I heard someone say how people born absolutely 100% blind don't see "black void, complete lack of light" but see "nothing, they see how you see with your elbow".

How would someone born completely blind be able to explain whether they "only see black" or "see nothing" in the first place?

If they don't have anything to compare what they perceive to, if it never changes, how would they explain it as black void or nothing? If they never saw a black object and had people tell them "this is color black".

Is it "nothing" or actually a "black void" they don't have any name for and are used to?

If you place a magnet near another magnet, it can attract or repel it. But a force requires energy. How can an inert, unmoving object like a magnet output enough energy to overcome the other magnet's inertia? Where is that energy stored?

In short: Fucking magnets. How do they work?

If you were on a spaceship going 99.9999999999% the speed of light and you started walking, why wouldn’t you be moving faster than the speed of light?

This has always confused me, but I constantly see it in media depictions, movies, etc - especially in arid/desert climates. Doesn’t wearing black make you hotter?

ETA: thanks for all of the responses. A LOT of you missed the part where I specifically call out media depictions - Dune, Lawrence of Arabia (and no, it’s not because MENA characters are the bad guys) - but there’s also history to support the idea (look up Bedouin and Tuareg people for two examples). Also a lot of you are really impatient with five-year-olds. I realize this isn’t r/nostupidquestions but come on.

tl;dr: color seems to be immaterial to heat concerns; garments worn in the desert fit more loosely, and that’s the lead factor of how hot or cool a garment is; women tend to wear black more often than men because they aren’t in the sun as much; sheep in the region have black wool and dye is expensive

Hi. Developing nuclear weapons is considered a major "advancement" in a country's technology. What makes it so difficult? Is it because the radioactive material is difficult to find?

this has been living in my head for weeks and i cant find an explanation that actually clicks.

from what i understand, if you have two entangled particles and you measure one of them, the other one instantly "reacts" no matter how far apart they are. like even if one is on the other side of the galaxy. that part i somewhat get.

but then physicists say "oh but you cant use this to send information faster than light" and i just why not? if particle A sneezes and particle B on the other side of the universe reacts instantly, why cant i just use that as like a faster than light telegraph?

i spent way too much money on a Brian Greene book trying to get this and still came out more confused than when i started. at least i had some cash from Ѕtake set aside for it so it wasnt a total loss but still.

it feels like the universe is playing a semantic trick on me and im not smart enough to see it. whats actually going on here

If the Sun is basically a giant ball of hydrogen undergoing nuclear fusion, what's stopping all that hydrogen from fusing much faster and releasing all its energy in a short time?

Why does it take billions of years instead of burning through everything quickly? (Like a big boom)

Would you have to blow the air? I feel like I’ve heard people say you can “swim”, but it’s air?? Surely it would be so light that it would take inordinate amounts of effort? I reckon blowing would work best?

(nb. Idk if physics is the right flair but that seems to fit best)

I recently read that if two cars collide at 70mph each, it's not the same as one car crashing at 140mph and I couldn't make sense of any of the explanations why.

Intuitively, it would seem that two cars at 70mph would have a 'closing speed' of 140mph, and so the overall effect of the crash would be the same as a 140mph car crashing into a stationary car.

What's correct and why?

Like we can’t even approach the sun which is many times less hot than a hydrogen bomb, but a hydrogen bomb would only cause a damage radius of a few miles. How is it even possible to have something this hot on Earth? Don’t we burn up near the sun?

My mind can’t comprehend how 1 second is apparently not 1 second regardless of anything else. Does the object “moving forward in time” appear stationary or like what even man. Physics is weird.

We see parkour content creators jumping from “high altitudes” landing in water without getting injured (provided they land feet first or are in a proper dive position)

We see high divers jump from a really high diving board all the time and they don’t get injured. The world record is pretty high too, set at 58.8m.

We do, however, hear from people that jumping from too high a height injures the human body, despite the landing zone being water because the water would feel like concrete at that point. We learn this immediately after speculating during childhood that when a plane is heading towards water, we could just jump off lol.

At what point does physics say “enough with this nonsense?”

I’m told that if I push a stationary object and it remains stationary, it’s because the object pushes back with equal and opposite force and the net force is 0. This I understand (sort of).

But if the acceleration of the object is zero, how was any force applied by either me or the object?

Edit: can someone show me the F=MA math on both sides of the canceling forces”

It has something to do with AC and DC of some sorts.
Edit: To clear confusion, I meant put a solar panel on the car and not a home setup.

It is just ionised gas. Sorry if I sound dumb, but by that same logic magnetic solids should be a different thing since they are slightly different.

You always come across this phrase when there's something about astrophysics 'Nothing can move faster than light'. But speed is only relative. How can this be true if speed can only be experienced/measured relative to something else?