Tuesday, March 18, 2014

Gravitational Waves and Andrei Linde gets a surprise.

Yes the great gravitational wave breakthrough was as expected announced yesterday.  Stanford University Professor Andrei Linde, one of the founders of inflation theory, and his wife fellow Stanford Professor the string theorist Renata Kallosh got a surprise visit:

Assistant Professor Chao-Lin Kuo surprises Professor Andrei Linde with evidence that supports cosmic inflation theory. The discovery, made by Kuo and his colleagues at the BICEP2 experiment, represents the first images of gravitational waves, or ripples in space-time. These waves have been described as the "first tremors of the Big Bang."
The original paper published yesterday at 10:45 a.m. is here.

Linde's shock at the result... "5σ r=0.2", Linde says "0.2!" in surprise.

It is surprising . The article on arXiv concludes:
Subtracting the various dust models and re-deriving the r
constraint still results in high significance of detection. For
the model which is perhaps the most likely to be close to re-
ality (DDM2 cross) the maximum likelihood value shifts to
r = 0.16 +0.06 −0.05 with r = 0 disfavored at 5.9σ. These high
values of r are in apparent tension with previous indirect limits
based on temperature measurements and we have discussed
some possible resolutions including modifications of the ini-
tial scalar perturbation spectrum such as running. However
we emphasize that we do not claim to know what the resolu-
tion is.
They are saying that their value of r which is the ratio of the tensor polarization from gravitational waves to the scalar polarization from the inflaton field, after correction for the effects of gravitational lensing, is incompatible with with the indirect limits established by satellite temperature measurements. From this r = 0.2 is surprisingly high.

These incompatibilities  need to be ironed out before this result is fully accepted.  This is just a
note of caution.  Lets hope everything is fine and we have witnessed a scientific revolution as big as that introduced by the CMB anisotropy results and the birth of precision cosmology.

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