> As Mark Twain said, “A lie can travel around the world and back again while the truth is lacing up its boots.” Actually he probably didn’t say that—but everyone keeps saying he did, illustrating the point perfectly.
It was Gandalf who said that of course. And before you try to contradict me, let me point out that Gandalf is a wizard that has no need to bother with silly things like spacetime continuity.
> In conclusion, there exists a family of expressions contrasting the dissemination of lies and truths, and these adages have been evolving for more than 300 years. Jonathan Swift can properly be credited with the statement he wrote in 1710 [(that does not mention footwear yet)].
You have to remember the "one particle in the pair fails to escape the event horizon" explanation is a simplification of the alleged reality, which is the scattering of particles (or fields) in the presence of an event horizon. As far as I know there is no intuitive, non-mathematical way to describe this accurately, so science communicators of all stripes tend to approximate it in ways that can mislead the audience.
The man himself (Hawking) said: "One might picture this negative energy flux in the following way. Just outside the event horizon there will be virtual pairs of particles, one with negative energy and one with positive energy. It should be emphasized that these pictures of the mechanism responsible for the thermal emission and area decrease are heuristic only and should not be taken too literally."
That one's a big white lie of how Hawking radiation works. It's not even an approximation, just a far-fetched metaphor that Hawking made up, presumably to satisfy science journalists.
> It would also mean that quantum field theory in curved spacetime can only be consistent if baryon number fails to be conserved! This would be utterly shocking.
Is it really shocking (today)? I mean, isn't this a logical consequence of Hawking radiation for black holes? I thought we were shocked by this a long time ago, but now we're ok with it. The authors of the paper in question may very well be wrong in their calculations (I can't say), but this blog post doesn't smell good to me because of doubtful statements like these, passed off as so obviously true that you must be an idiot not to agree. That kind of emotional writing does not become someone whose profession should focus on scientific persuasion.
From Wikipedia [0], itself citing Daniel Harlow, a quantum gravity physicist at MIT:
> The conservation of baryon number is not consistent with the physics of black hole evaporation via Hawking radiation.
>That kind of emotional writing does not become someone whose profession should focus on scientific persuasion.
What you'd probably prefer reading is one of the sources John Carlos Baez cites [0]:
Comment on “Gravitational Pair Production and Black Hole Evaporation”
Antonio Ferreiro1, José Navarro-Salas, and Silvia Pla
Where they take the equation used in the paper, and outline how there is a better way than using that equation
"... is obtained to the lowest order in a perturbative expansion, while the standard way to obtain the non-perturbative Schwinger effect using the weak field approximation is to perform a resummation of all terms"
and how the one in the paper being critiqued can't handle situations arising from electromagnetic cases, much less the gravitational one properly. These are the statements Baez makes but the cited paper gives in a much more professional tone and method.
>> if baryon number fails to be conserved! This would be utterly shocking.
> Is it really shocking (today)?
Moreover, there are a few experiments that try to measure the proton decay (that would break the baryon number conservation.) They are run on Earth, far away form any black hole. For now, all of them failed to find a decay, and the conclusion is that the half life of protons is at least 2.4E34 years. https://en.wikipedia.org/wiki/Proton_decay#Experimental_evid...
> The conservation of baryon number is not consistent with the physics of black hole evaporation via Hawking radiation.
There are other black hole models that can conserve these quantum numbers!
Speaking of things that are so obviously true that you must be an idiot not to agree, there are statements so obviously false that you have to be an idiot to agree: People keep repeating the nonsense put out by Penrose, which require non-physical timelike infinities to work.
The current "pop science" (nearly science fiction) statement is that it is possible to fall into a black hole and there is "nothing special" about the event horizon.
Quite often, just one paragraph over, the statement is then made that an external observer will never observe the victim falling in.
The two observers can't disagree on such matters!
To say otherwise means that you'd have to believe that the Universe splits (when!?) such that there are two observers so that they can disagree. Or stop believing in logic, consistency, observers, and everything we hold dear as physicists.
This is all patent nonsense by the same person that keeps insisting that brains are "quantum" despite being 309K and organic.
If the external observer doesn't observe the victim falling in, then the victim never falls in, full stop. That's the objective reality.
Penrose diagrams say otherwise because they include the time at infinity, which is non-physical.
Even if the time at infinity was "reachable", which isn't even mathematically sound, let alone physically, Hawking radiation is a thing, so it doesn't matter anyway: Black holes have finite lifetimes!
There is only one logically consistent and physically sound interpretation of black holes: nothing can ever fall in. Inbound victims slow down relative to the outside, which means that from their perspective as they approach the black hole they see its flow of time "speed up". Hence, they also see its Hawking evaporation speed up. To maintain consistency with outside observers, this evaporation must occur fast enough that the victim can never reach any surface. Instead, the black hole recedes from them, evaporating faster and faster.
This model (and similar ones), can preserve all quantum numbers, because there is no firewall, no boundary, nothing to "reset" quantum fields. Everything is continuous, consistent, and quantum numbers are preserved. Outside observers see exactly what we currently expect, black holes look and work the same, they evaporate, etc...
It's true, that paper is nonsense. There's not really much else to say. Preprint servers sometimes publish the sort of stuff that wouldn't pass peer review. (Remember that S.Korean "superconductor" from about two years ago!?) The press should be cautious when writing about it.
There's an issue this highlights and it's not that the original authors were stupid so much as there's clearly a lot of knowledge held in silos.
That's not a good thing if your goal is to advance everyone's knowledge. Whatever is going on in academia is failing relatively closely related fields which is not good.
Is it really that siloed? The condition mentioned in the article (there being a global timelike Killing field) is discussed in all introductory texts on quantum field theory in curved spaces, it's even present in the first few paragraphs of the relevant Wikipedia article[1]. Even if it doesn't apply here, the authors ought to have mentioned why not.
I don't think they were stupid per se, nor malicious, but perhaps cavalier in pushing a result with such unexpected consequences without getting a consult.
It certainly wasn't in "silos", it's all on arxiv!
But yes: the world is complicated and it's easy to make mistakes outside your core field. The point of the scientific process is to get things in front of eyeballs who can spot the mistakes, c.f. the linked blog post. Then everyone fights about it or points and laughs or whatever, and the world moves on. The system worked.
What the process is not good at is filtering new ideas before people turn them into news headlines. And sure, that sucks. But it's not a problem with "academia failing", at all. The eyeballs worked!
Well, there's another aspect which is that the original authors and pop-sci journalists don't seem to be able to understand where they went wrong or how outrageous their claims are, precisely because their jobs depend on not understanding. The could have corrected it. We could not still be circling this drain 2 years later, but we are.
I don't think it's quite that, since the eventual goal is to publish, not only publicly, but as publicly as possible. More like it seems like everyone tends to hold their cards quite close to their chest until the moment of pre-print publication. Which means you can be working on something that someone could have told you months or years ago you have a problem.
The scientific equivalent of polishing a branch before making a pull request, only to be told "this has a huge memory leak and moreover what you want already works if you use this other API".
I'm not really sure there's a human-scale solution: the research landscape is so vast that you can't connect everyone to everyone else and have everyone in need of valuable input get it, and have everyone able to give it not be inundated with half-baked rubbish. Even if you assume everyone from the top to bottom has pure motivations and incentives for doing the research in the first place (in the pull request analogy CVE spammers, for example).
Perhaps not having the universities themselves so keen for PR that they'll slap a press release together about anything that looks clickable without due diligence would at least prevent making a public spectacle outside of the academic circle now and then, but it wouldn't solve the fundamental issues.
> There's an issue this highlights [...] there's clearly a lot of knowledge held in silos.
I think the real issue this highlights -- which is something everyone knows and still everyone does -- is that people love to spread and discuss sensational stories, and no one likes to hear naysayers ruining the fun.
Look the discussion of the original story here in HN[1]. There's a comment by A_D_E_P_T way down in the discussion explaining why the paper is nonsense and pointing to one of the replies objecting to it mentioned in the article from this post. That comment was downvoted by HN readers. I know because it was greyed out when I upvoted it days ago.
So there's no knowledge silo -- us simple folk just want to discuss the newest breakthrough without looking too hard, because that spoils the fun.
I think it's just an intractable problem at this point. There's probably millions of physicists on Earth. Everyone working in a company knows just how hard it is to get even hundreds of people to agree and read and understand the same things.
The fact is, there are just too many people doing too many things. When any technical paper sounds like gobblygook to even people in the same field but in a different specialty, it's no surprise this happens, especially when coupled with the modern pressure to scientifically publish and modern "journalism" trends.
99.999999999% of people do not have enough knowledge to even dream of beginning to understand a majority of research. Adults can barely read, much less be able to pass Calc 1.
A Lot of these physics papers are interesting but ultimately just noise. An untested Theory is NOT fact, it's just someone (with or without a PhD) pulling something out of their arse that might explain things. Most of cosmology and physics is still theory (even the big bang, and string theory) and even if 90% of theory fits facts, they could still be wrong. I am seeing more and more of these un-testable theories, built on other un-testable theories, citing other un-testable theories, this is why theoretical physics is in a crisis IMHO.
MY mother and father also have an untested theory that explains all this too it's called "God", most Sci-Fi authors have plenty, and I am sure AI's will soon add to this pile.
Kudos to those scientists that create testable papers or experimentally prove stuff.
Is there a simple way to understand why massive objects don't radiate gravitationally? Accelerating observers see a bath of thermal radiation via something called the Unruh effect. If you're standing on a planet, you're accelerating under gravity, and therefore don't you see Unruh radiation? Does this have any connection to Hawking radiation?
I'm just learning this stuff so the details are hazy, bu my understanding is that there's a difference between spacetime curvature and spatial curvature. You can have a hyperbolic spacetime while at the same time having a flat three-dimensional spatial section of it.
It's not an assumption that space is flat. GR doesn't specify the global space curvature, so it's possible that it has a globally negative or positive curvature, but so far there's no evidence of any.
In black holes we have essentially a "loss of a dimension" (it's a much bigger story to explain what that even means, that I won't attempt here), so it might be the case that the three-quark arrangement known as 'baryons' only forms according to number of space dimensions (3D == 3 Quarks), making baryons only happen in 3D, so that when stuff reaches an event horizon, the quarks rip apart and rearrange into something where there's simply no such thing as a baryon (i.e. in 2D space). I'm someone who thinks the 'surface' of an event horizon is where the laws are preserved, and that the singularity or even perhaps the entire interior inside black holes may simply not exist at all.
Much of where Relativity "breaks" spacetime (i.e. problems with infinities and divide-by-zero) can be solved by looking at things as a loss of a dimension. For example, length contraction is compressing out a dimension (at light speed), and also time dilation (at event horizons, or light speed) is a removal of a dimension as well. Yes, this is similar to Holographic Principle, if you're noticing that. In my view even Lorentz equation itself is an expression of how you can smoothly transform an N-Dimensional space down to an (N-1)-Dimensional space, which happens on an exponential-like curve where the asymptote is reached right when the dimension is "lost". I think "time" always seems like a special dimension, no matter what dimensionality you're in, because it's the 'next one up' or 'next one down' in this hierarchy of dimensionality in spaces. This is the exact reason 'time' in the Minkowski Space distance formula must be assigned the opposite sign (+/-) from the other dimensions, and holds true regardless of whether you assume time to be positive v.s. negative (i.e. called Metric Signature). This of course implies our entire 4D universe is itself a space embedded in a larger space, and technically it's also an "event horizon" from the perspective of higher dimensions.
> I'm someone who thinks the 'surface' of an event horizon is where the laws are preserved,
I don't think this is a good way to think it. If black hole is big enough, there is nothing strange happening in the event horizon, no significant length contraction, nothing.
> I'm someone who thinks the 'surface' of an event horizon is where the laws are preserved, and that the singularity or even perhaps the entire interior inside black holes may simply not exist at all.
Sounds tempting, but then what happens at the transition : when a sphere of matter gets just a little bit too dense ?
Anyone that predicts an event that far out in the future let alone 100 years out I would bet against any day of the week. This is couple trillion of trillions years using physics no way of proving
Ok, we all understand the ancient problem and its current manifestation.
But what can be done? Science is not supposed to be the realm of disinformation, but it seems to have no real defenses. People are being paid to lie, no one is being paid to say they are liars, and from the outside scientific dispute looks a lot like politics, so scientists lose credibility by association.
This is partly why I roll my eyes when people who don't do research in a field start telling me about the "studies [they] found" while researching a topic. Unless you know the field and the research methods and have actually practiced them, reading studies is pointless, because you're too ignorant to evaluate them.
> As Mark Twain said, “A lie can travel around the world and back again while the truth is lacing up its boots.” Actually he probably didn’t say that—but everyone keeps saying he did, illustrating the point perfectly.
In a classic case of the Baader-Meinhof phenomenon, I recently read "The Truth" by Terry Pratchett, which repeatedly makes reference to that phrase, and I am now noticing it everywhere, whereas previously I can't recall being aware of it at all.
White dwarfs and neutron stars are generally considered "dead stars", since they no longer have active fusion processes. But they do radiate from energy left over from the star's "death". (Mostly thermal energy for a white dwarf, for neutron stars there is also a lot in angular momentum and the spinning magnetic field.) In theory, they will eventually radiate all of their energy away and become black dwarfs or cold neutron stars, but IIRC, that would take longer than the current lifetime of the universe.
I second that. A more accurate title would be "Only black holes emit Hawking radiation".
AFAIK everything above above absolute zero radiates, which effectively means that everything radiates. Black holes would be an exception if it wasn't for Hawking radiation.
In addition, (stellar) black holes are dead stars. Or at least, that's one way to see them.
Not if you know the reputation of John Baez: Anyone familiar with him or his writings would know without hesitation that he understands black-body and E&M radiation, so his choice of title is clearly meant to be provocative.
It says to the reader "I wonder what he means?" To this reader, I'll also say that he delivered a terrific blog post.
[+] [-] BlueTemplar|9 months ago|reply
It was Gandalf who said that of course. And before you try to contradict me, let me point out that Gandalf is a wizard that has no need to bother with silly things like spacetime continuity.
P.S.: https://quoteinvestigator.com/2014/07/13/truth/
> In conclusion, there exists a family of expressions contrasting the dissemination of lies and truths, and these adages have been evolving for more than 300 years. Jonathan Swift can properly be credited with the statement he wrote in 1710 [(that does not mention footwear yet)].
[+] [-] gruturo|9 months ago|reply
Both virtual particles-antiparticles survive (and promptly disappear because one didn't just cross an event horizon).
[+] [-] EA-3167|9 months ago|reply
The man himself (Hawking) said: "One might picture this negative energy flux in the following way. Just outside the event horizon there will be virtual pairs of particles, one with negative energy and one with positive energy. It should be emphasized that these pictures of the mechanism responsible for the thermal emission and area decrease are heuristic only and should not be taken too literally."
[+] [-] Sharlin|9 months ago|reply
[+] [-] cvoss|9 months ago|reply
Is it really shocking (today)? I mean, isn't this a logical consequence of Hawking radiation for black holes? I thought we were shocked by this a long time ago, but now we're ok with it. The authors of the paper in question may very well be wrong in their calculations (I can't say), but this blog post doesn't smell good to me because of doubtful statements like these, passed off as so obviously true that you must be an idiot not to agree. That kind of emotional writing does not become someone whose profession should focus on scientific persuasion.
From Wikipedia [0], itself citing Daniel Harlow, a quantum gravity physicist at MIT:
> The conservation of baryon number is not consistent with the physics of black hole evaporation via Hawking radiation.
[0] https://en.m.wikipedia.org/wiki/Baryon_number
[+] [-] AlecBG|9 months ago|reply
It's bloody John Baez, the man knows his stuff.
On you actual point, it is shocking because its claimed that baryon number is not conserved without black holes getting involved
[+] [-] molticrystal|9 months ago|reply
What you'd probably prefer reading is one of the sources John Carlos Baez cites [0]:
Comment on “Gravitational Pair Production and Black Hole Evaporation” Antonio Ferreiro1, José Navarro-Salas, and Silvia Pla
Where they take the equation used in the paper, and outline how there is a better way than using that equation
"... is obtained to the lowest order in a perturbative expansion, while the standard way to obtain the non-perturbative Schwinger effect using the weak field approximation is to perform a resummation of all terms"
and how the one in the paper being critiqued can't handle situations arising from electromagnetic cases, much less the gravitational one properly. These are the statements Baez makes but the cited paper gives in a much more professional tone and method.
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13...
[+] [-] gus_massa|9 months ago|reply
> Is it really shocking (today)?
Moreover, there are a few experiments that try to measure the proton decay (that would break the baryon number conservation.) They are run on Earth, far away form any black hole. For now, all of them failed to find a decay, and the conclusion is that the half life of protons is at least 2.4E34 years. https://en.wikipedia.org/wiki/Proton_decay#Experimental_evid...
I found an old article by quantamagazine explaining one of the experiment. It's a huge pool of very pure water and a lot of detectors. No black hole required. https://www.quantamagazine.org/no-proton-decay-means-grand-u... (HN discussion https://news.ycombinator.com/item?id=13201065 )
[+] [-] pfdietz|9 months ago|reply
[+] [-] jiggawatts|9 months ago|reply
There are other black hole models that can conserve these quantum numbers!
Speaking of things that are so obviously true that you must be an idiot not to agree, there are statements so obviously false that you have to be an idiot to agree: People keep repeating the nonsense put out by Penrose, which require non-physical timelike infinities to work.
The current "pop science" (nearly science fiction) statement is that it is possible to fall into a black hole and there is "nothing special" about the event horizon.
Quite often, just one paragraph over, the statement is then made that an external observer will never observe the victim falling in.
The two observers can't disagree on such matters!
To say otherwise means that you'd have to believe that the Universe splits (when!?) such that there are two observers so that they can disagree. Or stop believing in logic, consistency, observers, and everything we hold dear as physicists.
This is all patent nonsense by the same person that keeps insisting that brains are "quantum" despite being 309K and organic.
If the external observer doesn't observe the victim falling in, then the victim never falls in, full stop. That's the objective reality.
Penrose diagrams say otherwise because they include the time at infinity, which is non-physical.
Even if the time at infinity was "reachable", which isn't even mathematically sound, let alone physically, Hawking radiation is a thing, so it doesn't matter anyway: Black holes have finite lifetimes!
There is only one logically consistent and physically sound interpretation of black holes: nothing can ever fall in. Inbound victims slow down relative to the outside, which means that from their perspective as they approach the black hole they see its flow of time "speed up". Hence, they also see its Hawking evaporation speed up. To maintain consistency with outside observers, this evaporation must occur fast enough that the victim can never reach any surface. Instead, the black hole recedes from them, evaporating faster and faster.
This model (and similar ones), can preserve all quantum numbers, because there is no firewall, no boundary, nothing to "reset" quantum fields. Everything is continuous, consistent, and quantum numbers are preserved. Outside observers see exactly what we currently expect, black holes look and work the same, they evaporate, etc...
[+] [-] chrz|9 months ago|reply
[+] [-] cubefox|9 months ago|reply
Universe expected to decay in 10⁷⁸ years, much sooner than previously thought (phys.org) https://news.ycombinator.com/item?id=43961226 223 points, 5 days ago, 323 comments
[+] [-] A_D_E_P_T|9 months ago|reply
https://news.ycombinator.com/item?id=43964524
It's true, that paper is nonsense. There's not really much else to say. Preprint servers sometimes publish the sort of stuff that wouldn't pass peer review. (Remember that S.Korean "superconductor" from about two years ago!?) The press should be cautious when writing about it.
[+] [-] nimish|9 months ago|reply
That's not a good thing if your goal is to advance everyone's knowledge. Whatever is going on in academia is failing relatively closely related fields which is not good.
[+] [-] kmm|9 months ago|reply
I don't think they were stupid per se, nor malicious, but perhaps cavalier in pushing a result with such unexpected consequences without getting a consult.
1: https://en.wikipedia.org/wiki/Quantum_field_theory_in_curved...
[+] [-] ajross|9 months ago|reply
But yes: the world is complicated and it's easy to make mistakes outside your core field. The point of the scientific process is to get things in front of eyeballs who can spot the mistakes, c.f. the linked blog post. Then everyone fights about it or points and laughs or whatever, and the world moves on. The system worked.
What the process is not good at is filtering new ideas before people turn them into news headlines. And sure, that sucks. But it's not a problem with "academia failing", at all. The eyeballs worked!
[+] [-] kurthr|9 months ago|reply
Kinda classic. Kinda boring.
[+] [-] grues-dinner|9 months ago|reply
I don't think it's quite that, since the eventual goal is to publish, not only publicly, but as publicly as possible. More like it seems like everyone tends to hold their cards quite close to their chest until the moment of pre-print publication. Which means you can be working on something that someone could have told you months or years ago you have a problem.
The scientific equivalent of polishing a branch before making a pull request, only to be told "this has a huge memory leak and moreover what you want already works if you use this other API".
I'm not really sure there's a human-scale solution: the research landscape is so vast that you can't connect everyone to everyone else and have everyone in need of valuable input get it, and have everyone able to give it not be inundated with half-baked rubbish. Even if you assume everyone from the top to bottom has pure motivations and incentives for doing the research in the first place (in the pull request analogy CVE spammers, for example).
Perhaps not having the universities themselves so keen for PR that they'll slap a press release together about anything that looks clickable without due diligence would at least prevent making a public spectacle outside of the academic circle now and then, but it wouldn't solve the fundamental issues.
[+] [-] moefh|9 months ago|reply
I think the real issue this highlights -- which is something everyone knows and still everyone does -- is that people love to spread and discuss sensational stories, and no one likes to hear naysayers ruining the fun.
Look the discussion of the original story here in HN[1]. There's a comment by A_D_E_P_T way down in the discussion explaining why the paper is nonsense and pointing to one of the replies objecting to it mentioned in the article from this post. That comment was downvoted by HN readers. I know because it was greyed out when I upvoted it days ago.
So there's no knowledge silo -- us simple folk just want to discuss the newest breakthrough without looking too hard, because that spoils the fun.
[1] https://news.ycombinator.com/item?id=43961226
[+] [-] bmitc|9 months ago|reply
The fact is, there are just too many people doing too many things. When any technical paper sounds like gobblygook to even people in the same field but in a different specialty, it's no surprise this happens, especially when coupled with the modern pressure to scientifically publish and modern "journalism" trends.
[+] [-] unknown|9 months ago|reply
[deleted]
[+] [-] tekla|9 months ago|reply
[+] [-] boznz|9 months ago|reply
MY mother and father also have an untested theory that explains all this too it's called "God", most Sci-Fi authors have plenty, and I am sure AI's will soon add to this pile.
Kudos to those scientists that create testable papers or experimentally prove stuff.
[+] [-] qnleigh|9 months ago|reply
[+] [-] layer8|9 months ago|reply
> [in their 1975 paper] Ashtekar and Magnon also assume that spacetime is globally hyperbolic
Isn’t the modern assumption that spacetime is globally flat?
[+] [-] senderista|9 months ago|reply
[+] [-] griffzhowl|9 months ago|reply
It's not an assumption that space is flat. GR doesn't specify the global space curvature, so it's possible that it has a globally negative or positive curvature, but so far there's no evidence of any.
[+] [-] quantadev|9 months ago|reply
Much of where Relativity "breaks" spacetime (i.e. problems with infinities and divide-by-zero) can be solved by looking at things as a loss of a dimension. For example, length contraction is compressing out a dimension (at light speed), and also time dilation (at event horizons, or light speed) is a removal of a dimension as well. Yes, this is similar to Holographic Principle, if you're noticing that. In my view even Lorentz equation itself is an expression of how you can smoothly transform an N-Dimensional space down to an (N-1)-Dimensional space, which happens on an exponential-like curve where the asymptote is reached right when the dimension is "lost". I think "time" always seems like a special dimension, no matter what dimensionality you're in, because it's the 'next one up' or 'next one down' in this hierarchy of dimensionality in spaces. This is the exact reason 'time' in the Minkowski Space distance formula must be assigned the opposite sign (+/-) from the other dimensions, and holds true regardless of whether you assume time to be positive v.s. negative (i.e. called Metric Signature). This of course implies our entire 4D universe is itself a space embedded in a larger space, and technically it's also an "event horizon" from the perspective of higher dimensions.
[+] [-] nabla9|9 months ago|reply
I don't think this is a good way to think it. If black hole is big enough, there is nothing strange happening in the event horizon, no significant length contraction, nothing.
[+] [-] BlueTemplar|9 months ago|reply
Sounds tempting, but then what happens at the transition : when a sphere of matter gets just a little bit too dense ?
[+] [-] m3kw9|9 months ago|reply
[+] [-] w10-1|9 months ago|reply
But what can be done? Science is not supposed to be the realm of disinformation, but it seems to have no real defenses. People are being paid to lie, no one is being paid to say they are liars, and from the outside scientific dispute looks a lot like politics, so scientists lose credibility by association.
That's a real problem.
[+] [-] tbrownaw|9 months ago|reply
[+] [-] JohnMakin|9 months ago|reply
[+] [-] m3kw9|9 months ago|reply
[+] [-] globnomulous|9 months ago|reply
[+] [-] khanan|9 months ago|reply
[+] [-] lproven|9 months ago|reply
[+] [-] zabzonk|9 months ago|reply
[+] [-] dudeinjapan|9 months ago|reply
[+] [-] mlhpdx|9 months ago|reply
Well played.
[+] [-] frogulis|9 months ago|reply
[+] [-] deepsun|9 months ago|reply
[+] [-] unknown|9 months ago|reply
[deleted]
[+] [-] thayne|9 months ago|reply
White dwarfs and neutron stars are generally considered "dead stars", since they no longer have active fusion processes. But they do radiate from energy left over from the star's "death". (Mostly thermal energy for a white dwarf, for neutron stars there is also a lot in angular momentum and the spinning magnetic field.) In theory, they will eventually radiate all of their energy away and become black dwarfs or cold neutron stars, but IIRC, that would take longer than the current lifetime of the universe.
[+] [-] GuB-42|9 months ago|reply
AFAIK everything above above absolute zero radiates, which effectively means that everything radiates. Black holes would be an exception if it wasn't for Hawking radiation.
In addition, (stellar) black holes are dead stars. Or at least, that's one way to see them.
[+] [-] alienbaby|9 months ago|reply
[+] [-] jpmattia|9 months ago|reply
Not if you know the reputation of John Baez: Anyone familiar with him or his writings would know without hesitation that he understands black-body and E&M radiation, so his choice of title is clearly meant to be provocative.
It says to the reader "I wonder what he means?" To this reader, I'll also say that he delivered a terrific blog post.
[+] [-] davedx|9 months ago|reply