Well, it is. But the Proton “got smaller” just now. And, by “got smaller” I mean that the accepted measurement of the proton has been adjusted slightly. The new measurement for the proton’s diameter is about 0.00000000000003 mm (0.03 femtometers less than it was before. This is important:
“It’s a very serious discrepancy,” says Ingo Sick, a physicist at the University of Basel in Switzerland, who has tried to reconcile the finding with four decades of previous measurements. “There is really something seriously wrong someplace.”
The difference between the old and new measurement is actually a whopping 4 percent or so. The old measurement was based on the behavior of an electron associated with a single proton. The electron “orbits” the proton in a specific way, and observation of this behavior accurately predict the proton’s weight.
The new measurement uses a muon, ticked into orbiting the proton by firing muons at high speed at a cloud of hydrogen. Hydrogen, as you know, has one proton and one electron. Sometimes the muon fired at the hydrogen associated, electron-like, with a proton.
Muons are way bigger than electrons, which apparently matters, making muons more accurate than electrons. So, although the proton size measurement has been done several times with the electron, this new measurement carries some extra cred because it is a measurement made with muons.
“Something is missing, this is very clear,” agrees Carl Carlson, a theoretical physicist at the College of William & Mary in Williamsburg, Virginia. The most intriguing possibility is that previously undetected particles are changing the interaction of the muon and the proton. Such particles could be the ‘superpartners’ of existing particles, as predicted by a theory known as supersymmetry, which seeks to unite all of the fundamental forces of physics, except gravity.
The possibility that an error was made has not been ruled out.
Original paper: Pohl, R. et al. Nature 466, 213-217
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0.00000000000003 what Greg? Units!
Femtometers are the units. 🙂
Oh, sorry … right, I meant to put that in, was checking the spelling on it, then saw something shiny. Fixing it now.
Shouldn’t that be 0.035 femtometers?
0.87680
– 0.84184
———-
0.03496
The size is small but the percentage is HUGE. This could have implications on weak and strong force and all those other atomic measures. I’m waiting for a confirmation before I sell the house and move to a better understood universe.
Maybe it will make “dark matter” go away.
@Tom S.
Wouldn’t that be nice. Messy stuff, dark matter.
My last atomic physics course was many years ago and I do not remember if the altered dimension of the proton would affect it’s mass but I do not think so.
Anyone else getting a chuckle out of the fact that Carl Carlson is one of Homer Simpson’s fellow nuclear plant employees? Lenny Leonard couldn’t be reached for comment I guess.
Something is wrong in Sector 7g!
The radius of the proton probably derives from the position uncertainty of the three quarks that move about inside it and is in a reciprocal relation of some sort to the momentum of the electronic or muonic atom. Then the smaller proton radius observed with the heavier muon results from the greater momentum of the muonic atom.