Recent comments in /f/askscience

Nayir1 t1_j2w3wrm wrote

Reply to comment by BrobdingnagLilliput in How do galaxies move? by modsarebrainstems

Forget about accretion disks, that's a local phenomenon.You're right in the sense that galaxies exist because the Black hole at the center does not become massive enough to have all the matter. In the same sense that earth exists because of the sun because it the sun is not massive enough to have subsumed the earth. Also, nebulae are gas features within galaxies, but entire galaxies we're once called nebula before we realized they're just far away galaxies.

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Duros001 t1_j2vp2y3 wrote

Reply to comment by baggier in Molecularly, what make pine pitch sticky? by orangegore

True, but the interstitial pressure of a compound or emulsion is also dependent of the presence of micelles, as I presume tar is made up of various length hydrocarbons, some of which will be relatively short chain oils, among a soup of other organic compounds

Plus there are several types of “Tar” Pitch/Coal Tar are even lumped together on databases: 1.1-1.4 g/cm^3 (https://echa.europa.eu/registration-dossier/-/registered-dossier/15300/4/5) The water content, hydrocarbon lengths etc will depend on so many factors, temp it was refined at, local or actual source of “tar” (pine, coal, peat etc)

It’s almost like we’re trying to generalise a cake mix, made by thousands of different bakers, it contains mostly the same stuff, but will cook totally different :)

Edit: But yes, you are correct that viscosity is greatly affected by particle/molecular size :D thanks for the correction :)

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RaspberryTwilight t1_j2vnba0 wrote

Reply to Can the human body clear a HPV infection copletely? by Terradubia

Yes, but when it is not detectable in your body anymore, you never know if it really cleared or went dormant, so you still have to get checked. If it's dormant, then it is basically waiting for an opportunity and can become active again, starting cellular changes again when your immune system is suppressed (for example due to pregnancy or vaginal dysbiosis).

There are some studies that say estrogen and lactobacilli might be involved in the process, but there is no consensus as high levels of estrogen seem to reactivate the virus but estrogen also promotes lactobacilli which slows down the progression of the disease.

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hmartin430 t1_j2vktwh wrote

Reply to comment by Prestigious_Carpet29 in How close does one need to bring two coloured lights together to perceive a compound colour effect? by romxza

So I'm confused. If the fovea is responsible for highest resolution, and the fovea is packed full of cones which are color sensitive, how do we have more resolution with rods (black/white)?

My understanding was that rods are more sensitive to low light. That's why in the dark we have trouble discerning color. Also, our vision tends to be a bit less focused in the dark (more difficulty discerning details) because we're not getting much activation in the fovea, where our central vision is. In bright light, however, the cones will register the blue, green, red, far red wave lengths.

So we're sorta talking about two different "kinds" of light I guess?....white light/ambient light when it's daylight or you're in a lit room and then light in the form of the wave length being reflected off objects (like green curtains, say).

So wouldn't our color vision have higher resolution than our black/white vision, but that our color vision only works when the background intensity reaches a certain threshold. And our black/white vision has less resolution, but works in dimmer environments?

I'm no eye expert, but I spent a year working in a lab that was growing retinal organoids during a CIRM internship (super cool), it's been a few years so I could be remembering incorrectly, or perhaps understood incorrectly from the very beginning!

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