[Depfis] Premio Nobel 2004

[deflo en df.uba.ar]

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in 
Physics for 2004 "for the discovery of asymptotic freedom in the theory of the 
strong interaction" jointly to

David J. Gross
Kavli Institute for Theoretical Physics, University of California, Santa 
Barbara, USA, 

H. David Politzer
California Institute of Technology (Caltech), Pasadena, USA, and

Frank Wilczek
Massachusetts Institute of Technology (MIT), Cambridge, USA. 

 

A 'colourful' discovery in the world of quarks
What are the smallest building blocks in Nature? How do these particles build 
up everything we see around us? What forces act in Nature and how do they 
actually function?

This year's Nobel Prize in Physics deals with these fundamental questions, 
problems that occupied physicists throughout the 20th century and still 
challenge both theoreticians and experimentalists working at the major 
particle accelerators.

David Gross, David Politzer and Frank Wilczek have made an important 
theoretical discovery concerning the strong force, or the 'colour force' as it 
is also called. The strong force is the one that is dominant in the atomic 
nucleus, acting between the quarks inside the proton and the neutron. What 
this year's Laureates discovered was something that, at first sight, seemed 
completely contradictory. The interpretation of their mathematical result was 
that the closer the quarks are to each other, the weaker is the 'colour 
charge'. When the quarks are really close to each other, the force is so weak 
that they behave almost as free particles. This phenomenon is 
called ”asymptotic freedom”. The converse is true when the quarks move apart: 
the force becomes stronger when the distance increases. This property may be 
compared to a rubber band. The more the band is stretched, the stronger the 
force.

This discovery was expressed in 1973 in an elegant mathematical framework that 
led to a completely new theory, Quantum ChromoDynamics, QCD. This theory was 
an important contribution to the Standard Model, the theory that describes all 
physics connected with the electromagnetic force (which acts between charged 
particles), the weak force (which is important for the sun's energy 
production) and the strong force (which acts between quarks). With the aid of 
QCD physicists can at last explain why quarks only behave as free particles at 
extremely high energies. In the proton and the neutron they always occur in 
triplets.

Thanks to their discovery, David Gross, David Politzer and Frank Wilczek have 
brought physics one step closer to fulfilling a grand dream, to formulate a 
unified theory comprising gravity as well – a theory for everything.