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Comment by fooqux | Hacker News Reader

If I understand this correctly, couldn't this explain dark matter?

The article didn't say how dense this cloud was, but if it was still a cloud it couldn't be that dense right? Surely something that could exist in the cold vastness of space.

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The cosmic microwave background is 136000 times hotter, so I don’t think so, no.

Fair, but the article implied that it's a somewhat linear effect- you don't need absolute zero for it to make the cloud dim. The article didn't do a great job of saying what temps they were testing at.

Still, I'm not surprised. I doubt some armchair scientist is going to solve the riddle of dark matter. I was curious and got some good answers. Thanks!

"136000 times hotter" sounds a lot more impressive than "2.72546 degrees hotter"...

That was fun to read. Even funner to realize that the huge relative number is actually more useful too. Saying 2.72 degrees sounds small, but a difference that large on average throughout the universe would be absolutely insane And break basically all of physics

Is that temperature uniformly spread?

The temperature variance across the CMB is incredibly small. It depends on what you mean by uniformly spread, of course, but the fancy colorful images you often see are showing variance out to like 4 or 5 decimal places, if I recall. Like thousandths or ten-thousandths of a degree K.

Near absolute zero states of matter don't really work the same way. I wouldn't read too much into them saying "cloud".

No. The experimentalists used lasers to condense the atoms to high densities.

Sounds like a fun conspiracy. Aliens using space lasers to hide, what, 25% of the matter in the universe from us?

85%, not that it would matter for a conspiracy theory.

Nice pun :)

Would that be the 25% that isn't "Dark Matter"? Ergo, nothing in the Universe is observable ... wait.

They're saving it to use as fuel to survive until the next big bang.

Yeah the 25% coolest parts too.

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