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In 1783, an English rector predicted black holes using classical mechanics
- marcodiego 5y agoSpeed of light can be calculated using only classical mechanics and experiments. Same for gravity and gravitational constant. Predicting relativistic effects of high speeds and huge masses that is another thing.
- diedyesterday 5y agoThe true black-hole which is dark and black because of its horizon and from which nothing can escape, belongs only and truly to Einstein's general relativity with its curvature of spacetime; This is true but only by coincidence and by some wrong reasoning (existence of an invariant and maximum speed was not known or assumed until special relativity); Also a dark star (because it's so massive, corpuscular light cannot escape it) is a very different thing than a black-hole with horizon (=light and nothing can escape because there is no spacetime path that leads to its outside); Probably this is why his work was not taken much seriously at the time, at least on this point;
- jagrsw 5y agoIsn't it a bit like getting to correct answer by incorrect reasoning? I was thinking that knowledge of how space curves in presence of high energies/masses and time/length dilation concepts are necessary to come to the conclusion that light will be slowed down beyond its speed in certain circumstances? Maybe a bit similar to e.g. Gordiano Bruno's claim that stars are similar to our sun, and there are planets around them, not on the basis of observations and data analysis but b/c of some relatively unrelated to astronomy philosophical reasoning. Also, alchemy :) (some concepts were right)
- vanderZwan 5y ago> (some concepts were right) I would expect a lot of incorrect past models of science and its precursors to still be based on (mostly) correct data, so bad guesses were still informed bad guesses at least.
- roywiggins 5y agoThe corpuscular theory of light was one of those theories that was wrong but useful. The successor wave theory was also wrong. It may turn out that general relativity is founded on incorrect reasoning ("God does not play dice" for one), but that matters much less than it being fantastically useful. The basic idea- if light interacts with gravity, if you pack enough mass into a region you will get a dark star- is correct. It just turns out that the interaction can't be described by treating light as little particles and calculating by Newton's equations. There's been lots of wrong-but-useful theories, like phlogiston or arguably luminiferous aether: https://thonyc.wordpress.com/2015/10/23/the-phlogiston-theory-wonderfully-wrong-but-fantastically-fruitful/ https://thonyc.wordpress.com/2015/10/23/the-phlogiston-theor...
- whatshisface 5y agoIt's not founded on incorrect reasoning, which would imply a logical inconsistency or error in the deductions, but it could be founded on false postulates. (A postulate is like an axiom except that it is held to be true in the real world, as opposed to being abstractly true.)
- sillysaurusx 5y agoThat's true of all science since the beginning of science.
- jetrink 5y agoI don't think the reasoning is incorrect. It went like this: 1. What if the motion of light is influenced by gravity, as suggested by Newton's theory of corpuscles? (It is, just not in the way he thought.) 2. And what if there are supermassive, super-dense objects? (Turns out there are.) 3. Then light would be unable to escape such objects. That's pretty remarkable in my opinion, and no more "wrong" in its way than Newton's theory of gravity which was also correct for the wrong reasons.
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- Moodles 5y agoI suppose it's impossible to ever really know what the true nature of reality is. We only have models which have an accuracy of x%. It's quite possible, dare I say likely, that e.g. quantum mechanics as we understand it today is just an approximate model of how things really are. I suspect that the fundamental nature of reality is probably at a scale too small to be testable anyway.
- AltoidsTin 5y ago> incorrect reasoning If you haven't already, check out the Demarcation Problem and work by Feyeraband. Physics is such a philosophically tenuous science that its theories are perpetually incorrect reasoning.
- pdabbadabba 5y agoWe should bear in mind that, if the history of science is any guide, in 250 years' time relativity will probably seem pretty badly flawed as well leading some future person to criticize our science for "getting to a correct answer by incorrect reasoning." (If we're lucky. It might just seem wrong.) So we'd do well to be charitable in crediting our predecessors' achievements.
- lapetitejort 5y agoRelativity will probably suffer the same fate as classical mechanics: true for small values of v. In relativity's case, the small value will probably be about 0.99999999c.
- pdonis 5y agoI don't know where you're getting this from. We have a relativistic quantum field theory of light itself.
- tsimionescu 5y agoGiven what we know today, it seems that it's much more likely that special relativity will remain more or less as we know it today (a good approximation for relatively flat regions of space-time and non-accelerating bodies), and that GR will be a good approximation for something like large regions of space-time and huge masses (where "large regions" may mean anything larger than a few Planck lengths, and "huge masses" may mean anything greater than a few micrograms).
- raattgift 5y ago> non-accelerating bodies Accelerated bodies in flat spacetime (Minkowski space) are well-described by special relativity. One can even calculate usefully in accelerated reference frames. https://en.wikipedia.org/wiki/Acceleration_(special_relativity) https://en.wikipedia.org/wiki/Acceleration_(special_relativi... The Unruh effect can happen in flat spacetime, for example, and is a useful check on Hawking radiation (in a black hole curved spacetime). It's also interesting in understanding the weak equivalence principle in detail; very loosely, a small-mass object can rest quietly on the surface of a non-compact, non-spinning, spherical mass eternally, while it is at least very difficult to keep the same small-mass object accelerating uniformly in flat spacetime for even fairly short (compared to say the age of the universe, which is hardly eternal) finite times.
- zinclozenge 5y agoNot really. You can predict gravitational light bending with newtonian physics and a corpuscular approach to light. It gives you half the value of the relativistic value because the assumption is that light as a wave is unaffected by gravity due to no gravity-EM coupling.
- IncRnd 5y agoWhat was the incorrect reasoning?
- Enginerrrd 5y agoI can't say for sure on this particular case, but the usual reasoning is this: Using Newtonian Mechanics (I'll skip the derivation.) you can calculate escape velocity as follows: v = sqrt(2GM / r) r is the distance to the center of mass, G is the usual gravitational constant and M is the mass of the body. So, now we can reason about an object whose escape velocity is c. c^2 = 2GM / r and rearranging a bit: r* = 2GM / c^2. Thus, IF we packed a mass M into the radius r*, we would have a Newtonian blackhole. It turns out, quite incredibly, that this r* is in perfect agreement with the swarzchild radius from a non-rotating blackhole calculated using general relativity. Exactly why these two are in such agreement has never been explained to me other than as a coincidence. But it's quite incredible since usually r^3 terms pop up prior to the event horizon (at the same radius) which make GR make different predictions about orbits. (Such as the precession of mercury)
- mr_toad 5y agoDoesn’t GR always agree with Newtonian gravity when objects aren’t accelerating?
- Enginerrrd 5y agoFamously, not quite. See https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury https://en.wikipedia.org/wiki/Tests_of_general_relativity#Pe...
- Beldin 5y agoWhat's "not accelerating" about going in an ellipse? Doesn't that imply constant (and varying) acceleration?
- soheil 5y agoQuantum Mechanics most likely is not the true explanation of what is going on either, but it sure as hell accounts for a lot of it and is why we have modern computers.
- bokchoi 5y ago"An Inquiry into the Probable Parallax, and Magnitude of the Fixed Stars, from the Quantity of Light Which They Afford us, and the Particular Circumstances of Their Situation." Paper titles were pretty awesome back in the day.
- HeckFeck 5y agoNot to menion lacking any pretention. It states the subject precisely. An honest straightforwardness with nothing to hide.
- Phiwise_ 5y agoA massive proportion of all titles were this way. Take a look at fictional novels or political pamphlets some time. They're just three sentence long summaries and they're all delightful.
- whatshisface 5y ago"Tribological behavior and wear mechanism of Ti/MoS2 films deposited on plasma nitrided CF170 steel sliding against different mating materials" "Which Milky Way masses are consistent with the slightly declining 5-25 kpc rotation curve?" "Characterization of systematic error in Advanced LIGO calibration in the second half of O3" Randomly found on arXiv and ADS. I'm not seeing a lot of pretention, dishonesty or imprecision.
- thebooktocome 5y agoDrift into machine learning and you'll soon find content-free meme titles like "Building Rome in a day" or "YOLO9000: Better, Faster, Stronger".
- dav_Oz 5y agoThe "dark star" hypothesis given a finite speed and momentum of light (particle nature) combining with the escape velocity of stars isn't impressive by itself. But his scientific reasoning and methods very much so. He carefully conjectured what could be observed e.g. binary stars in amassing data points. Naturally, in a logical progression, he looked for stars which behaved as if they were in a binary systems but the partner i.e. "dark stars" could not been seen because its mass would be so big that the finite speed of light couldn't "escape". Brilliant. He, also, inherited Cavendish his "torsion balance" apparatus for measuring the mass of the earth for what later became the famous "Cavendish experiment" yielding an accurate measurement of the gravitational constant. The experimental basis for the advancement into the nature of gravity. Quite impressive. And he did not yell about it or seemed to care about what nowadays would be called the "impact factor". His impact was quite of another nature.
- hirundo 5y agos/inherited/bequethed
- groos 5y agos/bequethed/bequeathed :-)
- tomrod 5y agoNot related to the discussion, but I love these verbal dualities. give/take inherit/bequeath and so forth! ------- What fantastic reasoning! I am constantly amazed at the early and current astronomers, able to work out fairly and increasingly accurate cosmological views from pinpoints of light.
- argomo 5y agoGive/take duality is significant in the study of proto-indo/european language. IIRC, some root words took opposite meanings in their descendent languages. Some have gone so far as to speculate that this suggests reciprocality was an important culture expectation around gift-giving in PIE society.
- akvashi 5y agoPretty cool that this black mathematician is getting recognition now!
- sillysaurusx 5y agoWhoa, he is indeed black: https://en.wikipedia.org/wiki/John_Michell https://en.wikipedia.org/wiki/John_Michell > There is no surviving portrait of Michell; he is said to have been "a little short Man, of a black Complexion, and fat". Awesome!
- whimsicalism 5y agoDon't know that we can really read contemporary understanding of the word black into this quote. I think given the context of England at the time, as well as the description of his family background, it is very unlikely that he was black.
- tarkin2 5y agoBetween statistics and the description of the man, I find it difficult to be as sure as you are.
- whimsicalism 5y agoIt wasn't until 1786 that the British government first employed one of the (relatively few) black men in a minor role, yet I'm supposed to believe based on a contemporary reading of this text (before "black" was nearly widely used to mean what it does today) that this (at least 3rd generation) British professor at Cambridge was black? Highly doubtful. I'm not sure what statistics you are basing off of. Here's a more reputable source than me: > An account apparently purports him to be "a little short man, of black complexion, and fat", though we have been unable to locate any specific contemporary source. However, such words even if used do not necessarily indicate he is of black-African descent, as the term can refer also to Spaniards, Italians, Greeks, Arabs, Ethiopians, or Jews. Jonathan Swift uses the expression "a tall, thin, very black man, like a Spaniard or Jew." In the given context it is almost certainly intended as a slight against Michell by painting him as something he was likely not. The Royal Society famously refused election to Jamaican scientist Francis Williams (1702-1770), on account of his complexion, and it almost certainly would not have elected a black man as early as 1760. Moses Da Costa became the first Jew elected to the Society in 1736, and a second was elected in 1747; the first female was not elected until 1945. The earliest black individual we could determine that attended Queens College, Cambridge was an American, Alexander Crummell, who graduated 1853.
- bsenftner 5y agoI can see an interesting and controversial entertainment series based on an alternative history retelling of Einstein, in his role as patent clerk, reading John Michell's work and that is the seed which inspires Relativistic Theory. Tie the work of Mitchell and his world to Einstein's. The juxtapositions of time and culture, British 1770's versus Germany's early 20th century would be quite entertaining on their own.
- legohead 5y agoHow does a black hole trap light if it's not by gravity, is it purely by space curvature?
- ketralnis 5y agoFrom a newtonian perspective you can imagine that gravity emits a force between all pairs of massive objects. That's a good way to look at it for small values of mass. It works pretty well on the scale of our whole solar system. This is what you're imagining when you say "not by gravity but by spacetime curvature". But gravity is spacetime curvature. It is manifested by changes to spacetime itself made by that mass. For very large values of mass (or density in this case) that newtonian approximation doesn't hold according to experiment. We need a different model and the model that we've found that works is that mass changes the shape of spacetime. Its presence changes the nature of straight lines and the paths that you can follow (geodesics). A black hole causes all possible paths of spacetime, paths that light must follow because it travels through spacetime, to point into the black hole https://en.wikipedia.org/wiki/Black_hole#Event_horizon https://en.wikipedia.org/wiki/Black_hole#Event_horizon Light must follow straight lines but because the space containing those lines is curved, there don't exist any of those lines that point outside of the black hole. Once you've crossed the event horizon, space itself doesn't have any straight lines that point outward, there are no paths that you can follow. It's even weirder than this because we're mostly familiar with motion through space so that's probably what you (and I) are imagining, but this is motion through spacetime. So really the correct thing to say is that there exist no 4-d paths that point outside of the black hole that are also in the future. And that's even weirder than it sounds because you asked about light specifically and light doesn't experience time the same way you and I do. So our intuitions and our ability to map reality to the nice charts that we're used to looking at are pretty limited here.
- legohead 5y agoVery cool answer, thank you!
- nyc111 5y agoThis must be the same John Michell who gave Henry Cavendish his pendulum to measure the density of the Earth : „Many years ago, the late Rev. John Michell, of this Society, contrived a method of determining the density of the earth, by rendering sensible the attraction of small quantities of matter; but, as he was engaged in other pursuits he did not complete the apparatus till a short time before his death, and did not live to make any experiments with it. After his death, the apparatus came to the Rev. Francis John Hyde Wollaston, Jacksonian Professor at Cambridge, who, not having conveniences for making experiments with it, in, the manner he could wish, was so good as to give it to me.„[1] [1] https://royalsocietypublishing.org/doi/10.1098/rstl.1798.0022 https://royalsocietypublishing.org/doi/10.1098/rstl.1798.002...
- johnklos 5y agoNot about the article's content, but about the interestingengineering.com web site: it sucks. It consumes 100% CPU, tries to play multiple videos, and takes hundreds of megabytes of memory. No, thank you.
- sbayona573 5y agoRead “English rectum predicted black holes” for a sec
- exporectomy 5y agoSeems like he wasn't a "lowly country rector" since he had a masters degree from Cambridge, was a member of the Royal Society and had many other scientific accomplishments. The rectorship was apparently just a perk that came with being a successful scientist. I wish bloggers wouldn't try to create a false impression of things like that. It's disinformation - intended to mislead the reader.
- deleted 5y ago[deleted]