Report: First observation of gravitational waves

Today, the Laser Interferometry Gravitational-Wave Observatory (LIGO) reported the first observation of gravitational waves. You can read about it in The New York Times (warning: autoplay) or on Sean Carroll’s blog.  (ETA: also see the explanation in comic form.) I went straight to Physical Review Letters.

As an undergrad, I did some work on LIGO. Specifically, I was a data analyst looking for exactly the kinds of gravitational waves here observed. Anyway, I’m happy to play the role of your local expert, providing some context and answering any questions.

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You are the center of the universe

People have been asking me: “If the Big Bang began at a some point in space, then what–”

Hold it!  The Big Bang did not begin at any point in space.  The Big Bang is everywhere, it has no center.  The standard analogy is that space is like the surface of an expanding balloon, and as you can see a balloon has no center on its surface.

big bang balloonImage from “Misconceptions About the Big Bang“, which incidentally is a really good article.

People find this confusing though, since balloons do have centers (not on their surface).  Scientists also say that the universe as we know it used to be the size of a grapefruit.  Doesn’t a grapefruit have a center?  Well you got me there.  So where’s the center of the universe?

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In defense of circles

In the comments, I had a discussion on the structure of knowledge.  There are two general points of view.  The first point of view, called foundationalism, is that knowledge starts with a few basic principles, upon which the rest of knowledge is built.  The second point of view, called coherentism, is that knowledge is structured like a web, with inferences going in every direction.

This is a long-standing philosophical question, and you can read superior accounts from more authoritative sources.

Both coherentism and foundationalism have features which should raise eyebrows among critical thinkers.  Namely, foundationalism involves believing its foundations without evidence or reason.  Coherentism involves circular reasoning.

The Stanford Encyclopedia of Philosophy observes that coherentists typically defend their view by attacking foundationalism.  Here I will instead mount a positive defense of coherentism by arguing for the virtues of circular reasoning. Continue reading