In the wake of the announcement of gravitational-wave signatures from inflation in the cosmic microwave background, I was invited to contribute a piece to The Stone section of the New York Times, on “naturalness” and how it’s used in physics. Mostly The Stone is devoted to philosophy, but occasionally they’ll let an outsider opine about a philosophical-sounding topic.
The hook is obviously the fact that inflation itself is motivated by naturalness:
Cosmic inflation is an extraordinary extrapolation. And it was motivated not by any direct contradiction between theory and experiment, but by the simple desire to have a more natural explanation for the conditions of the early universe. If these observations favoring inflation hold up — a big “if,” of course — it will represent an enormous triumph for reasoning based on the search for naturalness in physical explanations.
I conclude with:
Naturalness is a subtle criterion. In the case of inflationary cosmology, the drive to find a natural theory seems to have paid off handsomely, but perhaps other seemingly unnatural features of our world must simply be accepted. Ultimately it’s nature, not us, that decides what’s natural.
I like to capitalize “Nature,” but nobody agrees with me.
Leonard Susskind, the noted string theorist who, much like Murray Gell-mann, enjoys playing mind games with the most brilliant people he can find, has already stated that promoting the multiverse idea to see how far it would go was one of his many practical jokes, for the stated purpose of observing how gullible they are. April 1 is coming up; expect more of those.
I put this idea in the same category as science fiction, wormholes, the Casimir effect, and the Easter bunny. For those who think the Casimir effect is a real way to get cheap energy out of the vacuum, reflect that Work = Force x Distance moved. How much distance is there between those plates again? See what I mean? Practical joke. If you bought it, the joke’s on you. An awful lot of people also buy into the QCD practical joke that most of the mass of atoms derives of quark-gluon interaction when the quarks get their masses from the Higgs mechanism, and the gluons are massless. The same people also buy easily into the idea that the sigma field and the Higgs field are separate entities. Did no one notice how much trouble QCD math got into simply trying to predict the mass of the proton in 2005, even with the 24 “free parameters” (‘fudge factors’) they had to play with in order to finally get within 2% of the value experimentalists each an every time a proton gets smacked into another one? And so then you are going to listen to these people about the existence of glue balls?
Some people are gullible, all right.
The Big Bang is unnatural.
The polarization of the CMB is further evidence our Universe spins about a preferred axis.
Our universe is a larger version of a black hole polar jet.
The Big Ongoing is natural.
“Nature” is a proper noun, like “France”. I agree, should be capitalised.
Revolt! Insist on capitalizing Nature! Please.
Sean,
It seems to me that what is going on is that physicists are making modifications to fit our own personal view of what should be “natural,” but are making sure that those modification fit the realm of where the data is pointing. Not actually founded completly in the data, but more like one step ahead of that. I’m not saying that’s a bad thing, but it seems like a fine line to be walking. I’m just trying to understand how the physics world is working.