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Two Stars Collided And Solved Half of Astronomy's Problems. Now What? (fivethirtyeight.com)
"It's hard to overstate the enormous leap forward that astronomy took on August 17, 2017," reports an article shared by schwit1:
On that day, astronomers bore witness to the titanic collision of two neutron stars, the densest things in the universe besides black holes. In the collision's wake, astronomers answered multiple major questions that have dominated their field for a generation. They solved the origin of gamma-ray bursts, mysterious jets of hardcore radiation that could potentially roast Earth. They glimpsed the forging of heavy metals, like gold and platinum. They measured the rate at which the expansion of the universe is accelerating. They caught light at the same time as gravitational waves, confirmation that waves move at the speed of light. And there was more, and there is much more yet to come from this discovery... "Now it's a question of, do we have the right instrumentation for doing all the follow-up work?" said Edo Berger, an astronomer at Harvard who studies explosive cosmic events. "Do we have the right telescopes? What's going to happen when we have not just one event, but one a month, or one a week -- how do we deal with that flood...?"
The August 17 gravitational wave gave astronomers a glimpse at an entirely different universe. For most of history, they've studied stars and galaxies, which seem static and unchanging from the vantage point of human timescales... But GW170817 revealed a universe alive, pulsating with creation and destruction on human timescales... [T]he event itself unfolded in less than three human-designated weeks. This faster timescale is "pushing the way astronomy is done," Berger said... In space, the Fermi space telescope glimpsed a burst of gamma radiation. Within an hour, astronomers made six independent discoveries of a bright, fast-fading flash: A new phenomenon called a kilonova... Nine days later, X-rays streamed in, and after 16 days, radio waves arrived, too. Each type of information tells astronomers something different. Richard O'Shaughnessy, an astronomer at the Rochester Institute of Technology, describes the discovery as a "Rosetta stone for astronomy."
"What this has done is provide one event that unites all these different threads of astronomy at once," he said. "Like, all our dreams have come true, and they came true now..." Thanks to the August 17 event, astronomers now know what to look for. Soon, they will be able to sift through an embarrassment of neutron-star mergers and other phenomena... And they are talking about how to turn their eyes to the sky, at a moment's notice, the next time the universe throws something big their way. "It's a wonderful time, it's a terrifying time," O'Shaughnessy said. "I can't really capture the wonder and the horror and glee and happiness."
The August 17 gravitational wave gave astronomers a glimpse at an entirely different universe. For most of history, they've studied stars and galaxies, which seem static and unchanging from the vantage point of human timescales... But GW170817 revealed a universe alive, pulsating with creation and destruction on human timescales... [T]he event itself unfolded in less than three human-designated weeks. This faster timescale is "pushing the way astronomy is done," Berger said... In space, the Fermi space telescope glimpsed a burst of gamma radiation. Within an hour, astronomers made six independent discoveries of a bright, fast-fading flash: A new phenomenon called a kilonova... Nine days later, X-rays streamed in, and after 16 days, radio waves arrived, too. Each type of information tells astronomers something different. Richard O'Shaughnessy, an astronomer at the Rochester Institute of Technology, describes the discovery as a "Rosetta stone for astronomy."
"What this has done is provide one event that unites all these different threads of astronomy at once," he said. "Like, all our dreams have come true, and they came true now..." Thanks to the August 17 event, astronomers now know what to look for. Soon, they will be able to sift through an embarrassment of neutron-star mergers and other phenomena... And they are talking about how to turn their eyes to the sky, at a moment's notice, the next time the universe throws something big their way. "It's a wonderful time, it's a terrifying time," O'Shaughnessy said. "I can't really capture the wonder and the horror and glee and happiness."
After some quick research I found this:
http://www.preposterousunivers...
It basically says, yes, the mass and size of the universe is (remarkably) close to that of of a black hole with the corresponding Schwarzschild radius, but, no, it does not seem like we live inside a black hole. The strongest argument is that the universe is expanding, not contracting as a black hole.
It does, however, resemble a white hole, which is a time-reversed version of a black hole.
The author still seems to have a problem with an "outside" of the universe....
That seemed so improbable that I figured you must have slipped a decimal pace somewhere and double-checked your work. Looks good though.
Here's the math for anyone interested
Schwarzschild radius r = 2MG/c^2
Volume of a sphere = 4/3*pi*r^3
density = M / [4/3*pi*(2MG/c^2)^3] = M * 3/4pi * (c^2 / 2MG)^3 = 3/32pi * c^6/(G^3 M^2)
Galaxy Mass ~~= 10^12 * M_sol (@ 2*10^30kg) = 2*10^42kg
black hole density = 3/32/pi*(300,000,000 m/s )^6 / (6.674×1011 m3kg1s2)^3 / (2*10^42kg)^2
~= 0.0008 kg/m^3
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