Thursday, March 21, 2013
A Map of Physics-Land, Circa 1939
Three-quarters of a century ago, this map of physics was published, its "rivers" leading from ancient Greek philosophers through to nineteenth- and twentieth-century scientists. You can find Faraday where the Electricity river joins with the Magnetism river to become Electomagnetic, because he's the prime figure in realizing those two forces are actually one and the same. Maxwell is at the junction of Light, Electromagnetic, and Mechanical into a sound labeled "Energy." Out there at the edge, Einstein and Dirac gaze out into the past future of physics.
Standing now this much farther down the river, we can see that the "Weak Force" river must have joined with "Electromagnetic" in the 70's to form the "Electroweak" river, with Salam, Glashow and Weinberg nearby.
Past that it's hard to plot history on the map. Grand unification of strong with electroweak, and of gravity with the other three, is somewhere out there, if theories check out. But they haven't, not yet.
How do we tell when we've passed from a river into a directionless swamp? Is that what String Theory is? All we have is a very nice map, but I haven't heard of any experiments yet that would confirm the reality of String Theory's extreme elegance. Multiverse theory seems to have broadened into more of a sea without direction than a river.
Apparently we found the Higgs, right where it should be. Because it was where it should be it looks like our maps have no problems with them. I can see why many physicists seem slightly disappointed with this. Where do we go next? Onward and upward to higher energies. What do we do with ourselves if our theories are perfectly right?
It's fascinating how different the physics world looks in 2013 as opposed to 1939. The first half of the twentieth century may end up being a time of discovery like no other, with a discoverer (Einstein) like no other.