I was mistaken. Here's the video! https://www.youtube.com/watch?v=yCsgoLc_fzI
Conterintuitive facts in mathematics, CS, and physics
321–330 of 335 posts
Re: Conterintuitive facts in mathematics, CS, and physics
#322I was mistaken. Here's the video! https://www.youtube.com/watch?v=yCsgoLc_fzI
The professor lost in the video -- he did not win. The one who _didn't believe_ that one could go faster downwind than the wind gave the $10,000 to charity. Or did I miss something?
Re: Conterintuitive facts in mathematics, CS, and physics
#323Re: Conterintuitive facts in mathematics, CS, and physics
#324Earlier quoted context omitted.
> Both the stellar day and the sidereal day are shorter than the mean solar day by about 3 minutes 56 seconds. This is a result of the Earth turning 1 additional rotation, relative to the celestial reference frame, as it orbits the Sun (so 366.25 rotations/y). https://en.wikipedia.org/wiki/Earth's_rotation
So we would need 367 unique date identifiers … but we’ve only got 366 (Feb 29th being the non-annual one). I get I may be being unintelligent, but isn’t the author confusing the rolling coin paradox with an obscure astronomical reference system and coming up with a ‘mistakenly technically correct’ result that doesn’t match experienced reality?
I made a visualization for
> Circle A has 1/3 the radius of circle B, and circle A rolls one trip around circle B. How many times will circle A revolve in total?
Re: Conterintuitive facts in mathematics, CS, and physics
#325>It is possible to compute over encrypted data without access to the secret key I don't think this is counterintuitive for most people. The most basic encryption scheme that everyone knows is the Caesar cipher. It's easy to see that shifts of the cipher text will cause shifts in the plain text.
But in a Caesar cipher only some types of computation is possible (to wit, addition and subtraction).
Now, "multiplication" of letters is, well, dodgy as a concept. But, the thing is that you can build encryption systems where D(E(k) op V) is equal to k op V, and op contains both addition and multiplication.
Re: Conterintuitive facts in mathematics, CS, and physics
#326The list is missing one of the most astonishing discoveries of all time: if you reflect the universe in a mirror, you can tell whether you are in our universe or in the mirror because the laws of physics are different in the mirror. See https://en.wikipedia.org/wiki/Wu_experiment
It is a great discover I agree, it might not quite fit in the list because it's not so counterintuitive for someone not into particle physics though. There are actually many examples of things working different for the mirror image, e.g. many medical/chemical compounds work differently based on chirality. The topic of chirality is fascinating, one of the big puzzles in nature is for example why it so strongly prefers…
> There are actually many examples of things working different for the mirror image, e.g. many medical/chemical compounds work differently based on chirality.
It "works different" because you consider only change in one part of system. You change compound, but rest of system stays the same. If you mirror entire system, it works almost the same way (differences due to parity violation by weak force are millions time smaller than required to even detect differences).
Re: Conterintuitive facts in mathematics, CS, and physics
#327The list is missing one of the most astonishing discoveries of all time: if you reflect the universe in a mirror, you can tell whether you are in our universe or in the mirror because the laws of physics are different in the mirror. See https://en.wikipedia.org/wiki/Wu_experiment
How can someone rigorously prove that? E.g. perhaps there is something inside quarks that has chirality which we haven't discovered yet.
One can't. It's science. One can't rigorously prove anything via induction.
Re: Conterintuitive facts in mathematics, CS, and physics
#328Earlier quoted context omitted.
The density of the sun is very low, like much lower than the atmosphere (throughout most of it, anyway,) But yes it has an enormous volume.
The density of the sun is 1.4 g/cm^3, which is 1.4 times the density of the water. The atmosphere is 0.0012 g/cm^3 or three orders of magnitude less dense than the sun.
The density of the Sun isn't uniform of course, but according to this[0] StackExchange answer, the density of matter in the Sun already reaches that of air at about 95% of its radius.
https://astronomy.stackexchange.com/questions/32729/at-what-...
Re: Conterintuitive facts in mathematics, CS, and physics
#329Surprising fact about the sun: it actually produces less heat per unit volume than a compost pile - this makes sense when you consider that fusion events are very rare. The reason the sun is so hot is that it has an enormous ratio of volume to surface area. Heat emission due to radiative cooling is proportional to the surface area, but heat creation due to fusion is proportional to the volume.
This is true only on its surface. Most fusion energy production happens in Sun's core and that stuff is both more dense and produces much more energy per unit volume than a compost pile.
Re: Conterintuitive facts in mathematics, CS, and physics
#330Earlier quoted context omitted.
16 is like the money hall problem. I understand the answer, the answer makes sense to me. And yet but when I think of it how I think of it initially ... it still makes no sense.
The limit case can be helpful here, a strawberry made of 100% water can be dehydrated to practically nothing and is still made of 100% water.
What you said makes no sense. If I'm only judged by how much money I have, then even if I have $0 I'm still a billionaire?