There are now 14 competing universes
this post was submitted on 15 Aug 2024
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Ugh... I hate it when my helium stockpiles run out every 13 or so billion years.
what do they even need all that helium for?
Not counting novelty balloons, MRI machines are probably the biggest "real world" use. Gotta keep those superconducting magnets superconducting and helium is just the thing. And every time an MRI machine has to be quenched (such as when some idiot leaves something metal too close to it), or decommissioned (which is surprisingly often) all the helium tends to be released because it's difficult to impossible to collect it.
Not sure if hydrogen could also be used, but in our high-oxygen atmosphere, having that much hydrogen in an enclosed space with spinning, sparking electrical motors is just asking for trouble, especially if the above release protocol has to be used. Fireballs are generally a no-no. Risking one in a hospital is plain insanity.
Most other uses are even more scientific, and helium has a few properties that nothing else has, so without it, the science that would use it either has to go the dangerous hydrogen route, make do with a heavier unreactive gas or just... stop.
Novelty balloons make up a fraction of a percent of helium usage, and the helium they use is generally not high quality.
For cooling purposes, is nitrogen not as good?
Best as I can make out, no. Current MRI tech apparently needs temperatures as low as 9 Kelvin and nitrogen freezes solid at 64. Since Kelvin units are an absolute scale, we could say that it needs to be 7 times colder than nitrogen can provide.
What I can't make out is whether nitrogen is any more dangerous than helium if it gets too warm and explosively decompresses.
Helium does have the advantage that it would escape straight up and through anything even vaguely porous, where nitrogen would just hang around displacing oxygen, causing more of a suffocation risk. How much more, again, I'm not sure.
Depends? Liquid nitrogen can freeze a lot of vibrational degrees of freedom in place, but if you want molecular rotations to stop as well, there's no way around He.
Squeaky voices
I sprinkle helium 3 on my breakfast cereal every morning. Sure, it's wasteful but don't tell me how to live my life.