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How do they know or believe that it doesn't contain dark matter?
Earlier quoted context omitted.
I've heard this idea in the context of Dyson spheres/swarms. The issue is that, while they'd be invisible or dim to the eye, the areas would be very bright in infrared.
The whole concept of Dyson Spheres, or anything even vaguely like that, is totally absurd. (Even Dyson said so.) Any space-faring culture will have mastered controlled fusion long ago, and have entirely left behind any material dependence on stars. The best places to live, then, are out in the Kuiper belts and beyond, where unlimited room and cold are available for free, and valuable gases are lying about, frozen. In…
This seems like an interesting thought experiment care to expand on that?
> The void, which is nearly a billion light years across, is empty of both normal matter and dark matter. The finding challenges theories of large-scale structure formation in the universe. How do they know or believe that it doesn't contain dark matter?
Posted it because it reminds me of an hypothesis I once saw, that we might be able to detect alien civilizations based on blank spots in the sky where they've managed to divert all the energy from their environment.
It might not be as empty as it looks. Maybe it’s just got a really big dark sheet over it. Astronomers don’t consider the possibility of ginormous dark sheets in space.
> The void, which is nearly a billion light years across, is empty of both normal matter and dark matter. The finding challenges theories of large-scale structure formation in the universe. How do they know or believe that it doesn't contain dark matter?
> The void, which is nearly a billion light years across, is empty of both normal matter and dark matter. The finding challenges theories of large-scale structure formation in the universe. How do they know or believe that it doesn't contain dark matter?
”The lack of radio sources means that there are no galaxies or clusters in that volume, and the fact that the CMB is cold there suggests the region lacks dark matter, too.”
Imagine being a civilization on the edge of a galaxy on the edge of the void. One direction, nothing whatsoever. The other direction, billions upon billions of galaxies. Would be neat!
Imagine being a civilization alone in the void, and not even a generation ship could make contact with anyone else, even if they knew which direction to send it.
[0] https://en.wikipedia.org/wiki/Giant_Void
Earlier quoted context omitted.
Sort of. In Vinge's world, the slow zone is just a natural phenomenon, not something artificially created. And in the slow zone you're basically limited to nearly-speed-of-light travel consistent with our contemporary understanding of relativistic physics (which is unbearably slow to anyone who can travel much faster than that outside the slow zone). Whereas in Liu Cixin's books, if I remember correctly, they actuall…
If I remember correctly, there's some ambiguity whether the slow zone was created by some power or naturally occurring (or a bit of both) although a bit of both is perhaps the natural answer.
Imagine being a civilization on the edge of a galaxy on the edge of the void. One direction, nothing whatsoever. The other direction, billions upon billions of galaxies. Would be neat!
I would be curious to hear if the odds of life existing on the edges of the universe were lower.
Imagine being a civilization on the edge of a galaxy on the edge of the void. One direction, nothing whatsoever. The other direction, billions upon billions of galaxies. Would be neat!
https://en.wikipedia.org/wiki/Local_Void
* 1 megaparsec = 3.26 million light years