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Dead Stars Don’t Radiate

johncarlosbaez.wordpress.com

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Re: Dead Stars Don’t Radiate

#131

Post by nothrabannosir »

jpmattia wrote: post #128
nothrabannosir wrote: post #123

Earlier quoted context omitted.

> It says to the reader "I wonder what he means?" This has become affectionately known as “click bait”. No disrespect to the pedigree of the clearly distinguished author.

Perhaps, but "Mathematical Physicists HATE when authors make THIS ONE ASSUMPTION!!1!" would be more click baity. I took it more as Baez writing for his physics audience.

Purely out of pedantic interest: is that a meaningful distinction, or is it just the same thing for a different audience? I'm reminded of chess youtubers who give similarly "click baity" titles to their videos which are only click bait to people who watch chess videos. Isn't it the same?

All the power to them by the way. It's the crushing power of the algorithm. No hard feelings, just something I've been wondering.

Re: Dead Stars Don’t Radiate

#132

Post by jpmattia »

nothrabannosir wrote: post #131
jpmattia wrote: post #128

Earlier quoted context omitted.

Perhaps, but "Mathematical Physicists HATE when authors make THIS ONE ASSUMPTION!!1!" would be more click baity. I took it more as Baez writing for his physics audience.

Purely out of pedantic interest: is that a meaningful distinction, or is it just the same thing for a different audience? I'm reminded of chess youtubers who give similarly "click baity" titles to their videos which are only click bait to people who watch chess videos. Isn't it the same? All the power to them by the way. It's the crushing power of the algorithm. No hard feelings, just something I've been wondering.

Well, you got me thinking about "What exactly is clickbait?"

So full disclosure: I've directly interacted with John Carlos Baez only in social media, with the topics as disparate as music and observational astronomy. My own QFT & GR background is grad course level but with little actual usage in my career. (I've done more solid-state + high-speed electronics work, with a bunch of programming as well.) With that background, and turning the pedantry dial up to 11:

To me, one distinguishing element of clickbait is that the post is ultimately disappointing. The usual M.O. for clickbait is that the website needs eyeballs for advertising, so they beef up a headline of an uninteresting article with the expectation of getting extra monetization compared to an honest headline.

I would venture a guess that he doesn't actually care about monetization, or really even extra clicks, with this post. The screenshot with the big red X through the popsci article sets the expectation pretty quickly, and the tone of the rest of the post is really a rant that mediocre science made it into PRL and then into the popular science literature. He explicitly calls out the popsci journalists for laziness, but in a clever (I'm pretty sure Mark Twain would approve of his name being taken in vain) and erudite (correct use of the subjunctive) way.

Would I have clicked on the title without seeing the authorship johncarlosbaez.wordpress.com? Maybe but I doubt it. There is so much bad popsci physics out there that I'm pretty trained to ignore obviously inadequate headlines. So on a scale of 1-10, I'd rate the click-baityness of the headline no more than a 3. He got me to click, but only because I knew it was his post.

As for others, the set of people who understand that Hawking radiation exists has nearly 100% overlap with those who know that black bodies and spinning magnets radiate, so for those folks who are in the set who are also unfamiliar with the author, perhaps it's more clickbaity.

[edit: And I can't believe you got me to write that many words on the clickbait philosophy. Have I been baited? :) ]

Re: Dead Stars Don’t Radiate

#133

Post by thayne »

jpmattia wrote: post #128
nothrabannosir wrote: post #123

Earlier quoted context omitted.

> It says to the reader "I wonder what he means?" This has become affectionately known as “click bait”. No disrespect to the pedigree of the clearly distinguished author.

Perhaps, but "Mathematical Physicists HATE when authors make THIS ONE ASSUMPTION!!1!" would be more click baity. I took it more as Baez writing for his physics audience.

> I took it more as Baez writing for his physics audience.

I have a degree in Physics with an emphasis in Astronomy, and my thought on reading the title was "that's absurd". Even if you somehow infer that "radiate" specifically means "emit hawking radiation" which I don't know how you would without more context, "dead stars" generally is considered to include black holes, which do emit hawking radiation.

Re: Dead Stars Don’t Radiate

#134

Post by jpmattia »

thayne wrote: post #133
jpmattia wrote: post #128

Earlier quoted context omitted.

Perhaps, but "Mathematical Physicists HATE when authors make THIS ONE ASSUMPTION!!1!" would be more click baity. I took it more as Baez writing for his physics audience.

> I took it more as Baez writing for his physics audience. I have a degree in Physics with an emphasis in Astronomy, and my thought on reading the title was "that's absurd". Even if you somehow infer that "radiate" specifically means "emit hawking radiation" which I don't know how you would without more context, "dead stars" generally is considered to include black holes, which do emit hawking radiation.

I wrote in the other reply:

> As for others, the set of people who understand that Hawking radiation exists has nearly 100% overlap with those who know that black bodies and spinning magnets radiate, so for those folks who are in the set who are also unfamiliar with the author, perhaps it's more clickbaity.

So according to my theory, you must in the set that understands Hawking radiation + black bodies + E&M, but not in the set familiar with Baez.

I worked hard on my theory, please don't let me down and be a counterexample. :)

Re: Dead Stars Don’t Radiate

#135

Post by ldunn »

mr_toad wrote: post #112
ldunn wrote: post #83

Earlier quoted context omitted.

Why wouldn't you be able to see your feet? Your head is also falling through the horizon (hopefully - otherwise you are going to be very unhappy), so the light from your feet doesn't need to escape the horizon for you to see it.

The horizon is the distance at which escape velocity is c. Closer to the centre, including your feet, the escape velocity is higher. Electrical impulses wouldn’t be able to travel from the bottom of your brain to the top, so you’d be unconscious anyway.

It is absolutely untrue that GR predicts that you would be knocked unconscious crossing the horizon. In fact one of the most fundamental aspects of GR (equivalence) predicts the exact opposite - there is no local experiment you can do as a freely falling observer to detect the horizon.

Re: Dead Stars Don’t Radiate

#136

Post by michaelmrose »

rubitxxx4 wrote: post #105
A_D_E_P_T wrote: post #47

lol, I wrote a very similar comment here a few days ago: 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.

Whether it’s nonsense or not, this quote in the critical assessment is concerning: > If I were a science journalist writing an article about a supposedly shocking development like this, I would email some experts and check to see if it’s for real. An attitude like that would have us all believing the earth is flat or that the sun revolves around the earth. After all, experts of the time believed both wrongly.

It is true that revolutionary theories may be both true and controversial but they are rarely friendless or obviously wrong to nearly all practitioners of the relevant fields and those theories are legion and without merit.

Without being up to date in the minutia of every field one will be ill disposed to judge which of 100 piles of nonsense extant at any given time are real discoveries and which bunkum and ones work as a journalist would be so compromised by the 1000 lies one spread that none should believe the one truth they uncovered.

I wouldn't credit anyone so stupid as not to consult ones peers.

Re: Dead Stars Don’t Radiate

#137

Post by michaelmrose »

boznz wrote: post #52
nimish wrote: post #4

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.

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, bui…

We call every model no matter how well founded a theory. An untested theory might be better called a hypothesis.

This mistake of language plays into the weirdos who opine we should disregard inconvenient ideas because they are just a theory failing to understand the difference between their own usage and the scientific usage.

Re: Dead Stars Don’t Radiate

#138

Post by bencyoung »

ldunn wrote: post #135
mr_toad wrote: post #112

Earlier quoted context omitted.

The horizon is the distance at which escape velocity is c. Closer to the centre, including your feet, the escape velocity is higher. Electrical impulses wouldn’t be able to travel from the bottom of your brain to the top, so you’d be unconscious anyway.

It is absolutely untrue that GR predicts that you would be knocked unconscious crossing the horizon. In fact one of the most fundamental aspects of GR (equivalence) predicts the exact opposite - there is no local experiment you can do as a freely falling observer to detect the horizon.

You can do plenty of experiments to see if you are falling, e.g. hitting the surface of a planet you are falling towards. The event horizon is a surface like any other with a location in space and you can definitely see when you hit it (it's the bit where no light is coming out). And once you've crossed it, literally no EM radiation can move further from the singularity

Re: Dead Stars Don’t Radiate

#139

Post by ldunn »

bencyoung wrote: post #138
ldunn wrote: post #135

Earlier quoted context omitted.

It is absolutely untrue that GR predicts that you would be knocked unconscious crossing the horizon. In fact one of the most fundamental aspects of GR (equivalence) predicts the exact opposite - there is no local experiment you can do as a freely falling observer to detect the horizon.

You can do plenty of experiments to see if you are falling, e.g. hitting the surface of a planet you are falling towards. The event horizon is a surface like any other with a location in space and you can definitely see when you hit it (it's the bit where no light is coming out). And once you've crossed it, literally no EM radiation can move further from the singularity

I agree that if you are freely falling and then you are suddenly not freely falling because you hit the surface of a planet and experienced a huge acceleration, you will notice. That doesn't have anything to do with anything I said, but it is undeniably true.

An event horizon is not like the surface of a planet - you will not be accelerated as you pass through it.

It is, once again, irrelevant that light cannot propagate outward once you're behind the horizon because, again, you are falling towards the center, and in particular you are falling through the future light cone of your feet. Please look at some spacetime diagrams if you do not believe me, preferably ones in Kruskal-Szekeres coordinates.

In GR spacetime is locally flat and for an inertial observer special relativity applies, up to tidal corrections which can be made arbitrarily small at the horizon by considering a suitably large black hole. This is a deep and important fact about GR. The idea that falling through the horizon causes you to suddenly not be able to see your feet anymore appears to obviously violate this basic principle, so if you think your assertion is true you should be able to explain why either this principle of GR is actually not true, or why your assertion does not actually violate this principle.

Re: Dead Stars Don’t Radiate

#140

Post by verzali »

m3kw9 wrote: post #93
thayne wrote: post #43

The title is... odd. 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 b…

He meant dead dead

Even dead dead stars radiate
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