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visits member for 3 years, 5 months
seen Mar 3 at 21:09

PhD student in CompBio. Also interested in Math, ML, and Optimization


Aug
23
awarded  Commentator
Aug
23
comment Bekenstein bound and the early universe
Ok. I vote to close my question then.
Aug
23
comment Bekenstein bound and the early universe
I was confused about the concept of entropy which is why I acknowledged that question as answering my question. I was mistakenly assuming that the high entropy of black holes today implied a high entropy right after the big bang.
Aug
23
revised Bekenstein bound and the early universe
added 204 characters in body
Aug
23
revised Bekenstein bound and the early universe
added 54 characters in body
Aug
23
comment Bekenstein bound and the early universe
If the a 10 mile diameter black hole was compressed in a 1 cm diameter sphere, why couldn't we speak of the entropy of that sphere? Similarly, all matter in the universe today including black holes were once compressed into a very tiny volume right after the big bang (as far as I understand). So why doesn't it make sense to speak of the entropy of that small volume?
Aug
23
revised Bekenstein bound and the early universe
added 39 characters in body
Aug
23
comment Bekenstein bound and the early universe
By "after the expansion", I meant after the universe had expanded enough -- for the purposes of this question, let's say it means at present time. "the planck/speed of light constants changed" -- because the bekenstein bound depends on those. If those have changed since the big bang, then so should the bound?
Aug
23
revised Bekenstein bound and the early universe
edited tags
Aug
23
revised Bekenstein bound and the early universe
added 74 characters in body
Aug
23
revised Bekenstein bound and the early universe
added 51 characters in body
Aug
23
asked Bekenstein bound and the early universe
Feb
27
comment In-flight damage to a supersonic jet
I think the pilots wear masks because a supersonic military jet is not pressurized. A conventional airliner could theoretically match that speed I guess by plunging down from a high altitude... Don't know if any modern plane would survive the stress though.
Dec
23
comment Why can't airplanes just keep going up?
Eventually, the oxygen will deplete so much that keeping the jet engine running will be impossible. Not to mention, the lift will decrease as the air thins out. This happens much sooner than the altitude of for instance the ISS.
Nov
5
comment Why don't experimental physics groups have statisticians in it?
@Ron: In the video, Michael Jordan gives a mathematical formulation of both approaches and illustrates via that where one approach might be preferable vs. the other. Finding a good prior is not always feasible especially in an automated setting. In many cases in fact, it's almost impossible. A bayesian approach cannot do well under those circumstances.
Nov
4
comment Why don't experimental physics groups have statisticians in it?
@Ron: I'm aware of that controversy. What I meant was I've never encountered an attitude of insisting on the use of frequentist methods for a practical application when the prior is known. There are good reasons to not use a Bayesian approach in many cases - for a description of when a frequentist approach might make sense, you could check out this lecture videolectures.net/mlss09uk_jordan_bfway/ by Michael Jordan. The problem of inference at any rate is certainly not trivial as you imply and the Bayesian appproach is not always the answer.
Nov
3
comment Why don't experimental physics groups have statisticians in it?
@Ron: I've never encountered this attitude. Can you point me to some reasonably cited papers which try to solve a problem that would easily be solved via an application of Bayes' theorem but the authors don't use it for philosophical reasons?
Nov
3
comment Why don't experimental physics groups have statisticians in it?
I've no idea what you're talking about. The hard part about inference is that we don't know the underlying probability distribution of y. And even if we did, finding the best values for the parameters x is extremely hard - in fact I'm pretty sure it's NP-hard. Bayes theorem is used extensively.
Sep
26
awarded  Scholar
Sep
26
accepted The Opera Neutrino Experiment and the Supernova 1987