I'm not saying it's about hiding something, just about demonstrating up to the level where the thing will work. I don't know how strong the surface tension is exactly. What I do know, is that atmospheric pressure is sufficient to have a siphon that's 10 meters tall and I very much doubt that surface tension comes even close to that value. I'm sure your friend would be able to calculate how high it goes, but I doubt that's more than a few cm high.

...and the former still being essential because if you lose cohesion you have two separate columns and nothing flowing.

Atmospheric pressure is what provides the cohesion in the normal case of the water siphon. It means you can in theory have a siphon that climbs up to 10 meters. The experiment in the video indeed does not use atmospheric pressure. It relies on surface tension, which is much weaker. Even if water didn't boil in a vacuum the siphon would work only work for a height around a mm or so (high high can you "pull" water using its surface tension?). The liquid used in the experiment has a much higher surface tension than water, which is shy the siphon works at all. That being said, I doubt it would work for much higher than what was shown in the experiment -- if it did, the experimenters would have shown us a more impressive siphon.

In this case they rely on surface tension, and while it works at a few cm height, I doubt it would work for a 1 meter siphon.

Atmospheric pressure isn't enough, but it's still required. In this experiment, 0.18 atmosphere is just enough for (in theory) a 1.8 meter siphon, had the guy attempted to get it to work at 2 meters, it would have failed because the atmospheric pressure needs to be high enough to hold the column of liquid.

As far as I'm concerned, the message should be:

"Here's the only link between vaccines and autism: if you don't vaccinate your children, they might die before they can even be diagnosed with autism."

Good, then you can make use of almost 16 bits!

Now only is 192 kHz/24 bit silly in general, it's even more silly for a portable music player, that's usually used in places with a higher background noise than your living room. Listening to music above 100 dB SPL in a cafe with noise at 50 dB SPL means you only need an SNR of 50 dB, just slightly more than 8 bits.

Consider this, if an electron were to transition from "really far" down to the first energy level of the hydrogen atom, then the photon emitted would have an energy of 13.6 eV, and the mass of the resulting hydrogen atom would be 13.6 eV less than the sum of the original masses.

Sorry, I meant to say 511 *keV* for the rest mass of the electron.

Actually, the mass of a hydrogen atom isn't equal to the sum mass of the proton and that of the electron. There's a 13.6 eV binding energy (good 'ol E-mc^2) that needs to be taken into account. Considering that the 511 eV rest mass of the electron and the fact that we're taking about measurements that are supposed to be accurate to less than 1 part per billion, then the binding energy is pretty significant. I suspect there are other effects that also need to be taken into account.

More generally, any device that lets energy (light, sound, heat, ...) only flow in one direction has to spend energy to avoid violating the laws of thermodynamics. That's true of this device just like for a heat pump. You could probably also create a real one-way mirror, but again it could not be a passive device and would require energy to operate.

There's about a 99% chance that the "problem" with gcc >=4.7 is that your code isn't compliant with the C standard (e.g. relies on undefined behaviour) and there's a new gcc optimization that makes a new (legal) assumption that your program violates.

Actually, I thought the whole idea of the "Goldilocks universe" was that life could develop anywhere without the need for a star at the right distance (otherwise there's no advantage). The problem then is exactly as you pointed out. There's no way for life to extract energy, no matter what the temperature is, because everything is at thermal equilibrium. The only way to get energy is through a star. And if you have a star, then having the microwave background doesn't help and is just likely to just make your planet too hot.

I use "nuclear fission" as a sort of "technological landmark". But I was thinking both in terms of "actively" wiping itself out (i.e. wars of some kind) and "passively" destroying itself just like we're currently doing by polluting everything and depleting resources at an insane rate.

A few things to consider here. First, I don't see a way any of that life at T+15M would have become intelligent before the background got too cold. Second, we do not know if it's even possible for life to actually colonize other star systems and even if it is, what's the percentage of intelligent civilizations that achieve that. Of course, the really interesting question is how long an intelligent civilization can last before either destroying itself or depleting all its resources. Personally, I would suspect the half-life of a civilization is less than 1000 years after discovery of nuclear fission.