Wednesday, June 27, 2007

CV reviews the mutual constraints of cosmology and particle physics

A delightful post for amateur physics junkies: Constraints and Signatures in Particle Cosmology | Cosmic Variance. CV reviews the constraints cosmology places on modeling particle physics, and conversely suggests some cosmologic puzzles that might inspire new particle physics. This one was knew to me:

... There are a number of hints that the highest energy cosmic rays may require exotic new physics for a complete understanding. Above a certain energy (the Greisen-Zatsepin-Kuzmin (GZK) cutoff), particles from cosmological distances shouldn’t reach us at all, because they would scatter off the CMB. This has led people to speculate that any ultra high-energy cosmic rays (UHECRs) may be a signature of new particle physics. Does your theory contain any particles or phenomena that could allow this to happen, and what spectrum of UHECRs should we expect? Some of those topological defects I mentioned above may be an example...

"Topological defects". A rather significant hint I'd say. Mark is referring to:

... Does your theory contain any new topological defects, such as monopoles, domain walls or cosmic strings? If the vacuum structure of your particle physics theory is sufficiently topologically complex, then any symmetry breakings that occur may lead to trapped regions of false vacuum that cannot decay. If so, then many of the constraints mentioned for long-lived elementary particles may apply to these objects. In addition, some topological defects can form networks that redshift more slowly then matter, coming to dominate at a later time in the universe, or can generate a spectrum of gravitational radiation that is in conflict with our detailed measurements of the timing of the millisecond pulsar. If this last constraint is a problem, then it is also possible that the defects unacceptably distort the spectrum of the Cosmic Microwave Background radiation (CMB)...

Keep your eyes open for wandering wrinkles in space-time. Should you happen upon one, email Mark at "once" ...

2 comments:

Unknown said...

Hi,
Have you looked at what Neil Turok has to say recently? He has an interview posted over at edge.org.

JGF said...

I think you mean this one:

http://www.edge.org/documents/archive/edge210.html#turok2

I've another post pending on something that might fit with the Turok interview, so I'll try to tie them together and back to here ...