The view (of the Universe) from Benasque
August is a slack season for research in southern Europe. The stagnant heat makes it difficult to sleep -even on the job, and the tony crowd heads for the mountains.
This August a conference held in the town of Benasque on the Spanish Pyrenees on Cosmology, Inflation and the CMB packed in the glitterati, not least because these subjects are hot.
Mukhanov one of the pioneers of the idea that- perturbations of the zero-point energy amplified during the exponential expansion of the universe (inflation) are responsible for the formation of structure in the universe - claimed quite forcefully that now could be proved as some sort of a mathematical theorem that quantum-gravity fluctuations need an exponential expansion to have observational consequences. I wanted to ask him why everyone blindly assumes that quantum qravity fluctuations have to be the source of structure formation in the universe. There is a well developed theory called "warm inflation" by Berera and co. where they show that thermal fluctuations during inflation can give rise to the type of perturbations which lead to formation of galaxies. So whether the primordial perturbations are of quantum or thermal origin is still an open question that should be decided by experiments. A similar question in foundational quantum mechanics -are the probabilities which we observe in quantum mechanics just classical probabilities associated with coarse graining over unobserved parameters - was resolved by a nifty experimental test proposed by John Bell (called Bell's inequality) and the experiments settled this question decisively in favour of quantum mechanics. A similar test is needed in cosmology which will enable experimentalists one day to
prove conclusively that the observed structure microwave anisotropy in the universe is of quantum mechanical origin or otherwise.
I wanted to ask Mukhanov all this but in the face of forceful authority I just nodded meekly while MEGO (My Eyes Glazed Over).
Dick Bond the guru of CMB data analysis informed the unwashed masses that the cognoscenti have jetissoned the frequentist interpretation of probabilities and switched to the Bayesian philosophy in deciding which theories fit best with experimental results. David Lyth, the grand old man of Inflation and cosmology who (literally) wrote the book, asked if this was an intermediate step when one is trying to test a large number of unmotivated theories on the basis of preliminary experimental data, and once we have a well founded theory it should be easy to check if its predictions pass through the experimental data points in the old fashioned way. The answer he got in return was a earful of statistical noise.
And finally here's a calm view of the universe from Benasque.
This August a conference held in the town of Benasque on the Spanish Pyrenees on Cosmology, Inflation and the CMB packed in the glitterati, not least because these subjects are hot.
Mukhanov one of the pioneers of the idea that- perturbations of the zero-point energy amplified during the exponential expansion of the universe (inflation) are responsible for the formation of structure in the universe - claimed quite forcefully that now could be proved as some sort of a mathematical theorem that quantum-gravity fluctuations need an exponential expansion to have observational consequences. I wanted to ask him why everyone blindly assumes that quantum qravity fluctuations have to be the source of structure formation in the universe. There is a well developed theory called "warm inflation" by Berera and co. where they show that thermal fluctuations during inflation can give rise to the type of perturbations which lead to formation of galaxies. So whether the primordial perturbations are of quantum or thermal origin is still an open question that should be decided by experiments. A similar question in foundational quantum mechanics -are the probabilities which we observe in quantum mechanics just classical probabilities associated with coarse graining over unobserved parameters - was resolved by a nifty experimental test proposed by John Bell (called Bell's inequality) and the experiments settled this question decisively in favour of quantum mechanics. A similar test is needed in cosmology which will enable experimentalists one day to
prove conclusively that the observed structure microwave anisotropy in the universe is of quantum mechanical origin or otherwise.
I wanted to ask Mukhanov all this but in the face of forceful authority I just nodded meekly while MEGO (My Eyes Glazed Over).
Dick Bond the guru of CMB data analysis informed the unwashed masses that the cognoscenti have jetissoned the frequentist interpretation of probabilities and switched to the Bayesian philosophy in deciding which theories fit best with experimental results. David Lyth, the grand old man of Inflation and cosmology who (literally) wrote the book, asked if this was an intermediate step when one is trying to test a large number of unmotivated theories on the basis of preliminary experimental data, and once we have a well founded theory it should be easy to check if its predictions pass through the experimental data points in the old fashioned way. The answer he got in return was a earful of statistical noise.
And finally here's a calm view of the universe from Benasque.
posted by Subhendra at 12:38 AM
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