PatrickKieliszek t1_je1s5yi wrote

There are actually some exothermic reactions that produce elements more massive than iron.

However, these are usually very short lived in the time immediately before supernovae and are limited by photodisintegration. They don't meaningfully contribute to the amount of heavier elements (Which are primarily produced during nova).


PatrickKieliszek t1_jbnvk7i wrote

How does this selection pressure tie in with the large amount of non-coding DNA in complex organisms?

Reading Wikipedia on this didn't leave me with the impression that there is consensus on the why of DNA that doesn't code for proteins or change transcription sites.


PatrickKieliszek t1_j9ayj1h wrote

It's important to know that radiation isn't one thing.

The three main types that people mean when they use that term are alpha, beta, and gamma.

Alpha particles are little helium nuclei. They can mess up DNA (maybe causing cancer), but they don't travel far and are usually only harmful if the source is inside you.

Beta particles are electrons moving at incredible speed. Not as likely to cause damage as alpha particles, but they travel much further and can cause damage if you are near the emitting material.

Gamma radiation is just very energetic photons (light). Gamma rays are the least likely to do damage because they will likely pass straight through you without interacting. They travel incredible distances though and are difficult to shield against.

X-rays are the same kind of thing as gamma rays, but they have less energy. They are more likely to interact with your body and are more easily blocked. They can do some damage, but the probability is relatively low. Prolonged exposure is bad, but they are low risk for occasional medical imaging.

It is important to note that all of these are harmful because they are ionizing radiation. They can damage complex molecules needed by the body (mostly DNA but also cell structure if in sufficient quantity).

Water is a very stable molecule and x-rays aren't powerful enough to change it. You can actually sterilize water by irradiating it with UV light or stronger (UV is like x-rays but even lower energy), because the molecules that make up bacteria and viruses are more fragile than water molecules.


PatrickKieliszek t1_j56qgmt wrote

I have been on a project that no one put a manual switch on. I insisted they add one. No one wanted to. Eventually they complied because I wouldn't stop saying we needed it.

Adding the shut-off cost less than a thousand dollars. Probably saved sevral thousand hours of machine downtime over the life of the project.


PatrickKieliszek t1_j1j3wii wrote

Gravity causes time to run more slowly. Speed also causes time to run more slowly.

On the surface of the Earth, we have higher gravity. This causes our clocks to run slower.

The ISS is moving much faster than we are. This causes their clocks to run slower.

The ISS is not that high up and it it moving VERY fast. The slowing effect from their high speed is greater than the slowing effect from our higher gravity.

Their clocks run ever so slightly slower than ours.


PatrickKieliszek t1_izo5c6g wrote

The solar wind is full of both positively charged hydrogen and free electrons.

The Earth's magnetic field captures more electrons than protons because the protons are more massive.

Eventually the net negative charge of the earth is enough to balance out the effect of the magnetic field and the rate of capture becomes even.

This causes the earth as a whole to have a slight negative charge.


PatrickKieliszek t1_ixxbped wrote

We could work out the star charts to an accuracy where they would be useful. Only unpredictable thing would be the addition of some stars that have died in the last 500,000 years.

Those shouldn't be hard to screen out.


PatrickKieliszek t1_iujc2s4 wrote

Although evaporation dominates as a method of heat loss, there are two biological mechanisms that I am aware of that can additionally decrease dry conduction.

Capillary constriction in the skin reduces blood flow and makes the skin a more efficient insulator.

Piloerection of hair follicles helps trap air against the skin and improve insulation (works better on hirsute people and is mostly redundant in people that wear clothing).