January 16th, 2011

Quantum mechanics is the physics of the smallest of things, while general relativity is the physics of the largest. Not surprisingly, many physicists have been obsessessed with finding a Theory of Everything (TOE) that encompasses both limits.

This has not been easy.

In previous posts I’ve written of the difficulties that arise in creating a coherent theory of quantum gravity, and how one popular approach, string theory, attempts to solve the problem. String theory is not a failure, but neither has it been the overwhelming success quantum mechanics and general relativity have been. In particular, string theory has in general failed to make verified predictions in fundamental particle physics. (NB: some of the mathematical techniques of string theory have been applied to other areas of physics, but this is not the same thing.)

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December 13th, 2010

A good public relations campaign can do wonders.

Science is empirical. If there is no experiment, no observation, then an idea is truly relegated to “it’s just a theory.” [1]

Yet, consider string theory, a mathematical exercise so intricate Einstein’s general relativity is easy in comparison, and with no experimental evidence backing it whatsoever.

In the popular imagination, however, string theory dominates modern physics. Popularizations of string theory have topped bestseller charts. Friends and neighbors ask me about string theory. Students tell me they want to be string theorists, even though they, along with most of the public, are unsure what string theory even is.

In this essay I’ll attempt to untangle string theory for you, explain what it’s good for, why there are such devoted proponents, and what the skeptics say. Read the rest of this entry »

November 22nd, 2010

You may have been in this situation:

You have two friends, your two *best* friends, both witty, fun, and thoughtful. An hour or so spent with either one leaves your brain buzzing with new ideas and insights. “I gotta get these two together,” you think.

You arrange a dinner, but the evening is a disaster. Your friends are incompatible in ways so deep, so fundamental, they can barely stand to be in the same room.

Now imagine your friends are physics theories; and not just any theories, but the two most revolutionary theories of the twentieth century, explaining entire libraries of data, predicting new, mind-blowing phenomena. They are quantum mechanics and general relativity.

And they do *not* play nice with each other.

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