The other answers about communicating are correct, we use radio wave which are light and which do not require a medium to propagate.

We freeze in space because there are no molecules in the air (there’s no air) bumping into our skin. On earth, air molecules are constantly bumping into you and transferring the energy they have picked up from the suns rays or from other air molecules. When this happens your badly stays warm.

But if you go to the top of a mountain, even in a sunny day it’s really really cold because the air is very thin. Actually you might be warm on the top of the mountain if you were in the sun because the suns rays would heat you up but if you were in the shade you’d get real cold. Even the back side of you body, the part not facing the sun would get real cold.

This is what happens in space as well. Things that are in direct sunlight are very hot and things that are in the shade are extremely cold. Because the only natural heat source when there is no air are the rays from the sun.

The James Webb Space telescope is over 200 degrees Fahrenheit on the sun lit side and is less that -350 degrees Fahrenheit on the dark side. There is almost a 600 degree difference. All because there is no air.

Why does lavender smell like sausage to me?

> Is the fact that angular momentum must be quantized a postulate of QM or is it derived from something more fundamental?

Quantisation of angular momentum follows from the mathematical definitions of wave functions and operators in QM. Specifically, it comes from the structure of the group of rotations in 3D, SO(3). In the end, this is Lie group and Lie algebra representation theory.

Definitely no sound in space. If you watched an explosion in space, it would be silent until the moment the edge of the explosion reached you and then it would be chaos. Because explosions are (usually, depending on what exploded) made of gas that will carry sound.

Isn't that what I said?

It’s not actually sound. It’s vibration. Sound is a propagating wave. The fork oscillates and when you put your face on it you’ve given the vibrations a medium to propagate through. Even if you put your ear drum directly on the fork the vibration would cause the ear drum to oscillate and then a sound wave would form in your cochlea (inner ear).

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The vast majority of black holes have accretion discs, which have such high amounts of hard radiation, any probe would be fried long before it gets anywhere remotely near the black hole.

Besides hard radiation, the only other really cool things we'd want to investigate are either gravitational (we don't have super-tiny gravity sensors to my non-expert knowledge) or quantum in nature (and I don't think we have a particle accelerator we can fit into a space probe.

And, using current spaceflight tech, it would take thousands of years to get a probe anywhere near one. So it would be an expensive investment, which might give us useful data in thousands of years.

Yep! Turns out you're correct (says Google). Lasers do follow the inverse square law. https://www.quora.com/Is-the-light-from-lasers-reduced-by-the-inverse-square-law-as-distance-grows-similar-to-other-light-sources

How powerful the transmitter will need to be is also a function of the gain of the antenna. In this case, the spread angle of the laser

Never? I'm pretty sure maths says it does it exactly twice per year, with the rise and set happenning at the same moment, at two specific points on opposite sides of the planet.

The fork is vibrating. It’s never causing a pressure wave through any adjacent medium. The fork itself has energy but if it was truely in a vacuum it would never make any sound. Vibration is not the same as sound.

I wasn’t saying that the fork energy ceases to exist at the boundary of the fork, it’s just not translated into any matter as the fork oscillates back and forth through empty space. It is the atomic structure of the tuning fork itself that will cause the vibration of the fork to eventually stop. With every oscillation of the forks tines the amplitude gets a little bit smaller and the energy witching the fork translates to head which is radiated away. Or conducted away through whatever is holding the fork.

None of this is sound though. Sound is a pressure wave propagating through a medium, by definition. A tuning fork normally makes sound when there is air around it because the oscillating of the fork causes alternating low and high pressure in the adjacent air. This is the part that can’t happen in a vacuum.

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Almost certainly yes, heat dissipation is a huge problem in space/space travel.

Another thing to consider is that a probe sent by future generations would almost certainly beat a probe sent today to the destination due to advances in propulsion technology.

But over long distances, it re-becomes inverse square again. After the waist of a laser beam, it spreads out like an inverse square law again, and when you're dealing with lightyears, most of the spread will be after the waist.

Hypertumors are tumors that invade and disrupt the growth of an already existing tumor. Hypertumors essentially “steal” nutrients from the “host tumors.” The host tumor and hypertumors essentially compete for resources.

See: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3060950/

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The nearest "black hole" is probably tens of thousands of light years away from the Earth. No one is sending a probe, unless you wish to wait for a very very very long time to get there and a very very very long time for any results to be returned.

About the central dogma of molecular biology, it doesn’t necessarily specify locations. Prokaryotes lack a nucleus and instead have a nucleoid, yet still follow the general basis of the central dogma. The central dogma moreso specifies products, DNA to RNA to protein.

I have learned that one big reason cancer cells cause problems is because along with crowding out space for normal cells. They steal nutrients and resources like water oxygen glucose and every other molecule needed for cell growth through angiogenesis. What if we were able to "starve," our cancer cells (this is where I would don't have a specific mechanism). Preventing them from having resources to be able to divide uncontrollably - it takes energy. Cool. Let's pull the plug on their source and let it naturally recede.

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Viruses = sneaky. Hijacking a cell's own mechanisms to replicate and go on to infect more cells.