31–40 of 84 posts
If the plasma jet is wildly larger than our entire galaxy, I wonder if some sort of exotic life could evolve inside the jet. Some sort of life that would be totally rare in the universe.
Sometimes I wonder if our whole universe is some kind of transient aberration, if you zoom out far enough
The jets are 23 million light years in length! That's 140 milky way galaxies laid out -- these are sizes I can't even begin to comprehend
The jets are 23 million light years in length! That's 140 milky way galaxies laid out -- these are sizes I can't even begin to comprehend
Imagine the amount of energy required to create a jet that large! The scales are so big, it makes me wonder if there isn’t an upper limit to energy density. How much energy can be in one spot before you inadvertently create a Big Bang?
Yes, in a sense. The point at which the energy bends space-time into a black hole.
I have a question about black holes, HN. Let’s say you have a black hole. You fire a laser beam straight into it. Just by symmetry, shouldn’t it blueshift on the way in, gain some preposterous amount of energy — enough that it can escape?
You're devilishly close to the Penrose process by which "energy can be extracted from a rotating black hole" [1]. (You can also make them explode [2].)
Earlier quoted context omitted.
This seems incompatible with inflation
Isn't universe inflation already on shaky ground though? https://www.scientificamerican.com/article/cosmic-inflation-...
Has that work developed and found traction among physicists in the 7 years since the article?
Earlier quoted context omitted.
Isn't universe inflation already on shaky ground though? https://www.scientificamerican.com/article/cosmic-inflation-...
Interesting read. Her proposal for a “bounce” cosmology sounds like it has a neat explanation for why things appear smooth, but as far as why/how the universe should bounce at all (especially given current consensus that the current universe will NOT bounce) are only briefly gestured at (“promising recent work”, to paraphrase). Has that work developed and found traction among physicists in the 7 years since the artic…
Earlier quoted context omitted.
Interesting read. Her proposal for a “bounce” cosmology sounds like it has a neat explanation for why things appear smooth, but as far as why/how the universe should bounce at all (especially given current consensus that the current universe will NOT bounce) are only briefly gestured at (“promising recent work”, to paraphrase). Has that work developed and found traction among physicists in the 7 years since the artic…
This was on the front page a couple weeks back iirc: https://www.livescience.com/physics-mathematics/dark-matter/...
Earlier quoted context omitted.
Not my field, but could the Big Bang have been a massive black hole that "spat" out jets of plasma that formed into new stars and galaxies? I call this the black hole big burp theory.
This is very close to an idea known as "Black hole cosmology" -- basically the idea being that the visible universe is inside a black hole, leading to a sort of "nested multiverse". https://en.wikipedia.org/wiki/Black-hole_cosmology A related theory, rather than being inside a black hole, is that the other side of a black hole is a "white hole". As matter collapses into a black hole, it is emitted from the white hole…
I’ve seen stellar engines [1] show up in fiction. Has anyone done a galactic engine? [1] https://en.m.wikipedia.org/wiki/Stellar_engine