Yep. It's called near field and far field in radio. In the far field you can approximate it as a beam from the transmitter, while in near field it's magnets and things can absolutely interact. You never want to put up a stand-alone antenna in the near field of something conductive. Those big tower antennas actually incorporate the ground as a critical part of their design, because of that and the non-negligible conductivity of ground water.
The current produced in the antenna does (induce a field which goes on to) cancel the wave out a bit. Not enough to be noticeable in the far field, for a normal-sized antenna, but some. Conservation of energy, right?
Yup. It's typically amplified quite a lot in the receiver, and the vast majority of power transmitted never is received, so it doesn't usually matter, but it's not a dumb question.
How side-by-side are we talking? If the antennas are closer than their size, yeah, it won't necessarily work the same way because they'll act like one antenna. If they're too far apart for "near field" effects (or if your antenna was tiny relative to the wave to start with, like with AM radio) it won't matter, because the wave in question will just kind of ooze around any obstruction, and received power will just go with inverse square of distance to source again.
In practice, it's unlikely to matter so much how loud the signal is, because (unless you're using a crystal radio) you are definitely going to amplify it quite a lot before it's useful, anyway. More of concern is how loud it is relative to any random noise that's present, which is not so dependent on antenna area.
Edit: I suppose if it's between you and the source, it will dim the signal a tiny, tiny little bit. Not the way a bigger thing can cast a shadow, though; think more like a slightly dirty lens.
We actually have less genetic variation than most animals. There was a lot of bottlenecking in the paleolithic. And what little we do have is still mostly confined to Africa, because the rest or the world shared common ancestry as we left our original continent.
Like, 1 in 200 people is colourblind, or something? I don't think that's a reasonable argument that we're not trichromats.
Yeah, we played paintball even, but stopped because one guy ran straight off like a 6 foot mini cliff. A couple of us were chasing him and he just disappeared. Was freaky as shit like that scene from LotRs.
Lol, yup, that sounds right. I did that once, although it was only like 3 or 4 feet, and I didn't like it one bit. Is was a sinkhole or something too, because it was cliff all around, and I had to find a spot to climb out. I didn't visit that area again.
I forget where I heard about the sailing thing now. That would be a 1 on the Bortle dark sky scale, though.
Optimised just means designed for something at the expense of other parameters. We lost our tepetum lucidum at some point in evolution, probably for the 3x-ish resolution gain, while becoming much more shit in lowlight in the process. That's a tradeoff, but a good one for a tree-based diurnal frugivore.
Cats (for example) still have theirs, which means light as two chances to hit their retina, but means there's an upper limit on how clear an image can be, exactly because there's light bouncing around. It sounds like 20/100 is typical for them, from a quick search. Cats are traditionally thought to be dichromats, as well.
I could nitpick some of the details there, but instead maybe I'll just ask what point you're trying to make? A healthy human can still pick out something small way better than a goat.
Hmm. Are we talking a high canopy, and fairly level ground? I feel like I'd definitely break an ankle if I tried sprinting otherwise.
I never had too much trouble, but sometimes things hiding in tall grass would surprise me, and in heavily treed patches I'd occasionally hit a low branch I didn't notice.
I also have to account for the fact that there was some light pollution, and I could always see skyglow from towns in the distance. I doubt land ever gets close, prehistoric or not, but in the darkest conditions that happen at sea apparently you can't see your own hands.
We're diurnal, and have eyes optimised to see maximum colour and detail instead of well in dim light (at least by mammal standards). It makes sense we'd gravitate to fairly dark conditions to sleep, because while nature at night is not perfectly unlit, it's still pretty dark. Darker than a developed-world urban area will ever get, for example.
That being said, many people are completely capable of sleeping in a bright area, myself included.
As for the bonus question, yes, the hormones at least work backwards in nocturnal animals. Melatonin wakes something like a shrew up.
but even in the absolute middle of nowhere with no artificial lights, you’re going to be able to see fairly well.
I'm not sure I'd say fairly well. Maybe always well enough to not walk directly into a tree in otherwise open terrain. A full moon will be comfortable to walk around in, but new moons happen just as often, and sometimes the moon is below the horizon.
Source: Have walked around in the country at night.
I mean, if you can create a vacuum, water at any temperature will boil-freeze. And the ice will sublimate afterwards above cryogenic temperatures, but I’m not sure how fast.
Even if you don’t mix the steam with the water, heat will seep in through the surface. At thousands of degrees you bet that water is gone fast - explosively - as long it’s not super deep. If this is for drying something, you can add a bunch of other hot inert gasses to dilute or push it out after, so when you cool everything back down it doesn’t re-condense.
If you have to add liquid water, it might be impossible, although I can’t say for sure there isn’t some weird non-linear evaporation effect that allows it to technically work on very cold water. Intuitively, you are always adding more additional water than additional heat, but water is crazy and breaks usual rules for matter fairly often. I’ll do a bit of digging and edit.
Edit: Research turned up nothing. As far as I can tell, water evaporation is calculated as being a linear rate. Like the light thing someone else posted, that doesn’t necessarily mean there isn’t a counterexample, just that it hasn’t been found and publicised well enough for a quick search around. So yeah, no wetting away a puddle.