Inflation happens and life goes on; we must simply live with it. But now we’ve been told the proton is smaller than it once was believed to be. How does one live with that? It all began with a particle called a muon. A muon resembles an electron in significant ways. It is classified a lepton. That means simply that it is a light particle, not a heavy particle. It has a spin identical to that of an electron, and it has the negative charge of an electron. So in some sense a muon should be interchangeable with an electron. Bring on the hydrogen atom.
A hydrogen atom – what one might call an ordinary hydrogen atom – consists of a single proton center or nucleus and a single electron traveling about the proton in a an orbit shaped like a sphere or ball. This isn’t hard to visualize. The hydrogen atom thus described is very stable. Yes, there also exists deuterium (hydrogen with one neutron in the nucleus next to the proton) and tritium (hydrogen with two neutrons in the nucleus), but by far the most common form of hydrogen has no neutrons, and it is nicknamed protium.
Keeping that atom of hydrogen in mind, imagine, now, you are about to begin a game of pool (“Eight Ball”) with a friend in his or her basement. First the fifteen balls are racked, and then the chosen individual-you-“breaks” the pack of balls with the first shot. Smack! The eight ball, you will recall, is in the center of the pack, like a neutron is in the center of our hydrogen atom. The pack is broken, and the outer balls are scattered. Now imagine you have, instead of a rack of balls on a pool table, a single hydrogen atom. You shoot at the atom, not with a cue ball, but with a muon particle. It sends the electron flying, and in its place, the muon remains behind and enters into orbit about the proton.
In the above illustration, what you’ve done is to create an atom of what could be called “muon hydrogen.” You have a proton at the center or nucleus, and a single muon in orbit about it. Now a muon weighs about 200 times as much as an electron-strange hydrogen, indeed! Now the catch is, the muon lasts only about 2.2 millionths of a second. So muon hydrogen lives for only a very short time. Short or not, though, it is enough time for the physicist to make some very important measurements and deductions. The increased mass of a muon over an electron means the size of the proton can be more accurately measured. What was the result? Nature News informs us, “Using lasers, the [Max Planck quantum scientists] measured… with extremely high accuracy and found… the proton was… smaller than previously thought.”
The Proton – a New Look
Using this very technique, a team of quantum physicists headed by Randolf Pohl determined that the proton is about four percent smaller than was previously thought. This could have serious implications, and will require some rethinking on the part of theoreticians. What are the implications for quantum physics? Among other things, many keystone constants could need readjustment. What new ideas and concepts will be developed to explain such a drastic difference in an established constant? Time is the great revealer of secrets.
References and Resources:
Nature News – “The proton shrinks in size,” by Geoff Brumfiel (Accessed August 2010)
Chemical & Engineering News – “Sizing the Proton,” by Jyllian N. Kemsley (Accessed August 2010)