Cosmology: time begins (Introduction)

by David Turell , Friday, May 23, 2014, 18:42 (3619 days ago) @ David Turell

"I've proposed that there is such a principle, related to the Second Law of thermodynamics. This, you might recall, is the law of nature which says that you can't build a perpetual motion machine; there exist processes in nature which are impossible to reverse.Technically, physicists define a number called the entropy to measure how scrambled-up the universe is at a given moment of time. The Second Law says that this number always increases as time passes.
 
"Even black holes obey a version of the Second Law. Their entropy turns out to be proportional to the area of their event horizon. In other words, the area of a black hole, plus the entropy of any matter outside of it, always increases with time. This formulation of the Second Law, discovered by Jacob Bekenstein and Stephen Hawking, is called the Generalized Second Law (GSL). In my dissertation research, I proved mathematically that the GSL is true in a broad range of circumstances.-"You can also use the GSL to show that time has to end at a singularity inside of black holes and had to have a beginning at the big bang. Otherwise, there'd be observers whose horizons wouldn't satisfy the GSL. Admittedly, no one really understands the laws of physics near singularities, so this part of my research is speculative and depends on what kinds of new physics might be relevant. It is conceivable that, even though the GSL is valid in all the situations we've been able to check so far, it is false near singularities." (my bold)-http://blogs.scientificamerican.com/critical-opalescence/2014/05/23/time-machines-would-run-afoul-of-the-second-law-of-thermodynamics-guest-post/