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Exploring Superstrings in the Lab
ultracool writes "Physicists at Utrecht University in the Netherlands have come up with a way of observing a superstring by utilizing Bose-Einstein condensation (BEC). A one-dimensional BEC in an optical lattice is rapidly rotated, causing a quantized vortex to form. The bosonic part of the superstring consists of this vortex line. Inside the vortex, they would trap an ultracold cloud of fermionic atoms. Hopefully this will allow observation of the supersymmetry between bosons and fermions, thus providing the first experimental evidence to support superstring theory."
A more detailed explanation of http://en.wikipedia.org/wiki/Superstringssuperstri ngs.
...to refer people to more information on Bose-Einstein condensates (BEC):
BEC wikipedia page
BEC home page at Colorado
BEC at NIST
What is a BEC?
this is the first experiment that could confirm the existence or non existance of super strings. This would begin to give emperical evidence to support String Theory. up until now most work on String Theory has been unable to provide a working way to test it. this could easily change the face of theoretical physics in the labs and particle accelerators.
Witten said that proving supersymmetry would be helpful in understanding string theory. From what I understand supersymmetry down the road implies string theory. So if supersymmetry is disproved by implication so is string theory. However if supersymmetry is proved is does not prove string theory. But rather add towards understanding and maybe later proving string theory.
but IANAST.
The best education consists in immunizing people against systematic attempts at education. - Paul Feyerabend
I'm also not a string theorist, but I believe that (string theory) + (supersymmetry) = (superstrings). This seems to be an attempt to construct a condensed matter analog of the superstring theory that could underly particle physics. In other words, it's an analog that doesn't necessarily mean that superstrings are or are not the underlying fundamental theory of physics.
Now, for the reason: if you know some quantum physics, think of taking two composite objects and interchanging them; fermions wavefunctions change sign under this interchange. For the composite object, its wavefunction looks like (an anti-symmetrized) product of single-particle wavefunctions. If those are fermionic and there are an odd number of them in the composite wave function, interchanging the two composite wavefunctions will produce an odd number of sign changes in the product, for an overlal sign change. If there are instead an even number of fermionic single-particle wavefunctions in the composite wavefunction, the resulting even number of sign changes under interchange produces no net sign change in the many-body wavefunction.
This is easily extended to composite objects that are a composite of both bosons and fermions.
http://www.pbs.org/wgbh/nova/elegant/program.html
All 3 hours of it are avaliable on PBS's website.
It's amazing stuff.
The book "The Elegant Universe" by Brain Greene is what the TV Special above is based on.
Definitly worth a look at - if you enjoy the TV special, have a look around for the book... It goes into a LOT more detail.
"Who says nothing is impossible? Some people do it every day!" - Alfred E. Neuman
So what's the definition of a fermion or a boson, and in this specific case, of a fermionic or bosonic nucleus?
Bosons have integer spin, and fermions have half-integer (n+1/2, where n is a nonnegative integer) spin. The spins of the individual quarks in nucleons (protons and neutrons) always add up to a half-integer, so nucleons are fermions. The quarks themselves are too. The spins of the nucleons in a nucleus can add up in different ways, depending on the number of each kind (proton and neutron) present. When the spins add to become an integer, the nucleus is bosonic. When the spins add to a half-integer, the nucleus is fermionic.
If a given nucleus is fermionic, then identical nuclei of that type obey the Pauli exclusion principle. If the nucleus is bosonic, then the Pauli exclusion principle does not apply to it, and the possibility of a collection of that kind of nucleus forming a BEC exists.
"It is nice to know that the computer understands the problem. But I would like to understand it too." --Eugene Wigner
So this is very cool (literally!) science, but NOT a test of superstring theory as a way to describe fundamental particles or interactions. At best, it will provide some interesting checks of the mathematical predictions of string-like theories, but only translated into this system. You still won't know if string theory has any hope of describing real electrons, photons, gravitons, etc.