Another great and thorough article from Ethan Siegel. Ethan gives a run down of density and gravity on his way to discussing how our current civilization will run out of helium.
I still clearly remember my 10th grade chemistry teacher telling me about this in the 80's. He was a retired geo-chemist and one of the singular motivations in my academic life.1 He was a genuinely caring, gentle and fun man in his 60's. One day we were having a casual conversation over our lab preparations when he stopped and looked at me. He had the look of a time traveler standing on the deck of the Titanic. "You know, we're all in big trouble when the helium runs out".
I've never forgotten that. I can't look at a balloon without seeing that look on his face. After two degrees in chemistry, I now understand that look. We are truly screwed when our helium runs out. Our least critical use of helium is in balloons. Need an MRI? You need helium. Want to take a safe pharmaceutical? A chemist needed helium to invent it.2 Until we have another way to maintain -269 °C, helium should be a protected resource.