Last time I started talking about entropy and a puzzle it presents in cosmology. To understand the puzzle we have to understand entropy, which is a crucial part of our view of physics. In fact, we consider entropy to be a (statistical) law about the behavior of reality. That law says: Entropy always increases.
There are some nuances to this, though. For example we can decrease entropy in a system by expending energy. But expending that energy increases the entropy in some other system. Overall, entropy does always increase.
This time we’ll see how Roger Penrose, in his 2010 book Cycles of Time, addresses the puzzle entropy creates in cosmology.
I’ve been chiseling away at Cycles of Time (2010), by Roger Penrose. I say “chiseling away,” because Penrose’s books are dense and not for the fainthearted. It took me three years to fully absorb his The Emperor’s New Mind (1986). Penrose isn’t afraid to throw tensors or Weyl curvatures at readers.
This is a library book, so I’m a little time constrained. I won’t get into Penrose’s main thesis, something he calls conformal cyclic cosmology (CCC). As the name suggests, it’s a theory about a repeating universe.
What caught my attention was his exploration of entropy and the perception our universe must have started with extremely low entropy.
I’m reading Our Mathematical Universe (2014), by Max Tegmark, and I’ll post about the book when I finish. However he got my attention early with the topic of eternal inflation. That got me thinking about how there are some key unanswered questions regarding the Big Bang and inflation of the non-eternal sort.
Inflation certainly does need some explaining. It may be related to dark energy, as both seem to do the same sort of thing (push space apart). The putative physics of inflation is bad enough; eternal inflation is (in my view) fairy tale physics.
For one thing, eternal? Seriously? Infinite something from nothing?
“Space is big. Really big.”
When I started blogging here, one of the first bloggers I followed was Robin, of Witless Dating After Fifty. Over the years, she’s several times mentioned a great question her dad often posed when discussing religion with someone: “How big is your god?”
Last week my buddy and I were having our weekly beer- and gab-fest and our (typically very meandering) conversation came to touch on the problems with young Earth creationism — the Christian fundamentalist idea that the universe is only thousands of years old.
In fact, there’s a pair of real whopper problems involved!
I think, I think.
A bit more than three years ago I began this blog intending to write about matters of existence and consciousness (and science and computing). Since then I’ve tried on other hats, stories from my past and present, opinions and views about society, even the occasional post above movies or TV. But those meatier topics — the ones the blog is named for — still attract me.
There are three problems, though. Firstly, other sites specialize in that sort of thing and do it very well. Secondly, they aren’t topics that attract visitors — my meaty posts get even fewer reads than my less weighty posts. And thirdly, I may not be as good as explaining things as I would like to be.
That said, sometimes I just can’t help myself, so here we go again.
Saw something worth sharing on the most excellent Bad Astronomy blog today. It’s a series of images by reddit user, jerfoo. Click the picture below to open a window on the whole thing (it’s very tall and skinny, so restore it to 100% magnification and scroll down as you read the “story’).