3 ms·

Is there a source you would recommend for further elaboration and exploration of this model?

by tofof 2y ago

jiggawatts 2y ago
One good paper is this one: https://arxiv.org/pdf/1907.04879 https://arxiv.org/pdf/1907.04879 Generally you can search for finite black holes and read things written in the last half a decade or so.
- raattgift 2y ago
  From the very top of the second page of that "One good paper": Can a BH form in a finite time as viewed by a distant observer? (Answer: Yes.) From your comment you appear to believe that preprint supports (emphasis yours): It hasn't finished forming because as its gravitational field increases its time distortion increases. Its formation is "frozen in time" (actually just very very slow), *it is never fully formed.* and you also write: If there is a paradox in your model, then your model is broken, end of story. Finally you write "relativity does not allow observers to disagree on observations of what" and also "Hawking showed that they evaporate in a finite time." Static and non-static observers in general curved spacetimes immersed in relativistic QFTs generically disagree on particle counts. The Unruh, Hartle-Hawking, Rindler, Minkowski and Boulware vacuums seem especially apposite search terms for someone who isn't among "the slow people at the back of the class". (Ginzburg & Frolov 1987 is a good starting point: https://iopscience.iop.org/article/10.1070/PU1987v030n12ABEH003071/pdf https://iopscience.iop.org/article/10.1070/PU1987v030n12ABEH... (one can also stick "sci-hub.se/" in front of the URL). It is cited a lot <https://scholar.google.co.uk/scholar?cites=12518697499517381912&as_sdt=2005&sciodt=0,5&hl=en https://scholar.google.co.uk/scholar?cites=12518697499517381...>).
  - jiggawatts 2y ago
    Keep reading to the end: "Moreover, even without invoking nonsingular models, it’s not clear that rotating or charged BHs form an event horizon at all when evaporation is taken into account." Even this paper using modern (2024-era) numerical methods struggles to model the complexities of physically realistic black holes, and ends with a "... more research needed" at the end. > Ginzburg & Frolov 1987 That was 37 years ago! We may have figured out one or two things about black holes since then.
    - raattgift 2y ago
      > Keep reading to the end I did. In particular I did not miss the whole preceding apparent horizon vs event horizon context of §VIII or the second half of the second column of p. 17, all of which conflicts with your: It hasn't finished forming because as its gravitational field increases its time distortion increases. Its formation is "frozen in time" (actually just very very slow), it is *never fully formed*. How do you square the emphasized part with, "Once the trapped region is formed, continued collapse is inevitable"? You should also note that your picture in your paragraph starting "Infalling observers..." is very different than theirs. And then this choice statement and your previous paragraph in mixed order: > That was 37 years ago! We may have figured out one or two things about black holes since then "Tell all physicists you don't read physics papers without saying you don't read physics papers..." [1] I mean, did you even look at the range of dates in your One Good Paper's bibliography? For starters, Ginzburg & Frolov was just a useful foundational paper (which I suspected you had never heard of) that shows that generically in curved spacetimes, different observers count different numbers of particles, and in particular one observer's vacuum can be another observer's cloud of electrons, positrons, and photons. This was a nice way of saying that your "relativity does not allow observers to disagree on observations of what" is just wrong. I gave you a google scholar link to the 37 year old paper paper so that it would be clear anyone with a slightly different academic background (and I hoped you) that it's a foundational theory paper. Frolov is the well-known author of two standard textbooks on the physics of black holes (with Novokov and with Zelnikov), both of which deal with Frolov's 37-year-old paper in the context of evaporation and of different observers counting different particle numbers and how that an acceleration between past and future observers accounts for Hawking quanta. Both Frolov textbooks appear early on the first page of google scholar results. (The 37-year-old concern is especially funny. Frolov's 21st century textbook, like practically all textbooks on gravitational phenomena and theory, even reference papers which are now more than a hundred years old, oh no! Choosing a recent GR textbook -- Carroll 2014 -- the author lists under Advanced General Relativity: Hawking & Ellis 1973, de Felice & Clarke 1990, Sachs & Wu 1977; and in the Graduate section: Wald 1984, MTW 1973, Weinberg 1972, ...) > modern (2024-era) numerical methods which are built to be compatible with ... what? Analytical and/or perturbation theory, right? (BTW, Stark & Piran published their computer results in 1985: <https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.55.891 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.55...>. Again, can be found by placing sci-hub.se/ before that URL. That's 39 years ago! "We have performed an extensive series of tests [including] known perturbation solutions.") One more kick at the ridiculous dead horse: at the bottom of p. 17 one finds, "We are not the first to propose a picture like the one presented throughout this section. As far back as theoriginal discovery of the Hawking effect, similar ideas were invoked in [4], and by various comments of [2, 3]". The dates of those are respectively 1974, 1975, and 1976. Oh no! Could it be that among the "one or two things about black holes since then" that "We" may have "figured out" is that early theory papers (the 80s are not early) turn out to have good support in things like astrophysics, magnetohydrodynamics, gravitational wave observations, Hulse-Taylor / PSR J0737−3039 etc. etc.? - -- [1] https://journals.aps.org/125years https://journals.aps.org/125years but uh oh that was 2018 and surely the list would be totally different now!

Is there a source you would recommend for further elaboration and exploration of this model?

by tofof 2y ago

Is there a source you would recommend for further elaboration and exploration of this model?

One good paper is this one: https://arxiv.org/pdf/1907.04879 https://arxiv.org/pdf/1907.04879 Generally you can search for finite black holes and read things written in the last half a decade or so.

raattgift 2y ago
From the very top of the second page of that "One good paper": Can a BH form in a finite time as viewed by a distant observer? (Answer: Yes.) From your comment you appear to believe that preprint supports (emphasis yours): It hasn't finished forming because as its gravitational field increases its time distortion increases. Its formation is "frozen in time" (actually just very very slow), *it is never fully formed.* and you also write: If there is a paradox in your model, then your model is broken, end of story. Finally you write "relativity does not allow observers to disagree on observations of what" and also "Hawking showed that they evaporate in a finite time." Static and non-static observers in general curved spacetimes immersed in relativistic QFTs generically disagree on particle counts. The Unruh, Hartle-Hawking, Rindler, Minkowski and Boulware vacuums seem especially apposite search terms for someone who isn't among "the slow people at the back of the class". (Ginzburg & Frolov 1987 is a good starting point: https://iopscience.iop.org/article/10.1070/PU1987v030n12ABEH003071/pdf https://iopscience.iop.org/article/10.1070/PU1987v030n12ABEH... (one can also stick "sci-hub.se/" in front of the URL). It is cited a lot <https://scholar.google.co.uk/scholar?cites=12518697499517381912&as_sdt=2005&sciodt=0,5&hl=en https://scholar.google.co.uk/scholar?cites=12518697499517381...>).
- jiggawatts 2y ago
  Keep reading to the end: "Moreover, even without invoking nonsingular models, it’s not clear that rotating or charged BHs form an event horizon at all when evaporation is taken into account." Even this paper using modern (2024-era) numerical methods struggles to model the complexities of physically realistic black holes, and ends with a "... more research needed" at the end. > Ginzburg & Frolov 1987 That was 37 years ago! We may have figured out one or two things about black holes since then.
  - raattgift 2y ago
    > Keep reading to the end I did. In particular I did not miss the whole preceding apparent horizon vs event horizon context of §VIII or the second half of the second column of p. 17, all of which conflicts with your: It hasn't finished forming because as its gravitational field increases its time distortion increases. Its formation is "frozen in time" (actually just very very slow), it is *never fully formed*. How do you square the emphasized part with, "Once the trapped region is formed, continued collapse is inevitable"? You should also note that your picture in your paragraph starting "Infalling observers..." is very different than theirs. And then this choice statement and your previous paragraph in mixed order: > That was 37 years ago! We may have figured out one or two things about black holes since then "Tell all physicists you don't read physics papers without saying you don't read physics papers..." [1] I mean, did you even look at the range of dates in your One Good Paper's bibliography? For starters, Ginzburg & Frolov was just a useful foundational paper (which I suspected you had never heard of) that shows that generically in curved spacetimes, different observers count different numbers of particles, and in particular one observer's vacuum can be another observer's cloud of electrons, positrons, and photons. This was a nice way of saying that your "relativity does not allow observers to disagree on observations of what" is just wrong. I gave you a google scholar link to the 37 year old paper paper so that it would be clear anyone with a slightly different academic background (and I hoped you) that it's a foundational theory paper. Frolov is the well-known author of two standard textbooks on the physics of black holes (with Novokov and with Zelnikov), both of which deal with Frolov's 37-year-old paper in the context of evaporation and of different observers counting different particle numbers and how that an acceleration between past and future observers accounts for Hawking quanta. Both Frolov textbooks appear early on the first page of google scholar results. (The 37-year-old concern is especially funny. Frolov's 21st century textbook, like practically all textbooks on gravitational phenomena and theory, even reference papers which are now more than a hundred years old, oh no! Choosing a recent GR textbook -- Carroll 2014 -- the author lists under Advanced General Relativity: Hawking & Ellis 1973, de Felice & Clarke 1990, Sachs & Wu 1977; and in the Graduate section: Wald 1984, MTW 1973, Weinberg 1972, ...) > modern (2024-era) numerical methods which are built to be compatible with ... what? Analytical and/or perturbation theory, right? (BTW, Stark & Piran published their computer results in 1985: <https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.55.891 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.55...>. Again, can be found by placing sci-hub.se/ before that URL. That's 39 years ago! "We have performed an extensive series of tests [including] known perturbation solutions.") One more kick at the ridiculous dead horse: at the bottom of p. 17 one finds, "We are not the first to propose a picture like the one presented throughout this section. As far back as theoriginal discovery of the Hawking effect, similar ideas were invoked in [4], and by various comments of [2, 3]". The dates of those are respectively 1974, 1975, and 1976. Oh no! Could it be that among the "one or two things about black holes since then" that "We" may have "figured out" is that early theory papers (the 80s are not early) turn out to have good support in things like astrophysics, magnetohydrodynamics, gravitational wave observations, Hulse-Taylor / PSR J0737−3039 etc. etc.? - -- [1] https://journals.aps.org/125years https://journals.aps.org/125years but uh oh that was 2018 and surely the list would be totally different now!