cosmic acceleration

An “expert voice” astrophysicist explains that the Big Bang is now the “vanilla Big Bang,” which is unpopular because it doesn’t explain all observations: The Big Bang model is our most successful explanation for the history of the universe that we live in, and it’s ridiculously easy to encapsulate its core framework in a single, T-shirtable sentence… But But there’s no reason for our universe to be flat. At large scales it could’ve had any old curvature it wanted. Our cosmos could’ve been shaped like a giant, multidimensional beach ball, or a horse-riding saddle. But, no, it picked flat. And not just a little bit flat. For us to measure no curvature to a precision of a few percent in Read More ›

Rob Sheldon mentioned a story going the rounds earlier today, about whether dark energy was “even allowed.” Here’s the story, from ScienceDaily: In string theory, a paradigm shift could be imminent. In June, a team of string theorists from Harvard and Caltech published a conjecture which sounded revolutionary: String theory is said to be fundamentally incompatible with our current understanding of “dark energy” — but only with “dark energy” can we explain the accelerated expansion of our current universe. Timm Wrase of the Vienna University of Technology quickly realized something odd about this conjecture: it seemed to be incompatible with the existence of the Higgs particle. His calculations, which he carried out together with theorists from Columbia University in New Read More ›

And cosmologists race to win a “great cosmic bake-off” to produce a new one, says astrophysicist: Just as cosmological measurements have became so precise that the value of the Hubble constant was expected to be known once and for all, it has been found instead that things don’t make sense. Instead of one we now have two showstopping results. On the one side we have the new very precise measurements of the Cosmic Microwave Background – the afterglow of the Big Bang – from the Planck mission, that has measured the Hubble Constant to be about 46,200 miles per hour per million light years (or using cosmologists’ units 67.4 km/s/Mpc). On the other side we have new measurements of pulsating Read More ›