Recent comments in /f/explainlikeimfive

ThepunfishersGun t1_jabiieu wrote

Henry's Law (I believe, been awhile since college/grad school) partial pressure of dissolved gas in liquid is proportional to partial pressure of undissolved gas. IIRC, it goes: p1/a1 = p2/a2 where one side of the equation describes gas dissolved at a given atmospheric pressure and the other side describes gas dissolved at a changed atmospheric pressure.

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yono1986 t1_jabhzg2 wrote

Boxing is scored by the 10 must system. In a typical round, a judge gives whoever they think won the round 10 points and the loser gets nine. If somebody gets knocked down, then it is generally 10-8 against them. Every once in a while you will have 10-7 rounds, but you have to be truly awful to get that score.

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Ojisan1 t1_jabhmis wrote

It’s like asking the question what’s at the edge of the earth? The answer is more earth. Just because you can’t see over the horizon doesn’t mean that’s all there is.

Similar with the universe - we can only see as far as light can travel in the amount of time since the universe began, just under 14 billion years. That’s like the horizon. But if you were able to magically teleport to 14 billion light years away from here, you’d still be able to see 14 billion light years in every direction. Similar to how if you teleported to the horizon on earth, you’d still just see the same distance to the horizon in every direction.

It’s more complicated because we are 3 dimensional beings in a 3 dimensional space, versus being 3 dimensional beings looking at the 2 dimensional surface of a sphere. If we were 4 dimensional beings, we could look at the 3D universe from a vantage point that would make it just as obvious that there’s no edge as it’s obvious to you that there’s no edge of a globe. But we aren’t 4 dimensional beings so we have to use analogies to understand without using math.

The way to understand expansion is that everything is getting further away from everything else. No matter where you are, everything else that exists is all moving away from you.

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yono1986 t1_jabh64w wrote

Before time zones, there was local time. Essentially, whenever the sun at its highest point in the sky is noon. This was particularly difficult for rail travel, because a town that is a few dozen miles away has a slightly different local time, and you can't set a train schedule unless everyone agrees what time is when. Trains also move fast enough that you can notice time zones. Horse and foot travel are too slow for this. The other big thing was the telegraph. With telegraphs, you can now communicate with people who are clearly experiencing a different time.

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Mkwdr t1_jabh5kk wrote

With some of these questions you could say we have working assumptions rather than absolute knowledge. To have an edge there would , I think, have to something that wasn't universe but the universe seems like all the space/time there is.

Though we don't know for sure , there is some reason for thinking it might also be infinite in size. There is in edge in the sense of the limit of our ability to observe. The observable universe has for us increased in size as telescopes get better though you could say that its also a sort of illusion since the further we look , the further back in the universe's history we are seeing. We are seeing it as was. We can only see as far as light has had time to travel. The limit is called the cosmic horizon.

And we also have some reason to think its pretty much the same everywhere in general. Though some bits are clumping together the space between is increasing everwhere. At one point in the past it infected very fast , slowed down and is now accelerating again. But as far as we know whereever you were in the universe you would look out and observe something similar to another observer. If the universe continue expanding its possible that we could imagine one day an observer looks out and sees nothing because all the stars would be too far away for light to reach them.

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Jamie_1318 t1_jabh4vp wrote

The space in the nostral also seems to matter. That 'fresh rain smell' primarily consists of a compound called geosmin. It smells fresh and nice from outside, but injesting it tastes moldy.
https://www.youtube.com/watch?v=_8vHsY_QVHM

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apoeticturtle t1_jabgplj wrote

There are many things in my life that I do have to decide if I am OK with, but thankfully not this one. I cannot even imagine "nothing" and having less than nothing (that which lies beyond our Universe's edge) is as mind-boggling as it is speculative. All the energy in our Universe may be just a tiny fraction of all the energy everywhere/when. It seems more likely, to me, that our Universe is a tiny part of something bigger. If not, what a waste of energy and time/space.

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Ishidan01 t1_jabg9c0 wrote

Radar works by transmitting and observing the reflections of radio waves. Which are electromagnetic waves not unlike visible light, except in a different frequency, so we can use a visible light metaphor.

Imagine you are in the middle of a vast open field, and it's the middle of the night: there is no ambient light. But you have been equipped with a powerful flashlight, which you can point in any direction you like. You are also equipped with a partner we'll call Sam. Sam will go where you point if you command him to, and he's a very fast runner, but it takes him a few second

There are five enemies out there. Their job is to tag you out, but they lose if Sam tags them first.

Assassin 1 is vastly obese and is wearing a cheap white shirt. You spot him easily and Sam tags him out: he has an immense cross section.

Assassin 2 is just as obese but is wearing all black. Your flashlight does not reflect off him as well, but as he is such a large and slow moving target you have no problem seeing him in time to send Sam after him. His physical cross section is the same but his visual cross section is far less.

Assassin 3 is very athletic- not as fast as Sam, but damn fast. Still didn't pay attention to his wardrobe, though: his white shirt gives him more than enough cross section for you to see him and Sam to run him down before he reaches you.

Assassin 4 is like 3 but wearing all black. You barely spot him in time.

Assassin 5 came prepared. He spent a lot of time, money, and effort to camouflage himself. He can't change his physical cross section, but visually, you can't detect him because none of the light from your flashlight is returning to the detector-your eyes- in a way you recognize as a meaningful object.

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