2.4ghz isn't great at detecting small obstacles like wires. There's a smartphone mounted device that can do this with 60ghz: https://walabot.com/
Have you tried this product? What do you think of it?
Readit Newsthinkfaster commented on Ask HN: Any tools to do generic WiFi imaging? · Posted by u/selfsimilar
thinkfaster commented on How do jewellers capture every last particle of gold dust? (2017) ft.com/content/0512638c-b... · Posted by u/EndXA
Another fun Manhattan fact: They needed a code name for plutonium, so they called it "copper", but what was a poor scientist or engineer who needed to use actual copper to do? The official code name for copper was "Honest-to-God copper".
And they wondered how the Soviets infiltrated the project so thoroughly.
Millions of people use aspirin everyday to relieve aches and pains. 43 deaths is nothing compared to the benefits, especially since those people are intentionally overdosing with the intention of killing themselves.
Some of us are explicitly forbidden to take aspirin by their Dr. so the population of asprin takers is biased towards a cohort for whom asprin is safe.
Dead Comment
thinkfaster commented on The Race to Seal Helium HDDs (2021) blog.westerndigital.com/r... · Posted by u/Quizzical4230
Are HDD's a significant consumer of the world's helium, in the scheme of things? I had thought helium was used only in a few bleeding edge drives, and they went to normal air as the tech matured.
Helium in the atmosphere is almost two orders of magnitude more common than xenon and three times as concentrated than krypton. Both are extracted from air.
Even though He is constantly venting to space, alpha emitters keep replenishing it.
Cheap helium from 7% CH4 wells is not going to last. But we're not going to run out of He. Just the energy to extract it.
thinkfaster commented on The Race to Seal Helium HDDs (2021) blog.westerndigital.com/r... · Posted by u/Quizzical4230
Pretty sure it would simply equalize to the external pressure.
Consider it another way. If you have such a device with a vacuum inside, would it not pull in the external helium over time to reduce the vacuum?
A real material would. But thermodynamically OP is right, you'd get a vacuum.
thinkfaster commented on The Race to Seal Helium HDDs (2021) blog.westerndigital.com/r... · Posted by u/Quizzical4230
What would happen if you had a rigid structure that helium could permeate, but nothing larger could, and then filled it up with helium and waited?
Would most of the helium exit, until it was balanced with just the partial pressure of helium in the atmosphere? That would be nearly a vacuum, wouldn't it?
It would create an almost perfect vacuum. You could then extract work by collapsing the vessel. The free energy for the work would come from putting the trapped helium (state 1) in a higher entropy state (state 2).
For what it's worth, this is done industrially to separate gasses using porous membranes.