Thursday, November 7, 2013

The Universe in a Nutshell

A less daunting read than A Brief History of Time (1988) due to the many full-colour illustrations -- at least one on every page and many of them gorgeous -- plus Hawking's chatty approach and puckish sense of humour.

At one point he mentions giving a seminar on black holes in Paris. It did not go over well, in part because the literal translation of black hole, trou noir, had "dubious sexual connotations."

Still, many of the concepts are beyond easy understanding, and remind one of medieval debates about the number of angels that can tread upon the head of a pin. Some of the terminology reflects this: imaginary numbers, virtual particles, shadow galaxies, dark radiation, vacuum energy. Imaginary time, for example, is measured by imaginary numbers and runs at right angles to normal time.

A few interesting quotes:

Our past is pear-shaped.

The first discussion of black holes appeared in 1783.

One can think of the universe as being like a giant casino.

The universe has multiple histories, each of which is determined by a tiny nut.

You might wonder if this chapter is part of a government coverup on time travel. You might be right.

The anthropic principle says that the universe has to be more or less as we see it, because if it were different, there wouldn’t be anyone here to observe it.

The book's final chapter begins with this intriguing thought: do we live on a brane or are we just holograms? And it concludes by mentioning the Large Hadron Collider that was still under construction in Europe when the book came out in 2001. It may, Hawking says, help us learn whether or not we live on a brane:

If we do, it will presumably be because the anthropic principle picks out brane models from the vast zoo of universes allowed by M-theory. We could well paraphrase Miranda from Shakespeare's The Tempest:

O Brane new world
that has such creatures in't.

That is the universe in a nutshell.

A typical snazzy illustration: Could an advanced civilization build a time machine?