The ISS has been pinholed by debris a few times. Likely paint. The shuttle was damaged by foam breaking off, amongst other events.

By comparison orbital velocity is around 7km/s, while a bullet is around 0.367km/s. Any mismatch will push debris up to bullet speeds easily.

As for relativistic speeds. C is 300,000km/s assuming you get up to 1/3C (barely relativistic) you are moving at 100,000km/s or 14,000x faster than the ISS moves, or 39000x faster than a bullet. A 10g rock would hit with 10kilotons of energy. About 2/3 the energy of the first atom. bombs.

It’s actually a legit concern with any (hypothetical) interstellar mission. Even hydrogen atoms will hit with significant force. Dust hits like nukes, and an asteroid is just game over.

The maxim used in a lot of sci-fi is an ablative armour plate. Often in the form of ice. Interstellar ships would likely aldo be needle like, to minimise their cross section. We could also use electric and/or magnetic fields to move smaller particles out of the way.

As for densities, I believe it’s a couple of hydrogen ions per m^3 . Dust is rarer, but still present. It’s only bigger rocks that are rare enough to just hope to avoid.

The film hot fuzz has an amazing take on this. They need to talk to a farmer, but end up bringing the dog handler along. It turns out it’s not for the dog. It takes 2 accent translations to make sense of what he is saying!

https://youtu.be/Cun-LZvOTdw

I had a Welsh work colleague years ago. A few times he was on the phone and spoke Welsh. None of the mental markers on what language he was speaking seemed to change. It sounded like English, spoken with a Welsh accent. Until my brain tried to interpret it. It was like I had had a stroke. It parsed as English, but wouldn’t make sense. It took a conscious effort to remind myself that he wasn’t speaking English.

It works on frogs. The force is distributed over the whole body, so it’s no worse than gravity is on our bodies.

I disagree. The human body is mostly water. Water is slightly diamagnetic. Therefore, a sufficiently strong magnet is capable of levitating a human body off the ground.

Magnets can definitely have an effect, just not at puny neodymium magnet levels!

Interestingly, some lights are set up to deliberately slow down speeders. If you are above the speed limit, they turn red, just to slow things back down. Unfortunately, most of the people involved never put cause and effect together.

Entropy is the tendency of systems to move from order to disorder. It’s intrinsically tied to energy and its flow.

Basically, if I gave you a box with 1000 dice, all showing 6, bar 1 showing 5, it has an extremely low entropy. If you shake it, the entropy will tend to increase. You’ll likely get an event spread of values. This is a high entropy state. The chances of all 6s is tiny, and gets everything smaller as the number of options gets bigger.

Gas expanding into a space is another example. The entropy of the gas increases as it expands.

The rule of thumb is that entropy always increases in a closed system. If it seems to decrease, you’ve likely missed something.

Increasing entropy can also be harnessed for energy. An expanding gas can drive a piston upwards. We can even work out the amount of energy that can be extracted from a system, based on the entropy change involved.

That about covers the basics of entropy, without diving into the maths.

This sort of comic always bugs me. Observation in QM is not the same as observation in layman terms.

Best think of it as hit it and watch the pieces fly. When you get small enough, you can’t approximate out the impacts. It’s akin to studying road traffic by sending an overloaded freight truck the wrong way and counting tires that hit the verge. It might also affect the current traffic’s motion.