Group items tagged

On October 11, 2010, Laura Mersini-Houghton appeared in a BBC programme What Happened Before the Big Bang (along with Michio Kaku, Neil Turok, Andrei Linde, Roger Penrose, Lee Smolin and other notable cosmologists and physicists) where she propounded her theory of the universe as a wave function on the landscape multiverse.[11] The programme referred to three observational tests of her theory's predictions, which makes it the only theory on the origins of our universe ever to offer predictions and have them successfully tested. Mersini-Houghton's work on multiverse theory is discussed in the epilogue of a recently published biography of Hugh Everett III.[12

Space is festooned with vast "hyperclusters" of galaxies, a new cosmic map suggests. It could mean that gravity or dark energy - or perhaps something completely unknown - is behaving very strangely indeed. We know that the universe was smooth just after its birth. Measurements of the cosmic microwave background radiation (CMB), the light emitted 370,000 years after the big bang, reveal only very slight variations in density from place to place. Gravity then took hold and amplified these variations into today's galaxies and galaxy clusters, which in turn are arranged into big strings and knots called superclusters, with relatively empty voids in between. On even larger scales, though, cosmological models say that the expansion of the universe should trump the clumping effect of gravity. That means there should be very little structure on scales larger than a few hundred million light years across. But the universe, it seems, did not get the memo. Shaun Thomas of University College London (UCL), and colleagues have found aggregations of galaxies stretching for more than 3 billion light years. The hyperclusters are not very sharply defined, with only a couple of per cent variation in density from place to place, but even that density contrast is twice what theory predicts. "This is a challenging result for the standard cosmological models," says Francesco Sylos Labini of the University of Rome, Italy, who was not involved in the work.

Physicists struggling to reconcile gravity with quantum mechanics have hailed a theory - inspired by pencil lead - that could make it all very simple

Unification theory with no extra dimensions. The first part unifies the strong nuclear force with the gravitational force in a mathematical way; the quantum vacuum is treated as a deformable system by the strong nuclear force. The second part unifies the nuclear force with the quantum vacuum in a hypothetical structure; the quantum vacuum is treated as a supersymmetric and metastable system with properties related to the different types of particles' motion.

A small change to the theory of gravity implies that our universe inherited its arrow of time from the black hole in which it was born.

Physicist Brian Greene was propelled into the spotlight thanks to The Elegant Universe, his bestseller on string theory. Now he's turned his attention to parallel worlds. He tells Amanda Gefter about his favourite multiverse, why we might be living in a computer simulation and the questions that keep him awake at night

May 4, 2011: Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.Researchers confirmed these points at a press conference today at NASA headquarters where they announced the long-awaited results of Gravity Probe B (GP-B)."The space-time around Earth appears to be distorted just as general relativity predicts," says Stanford University physicist Francis Everitt, principal investigator of the Gravity Probe B mission.

A theory of reality beyond Einstein's universe is taking shape - and a mysterious cosmic signal could soon fill in the blanks