This morning I was reading once more about Stephen Hawking’s misinterpreted statement on the existence of black holes, which led to a blog I’d not read before. My great loss. I’ve since spent several hours catching up, and Backreaction is definitely my new favourite blog for all things physics, astro~, quantum~ or otherwise. And philosophy!
I’ve also been swirling around thoughts on Parsifal, which I haven’t blogged about as much as I’d hoped, and then read her post, A moment of silence replaces the big bang. She says:
A completely different approach to quantum gravity that we discussed recently is Causal Dynamical Triangulation which avoids singularities by discretizing space and time into chunks of finite size. In this approach it was recently found that space-time can exist in different phases, much like water exists in different phases. In the early universe, temperatures were high, and space-time might have been in a different phase, one in which space-time falls apart into causally disconnected pieces.
And then summarises the main conclusion from a paper by Jakub Mielczarek, Asymptotic silence in loop quantum cosmology:
The higher the density, the slower the speed of light. At half the critical density, the speed of light reaches zero – this means points become causally disconnected. But things become even more interesting when the density becomes larger than half the critical density and increases towards the critical density. In this range the speed of light becomes an imaginary number and its square becomes negative. This means that time stops existing and turns into space. Physicists say space-time becomes Euclidean.
“… time stops existing and turns into space.”
Parsifal: Ich schreite kaum, – doch wähn’ ich mich schon weit.
I barely step, – yet believe myself come far.
Gurnemanz: Du siehst, mein Sohn, zum Raum wird hier die Zeit.
You see, my son, time here becomes space.