Recent comments in /f/askscience

heresacorrection t1_jas3i1z wrote

Does being sick reduce your ability to form memories and remember? Yes https://www.jwatch.org/jp199906010000009/1999/06/01/does-fever-affect-memory

Confirmed in rats: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2630971/

Is amnesia (completing forgetting events) associated with being sick? I would say very rarely - since the only documented cases I could find were mainly in the elderly where the infections cause significant brain damage. https://pubmed.ncbi.nlm.nih.gov/14589627/

EDIT: found a case in a younger person - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3766455/ so yes it could happen but is clearly so rare that doctors can publish a paper when it occurs

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alyssasaccount t1_jas19c0 wrote

> would happen due to the magnetic field way before gravity

There isn’t necessarily any magnetic field. Spaghettification happens even in an idealized non-rotating, charge-neutral black hole.

> ripping of the physical structure across the weak points

Those points are bonded together by some kind of chemical bond, like hydrogen bonds between different atoms.

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ferrdek t1_jarv0ep wrote

>"Warped" does not mean "expanding". It's more of a local deformation

Lets assume we have some point in space and we travel through it twice. First time the space is empty and the second time some massive object appear on our path (for instance a star) and we travel close to it, going through space warped by its gravity.

is the time needed to travel from point A to point B in warped space longer than time needed to travel that distance through unwarped space? Or the opposite? Or there is no difference?

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Blakut t1_jars76x wrote

no they are not, i was thinking of something completely different. The stuff i work with, astrohysical sources, usually have two kinds of spectra: continuum which can come from a few things, such as free free emission, synchrotron emission, thermal emission from dust, and spectral line emission. The thermal part of the spectrum is usually very close to the ideal black body and deviations happen moslty because of geometry of particles (such as dust) and other stuff along the way, so i can separate the continuum from the spectral part. This of course gave me the wrong impression that most objects (also on earth) must have a spectrum close to a black body, and deviate from that only slightly because of things "around" the emitting body, such as gases absorbing/emitting, without considering that of course, Kirchoffs law applies to solids and everyday objects too (i only studied this in relation to gasses and some line emission scenarios).

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alyssasaccount t1_jarry8z wrote

In short, it’s basically a hybrid.

From the point of view of a body experiencing it, it’s just an extreme tidal force (which is not actually a force, but the rate of change of acceleration induced by some force with respect to position). It is space time being stretched, and that would produce tension on an object falling into a black hole (and I think there’s also compression in directions perpendicular to that tension, as depicted in the image you shared, but I don’t recall the details off the top of my head). Early on, that tension is not sufficient to break apart molecular bonds, but eventually it is, and the object will indeed get ripped apart. Eventually that tidal force might be strong enough that molecules get ripped apart, and at some point the curvature could be enough that you have to modify the very description of fundamental particles, at which point you’re getting into questions of quantum gravity, which are beyond the scope of experiment at present, and for which there are no generally accepted theories.

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4a61756d65 t1_jarq3pl wrote

Ah, you're right, but you're not talking too much about the emitter when you show plank, just about the EM field itself (and if you do it somewhat rigorously you at least mumble the words ergodicity/equidistribution, which fail in dilute gases with quantum electrons for example, so you get emission lines) I'm saying classical electrons are not enough to explain emission fully even in solids (that being said I don't know much/anything about the thorium case specifically)

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Blakut t1_jarouro wrote

But the planck spectrum uses quantum physics... It cannot be explained classically.

edit: idk why i considered gases (which i thought i know) and solids (which i know i don't know) as so different. Kirchoffs law applies to solids too, so if a solid is a poor absorber at a wavelength, it must be a good emitter.

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4a61756d65 t1_jarn8c0 wrote

Yeah, you can derive some forms of thermal emission from pretending electrons are classical point charges. That doesn't mean doing it will always explain the real world correctly! That's why we need quantum physics.

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Quinny-o t1_jarn89m wrote

You can have genetic mutations that leave you more susceptible to getting cancer. But it’s the cells that mutate…for example, a keratinocyte, that if dividing haphazardly will develop into squamous cell carcinoma (a skin cancer). You can’t change your DNA but things like lifestyle modifications go a long way. For example just because someone has a gene for breast cancer, does not mean that they will get breast cancer.

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