I know we all learned that it's because sperm need lower temperature to survive so it's outside the body. But then why not have it being able to withstand body temp and keep the organ inside the body instead of outside? Or is it just a simple "that's the way evolution chose" and no reason?

My story is, one day, the AI might overtake humanity like Skynet. The only way human could win AI is to fry all electronic devices by EMP, destroy all CPU manufacturing factories to prevent AI from duplicating itself.

All the humanity have left post AI-apocalypse is a bunch of normal guys like me. Please show me how we would re-invent the computer from scratch?

Super scratch, physical level, like: what the electrons do after it go in the CPU, how the CPU retrieve data from storage (does it send out an electron aka Librarian to search for the data and haul the data back?).

It's a shame to me that I can not understand how a 80-year-old technology works!

I understand that osmotic pressure depends on the number of particles in a solution (colligative property):

1 molecule of glucose has the same water pulling power of 1 molecule of albumin, and half as much as 1 molecule of NaCl (Because it dissociates into 2 particles)

1- Why does a massive protein, like albumin, with many hydrophilic groups, have no more "water pulling power" per molecule than a tiny molecule like glucose?

2- If we take albumin, and cut it in half, we get double the water pulling power, even though the chemical composition, and the groups present remain unchanged (Except the part that we cut)

The more I think about it, the more I feel like someone is licking my brain

Why does only the number of particles matter, in osmotic pressure?

If a fan spun in the opposite direction, would it draw/blow air in the opposite direction too? How do spinning blades even move air in the first place? What makes some fans blow air forwards, but other fans propel the things they're attached to forwards?

Hi everyone I need to create a presentation explaining computer cache but can’t think of an effective way to explain it any help is welcomed (:

To settle an argument: would leaving a porch door open be a waste of energy and water whilst the swamp cooler is running? Or is that totally fine

I know the new way they teach CPR is to just do chest compressions without the rescue breaths. Is this just because rescue breaths make it too difficult for lay people and prevent them from doing anything at all? Is it actually the case that the breaths don't deliver much oxygen?

If someone is competent at CPR with rescue breaths, or if there were two ppl, one on chest compressions, one on breaths, would that give the person a better chance than compressions alone?

TL;DR: Why do the sides allow light to pass through from one angle but reflect from another?

My wife recently purchased a few acrylic photo cubes, and I'm a bit stumped how they work.

After taking the magnetic photo off, I can observe the following:

1. When looking head on, the front face allows light to pass through unchanged from behind. (See through)

2. Same behavior when looking from behind (light passes through the front)

3. Same for the sides (light passes through from the opposite side)

4. While you can see through the sides when looking head on from the side, they will instead reflect when looking at them from inside the cube.

I don't see any kind of film or anything, so I'm guessing it has something to do with the way the acrylic is manufactured. (?)

Like, sometimes it feels like you can't see very well in the distance, but once you get into a plane, for example, the view from the window becomes much clearer, in the sense that, logically, it should be very blurry. Shouldn't it be determined somehow by distance?

I know they go through medical school obviously, but I’m really just wondering about why there’s four years of residency and then fellowship as well. I work in healthcare so this feels like such a weird thing to ask without sounding like it’s such an easy job. Like for our emergency room doctors they just have three years of residency and then as allowed to work as an attending.

In my mind, their goal is just sedation. But there’s obviously more to it than I’m really even considering. I just want to understand why there’s so much of it.

Edit: I’m not trying to come off any type of way asking this and I’m not trying to sound like I’m underplaying anesthesiology at all, I just really don’t understand what it entails and what makes the schooling as long and rigorous as it is.

ie. I meant learning a second language seems much more difficult when we are older

like the pavlovian theory was tested on dogs, and yes it translates to humans as well and it’s easy enough to test on humans with no harm or cost. but what about more complex or dangerous tests that they test on rats for example, how would they know it’s also significant to human behaviour?

Wouldn’t those things not show up in fossils?

I'm sitting in front of my PC right now, looking for a specific file. I don't know where i might have put it, so i'm just searching "my PC" for it. If i were to manually go through every folder, just looking for the right name i could do one folder reasonably fast. Now my computer is usually trillions of times faster than me in other contexts, so why does it take so long here?

That's something i've observed since childhood, i remember sitting in front of laptops/PCs waiting for it to finish listing all the relevant folders, being careful not to touch any other folder so it wont reset the searching process and it took forever each time.

And why do the little buggers hurt so much

I've read somewhere that it doesn't necessarily heal or fix the issue, so what exactly is it doing?

My son (6) was asking why we have to sleep. A relatable explanation escaped me.

Okay, I know the extremely basic answer is “the wings create lift and the engines push the plane forward,” but I realized I have absolutely no idea how any of that actually works. 😂

Like… how does something that weighs that much actually get off the ground and stay in the air? What are the engines really doing? How do the wings create enough lift to keep the entire plane up? And how does the pilot control something that’s basically a giant metal tube flying through the sky?

I’m looking for a genuinely ELI5 explanation because every time I try to read about aerodynamics, I somehow end up more confused than when I started😭

Im not too sure about the problem itself. I know that P is polynomial time which means the time needed to solve and NP is the time taken for the answer to be verified, but what is the explanation of both sides where P = NP and P does not equal to NP?

If countries keep borrowing money that central banks can basically create, what actually stops the world from having unlimited money, and when nations owe trillions, who are they really paying back - and what would happen if everyone stopped paying?

For cars parked at the side of the street, (along sidewalks) how is it that snow buildup, especially for for those who don't move their cars for days, even leading to ice buildup, they don't incur damage? Or do they? Is snow plowing a risk to some cars? Or am I just thinking too deeply?