3 ms·
Perhaps some local astrophysicists can chime in on how the gas could be characterized as "hot" - my naive assumption is that could only be relative?
by blacksmith_tb 1y ago
Perhaps some local astrophysicists can chime in on how the gas could be characterized as "hot" - my naive assumption is that could only be relative?
- reliablereason 1y agoI want to hear what Sabine Hossenfelder says. I trust that she will say her honest truth.
- tux3 1y agoThe Youtube algorithm unfortunately had the same effect on Sabine as it has on every Youtuber who depend on the platform for income Sabine has always been a little bit on the fringe of physics (e.g. Superdeterminism has had a, let's call it, less than mainstream appeal) But now every other video is some complete crackpot nonsense being given consideration for 5 minutes and, hastily debunked in the last minute, and with a title like Could This New Theory of Everything Solve Consciousness and Dark Energy? Sabine's Youtube is a very different type of content than the old BackReaction days.
- jl6 1y agoThe modern version of History Channel shows with titles like Ancient Nazi Alien Secrets Exposed.
- bamboozled 1y agoIt’s sarcasm …
- hyperhello 1y agoWouldn’t that be trivially the average velocity of the particles?
- AnimalMuppet 1y agoAverage velocity of the particles if there are enough of them to collide frequently (and if you can factor out bulk motion). But you can also look at average vibrational energy.
- blacksmith_tb 1y agoSo collisions would provide enough energy to call them hot, or is that a term of art, like calling all non-hydrogen, non-helium elements "metallic"?
- sieabahlpark 1y ago[dead]
- thayne 1y agoSo, temperature is basically a measure of the average kinetic energy of particles in a substance. When you have an extremely diffuse gas, as is the case between galaxies, the particles can be moving very fast, but energy density is still low, because there are so few particles. According to the abstract of the paper, this gas is just 10^-3 particles/cm^3 or 1000 particles per cubic meter. That is 5 orders of magnitude less than the space between planets in our solar system. So, yes, it is hot. But it also very, very sparse. According to Wikipidia 10^5 to 10^7 K[1]. But there isn't very much of it. As to why they are hot, from what I've been able to find, it is at least partly due to gravitational potential energy being converted to thermal energy, as it falls into filaments. [1]: https://en.wikipedia.org/wiki/Warm%E2%80%93hot_intergalactic_medium https://en.wikipedia.org/wiki/Warm%E2%80%93hot_intergalactic...
- gus_massa 1y agoAssuming it's not a fabrication of the press release, it may be jargon. Astrophysicists call "metal" everything that is not Hydrogen or Helium, but Chemist disagree heavily. In this case, the paper don't call it "hot" but it says that 99.99% of the Hydrogen is ionized. To ionize one Hydrogen you need 13.6eV. The average energy is temperature*k_Boltzmann. So if the temperature is 13.6eV/k_Boltzmann ~= 160000K then the 50% of the Hydrogen is ionized and 50% not ionized. To get only 0.01% not ionized you need to increase the temperature, IIRC -log(0.01%)~=9 times. So the temperature is ~1400000K. Unless I'm making an horrible stupid mistake, I agree it's hot. (I may be missing the 4.7eV of the dissociation of H2 molecules into two H atoms, that would increase the temperature like a 40%.)