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Archive 1

Personal pronouns

I slept on this one. With regard to the trouble with personal pronouns, where this edit revised text such as this:

Sagittarius A*, the black hole at the center of our Milky Way galaxy, is 3.7 million solar masses. If it is actually a fuzzball, it has a density 70 times that of gold. At 3.9 billion solar masses, near the upper bounds for supermassive black holes, a fuzzball would have a radius of 77 astronomical units—about the same size as our solar system’s heliopause…

…to this to eliminate personal pronouns:

Sagittarius A*, the black hole at the center of the Milky Way galaxy, is 3.7 million solar masses. If it is actually a fuzzball, it has a density 70 times that of gold. At 3.9 billion solar masses, near the upper bounds for supermassive black holes, a fuzzball would have a radius of 77 astronomical units—about the same size as the solar system’s heliopause…

…or the Cygnus X-1 caption, which reads as follows:

Cygnus X-1, an 8.7‑solar-mass black hole only 6,000 light years away in our own Milky Way galaxy, belongs to a binary system along with a blue supergiant variable star. If Cygnus X-1 is actually a fuzzball, its surface has a diameter of 51 kilometers.

…but could be revised to omit the personal pronoun “our” as such:

Cygnus X-1, an 8.7‑solar-mass black hole only 6,000 light years away in the Milky Way galaxy, belongs to a binary system along with a blue supergiant variable star. If Cygnus X-1 is actually a fuzzball, its surface has a diameter of 51 kilometers.

Note that in all these cases, an important concept is being conveyed: that the noun being discussed (solar system or Milky Way) is not a far-away one, but is the very one in which earth resides. Granted, there is only one Milky Way and it is the galaxy to which our own solar system belongs, but the wording “ours” is an exceedingly efficient way to drive that point home. Moreover, referring to “the solar system’s heliopause” is very unclear as to which solar system we are discussing given the nature of that sentence.

Alternative language to work around this issue, such as the black hole at the center of the Milky Way galaxy (the very same one to which the Sun and Earth belong) (no personal pronoun and doesn’t end with a preposition) is unnecessarily cumbersome.

Note also that Enyclopedia Britannica—considered to be the best English-language print encyclopedia there is and which has professional copy editors with journalism degrees—uses this very same technique to simply clarify the fact that “Milky Way” is our own galaxy: they use …about 4.5 million Suns lies at the centre of our own Milky Way Galaxy.

Generally, personal pronouns are to be avoided in encyclopedic text. But where their use serves an important (and tidy and compact) purpose of clarifying “which particular one” is being discussed or for emphasizing that the Milky Way galaxy is the one in which we reside, personal pronouns like “our” (to mean “mankind’s”) are superior to the available alternatives and are considered to be encyclopedic prose.

I do, however, wholeheartedly agree with your correction of …still technically exists in our universe; there is, after all, only one universe so your correction to …still technically exists in the universe is a clear improvement. Thanks. Greg L (talk) 17:29, 28 April 2009 (UTC)

Question about Planck density

This isn't really about Fuzzballs, but I noticed the article defines the Planck density as "mass of the universe packed into the volume of a single atomic nucleus". OK but what is the universe? Is it the part that is within our light cone? Is it also the parts that lie without? Does it also include other (hypothetical) bubble universes in the multiverse?--Goodmorningworld (talk) 14:39, 11 May 2009 (UTC)

Waiting for some professional help…

When I started on this article, it looked like this. As of this writing, it appears like this. And this is what it looks like now. As one can quickly see, I didn’t cite anything yet; this is very much a work in progress. I e-mailed Dr. Samir Mathur (the Ph.D. co-researcher at Ohio State University who helped propose the theory of fuzzballs) and asked that he check the article for factual errors. He e-mailed me back on December 10th that he is in India at the moment and will check the article when he gets back at the end of the month. Greg L (talk) 06:15, 12 December 2008 (UTC)

  • Update: I spoke today with Dr. Mathur. He will be reviewing the article Monday for accuracy and e-mail me the corrections and suggestions. Currently, this article gets only about three hits per day; that is too low. Before I add links pointing to this page in the See also sections of articles like Black hole, I want to establish a historical marker revision of this article that is known to be 100% factual. Why? Well…

    Clearly String Theory is an advanced concept that exceeds the expertise of over 99.9% of our active Wikipedians—myself included. Moreover, this article will suffer from a much greater number of “drive‑shootings” by non-registered editors once pointer links are added to Wikipedia. Dr. Mathur is willing to go on the record here on this discussion page once this article is perfectly correct. That “signed‑off” version will serve as the factual check standard against which future edits may be compared.

    Another thing Dr. Mathur offered to do was put me in touch with one of his graduate students, who can provide crucial assistance in adding an advanced-theory section to this article. That graduate student should soon have my e‑mail address, but in case he/she loses it, I can be reached here.

    Again, I plan to avoid salting Wikipedia with links pointing to this article until after it has been signed off by Dr. Mathur. Greg L (talk) 18:40, 25 April 2009 (UTC)

  • Update: Dr. Mathur e-mailed me suggested corrections today and I’ve revised the article accordingly. I am awaiting a sign-off by him. Greg L (talk) 01:27, 12 May 2009 (UTC)

(Complaint by I.P. editor

The whole article is flawed. If one has no idea of how string theory works one should better be quiet. Fuzzballs are no alternatives to black holes or a string physicists alternative to black holes! Fuzzballs are black holes! If you average over the exp(Bekensteinentropy)~infinity fuzzballs (microstates) you will get the simple black hole geometry even with the singularity. See Class.Quant.Grav.25:214004,2008 or http://arxiv.org/abs/0811.0263

The whole article has to be replaced or erased!!!

As a first step I erased the part with the density of the fuzzballs. The density is not constant over the interior and grows towards the center. Remember that the coarse graining should yield the classical black hole geometry. —Preceding unsigned comment added by 131.220.99.130 (talk) 11:58, 1 July 2009 (UTC)

  • Quoting you: Fuzzballs are no [sic] alternatives to black holes or a string physicists alternative to black holes! Fuzzballs are black holes! I agree. Please take care to not skip over the very first sentence of the article next time, for it says, “Fuzzballs are theorized by some string theory scientists to be the true quantum description of black holes.”

    As for the density being a gradient, yeah; same thing goes for neutron stars as they too have a pronounced density gradient. But that doesn’t stop physicists and astronomers from speaking of the bulk density of the object in question now, does it? A discussion about the density gradient from the core to the surface is entirely beyond the scope of a general-interest article on this topic.

    As for this quote from you: If one has no idea of how string theory works one should better be quiet. The present version of the article—after it was restored after you deleted most of it (ain’t that ‘delete’ key fun?)—has been reviewed by Dr. Samir Mathur, the Ph.D. and co-discoverer of fuzzballs and the string-theory math underlying them. He has also offered to have a graduate student of his help in adding an advanced-theory section to this article.

    If you would like to declare that you have some insight into string theory Dr. Mathur doesn’t have, please disclose a reputable, peer-reviewed scientific journal in which you have been published. Greg L (talk) 06:03, 1 July 2009 (UTC)

  • I see you’ve once again found your delete key. I explained above that it is extraordinarily common for physicists and astronomers to refer to the density of neutron stars in terms of “XX billions of tonnes per teaspoon”. Also as explained above, it is far beyond the treatment of this subject in a general-interest encyclopedia to discuss how dense a fuzzball might be at the surface v.s. how dense it would be in its center. It is entirely sufficient to express the bulk density as the product of the number of solar masses divided by its Schwarzschild radius. Finally, and most importantly, this entire article was reviewed by Dr. Mathur for accuracy. He and I have communicated via multiple e-mails and phone calls. If you persist with your edits, which are contrary to common sense and the very Ph.D. who invented the theory, I will seek to have your I.P. address blocked. Greg L (talk) 16:51, 1 July 2009 (UTC)
  • By the way, I added a short, sweet ref note to the article, which addresses the point about how fuzzball density isn’t the same at all points in its interior. I find that to be far superior to deleting an entire section which had been proofread by Dr. Mathur himself because an arcane nuance wasn’t mentioned. Solution: add arcane nuance as a ref note. I’m quite happy with this solution; I think the article is better off as a result. Greg L (talk) 17:34, 1 July 2009 (UTC)

Again!! Dear Greg L: You can`t compare the density of the nearly infinite fuzzball states with ordinary matter because the density is not constant over the interior as I mentioned before. Furthermore fuzzballs are no alternatives to black holes or a string physicists alternative to black holes! Fuzzballs are black holes! If you average over the exp(Bekensteinentropy)~infinity fuzzballs (microstates) you should get the simple black hole geometry even with the singularity. See Class.Quant.Grav.25:214004,2008 or http://arxiv.org/abs/0811.0263 . So instead of deleting my comments again you should write an abstract that the classical black hole geometry emerges by coarse graining over the individual single fuzzball geometries.

  • As you have finally discovered, I haven’t been *deleting* your posts; I’ve been moving them down here where they are under their own section heading. Allow me to teach you some stuff here, as you seem most unfamiliar with anything whatsoever about Wikipedia except that hitting the ‘delete’ key is fun!:
  1. You don’t insert posts at the top of talk pages, inserted right smack into the middle of another thread.
  2. You don’t shout, in bold text
  3. You learn to click the History tab at the top of the page, where you will benefit from edit summaries left by others, such as mine, where I even gave you a link in my edit summary directing you to this discussion thread
  4. You read other editors’ responses to your “edits” and discuss things before wading into articles with your liberal use of the ‘delete’ key.
Now, if you would bother to read the above, you would see that you are wrong on a number of counts, and (sorta) correct on one. I took your point about variable density v.s. depth (something Dr. Mathur and I had discussed before) and added a footnote to the article addressing your point. I won’t repeat anything else about that, as I am going to give you an opportunity to actually read for once. Greg L (talk) 21:19, 1 July 2009 (UTC)

Density

Again!! Dear Greg L: You can`t compare the density of the nearly infinite fuzzball states with ordinary matter because the density is not constant over the interior as I mentioned before. Furthermore fuzzballs are no alternatives to black holes or a string physicists alternative to black holes! Fuzzballs are black holes! If you average over the exp(Bekensteinentropy)~infinity fuzzballs (microstates) you should get the simple black hole geometry even with the singularity. See Class.Quant.Grav.25:214004,2008 or http://arxiv.org/abs/0811.0263 . So instead of deleting my comments again you should write an abstract that the classical black hole geometry emerges by coarse graining over the individual single fuzzball geometries.

  • (*sigh*) I’m not deleting your comments; I’ve been moving them all down to the proper place, per convention used throughout Wikipedia: at the bottom of the page with its own section heading. Your post here inserts big bold text right smack in the middle of a much earlier post, which has an unrelated section heading. Rather than move it to the bottom of the page (something that seems to utterly confuse you), I’ve simply copied it and left your original post here. I’ll delete this copy later, after I see that you’ve had your epiphany of proper protocol on Wikipedia talk pages.

    Since you seem to be utterly disinclined to read anything on these talk pages (you know, actually use the thumbwheel on your mouse and, you know, read) in order to discover what has transpired, here are three links to direct you straight to threads of interest on this talk page:

  1. I moved your posts down to the bottom here
  2. I’ve been collaborating with the Ph.D. who developed the fuzzball aspect of string theory, as disclosed here (a few centimeters down).
  3. All the key assumptions I’ve used in this article are disclosed here (something you will very rarely get anywhere else on Wikipedia).
Greg L (talk) 21:35, 1 July 2009 (UTC)

@Greg: Read the abstract of the paper I quoted.

"In this review we would like to address the question of how the classical black hole geometry itself arises as an effective or approximate description of a pure state, in a closed string theory, which semiclassical observers are unable to distinguish from the “naive” geometry" (from de Boer at al. 2008)

Or should I cite Mathur himself? (from http://arxiv.org/abs/0810.4525 )

"Fuzzballs states are not expected to have such a singularity individually (though the quantum fuzz does get more dense towards the center for a typical state). But when we take an average over fuzzball states, the traditional black hole geometry can appear as a saddle point of the entire sum"

Do you understand? The density is not constant. I hope that there are other and more clever people than you who will understand my intention to rewrite (or delete at least part of) this article. —Preceding unsigned comment added by 131.220.99.148 (talk) 01:01, 2 July 2009 (UTC)

IP, please sign your posts with four tildes (~~~~) and put new posts at the bottom of threads, or start new threads at the bottom of the page. Also, personal attacks aren't allowed here. Don't comment on the cleverness of editors (or anything else about them), comment only on content and sources.
The varying density is noted in the article at Fuzzball (string theory)#cite note-3. Perhaps this should be put in the body of text? Gwen Gale (talk) 01:13, 2 July 2009 (UTC)
  • IP, yes, I know; bulk fuzzball density doesn’t in the least imply that all portions of a fuzzball have the same density. What you are pointing out is not a new idea that is lost on anyone. Dr. Mathur and I discussed this topic during the writing of the article. Density variation-with-depth is an arcane nuance that is beyond the scope of the general-interest portion of this article. Nevertheless, as Gwen pointed out, the article has a note regarding your point.

    Before you respond again with your reoccurring message point about how fuzzball density varies with depth, I would appreciate it if you would read my responses in the above thread. Please note in particular, paragraphs #1–4 of my 06:03, 1 July 2009 (UTC) post, as well as my 16:51, 1 July 2009 (UTC) post, as well as my 17:34, 1 July 2009 (UTC) post. Greg L (talk) 04:53, 2 July 2009 (UTC)

    P.S. I just revised the article so in the relevant places, it says “mean density,” not merely “density.” This is, I suppose, something that Dr. Mathur and I should have caught earlier in order to have maximum scientific rigor. I wish you could have found a less disruptive way to make the point rather than delete colossal-size swaths of the article—you might have added the “mean”s yourself. Between the tweaks with “mean density” and the ref-note, I think the article now properly touches upon the issue and is exceedingly precise without burdening a general-interest article with cumbersome, arcane verbiage. It better have addressed your point; for if it doesn’t, you might be tempted to go to our Jupiter article, which also speaks of its “mean density” (it has metallic hydrogen and iron at its core) and delete large swaths of that article next. I trust, not? Greg L (talk) 05:54, 2 July 2009 (UTC)

It`s true that this was a classical overreaction and I`m sorry for that because its unprofessional and unfair. The point is the following. If someone reads this article she/he will get the impression that these beasts which we call black holes are nothing else than giant macroscopic balls of strings. I`m sure this is true but it depends on the perspective. Classical or even semiclassical observers (like you and me) will never be able to measure with such a high precision that we could discriminate between the nearly infinite fuzzball states (or if you use a more abstract Hilbert space than Mathur and Co., call it microstates). Probably it`s forbidden even in priciple to achieve the needed resolution once you entered the black hole (or fuzzball if you want). And here comes the paper from Jan de Boer (which is from my point of view the leading expert in black holes and string physics). He worked out that for all observers beeing unable to discriminate between the fuzzball states the classical black hole geometry (even with the singularity!) re-emerges. So if you would jump into such a beast you would have no chance to observe the workings of these single microstates. Instead you would encounter a coarse grained mess of nearly infinite fuzzball states which would exactly look like the classical black hole geometry and one would find his doom near the effective singularity. So again: If someone reads this article one could think of fuzzballs as alternatives to black holes which they aren`t. They are the microscopic constituents of black holes (not measurable by semiclassical observers) and nothing more or less. —Preceding unsigned comment added by 131.220.99.177 (talk) 22:15, 2 July 2009 (UTC)

From fuzzballs to classic black hole geometries

I wrote a small new part about coarse graining... Improvements are welcome. —Preceding unsigned comment added by 131.220.99.180 (talk) 18:17, 30 July 2009 (UTC)

  • I.P editor: I started to clean up your citations and put them into the proper, footnoted form. I cleaned up the first one (the iop.org abstract). Then I got to your second, arxiv one, which is downloadable. So… I downloaded it and actually read it. I can find no evidence that the paper speaks to the issue you say it does (where it says “Furthermore its not known at the moment if such high precision measurements are possible at all inside black holes”). You need to quote the passages from the articles. Please also e-mail me the iop.org article as I don’t have a subscription. I’ve moved your proposed addition to here (below in “Sandbox”), where you can work on it, clean it up, and better cite it.

    It would be awfully nice if you would explain what “course graining”and “microstates” mean. Quantum theory and string theory are exceedingly advanced scientific disciplines and this article is geared towards a general-interest readership. Arcane terminology used within the discipline must be clearly explained so the article remains accessible to to a general-interest readership. Given what you currently have, it is nearly impossible for most readers to understand what your point is. Wikipedia is not a resource for particle physicists to go to so they can catch up on the latest with advanced theories.

    Frankly, reading through what you have below, it appears you are trying to buttress points by citing work which isn’t even trying to make the point you say they are supposedly making; the cited articles are off on entirely different issues and are busy addressing far more arcane points on the detailed structure of black holes. Cherry picking scientific articles like this is known on Wikipedia as Point Of View pushing. Please accurately quote cited scientific papers, cite the actual passage, and explain the thrust of your point using plain-speak so it is understandable to a general-interest readership. Greg L (talk) 03:33, 31 July 2009 (UTC)

  • (Trying to wade through and parse what you wrote, below)… Quote: “…as the classic black hole even with its singularity at the center as long as they measure with sub-planckian precision.” Where are you getting this stuff? “Sub-planckian”?!? The Planck length and its derivatives, like the Planck volume are the smallest dimensions that have any meaning whatsoever in physics; it is nonsensical to conjecture about smaller dimensions. This is unparseable gobbledygook. Wikipedia is not the proper venue for such exceedingly advanced, left-field material. Greg L (talk) 04:10, 31 July 2009 (UTC)
  • P.P.S I e-mailed Dr. Mathur and asked him to comment on this. Your point seems to be that the very heart of a fuzzball has properties that approach that of a singularity. I’ve asked Dr. Mathur if there is a (much) simpler way to make this point while maintaining scientific rigor. Greg L (talk) 04:30, 31 July 2009 (UTC)

So the point is the following. Coarse graining means that you average (sum) over all the single fuzzball states in order to get the classic black hole geometry. One can also find the first paper on arXive ( http://arxiv.org/abs/0811.0263 ). Usually it is assumed that these black hole microstates are very small, perhaps beeing as small as the planckian or string scale. Lets first see what Mathur has to say....

  • Dr. Mathur responded this morning with “the material is not incorrect”. I then asked him to clarify and focus on the “sub-planckian” sentence. The task before us seems to be to get this material so it can be understood by the average Joe. Your I.P. address resolves back to a German university. What is your major? Next…

    Pretend you are at a pub with your half-drunk friend who is working on his art major; how would you, in thirty seconds, describe the point of your paragraph, below? Note that back in May, Dr. Mathur’s first response to my request for review included the following comment from him: “The density of strings may be high nearer the center, and this may approximate a singularity in some fashion, but the details of this are not known.” Is that your point here? If not, what is the central point you were trying to make (plain-speak only) and how much of that point can be directly cited with peer-reviewed papers? Note that Dr. Mathur doesn’t seem inclined to want to devote an awful lot of time to proof-reading and correcting this article. Let’s try to keep this simple and on the straight and narrow so that we don’t have to intrude on the fellow too much more.

    Let’s look at that second paper, “Black Holes as Effective Geometries”, (thanks for providing a link where I can read the paper). As with the second paper, I don’t see that it speaks to the issue of measuring at sub-planckian precision. Wikipedia goes only with citable material and doesn’t publish what is known as original research.

    Finally, please provide me with your name (or Wiki-name, if you prefer); I tire of referring to you as “I.P. editor”. Greg L (talk) 14:27, 31 July 2009 (UTC)

  • The English language does not attach that meaning to the prefix “sub”; quite the opposite. “Sub-millimeter resolution” means “resolving to less than one millimeter.” I don’t find the term in the two papers you cited. Dr. Mathur just responded that the term is occasionally used. However, it is counter-intuitive and confusing “insider-speak” that isn’t suitable for a general-interest audience. Greg L (talk) 14:27, 31 July 2009 (UTC)
  • (*sigh*) I read into the arcane techno-babble of black hole string theory more than I wanted to. String theory papers are far more arcane for me to extract any real pleasure from the exercise. That’s why I have been in contact with the experts who wrote these papers in the first place; they are uniquely qualified to explain what various bits really mean and explain what is a widely accepted view and what is mere conjecture.

    “Coarse graining” pertains to the discipline of black hole thermodynamics and how one statistically examines the thermodynamic and quantum nature of a fuzzball. It is possible to interpret some of the papers as suggesting that fuzzballs have some singularity-like properties at their centers. However, like Dr. Mathur pointed out, no one really knows what the properties are at the center of a fuzzball. Dr. Mathur strikes me as quite a humble guy and this underlies why he wrote “the material is not incorrect”. However, Dr. Mathur has no knowledge of Wikipedia’s policies regarding how articles may not be slanted by placing undue weight on what is nothing more than a conjectural interpretation of a theory that isn’t widely accepted as fact within the art.

    “Singularities”: Modern physicists since 1972 don’t like them one least bit. Were I to take an educated guess, I would say that the center of a fuzzball might have a density equal to the Planck density (5.155×1096 kg/m3). However, this density is infinitely far from the infinite density of a singularity. Moreover, as Dr. Mathur pointed out, no one really has any idea what the properties of a fuzzball really are at its core.

    The paragraph in the below sandbox amounts to POV-pushing in that it has cherry-picked citations not only out of context, but has attached citations to assertions that the papers didn’t even make. And this whole effort seems to be designed to promote the view that any detailed analysis (steeped in impressive but hard-to-understand terminology like “coarse graining” and “microstates” and “sub-planckian”) supports a likely conclusion that fuzzballs, in the final analysis, are really just classic black holes with singularities—“(at least to some approximation)”. This is misleading and is impermissible POV-pushing. It occurs frequently on Wikipedia, especially on the more technically complex scientific articles. It will continue to be a problem as long as the experts are loath to contribute to Wikipedia. And who can blame them? While working on Kilogram, I had one expert react with astonishment that any expert would write something on Wikipedia when some kid in 9th grade can revert them an hour later.

    The whole point of black hole thermodynamics is to show how quantum information doesn’t disappear into a singularity. Today, this is the entire thrust and direction of that discipline. Dr. Mathur’s theory of fuzzballs (now the subject of many derivative papers by other scientists) is a slick advancement that marries string theory and black hole thermodynamics and quantum theory and other laws of physics. And it does so without relying upon the singularity that no one in the business likes. Greg L (talk) 18:01, 1 August 2009 (UTC)

Currently I have not the time to go into datails, but let me shortly explain the whole idea in a very simple (perhaps much too simple) way. Since Hawking and Jackob Beckenstein came up with their idea that a black hole carries an entropy proportional to the 1/4 of the area of their event horizon it was clear that, if you want to explain their behavior microscopically (that is important to solve the black hole information paradox), you have to deal with (and find) exp(Bekensteinentropy) microstates. This is due to the simple fact that the entropy is nothing else than the natural logarithm of the number of microstates. For a 1 solar mass black hole you would need exp(10^{77}) microstates. For a 1 billion solar mass black hole you would need exp(10^{95}) microstates. In other words you need almost an infinit amount of microstates to "produce" a black hole. String theory found some potential black hole microstate candidates. Most of them are found to be elements of rather abstract Hilbert Spaces. Today it is not clear what are the most realistic ones. The fuzzball microstates are a possible choice (and from Mathurs view they are the best ones, but others are not convinced and there are hundreds of other papers.... But from my point that`s a technical discussion).

So lets assume you have found the required microstates. First you can compute their quantum mechnical characteristics. That was done by Mathur and many others. From the quantum persective you can solve the information paradox easily because none of these single microstates possess a horizon or singularity.

The much more difficult part is to sum over all these microstates to get the classic black hole geometry back. This is so hard that nobody achieved this as of today. Here comes the De Boer paper into the play. These guys are really clever. They do not average over all the microstates but instead choose the perspective of observers which aren`t able to resolve the microstates. If you would look at black and white pixels but lacking the needed resolution to see them directly, all you see would be gray! Therefore all observers which are not able to achieve planckian/stringy (or even better) resolution would see all these microstates as a coarse grained mess. As not mentioned before, nobody knows about the true size of these microstates and it is still possible that they don`t even have ordinary physical dimesions like atoms or something else because most of them are elements of truly abstract Hilbert spaces (I`m not so sure about the special fuzzball states)! Nevertheless it is (at least) plausible that you need planckian resolution to see them (remember that nearly infinite of them are confined inside black holes and the stringy scale is near to the planckian one).

So what Boer and Co found was that this coarse grained mess looks exactly like the classic black hole metric. It is not important if the density of all the fuzzball states is planckian, infinite or something else near the center. As long as you would not be able to resolve single microstates all you would feel is the classical black hole geometry which would crunsh you out of existence or perhaps you would die much earlier by tunneling into the microstates.

Hope you get the idea.

Ps. It is therefore disturbing to talk about the mean density of the microstates because it is tempting to think of them as a fluid with some density....definitly not the case. —Preceding unsigned comment added by 131.220.99.183 (talk) 15:05, 2 August 2009 (UTC)

  • Thank you; that was a very good explanation (although still awfully complex stuff for a general-interest audience). The only part I have trouble with is your jump from your explanation to your last paragraph, where you write how you have trouble with how the article improperly makes it “tempting” to think of a fuzzball as a “fluid” with any given density. You added that such a notion is “definitly not the case.” Note again, this article is about fuzzballs and that Dr. Mathur, the co-author who helped write the first papers on the subject, reviewed this article and had no problems with it.

    Here is what I think this boils down to: you prefer to eschew the basic premise of fuzzball theory that the event horizon truly delineates the physical, albeit fuzzy, surface of a fuzzball. Instead, you seem to embrace the notion that—*really*, when one examines them the right way—fuzzballs are, “(at least to some approximation)”, a singularity. I believe that this view of yours is wholly at odds with the basic fundamentals of the theory. Clearly, the central tenet of Dr. Mathur’s and Oleg Lunin’s theory is that fuzzballs have a physical surface and that a fuzzball’s mass—while no-doubt unevenly so—is really and truly distributed throughout its volume. More troubling is the citations you gave don’t directly support your conclusion when one objectively reads them. Yes, I’m sure there are some string-theory papers that are making an abstract point along these lines, but I suspect you have taken it well out of context (I can’t find the sweeping conclusions in the papers you’ve attached them to in the sandbox, below). The real question is this: what do these papers really say and what view is broadly accepted within the scientific community that is working on this theory? Neither you nor I are qualified to make that judgement.

    This state of affairs has all the hallmarks of Point-Of-View-pushing, which is not permissible on Wikipedia. Wikipedia follows the weight of the scientific community’s view on matters, requires that citations truly buttress points being made, and does not allow undue weight to niche theories. In most cases, these content-dispute issues are resolved by placing a very high threshold on citations and requiring that the citations be to preeminent, peer-reviewed journals; a test of “Oh yeah, where exactly does the citation make the point you’re saying it makes?” This is much like how on Wikipedia, we write that “America landed on the moon in 1969” (written like a simple fact) rather than “Many scientists believe that America landed on the moon in 1969” (equivocation to allow for dissenting views regarding conspiracies and sound-stage production).

    Fortunately, this dispute can easily be resolved. The locus of this dispute lies in mentioning mean densities of fuzzballs. You and I both recognize that a mean density is pretty inconsistent with the view that fuzzballs are really just a mathematical abstract for what is really and truly a singularity in the final analysis “(at least to some approximation)”. A mean density is, however, entirely consistent with the notion that a fuzzball is a big ball of strings. Focusing on this central point allows us to dispense with the fruitless exercise of trying to prevail in our arguments using language like “coarse graining,” “microstates,” and “sub-planckian resolution” and other techno-babble that probably neither of us is truly qualified to discuss and which exceptionally few readers could begin to fathom. I’m not going to go down that path; it’s utterly pointless. So…

    I’m going to e-mail (badger) Dr. Mathur one more time as to whether the most widely accepted view of fuzzballs fairly sees them as having a fuzzy surface below which significant amounts of strings (and mass) would be expected to be found and whether this means it is fair to think of the entire region below the event horizon of a fuzzball as singular collective that can fairly be described as having a mean density. You know; cut to the chase, go to “the man,” and handily resolve this without you and I pretending we have a solid grasp of this exceedingly complex and arcane material.

    Note that Dr. Mathur previously reviewed and signed off on all this article’s contents. And that was back when it referred to the “density” of a fuzzball, not “mean density”, which I changed to address your objections. Dr. Mathur has the final say on this; he is the expert, not you or me. We could argue about “coarse graining” until the heat death of the universe. You seem to be logical and scientific and willing to accept Dr. Mathur’s verdict. I have every confidence that this won’t degenerate into another cold fusion fiasco on Wikipedia, which consumed far too much of everyone’s time (but which, at least, reinforced our policy of following the widely accepted scientific view). Greg L (talk) 18:10, 2 August 2009 (UTC)

  • Verdict from Dr. Mathur: He responded this morning (Wikipedia's fuzzball article, August 5, 2009 1:38:29 PM PDT). In a nutshell: the central tenet of fuzzball string theory is “that you do not get the empty space between the horizon and the singularity that people used to traditionally expect … the space is now filled.” As with neutron stars, or even Jupiter, which has a dense iron core that is likely an exotic ultra-high-density phase, it is perfectly appropriate to refer to their mean density because Fuzzball theory holds that they are not a singularity and that they truly have a physical surface. Physicists refer to how much a teaspoon of a neutron star would weigh on earth all the time, and neutron stars have an extreme density gradation with depth. Nevertheless, that complexity stops no one from taking their mass, dividing it by their volume, and expressing it as a mean density. Moreover, the variation of density with depth of a neutron star is a rather well understood theory. However, as Dr. Mathur further reinforced (again), the region below the physical surface of a fuzzball is not well understood and everyone is just guessing as to its physical properties. So it is perfectly appropriate to refer to a fuzzball’s mean density because the whole point of the theory is that they are truly a ball of strings.

    I expect you to drop this, I.P. editor. Your view of fuzzballs—that when one takes a proper, detailed look at them, they are really, “(at least to some approximation)”, an event horizon surrounding empty space with a singularity at the very center—is clearly intended to entirely undercut the validity of this paragraph in the article:

…and such a view therefore flies in the face of the central tenet of fuzzball theory; Dr. Mathur (someone with a doctorate who teaches at a university and published this theory in a preeminent, peer-reviewed journal) says so. Unless you, anonymous I.P. editor, have yourself been published in a peer-reviewed journal, Dr. Mathur’s writings shall, for the purposes here on Wikipedia, be considered to be the prevailing scientific view.

BTW Dr. Mathur also answered some other questions of mine. Fuzzball theory relies on Superstring theory (not regular String theory). Also, I had been prepared to Photoshop the picture of the Fuzzball to add the fuzzyness to its margin. According to Dr. Mathur, he guesses the fuzzyness is on the order of a few Planck lengths. I’ve revised the article accordingly. Greg L (talk) 21:58, 5 August 2009 (UTC)

Sandbox

A central aspect of the fuzzball proposal is its relation to classic black hole geometries. Besides the fact that the whole fuzzball picture seems to imply that black holes are pure quantum mechanical objects, coarse graining over the individual fuzzball states should yield the classical known black hole geometry (at least to some approximation). One step into this direction was done by a group headed by Vijay Balasubramanian in 2008.[1] Instead of explicitly coarse graining over the individual black hole microstates the scientists choose the perspective of classical/semiclassical observers which are per definition not able to discriminate between planckian sized objects like the microstates. Such observers would perceive the coarse grained mess of the nearly infinite microstates (the number of microstates is proportional to the exponent of the Beckenstein/Hawking entropy) as the classic black hole even with its singularity at the center as long as they measure with sub-planckian precision. Furthermore its not known at the moment if such high precision measurements are possible at all inside black holes ([1]) nor if (test) bodies would find their doom near the effective singularity or much earlier by disintegration into black hole microstates when falling in.

  1. ^ Black holes as effective geometries, Vijay Balasubramanian et al. 2008, Class. Quantum Grav. 25 214004 (50pp) (iop.org abstract)

Issues to double-check

  • Is the science of fuzzballs underpinned by String theory or Superstring theory? If superstring, which one?? Resolved. Superstring. (Wikipedia's fuzzball article, Dr. Mathur, August 5, 2009 1:38:29 PM PDT). Greg L (talk) 02:01, 7 August 2009 (UTC)
  • With regard to Hawking radiation, can a singularity retain the property of angular momentum and have spin?
  • What is the radius of the “fuzzyness” for 10-solar-mass fuzzball? Resolved. Probably on the order of a couple of Planck lengths. (Wikipedia's fuzzball article, Dr. Mathur, August 5, 2009 1:38:29 PM PDT). Greg L (talk) 02:02, 7 August 2009 (UTC)
  • How is fuzzball theory testable?

Fuzzball density figures – surely "locally" they would be much denser?

A question for wiki-contributors here, and/or Samir Mathur if pondering "signing off" as Greg L says:

The article gives density figures for various sizes of fuzzball (all of the sort mimicking a Schwarzschild, i.e. nonrotating and uncharged, black hole – a case I don't think anyone's actually mimicked yet, but here's hoping!). At the moment, these figures are got by simply dividing the fuzzball's energy at infinity by the Euclidean volume of a 3-ball whose 2-sphere surface would match the fuzzball's effective surface (the would-be Schwarzschild event horizon, which a fuzzball seems to have but actually doesn't). I have two worries about calculating density this way, one (probably) minor and one (surely) major.

My minor worry is with the denominator – the volume. Inside the fuzzball, the geometry is likely "strange" in some way or other: presumably in fact a superposition of geometries, few of which are quite like a Euclidean 3-ball. (Or maybe even a structure with no, rather than many, associated classical geometries.) I call this worry "minor" because I'm guessing the difference this makes is just of order 1. (For example, if a leading contributor to the superposition turns out to be, for the sake of argument, one hemisphere of a 3-sphere, neatly "capping" the exterior geometry, well then, its volume is pi-squared times R(Sch)-cubed instead of 4/3 pi R(Sch)-cubed. So the density figures should all be roughly cut in half. An O(1) correction.)

My major worry is with the numerator – the use of the mass at infinity. By analogy with those famous old thought experiments where a bucket is lowered into (or almost into) a black hole and its potential energy extracted, one must surely expect that the mass defined locally inside the fuzzball will be far higher than the mass at infinity? After all, the fuzzball's exterior geometry is an essentially perfect mimicking of classical GR, and so the entire fuzzball is at the bottom of a deep potential well. Thus, it surely takes many, many units of locally defined mass down inside the fuzzball to equal 1 unit of mass at infinity. The locally meaningful density, then, would be far higher than the "formal density" figures given.

I call that second worry "major" because I'm guessing (yep, guessing again...) that this correction could be huge. To give perspective: If the classical exterior geometry were to be exactly mimicked, the correction would in fact be infinite! A mimicking that becomes less than exact just outside the would-be horizon would presumably give an extremely large but not infinite correction. And if I can make a bold further guess, I'd even speculate that a larger fuzzball would achieve a more exact mimicking and thus need a higher correction factor, compensating (exactly? or just to some extent?) for its lower "formal density". Who knows, we might even just always end up with string-scale or Planck-scale density inside any size of fuzzball!

So, as a stop-gap before someone (Samir?) can give an informed judgment on all this, I think we should describe the density figures as "formal densities ascribed by an observer at infinity", and warn that they may differ from the actual densities one would experience if one was unlucky enough to fall in. Later, the actual locally meaningful densities – or perhaps the lack of applicability of the density concept altogether? - may become clear, and we could then add a useful note comparing and contrasting formal vs. actual (or formal vs. lack of actual). Iain David Stewart (talk) 00:59, 5 June 2009 (UTC)

  • Iain David Stewart: "Formal densities ascribed by an observer at infinity" is assumed when making physical observations of neutron stars, black holes, and fuzzballs. To do otherwise is like talking about how the mass of the International Prototype Kilogram is “only precisely one kilogram if it is stationary and isn’t traveling at a relativistic speed with respect to the observer when the mass measurement is made.” Similarly, it is assumed that one isn’t measuring the properties of a fuzzball (or neutron star) from the point of view of someone inside the fuzzball where time is at a complete stand-still.

    The Schwarzschild radius is 2954 meters per solar mass as observed by an observer free of the relativistic effects of the fuzzball. The value of one solar mass is given under the same circumstances. This establishes density from the perspective of a distant observer where time and space still work normally.

    All the densities—as well as every other numeric equivalency disclosed in the article—has been reviewed by Dr. Samir Mathur and, notwithstanding the tendency of Ph.D.s to attach caveats to seemingly everything, he had no problem with them. Since he is one of the co-authors of the string theory papers, he has some facility in this area and is considered an expert. The final “sign off” is for him to review the material I corrected per his suggestions. It was not my intention to ask him to tell me a second time if the material he already said was correct is still correct.

    And (just a nitpick): it isn’t necessary to truly be at “infinity” when making an observation of black holes and fuzzballs to be—for all practical matters—free of relativistic effects. It’s fair enough to say that we can speak of the size, mass, and density of Sagittarius A* (the super-massive black hole) from our vantage point here on Earth, which is in the same Milky Way galaxy as Sagittarius A* (a distance that is infinitely shorter than infinity). In fact, merely backing off 181 kilometers from the surface of a 6.8-solar-mass fuzzball would expose an observer to a gravitational acceleration only 1% the escape velocity of light. Clearly, it is exceedingly helpful, when making measurements of fuzzballs, to not be so close to them that one is being spaghettified by the mass of the object they are observing.

    The nuance you are suggesting, while not incorrect, is routinely ignored since it is entirely beyond the scope of the treatment for a general-interest audience. Greg L (talk) 06:18, 5 June 2009 (UTC)

  • Well, indeed, I don't mean at all to dispute the usefulness for distant observations of the formal densities at infinity of all the various astrophysical objects... sorry if it sounded as if I wanted the concept deprecated, I don't, I can see its value! I just mean that for those researchers (present and future) calculating what's going on inside a fuzzball, locally meaningful density would be what they'd be most interested in – in exactly the same way that (say) neutron star researchers, thinking about things like "is the matter near the core dense enough that it'll turn into such-and-such a phase?", must of course use locally defined density when they try to answer that sort of question. Apologies if I was taking things to a greater level of detail than you think is appropriate for a general audience!

    (I still think it would be best to at least briefly note the nature of the densities given, just in case some people do think "ah, so that's the density I'd be wading through if I was inside a fuzzball and still alive!". In fact, here's an interesting and possibly unsolved question, which again you may feel is inappropriate to dwell on in a general article: how big does a fuzzball have to be before its density is low enough that a human being [or other physical system of interest] can survive for at least a while inside it? Naturally, it's locally defined density which anyone working on that question must choose to care about...) Iain David Stewart (talk) 22:55, 9 June 2009 (UTC)

  • Hi Iain. Quoting you: how big does a fuzzball have to be before its density is low enough that a human being [or other physical system of interest] can survive for at least a while inside it? I should think that the problem with a super-massive fuzzball of 3.9 billion solar masses wouldn’t be its density, which is the same as air (as observed from a safe distance where the fuzzball’s size can be accurately measured). Nor would such a super-massive fuzzball be capable of spaghettifying a person since the tidal force across a couple meters of a person’s length wouldn’t be enough to even feel. The part that makes it impossible to survive is that the entire zone inside a fuzzball is one where the gravitational acceleration exceeds the escape velocity of light and this 1) causes matter to degenerate into strings, and 2) causes time to come to a complete standstill, and 3) causes the “space” portion of timespace to no longer exist. Being in a fuzzball doesn’t seem like something one would look forward to. I haven’t a clue whether the last moment before one arrives at the fuzzy surface of a fuzzball would be unpleasant or not. My hunch, however, is that one would exist totally undistorted the entire ride in and would simply dissolve at the exact instant they reach the fuzzball’s surface. Can Hawking radiation carry away, encoded in the delicate correlations of its outgoing quanta, a scream? Greg L (talk) 06:30, 10 June 2009 (UTC)

So, is there actual mass inside fuzzballs (excluding the trapped stuff), or does the curvature of space time inside the fuzzball just mimic the curvature of space time mass creates? 24.155.222.25 (talk) 22:14, 19 August 2009 (UTC)

Fixed image sizes

A quick note regarding the use of fixed images sizes in this article:

For images where there is high-contrast visual information at high spatial resolution, it is important to use size reductions that are integer fractions of the full-size image. Examine the below three example images of Cygnus X-1:

File:800px-Cygnus X-1.jpg
The full-size source image to which this links is 800 pixels across. By specifying one-third that value, 267 pixels, the stars in the background remain tack sharp. This is accomplished by specifying a fixed width, by coding as follows: [[Image:800px-Cygnus X-1.jpg|thumb|left|267px|…
File:800px-Cygnus X-1.jpg
By omitting a width specification, which is done by coding as follows: [[Image:800px-Cygnus X-1.jpg|thumb|right|…, then the image size defaults to registered editors’ preference setting. Many registered editors might chose 250 pixels. This is what they would see. Note how blurry the small background stars are; the ones underneath the black hole in the bottom right-hand corner almost disappear. Note too that our I.P. users don’t get a preference, so they see 180 pixels across (shown below).
File:800px-Cygnus X-1.jpg
By omitting a width specification, which is done by coding as follows: [[Image:800px-Cygnus X-1.jpg|thumb|left|…, then the image size regular I.P. users see (99.99% of Wikipedia’s readership) is only 180 pixels wide. Note how ridiculously small this default size is for our I.P. users; the black hole itself comprises a single pixel.

 
 
 
 
 
 

I set the background here to black so that bright white screens down wash out the stars.

Greg L (talk) 04:01, 5 May 2009 (UTC)I set the background here to black so that bright white screens down wash out the stars.
   The cryptic caption ″I set the background here to black so that bright white screens down wash out the stars.″ could make at least a little more sense than is apparent to me, if that quote (Is it attributable to Greg L, or to the creator of a graphic?) used ″down″ as an idiosyncratic spelling of ″ don' ″, which is a contraction of ″do not″ (a spelling that i think i've heard, tho i don't recall ever seeing in writing), even tho the grammar calls not for ″does not″ rather than ″do not″. YMMV, and may be more informative than mine.
--Jerzy•t 11:05, 6 May 2016 (UTC)

What a difference a couple of months makes

I almost got hit by a Fuzzball the other day, I am still trembling but I managed to shoot this photograph. A buckyball came along and annihilated it just in the nick of time. Goodmorningworld (talk) 22:25, 10 August 2009 (UTC)

When last I looked at this article (in May) it was promising but still in an uncomfortable limbo between different registers, from overly simplistic to highly arcane. Also, too much content then was copied nearly intact from various .edu websites. Now it's grown and progressed by leaps and bounds. I could see this article holding its own now against articles published in the better-quality popular science magazines. But I have another question.

From the above discussions, which I can follow but imperfectly, it appears that Fuzzball theory may be sufficiently different from classical black hole theory to be called independent, yet its predictions – although they are arrived at by different routes – ultimately do not differ from classical in important (or all important) respects. (Correct me if I am wrong.) If so, could this be something analogous to the different, non-canonical interpretations of quantum mechanics, where such alternatives as the Transactional Interpretation developed by John G. Cramer also end up making identical predictions to the Copenhagen interpretation? In other words, could this end up being fascinating in its own right but ultimately a case of "six of one, a half dozen of the other"?

Greg, if you could please convey my thanks to Dr. Mathur for taking the time help out us humble amateurs, I appreciate it very much.Goodmorningworld (talk) 21:30, 10 August 2009 (UTC)

  • Thanks for the accolades Goodmorningworld.

    In a nutshell: no; this is not an issue of “you can look at a moving magnetic field cutting across a conductor as being just the same as a moving conductor cutting across a magnetic field.”

    Classic black hole theory long held that the volume below an event horizon contained nothing whatsoever (when there is no in-falling matter-energy (mass) to complicate the picture) and it was devoid of structure all the way until you got to its very center. All its mass was thought to be concentrated into a zero-dimension singularity at the very center. All quantum information was thought to be utterly squashed out of all existence. The singularity’s volume was utterly and truly zero. This classic view violated many aspects of physics, not the least of which was the law of reversibility. The density of a singularity (infinite) exceeded even the Planck density (5.155×1096 kg/m3), which is the greatest mass density that has any meaning in polite physics. Yet…

    Physicists and mathematicians simply shrugged their shoulders and accepted this classic view of black holes, notwithstanding all its shortcomings. Why? Because no one had proposed a theory to circumvent the dilemma; there was no model to liberate physicists from a self-referential mental trap: that once you get beyond the escape velocity of light, mass condenses until there is infinite spacetime curvature, which means there is zero volume, which means there is infinite density, which means there is infinite spacetime curvature, which means….

    The “Fuzzball” sub-theory of superstring theory breaks this nonsensical dog-chasing-its-tail problem by advancing a mechanism whereby ordinary spacetime that is capable of comprising a vacuum can warp no further than the escape velocity of light. The theory holds that the entire region within the event horizon is filled with a ball of strings. The internal properties of fuzzballs are, today, not well understood. What is well understood about the theory is that in-falling mass, instead of falling past a region of no-return on its way to a singularity, simply falls onto the physical surface of a fuzzball, which is located exactly at the black hole’s event horizon. Fuzzball theory has mathematic beauty (the superstring calculations produce radii that precisely match Schwarzschild radii); it solves the intractable problems that singularities have long posed for physics; and it is a black & white, very tangible difference from the classic view of black holes as singularities surrounded by an emptiness that is totally devoid of any quantum structure.

    In all other respects, a fuzzball is a black hole: it warps spacetime just the same and effects everything else that is at least several Planck lengths from its surface just the same as a classic black hole. To that extent, you are right; a fuzzball does not differ from classic black holes. However, at the quantum level, they are very different. Fuzzball theory is simply thought by its proponents to be the true quantum description of black holes. Moreover, the theory purports that its assertions are testable via the imprinting a fuzzball would have on Hawking radiation.

    The important thing to remember here is that because of the extreme warping of spacetime, the region of quantum scrutiny is no longer constrained to a zero-dimensional singularity; it is now 40+ km in diameter. This notion—that quantum effects can collectively grow to macro proportions—should be no more unfamiliar of a phenomenon than a magnet, which, due to its huge collective of shared electron spins, is a quantum phenomenon grown to such macro proportions that we humans can perceive the virtual photons (the force carrier for electromagnetism) with our hands. Superconducting electrical currents are another that comes to mind. Helium II is yet another. Whenever you back out the kinetics of heat, matter increasingly takes on the wave properties of the energy it is comprised of. In fact, whenever you don’t poke and probe at matter, it tends to revert to an energy wave; check out Physics World’s “Probing the limits of the quantum world”, which is an extraordinarily well-written account of how not only photons can be made to create interference patterns using interferometers, but molecules as large as 1632-dalton fluorinated buckyballs can be made to exhibit quantum interference (the molecules, as waves, simultaneously go through both slits) whenever you don’t “poke” at them or cause them to leak information that could potentially reveal “which slit” they go through. The article explains how the implications of these experiments challenge the human perception of reality. That matter is really just waves of energy can be demonstrated with table-top experiments; we are not dependent upon abstract formulas like E = mc2 to understand how intertwined matter and energy truly are. And that strings (energy waves) have some definite minimum volume keyed to the escape velocity of light should surprise no one. That fuzzball theory solves nasty violations of fundamental laws of physics posed by singularities should make it downright easy to accept it. I rather hope that fuzzball theory might one day help explain why the speed of light has that particular magnitude.

    There is much more theoretical work on fuzzball theory being performed by many other researchers; the field of fuzzball theory is rapidly advancing and it is filling in gaps in the discipline of black hole thermodynamics. In my mind, fuzzball theory is like when Newton used a glass prism to refract white light into a spectrum: Hmmm… something new. Over a century later, William Herschel put a thermometer off both ends of the visible spectrum and their temperatures rose. The prism instantly explained a lot about light and uncovered much more for others to discover and ponder upon. Same here. Like Dr. Mathur wrote, no one really knows what the properties are like inside a fuzzball. Accordingly, there is large amount about timespace and fuzzballs yet to be discovered.

    I’ll pass along your words of appreciation to Dr. Mathur on the next occasion I have to communicate with him.

“Somewhere, something incredible is waiting to be known.”

 Carl Sagan

Greg L (talk) 18:40, 11 August 2009 (UTC)
Greg, thank you for taking the time to patiently explain to me again what is already explained in the article. What can I say, I am dense :-) And so I appreciate someone who does as the captain on the fishing boat where I served as a deck hand, who said to me, "I have told you this before but it does not matter, I will tell you again… and again… a thousand times, until you understand." (No, he was not throttling me at the same time, that is just an ugly rumor :-) ) Goodmorningworld (talk) 11:11, 12 August 2009 (UTC)
  • No need for the apology. I’ve got a pretty good hunch you skimmed the article; more interested in the nature of the dispute than in really understanding the subject in depth on your first go-around. Either that, or you skimmed the arcane dispute here on this page, not appreciating how utterly incompatible the above I.P. editor’s views are with the central tenet of fuzzball theory: a fuzzball has a physical surface that in-falling matter crashes into and, therefore, the entire region within the event horizon is filled with mass.

    A fuzzball is like an extra-dense neutron star, only its neutrons have decomposed or “melted.” A fuzzball can be thought of as the ultimate in degenerate matter. Greg L (talk) 17:31, 12 August 2009 (UTC)

    P.S. That last paragraph, above, is actually pretty good at giving a nutshell overview of what the hell a fuzzball is; I’m half-tempted to use it in the article. Except that would be editorializing beyond the bounds of citeable material and I’m not positive it is accurate. I’d have to go back to Dr. Mathur for a sanity check, and I’ve badgered him enough for the moment.

    My last go-around with Dr. Mathur was over the notion that a singularity could retain the property of angular momentum (and that Hawking radiation could reveal it). This issue is the second bullet point in Issues to double-check, above. Angular momentum derives its magnitude from the sum of the kinetics of the in-falling particles, which is all just thermodynamics (quantum information) that—in my mind—ought to vanish in a zero-dimensional singularity with zero volume. Angles and angular momentum are properties that occur with respect to a 3-dimensional, XYZ coordinates reference frame; “something” that has zero dimensions shouldn’t, in my mind, be able to spin. Or, said another way, a rod measuring two Planck lengths long can certainly tumble end-over-end. A *spot* measuring one Planck length in diameter would have a tough time being thought of as spinning. It’s double-tough to think of something with zero dimensions (not even one Planck length in diameter) as being able to spin with respect to 3-D space.

    I haven’t received a response to my second e-mail to him on this issue. I think my questions on this issue put him in the unfortunate position of attempting to support a detail about an object (a singularity) that neither of us think makes any sense from the get-go. Greg L (talk) 20:09, 12 August 2009 (UTC)

  • P.P.S. I asked Dr. Mathur whether this sentence was correct:

A fuzzball is like an extra-dense neutron star, only its neutrons have decomposed or "melted" to liberate the quarks (strings) they are comprised of. A fuzzball can be thought of as the ultimate in degenerate matter.

He responded (“Simple description”, August 13, 2009 10:29:13 AM PDT) that it was correct. I’ve updated the article accordingly. Greg L (talk) 17:55, 13 August 2009 (UTC)
Then what is the difference to a quark-gluon plasma? Also, if a Fuzzball is a better description of a black hole than a singularity but the singularity comes out of General Relativity (GR), is the Fuzzball the first stone to make a dent in the edifice of GR? Also, how much buck could a fuzzy buck if a buzzy foot bucked wood? Goodmorningworld (talk) 22:28, 18 August 2009 (UTC)
  • Oh, that probably clarifies the matter i addressed in a reply some minutes ago at the end of #Fixed image sizes: ″Duknow″ is no doubt a similar idiosyncratic spelling of ″[I]'dunno″, for the typical slang that means ″I don't know″.
    --Jerzy•t 11:17, 6 May 2016 (UTC)

Mathematically speaking?

Section Physical characteristics, has a:

mathematically speaking, infinitely far from infinite density.

While being a rhetorically pleasing statement, mathematically it reads as

infinity minus infinity

which is just "whatever", up to and including infinity itself. The statement fails to make sense, mathematically speaking. Rursus dixit. (mbork3!) 20:51, 4 December 2010 (UTC)

The phrase…
Though such densities are almost unimaginably extreme, they are, mathematically speaking, infinitely far from infinite density…
…is correct and is not equivalent to stating this:
infinity minus infinity.
One might think that since the set comprising the integer numbers is infinite in size, the set of even integers must be some sort of “half-infinity.” Alas, both sets are equally infinite. The best mathematically true analogy I can advance to help make this concept clear is to take the inverse of density (specific volume), as follows:
Though such volumes are exceedingly compact for a star, they are, mathematically speaking, infinitely larger than zero volume.
In fact, any volume, even a cubic Planck length, is infinitely larger than zero volume. Greg L (talk) 00:53, 6 July 2017 (UTC)

Current black holes or their future state?

I've been reading the fuzball FAQ (not understanding much, ofc), and I cannot understand a crucial point – is this description supposed to be correct for astronomical black holes today, or is it about black holes the way they will become after the strings in the matter relax into a typical state, which would happen in up to circa 10^60 years, an unimaginably far future from which the time when the last protons decayed and the last bits of matter were eaten up by black holes is essentially as far into the past as it is a remote future from now? Because, the FAQ seems to state that on the timescale of the crossing of the horizon by a piece of matter – ie any timescale approachable by humans – the classic description is pretty much OK? He states that the time for 'ergodisation' of a black hole can be up to 30% of its 'lifespan', which is to say up to within an order of magnitude from it. But one section, about quantum tunneling, looks like it implies it might happen much sooner. If this description still admits something like a light-horizon (he does stress there is no horizon but maybe the term has some additional meaning in terms of geometry than just light not being able to come out; again not sure how else to make sense of this) and all the mass in something on the order of planck length as the state of an astronomical black hole of the typical age of existing stellar remnants, that seems like quite different from the imperession I got from the article. 82.132.66.18 (talk) 12:31, 11 January 2011 (UTC)

Sorry about getting back to you six years later. Time flies when you're having fun.
Dr. Mathur’s theory of fuzzballs purports to describe the nature of black holes as they exist today. The theory unites the general theory of relativity with quantum theory, which is a good thing. It also rids the universe of masses with zero volume, which is an exceedingly good thing since it rids the mathematicians’ work of pesky infinities, like infinite density, infinite distortion of spacetime, and escape velocities infinitely greater than the speed of light.
Why is that a good thing? Because mathematicians, like most people in academia, must publish to make their next dime or perish. This pressure makes them do things like publicly declare that the universe appears to be fouled up beyond all comprehension because they’re looking at a formula on their chalkboards featuring a divide-by-zero term. Anytime mathematicians declare that their formulas prove that nature has a paradox or is doing impossible things, they might be writing their formulas correctly but they are obviously missing a piece of new physics and the accompanying mathematics.
I don’t know if the theory of fuzzballs is correct, but it is appealing because if resolves a number of deeply troubling theoretical interpretations of the natural world. I think that because the theory of fuzzballs is predicated in string theory, it encounters resistance because string theory posits lots of counterintuitive “extra dimensions” to space beyond the three we can naturally intuit. I personally believe one can properly view these extra dimensions as being equivalent to “different ways energy can vibrate”; akin to how complex molecules have different degrees of freedom in the way they can vibrate with kinetic energy. Greg L (talk) 01:52, 6 July 2017 (UTC)

The Start

Just started the article on Fuzzballs, gave the bare essential infomation concerning the idea. Any help is welcome as this can be quite an extensive article that delves into many different cosmology ideas, at the moment I am relying on outside links but in the future I would rather not. 11:25, 21 January 2005‎ Jordan14 — Preceding unsigned comment added by Jordan14 (talk • contribs) 11:25, 21 January 2005 (UTC)

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