Recent comments in /f/askscience

Dramatic-Emphasis196 t1_jau6nai wrote

Reply to What exactly does Spaghettification mean? by mark0136

Spaghettification is due to strong gradient in gravitational pulls between different parts of an object while approaching a black hole

Getting close to a black hole, gravitational pulls can vary significantly also in a matter of microscopic distances, and because of that the closest parts of the object get accelerated before the others so strongly, that the object breaks and gets "spaghettified", meaning "reduced to strings of atoms orbiting or falling into the black hole", instead of falling into it or orbiting it while maintaining its original shape

You can experience a similar event if you drop some ink close to a water vortex, you will notice it creating strings following the path described by the vortex itself, because part of the ink gets captured by the circulating waves simulating the gravitational pulls of the black hole (you can look for something about using fluid dynamics to simulate conditions close to black holes)

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MildElevation t1_jau2imx wrote

Reply to If teeth are mounted in sockets in the jaw bone, how do braces move them around? Do the sockets move with them? by MyCodesCumpie-ling

Teeth are anchored by the periodontal ligament. The pressure exerted by the braces on the tooth is sensed by mechanoreceptors within the periodontal ligament, signaling osteoclasts to alleviate the pressure on the alveolar bone by breaking it down locally. The bone is then restructured around the tooth when the pressure has subsided.

Retainers hold the teeth in place afterwards and avoid movement caused by things like healing tissue, elastic action of the periodontal ligament, or occlusion (how your teeth contact with biting/chewing).

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JackTR314 t1_jatyoun wrote

Reply to comment by Ieatadapoopoo in Does being sick impair the body’s ability to form memories during that time? by Temporary_turbulance

I can try to find the study for you, but they infected brain organoids with covid, and then found hyper active immune cells, causing significantly fewer neuron synapses.

Basically a type of immune cells that normally cleaves axons and synapses as part of healthy function became over active. The reduced synapses were hypothesized to be a potential cause of the brain fog post covid.

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Speed_Alarming t1_jatxu4a wrote

Reply to comment by Dominik_1102 in What exactly does Spaghettification mean? by mark0136

A car is a pretty rigid, contiguous unit tho. Pull hard on the bumper(fender, whatever) and it’ll rip right off, but pull hard on the chassis you take the whole car with you. Humans aren’t as rigid or strong, but we’re also much smaller. You’d have to be super close to the centre to feel a difference from one part of you to the next and by then you’ve got plenty of problems to deal with.

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Speed_Alarming t1_jatx12a wrote

Reply to comment by pzerr in What exactly does Spaghettification mean? by mark0136

Yeah, I always found this whole thing to be hyperbole and sensationalism by people looking for a cool sound-bite for a tv bit. For a human-sized human crossing the event horizon of a black hole from a gravitational viewpoint you’d not even notice unless the black hole was super tiny and you were insanely close to the singularity itself. From your own perspective you’d just continue accelerating. The fact that no known force could prevent your inevitable “swallowing” is largely irrelevant. Going from almost an infinite amount of energy required to an infinite amount of energy? What’s the difference in the real universe? I imagine that the radiation environment from things being almost caught but instead yeeted out into the void would be more of a pressing issue. There’s likely layers of that depending on the size, nature and velocity of things in orbit.

From an outside observer’s perspective all sorts of crazy things would appear to happen, depending on your relative distances and the size of the black hole and the radius of its event horizon etc. None of that would be experienced by you, the poor hapless chappy in peril, you’d be dead from something long before you got close enough to get actually super-stretched.

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babar90 t1_jatnibj wrote

Reply to comment by legendsplayminecraft in Mercury has a very elliptical orbit, but does it influence its temperature? by legendsplayminecraft

Basic trignometry gives the irradiance curve, assuming that each region of the planet surface is disconnected from others (ie. no heat equation between day and night parts of the planet and whatever dominates its core temperature) and is at thermal equilibrium you can approximate the temperature with a constant time the 1/4th power of the irradiance

https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law

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pzerr t1_jatn8f8 wrote

Reply to comment by DCSMU in What exactly does Spaghettification mean? by mark0136

The guy falling in does not experience any time dilation. From his perspective, it will happen at normal speeds. Ignoring that radiation would likely kill you before the tidal effect, it would be quite painful but possibly too fast to be noticed.

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