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Big Physics News: The Proton is Small(er)!

July 10, 2010 2 comments

Its not very often that a fundamental measurement in physics gets changed. But that is exactly whats happened this week.

The radius of the proton, one of the fundamental building blocks of matter, has just been re-measured to a very high degree of accuracy. The surprising thing, though, is that this measurement says the proton is about 4% smaller than we previously thought.

To put a number on that, it makes the proton 0.00000000000003 millimeters smaller than we thought before. (For the statistically inclined, this is 5 standard deviations different than the current accepted CODTA value of the proton radius. Meaning, its pretty significant.)

So big deal, right?

Well it really IS a big deal! (Using the word ‘big’ to talk about nuclear physics seems strange to me, but whatever…)

“Something is missing, this is very clear,” said Carl Carlson, a theoretical physicist at the College of William & Mary in Williamsburg, Va.

Yes, his name is ACTUALLY Carl Carlson. Awesome.

The entire Standard Model of physics, the primary theory which describes particle interactions, could be totally shaken up by this new finding. At the nuclear scale, the strength of the electromagnetic, strong and weak nuclear forces vary extremely quickly. A 4% change in the radius of the proton can really throw the equations out of whack (excuse my technical terminology).

This is why science is great. Any day of the week the entire system can get shook up. One of the coolest things about science is that it is inherently self correcting. Different groups are always checking each others measurements and looking for mistakes. I love science!