In my note on Filippenko and Smoot I wrote that I did not explain myself well to Alex. Here is what Alex understood.
"In Mexico, when you mentioned that intermediate-mass black holes might produce the acceleration, I was skeptical. I still am, after looking up some references. Black holes are gravitationally attractive, not repulsive. Their entropy is *not* the entropy associated with some putative holographic membrane at the boundary of our observable universe, or anything like that. Moreover, large numbers of intermediate-black holes have *not* been found. Such black holes, even if they exist, could *not* be extremely numerous if they formed from stars or normal matter, because quite independent arguments (based on primordial nucleosynthesis, and independently the CMB fluctuation power spectrum) suggest that the amount of *baryonic* dark matter in the Universe is only about 4% of the total matter/energy content of the Universe. Thus, Frampton has to postulate that such black holes formed in the first few moments after the birth of the Universe... but this can probably happen only if there are two episodes of early inflation, not one. This is quite unlikely, making the existence of such black holes improbable. For a much earlier suggestion of this sort, see P. Ivanov et al. "Inflation and primordial black holes as dark matter" Phys. Rev. D 50, 7173–7178 (1994). "
I should have been more clear.
At that time I hadn't sudied Frampton's proposal, I had read only one of his papers. When I followed the Entropic paradigm, I saw that he had something to say: you can read his two papers with Easson and Smoot.
I still do not know if he is right, but I do not believe that black holes explain the acceleration, as Alex points out in his e-mail, they only attract. The proposal now is, that we may not need dark energy if some of this hullabaloo about entropy is correct.
I checked Prof. Smoot paper today. It is still there; so it was not an April Fool's joke, as I was starting to think.
We are closer to a Quantum Theory of Gravity now. Many names will be in the credits. Maybe the oldest reference for this excitement is Ted Jacobson, it seems that he started the whole thing; people that know him tell me he is smart.
"In Mexico, when you mentioned that intermediate-mass black holes might produce the acceleration, I was skeptical. I still am, after looking up some references. Black holes are gravitationally attractive, not repulsive. Their entropy is *not* the entropy associated with some putative holographic membrane at the boundary of our observable universe, or anything like that. Moreover, large numbers of intermediate-black holes have *not* been found. Such black holes, even if they exist, could *not* be extremely numerous if they formed from stars or normal matter, because quite independent arguments (based on primordial nucleosynthesis, and independently the CMB fluctuation power spectrum) suggest that the amount of *baryonic* dark matter in the Universe is only about 4% of the total matter/energy content of the Universe. Thus, Frampton has to postulate that such black holes formed in the first few moments after the birth of the Universe... but this can probably happen only if there are two episodes of early inflation, not one. This is quite unlikely, making the existence of such black holes improbable. For a much earlier suggestion of this sort, see P. Ivanov et al. "Inflation and primordial black holes as dark matter" Phys. Rev. D 50, 7173–7178 (1994). "
I should have been more clear.
At that time I hadn't sudied Frampton's proposal, I had read only one of his papers. When I followed the Entropic paradigm, I saw that he had something to say: you can read his two papers with Easson and Smoot.
I still do not know if he is right, but I do not believe that black holes explain the acceleration, as Alex points out in his e-mail, they only attract. The proposal now is, that we may not need dark energy if some of this hullabaloo about entropy is correct.
I checked Prof. Smoot paper today. It is still there; so it was not an April Fool's joke, as I was starting to think.
We are closer to a Quantum Theory of Gravity now. Many names will be in the credits. Maybe the oldest reference for this excitement is Ted Jacobson, it seems that he started the whole thing; people that know him tell me he is smart.
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