[Ayudantes2] Premio Nobel 2004

[Secretaria Academica - Departamento de Fisica]

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.




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