- News Home
17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Freeing Up the Strong Force
5 October 2004 (All day)
It might be fun to blow things up, but if you want to win a Nobel Prize in physics, perhaps it's wiser to keep things--especially equations--from blowing up. That's what this year's winners did to win the plaudits of their colleagues.
The three new laureates, Frank Wilczek, David Gross, and H. David Politzer, discovered a property of the strong force--the force that glues quarks to each other--known as "asymptotic freedom." Not only did the idea explain some baffling experimental results in particle colliders, it also showed how to keep the equations that describe the strong force from blowing up--producing meaningless infinities in certain situations.
Particle physics is swimming with scenarios in which the equations that describe the behavior of a particle seem to explode. For example, the plain-vanilla equations of the Standard Model say, strictly speaking, that the charge of the bare electron is infinite; as you approach the electron, the measured charge increases without bound. Researchers have developed mathematical tools to keep their theories from being derailed by this type of infinity.
In the early 1970s, physicists studying the strong force were beating their heads against a similar problem. The infinity-coping techniques developed for the electric force (and for the weak force, which is responsible for phenomena such as nuclear decay) didn't work for the strong force. In 1973, Politzer, currently at the California Institute of Technology, and, separately, Wilczek, at the Massachusetts Institute of Technology, and Gross, at the Kavli Institute for Theoretical Physics, realized the problem: Unlike the other forces, the strong force is weaker at close range.
Stick a particle right next to a quark and it wouldn't feel the strong force at all; it would be "asymptotically free" from the strong force, and quarks forced into close proximity would behave more or less like hard particles rather than a sticky clump. This is precisely what experimentalists had found a few years earlier at the Stanford Linear Accelerator Center by scattering electrons off of protons. Turning around the logic of asymptotic freedom explains why quarks are never found roaming free from each other: At large distances and low temperatures, the strong force is too powerful to overcome.
"They made the discovery and saw the significance of it," says Niels Kjaer Nielsen, a physicist at the University of Southern Denmark in Odense. "[The prize] is fully deserved." And although Wilczek admits that he expected the prize at some point, today's early-morning phone call from the Royal Academy caught him off guard. In fact, he was right out of the shower, dripping wet and naked. "It was a bit uncomfortable talking to one Swede after another," in that condition, he says.