measure the motions of stars and gas in a galaxy, you can predict the mass in stars the galaxy has with pretty high accuracy," said Susan Kassin, a post-doctoral researcher at the University of California, Santa Cruz and lead author of the study.

Usually the Tully-Fisher function (relating a galaxies rotational speed to its luminosity) was all that could be used for spirals, with the Faber-Jackson relation (relating the luminosity and the central velocity dispersion) being used for ellipticals.

Now the AEGIS program can take direct measurements of star speeds, a more accurate technique.

What's been found is a consistent relationship for all galaxies that relates the baryonic mass (nucleons, delta, sigma, xi etc) of stars to the rate at which they rotate in their galaxies, accurate for most of the life of the universe.

This is one of the predictions of modified gravity (Modified Newtonian Dynamics = MOND) theories that seek to displace dark matter. As such it could well be a spear in the side of cold dark matter theories.

MOND theorises that over long distances the old F=m/a formula does not work, introducing an artifact that has been interpreted into dark matter.

Instead it suggests F=mµ(a/a0)a; where µ(x) is a function that for a given variable x gives 1 if x is much larger than 1 ( x≫1 ) and gives x if x is much smaller than 1 ( 0 <x≪1 ).

The term a0 is a proposed new constant, in the same sense that c (the speed of light) is a constant, except that a0 is acceleration and c is speed.

[Technoid]

Don't put dark matter and dark energy in one basket
Two different things...

why not?

They are both in the same basket: excuses used when the preferred "theory" doesn't quite measure up

[Nowhere]

Actually they are in the "preferred" category...oh, and BTW, dark energy was proposed by Einstein right at the start of existence of general relativity. And dark matter...what, you'd prefer that they ignore observations? (and there is a handfull of alterantive theories as Doc pointed out...)