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Experts Doubt the Sun Is Burning Coal (1863)

scientificamerican.com

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Re: Experts Doubt the Sun Is Burning Coal (1863)

#121

Post by jaggederest »

adrianN wrote: post #112
ufo wrote: post #64

Earlier quoted context omitted.

Actually, main thing that kelvin got wrong is that the Earth has a liquid mantle. Convection in the mantle means that the surface receives more heat from the interior and takes longer to cool down to the present temperatures. Radioactive decay inside the earth also adds to the age of the earth but not as much as the convection in the mantle does.

I don't understand how convection can increase the time to cool down. It seems to me that the higher temperatures closer to the surface facilitated by convection would lead to faster cooling.

Faster cooling, but smoother gradients. It means that if you go down a hundred miles, it will be warmer, but the entire center of the earth will be closer to the same temperature. If you assume a solid, you assume a certain constant thermal conductivity, as Kelvin did, even though with a liquid, that's not true. Basically, he assumed that the heat was diffusing slowly, and that it couldn't go above a certain temperature at the core (i.e. not a gas or liquid), and so you had hard limits on the total reservoir of heat in the planet and could calculate a linear fit on it. It turns out the effective thermal conductivity of the center of the earth is much higher than the thermal conductivity of e.g. continental crust.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#122

Post by a1369209993 »

DonHopkins wrote: post #95
hedora wrote: post #27

Earlier quoted context omitted.

It’s also the namesake of ethernet.

And before Ethernet, there was Chaosnet! https://en.wikipedia.org/wiki/Chaosnet Define by CHAOS ORDER: http://sv.svensson.org/SYSDOC%3BCHAORD

  > Data grams seem to have a bug that the two parties can never
  >  agree on whether they both agree that it really happened.  Am I losing?
Oh, hey, byzantine generals problem.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#124

Post by ardy42 »

AareyBaba wrote: post #90
philipkglass wrote: post #60

Here is the longer original article, scanned by Google Books and hosted by the HathiTrust project: "Age of the Sun -- Force and Heat" Scientific American Vol IX -- No. 7 August 15 1863 https://babel.hathitrust.org/cgi/pt?id=uva.x001601382&view=1...

Interesting to read. The Sun is referred to as 'he' and people were just beginning to understand how heat energy and mechanical energy could be transformed into one another. "He has enlightened our globe from one generation to another without any apparent diminution of strength, and we have formed the instinctive belief that no limit in the past or any in the future can be assigned to his functions. No proof of progr…

> The Sun is referred to as 'he'

I wonder if they picked pronouns for the planets in accordance with the associated gods of Greco-Roman mythology? IIRC, the Greco-Roman sun gods were all male (e.g. https://en.wikipedia.org/wiki/Helios).

If I'm correct they'd use male pronouns for the sun, Mars, and Jupiter; and female pronouns for Earth, the Moon (Luna), and Venus.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#125

Post by fsh »

jaggederest wrote: post #118
archgoon wrote: post #18

Earlier quoted context omitted.

Einstein did not determine that the sun was nuclear powered. That was Hans Bethe in 1939 (based on data produced by Bengt Strömgren).

Right, I wasn't saying he did. I was trying to say that, without a theoretical framework to hang that kind of energy generation on, there was no capacity to understand what was going on. E=MC^2 is precisely that kind of theoretical framework. Pretty amazing, to me. Being able to say "It's this far away, this hot, and this large, but why?"

E=mc^2 is a consequence from special relativity, not a theoretical framework. It also has very little to do with the understand of nuclear reactions. The reason why nuclear reactions release much more energy than chemical reactions is that the binding energies inside the nucleus are much larger than inside the electron shell. Mass-energy equivalence exists in both cases.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#126

Post by elvinyung »

AareyBaba wrote: post #90
philipkglass wrote: post #60

Here is the longer original article, scanned by Google Books and hosted by the HathiTrust project: "Age of the Sun -- Force and Heat" Scientific American Vol IX -- No. 7 August 15 1863 https://babel.hathitrust.org/cgi/pt?id=uva.x001601382&view=1...

Interesting to read. The Sun is referred to as 'he' and people were just beginning to understand how heat energy and mechanical energy could be transformed into one another. "He has enlightened our globe from one generation to another without any apparent diminution of strength, and we have formed the instinctive belief that no limit in the past or any in the future can be assigned to his functions. No proof of progr…

Maybe "he" is short for "Helios" :-)

Re: Experts Doubt the Sun Is Burning Coal (1863)

#127

Post by fsh »

Ono-Sendai wrote: post #98
_bxg1 wrote: post #7

My personal favorite "old science" theory: https://en.m.wikipedia.org/wiki/Luminiferous_aether > Luminiferous aether or ether[1] ("luminiferous", meaning "light-bearing") was the postulated medium for the propagation of light.[2] It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do. The assumption of a spatial plenum o…

The aether exists, we just call it the electromagnetic field.

The very idea of special relativity is that EM-fields exist without an aether.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#128

Post by michaelmrose »

tialaramex wrote: post #59
gerdesj wrote: post #15

I had absolutely no idea that SA is so old. New Scientist - https://en.wikipedia.org/wiki/New_Scientist is a mere whippersnapper. It doesn't matter that the article is bollocks. It is reasoned bollocks. That is basically what science is all about! I would prefer if there was some more working shown to back up the article but it seems to imply that some might be available rather than just simple assertions. We live in…

I'm not sure it's helpful to describe this 1863 article as "reasoned bollocks" In this same timeframe Kelvin supposes the Earth cannot possibly be billions of years old because it's warm underground. You can measure and verify that the Sun can't be keeping the Earth this warm, if it was just down to the Sun this place would be uninhabitable. Nothing could be this warm after cooling down for billions of years with jus…

Kelvin also publicly stated we would never have heavier than air flying machines.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#129

Post by dsign »

It's curious how in less than two hundred years our world-view has changed so drastically. Of course, scientific advances compound. But so do ways of thinking. Anybody who is lucky enough to get the word "Almighty" in a Science paper these days is just cracking a very good joke that made it through a lot of reviewers. But less than two hundred years ago people still felt they had to acknowledge His existence in words while undoing Him in facts.

Re: Experts Doubt the Sun Is Burning Coal (1863)

#130

Post by QuesnayJr »

jolmg wrote: post #5

That passage really brings into perspective how old Scientific American is, or maybe how little ago it must've been that the composition of the sun was discovered. This was during the American Civil War.

It's shocking how in a century (say from 1850 to 1950) we went from basically knowing nothing to basically knowing everything.
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