David's Blague

New Scientist had a fun article last week, Seven questions that keep physicists up at night. I'm not sure why they didn't send them to me first, but better late than never. Here are my seven answers. Now the physicists can all go back to sleep (yes, Maggie, that means you). Without further ado...

Why this universe?

A good first question. You think about the universe the way you do because your distant ancestors needed to eat and breed. It's important to remember that the universe in our heads is not the same as the universe out there. Case in point: Euclidean geometry. For thousands of years, we assumed that the system of rules called Euclidean geometry had a very close correspondence to the way things work in the universe. A hundred years back, someone called that into question, and quite profitably came up with relativity.

Perhaps a more fair wording of the question would be, "Why am I thinking about this universe?" To that question, I propose a different answer: because you are. Now stop, and think about a different one, and see if you wake up there (since you're going to be able to sleep tonight, after all).

What is everything made of?

Softball. Everything is made of everything else. Strange, but true.

How does complexity happen?

Harder than the previous question, but I'm still not breaking a sweat. Interestingly, the answer to this question is tied up in the previous one, which, in turn, is tied up in La Monadologie. Leibniz nailed it: "there must be simple substances, since there are compounds; for a compound is nothing but a collection or aggregatum of simple things."

Complexity happens because simple things (he calls these simple things "monads", but there have been a number of names for them, I like Stephen Wolfram's "rules" for instance) combine. The combination of simple things yields something which can be perceived, and once perception happens at any scale, we assign a label to it: complexity. When we say something is complex, all we mean is that it consists of parts. It is divisible. If something consists of parts which are in turn complex themselves, we might say "very complex."

Since this answer begs a followup question, I'll throw in one for free. Parts combine when, and only when, they are perceived as a whole. Complexity arises from observation. QED.

Will string theory ever be proved correct?

STUPID FUCKING QUESTION.

Theories are not proved correct, theories are proved incorrect.

Come on, people, this is keeping you up?

What is the singularity?

Better question, still not great. A singularity is something singular. As opposed to, for instance, a plurality. As such, "the singularity" doesn't really have a frame of reference other than itself. In fact, in complex analysis (e.g. calculus), a singularity is just the point at which the function is undefined, or degenerate.

But leaving aside the technobabble and the sidestepping, I think I understand why this is keeping you up, and I can help.

A singularity is one of those things that is most easily explained by pointing at it and saying, "that's a singularity." In the case of The Singularity, there was presumably a point at which there was a Not A Universe, and it became A Universe. This one, presumably. However long that transition lasted, however it happened, you physicists would like to understand the mechanics of it.

Here's how I'm going to help. I'm going to answer a different question: 42.

What is reality really?

Now we're getting somewhere. Reality, as you may have already heard, is really a simulation, running on a computer, run by mice. And the dolphins are leaving. Seriously, this is one of those questions that probably ought to keep you up at night, but only one night per week. If my kids asked this question, I would say, "what do you think it is, pookie?"

How far can physics take us?

The bad news is, we're there. The good news is, we can happily invent something new, and call it physics, and everyone will still think physicists are smart. Unless what's keeping you up is actual space travel, at which point I want to tell you that you're thinking about EXACTLY THE RIGHT THINGS. How far can we go? How fast can we get there?

Get to work!