Brightnesses are cursed

hillexed@email.com (hillexed) — Tue, 15 Aug 2023 20:46:47 +0000

Today I learned that astronomers measure star brightnesses in the modern AB system, using (logarithmic) units of Janskys, where one Jansky is 10⁻²⁶ W⋅m⁻²⋅Hz⁻¹. Why is there the extremely cursed Hz⁻¹? Hz is already s⁻¹. Why is it like that. Astronomers, why is it like that. s^−1⁻¹ is just seconds

If you cancel all the units, you get… 1 Jy = 10⁻²⁶ kg m² s⁻³m⁻² s^−1⁻¹ = 10^-26 kg s⁻². …so we measure starlight in the same units as surface tension. If you really wanted to, you could talk about how bright a star is by how much its light would stretch a soap bubble.

Ionic Liquids

hillexed@email.com (hillexed) — Tue, 25 Apr 2023 14:38:14 +0000

Today I learned liquids don’t exist in space. It’s either gas or solid because apparently liquids only exist when you have a ton of force squishing atoms together and forcing them to intersct and normally that’s air smashing into things at high speed. Crazy. Space whales won’t know what liquids are

Later that day…

I found https://www.nasa.gov/ames/flute ! They want to use reflective liquids to make perfect parabola shapes for mirrors! I was hoping they found a liquid which stays liquid in space… but their liquids are kept inside pressurized space stations. Their plan so far is to use a liquid then harden the liquid into a solid by polymerizing it before exposing it into space. Nasa hasn’t found liquids that exist in space either :(

Even later…

A friend told me about “ionic liquids”. Like how table salt is made of sodium ions and chlorine ions, an ionic liquid is made of negatively and positively charged ions which attract - except the ions are intentionally so big and ugly they can’t fit right next to one another to make a symmetric solid structure, so they stay liquid. And they might survive in space!

So I researched them! I followed a citation on its wikipedia page to https://www.nature.com/articles/439797a, there’s a paragraph there which mentions “Ionic liquids have also been used in ultra-high vacuum conditions of 10−9 millibar for X-ray photoelectron spectroscopy analysis without decomposing or evaporating”, which cites https://pubs.rsc.org/en/content/articlelanding/2005/cc/b512311a#, which says 1-ethyl-3-methyl imidazolium ethylsulfate is an ionic liquid.

So I searched for that and found this chapter from a book on ionic liquids https://www.intechopen.com/chapters/40002 which cites that paper, all about putting ionic liquids into scientific tools which require vacuums (and they mention ionic liquids used for making nanoparticles and coating things so you can see them in scanning electron microscopes, whoa), and that chapter cites a paper https://pubmed.ncbi.nlm.nih.gov/20437507/ which suggests ionic liquids could be used as lubricants in outer space! That paper is wild, with examples of using ionic liquids to make gold nanoparticles, ionic liquids to help take scanning electron microscope images of things which normally can’t survive vacuums like seaweed without being dehydrated, using “electrowetting” to make little flagellae which move based on the voltage you apply (they use the word “electrocapillary”, which is made of two words that shouldn’t be next to each other what are you doing there)

I asked in a different community if anyone knew what they were and one friend said they had a friend who works on ionic liquids who can’t reveal what they’re up to, but pointed me to https://pubmed.ncbi.nlm.nih.gov/35956982/ a paper on trying to make insulin into a pill you can take by mouth. Someone else found a bacterium that could survive some ionic liquid along with its water: https://www.pnas.org/doi/full/10.1073/pnas.1112750109

In summary: ionic liquids are crazy things which CAN survive vacuums, and other ionic liquids can survive temperatures of -4 to 400C without freezing… but is there an ionic liquid which can stay liquid in both a vacuum and -250C, so it can stay liquid in space? No clue. The hunt continues.

Physics on Hill's Space

Brightnesses are cursed

Ionic Liquids

Later that day…

Even later…