## 2013 in review

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A San Francisco cable car holds 60 people. This blog was viewed about **2,100** times in 2013. If it were a cable car, it would take about 35 trips to carry that many people.

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## Comments

Dear Dr Mitra, This is a fascinating blog. I first heard about you several years back when you were in the news for your anti-mainstream views. I am glad to see that you are still active in research and that you have published your work in leading physics journals. I would like to know what your opinion is on the latest claims of Stephen Hawking reported in the press, namely, “black holes do not exist”. They seem to be somewhat similar to what you have been saying all along, although I am no expert in this area. Best regards.

Dear Friend,

Hawking’s preprint is a loose essay, no calculation, no math, hardly any theory. It is confusing, convoluted. In contrast, my research is exact, precise, published in almost 10 papers (2000-13). Since i am no Hawking, my papers went though cruel reviewing. Had i sent the present Hawking like manuscript to any respectable journal, editors would have returned it without review. My posting to net would have been called “cranky”. Yet he is “one of the greatest theoretical physicists” and i am an unknown indian physicist!

Hello Dr. Mitra, I am writing this reply because what seems to be new theory that denies the existence of black holes. I am referring to the paper “Back-reaction of the Hawking radiation flux on a gravitationally collapsing star II: Fireworks instead of firewalls” by Mersini-Houghton and Pfeiffer, which appeared in arXiv. While I am no expert to analyze this paper, its conclusions seem clear as quoted below: “The star never crosses its horizon, so neither unitarity nor causality are violated, thereby solving the longstanding information loss paradox. This investigation shows that universally collapsing stars bounce into an expanding phase and probably blow up, instead of collapsing to a black hole.” From my understanding of your work, you claim from purely theoretical considerations that black holes do not form because the collapse phase is eternal, that is, takes infinite time. This seems to contradict the conclusions of Mersini-Houghton et al which are arrived at by numerical calculatoins. I also note that they do not cite your work which is published in leading physics journals, This is an unfortunate tendency amongst the Western scientists, it seems, when they encounter original work from third-world scientists that contradicts their beliefs.

Dear Dr. Mitra, I have a couple of questions/comments on the arXiv paper of Mersini-Houghton and Pfeiffer (M-HP). Of course, I am not a theoretical physicist, but I do have some basic knowledge of physics, mathematics and logic, to be able to understand that their claims are anything but rigorous. Briefly, let me state my points in order.

1. In Sec. II A (“Choice of the energy conversion rate C”) they choose, via their equation 18, a “scenario where the luminosity at infinity is equal to the expected Hawking radiation”. Does this choice presuppose the formation of an event horizon, which does not occur in this scenario? In the concluding remarks of your Pramana paper “Quantum information paradox: real or fictitious?” you state that “Since there is no exact BH, no Event Horizon, there is no Hawking Radiation and Quantum Information Paradox.” So you would seem to disagree with the choice of boundary condition in Eq. (18) of M-HP, which is crucial for their conclusions.

2. For the sake of argument, let us grant MH-P their equation (18) as boundary condition. According to their conclusion, “Physically the backreaction of ingoing negative energy Hawking radiation reduces the gravitational binding energy in the star with the maximum loss near the last stages of collapse, while taking momentum away from the star. This is the reason for the universal feature of the explosion in the star instead of its collapse to a black hole singularity.” Again granting that the star does expand (to a radius much greater than its Schwarzschild radius) due to the Hawking radiation, at some point during the expansion, should we not expect that the Hawking radiation again becomes insignificant, as was the the case initially in their scenario? Since they claim that it is the Hawking radiation that is responsible for the expansion, then why shouldn’t we expect the star to revert back to the gravitational collapse state? Maybe I am asking a wrong question here due to my limited knowledge of black hole physics. But it seems to me that they have not even come close to establishing that a final “explosion” occurs during the expansion phase, since their numerical code breaks down during this phase (by their own admission).

3. An interesting aside: M-HP’s list of references does contain Hawking’s most recent arXiv preprint which you refer to as a “loose essay” in your comment above. I was curious to know what M-HP had to say about this preprint, but strangely, they have not referred to it at all in the text of their paper! Maybe an oversight, or is it deliberate?

Best regards.

Dear Dr Srinivasan, Thank you very much your query. Allow me few days for due response. Regards