Wikipedia:Reference desk/Archives/Science/2023 February 3

= February 3 =

End of the sun
Please read the whole section of this page:

https://www.knowledgepeoplecreators.com/2021/03/what-are-zodiac-signs-will-sun-ever.html

...that is titled "Will the sun ever stop shining??" (That is, keep reading until you reach the next section, which is about the moon shining.) Do some scientists disagree with some parts of this?? Georgia guy (talk) 00:34, 3 February 2023 (UTC)
 * It seems reasonably accurate for a very brief summary. See Formation_and_evolution_of_the_Solar_System for a more detailed description. I don't think there's much scientific debate about the future evolution of the Sun in broad strokes, although there may be some disagreement about the details. For instance, it's not clear if the expanding Sun will envelop the Earth like it will swallow Mercury and Venus, since Earth's orbit is just on the boundary of where it might be enveloped. Of course, for some definition of "scientist" and some definition of "disagree", there are surely some "scientists" who "disagree" with "some parts of this". Is there a particular point that you have a question about? CodeTalker (talk) 02:20, 3 February 2023 (UTC)
 * They have some stuff backwards. So, to calibrate your thinking here, it's important to understand that stars get brighter with age on the main sequence. The reason is, as they fuse hydrogen in the core into helium, the core becomes denser. The core pressure thus goes up, and this is what determines the rate of fusion in the core, so the rate of fusion goes up, producing more light—a positive feedback loop, just a really slow one, to human time scales, since stars are really big. When the Sun formed it was only about 60% as bright as today: see faint young Sun paradox.
 * When a planet is "too close" to its star, it gets enough light that it's too hot for liquid water to exist, and if there's a lot of water, a runaway greenhouse effect happens as the water evaporates into the atmosphere. Water vapor is a really potent greenhouse gas. Then, gradually, the H2O gets photodissociated by ultraviolet light from the star into H and O, and the hydrogen can then escape into space, as terrestrial planets are too light for their gravity to hold on to the lightest element. This is why Earth doesn't have a bunch of hydrogen or helium floating around. The thinking among scientists has come around to believing this is likely the exact process that happened on Venus billions of years ago. Venus is almost exactly the mass of Earth, Earth's "twin", and likely looked very similar when the Solar System formed. But, it was "too close" to the Sun, outside the circumstellar habitable zone (CHZ), and thus the Sun fried it and drove off all its water.
 * Then if you put two and two together: the CHZ moves outward as a star ages, because it gets brighter. So, the Sun's CHZ has slowly been moving outward, and estimates are in around 600,000,000 years it will start moving outside of Earth's orbit, and the same processes that likely happened to Venus will repeat on Earth. The Sun still has 5 billion years left on the main sequence, which gives plenty of time for it to drive off all of Earth's water and leave it a dessicated husk like Venus.
 * Helium flash.svgar evolution: Then, yes, the Sun will finish its life on the main sequence and enter the red giant phase. There is no real debate here since the physics are quite well-understood. Eventually the core has used up enough hydrogen "fuel" that it stops producing enough energy to "inflate" the star's upper layers against gravity, which keeps trying to collapse the star. Gravitational collapse ensues until a "shell" around the core becomes hot enough to start fusing hydrogen. This halts the collapse, and in fact then starts to inflate the star hugely. The reason is the square–cube law: the shell surrounds the core, so by definition it has a larger volume. Any shape's volume grows more quickly than its surface area does—the volume goes up with the cube of size, while surface area only goes up with the square. This is why elephants can't jump like rabbits among other things. In our star, the photon flux through any given "slice" of the star is now much higher, and so the outer layers of the star heat up and expand from all that energy. Then as more "fuel" gets used up, the helium core ignites, followed by fusion in upper layers, which gradually "blows off" the outer layers from the extreme stellar wind produced (again, because of that square–cube law) and what's left is a white dwarf. --47.147.118.55 (talk) 10:23, 3 February 2023 (UTC)


 * If by "some" you mean "more than one" and if by "scientists" you mean "a person who does science", then I have no doubt you could find at least 2 scientists who disagree with 2 parts of that article, so the answer to your question should be an unambiguous yes. Undoubtedly some scientists disagree with some parts of that article. -- Jayron 32 11:48, 3 February 2023 (UTC)

I was at a lecture on the history and future of the sun, some years ago. Afterward, a lady asked with alarm if it was really true that in a few million years the sun would swell up and kill the earth. The presenter said no, billions, not millions. The lady breathed a sigh of relief -- as if that difference mattered to her, or to humanity. Dicklyon (talk) 12:09, 5 February 2023 (UTC)
 * That's an old... I say, that's an old joke, son. :) ←Baseball Bugs What's up, Doc? carrots→ 13:15, 5 February 2023 (UTC)

Kidney theft in real life?
I just watched the wonderfully silly Jean-Claude Van Damme movie, Pound of Flesh - which has the premise of "they stole JCVD's kidney - and now he's going to kill all the bad guys to get it back!".

Features the old "guy wakes up in a bath of ice after being drugged, to find his kidney removed" story. I used to think it was just a urban legend - but hasn't this actually really happened a few times now, with organ trafficking gangs? Anyone know of any actual specific examples? Iloveparrots (talk) 17:15, 3 February 2023 (UTC)
 * Wikipedia has an article titled Organ theft. The classic story of someone waking up in a bathtub of ice and a note on their chest, having had their kidneys removed, is not a thing that has ever happened, but there are documented cases of shady organ trafficking schemes, but these usually fall under the realm of coercing people who are either prisoners, or poor, into giving away their organs against their own interests.  -- Jayron 32 17:20, 3 February 2023 (UTC)
 * Forgive this psuedo-WP:NOTAFORUM divergence, as this is definitely not what the OP was inquiring about, but in the context of Jayron's response, this recent development felt rather apropos. SnowRise let's rap 05:42, 4 February 2023 (UTC)


 * Snopes says it's a myth. Clarityfiend (talk) 23:12, 3 February 2023 (UTC)

Ehlers-Danlos and beeing fast
It's true, that Humans with Ehlers–Danlos syndromes have usually a talent with running and speeding running. 2A02:908:424:9D60:C51C:BD84:3557:7240 (talk) 23:37, 3 February 2023 (UTC)


 * See Verifiability, not truth. Do you have a question? Shantavira|feed me 09:15, 4 February 2023 (UTC)
 * The notion of "having a talent" is hard to define. If they have this talent, they should be advised that at least some physical therapists think that patients with EDS should be encouraged to avoid high-impact activities, including running . --Lambiam 22:00, 4 February 2023 (UTC)