Nov 4, 2020 07:10 PM
(This post was last modified: Nov 5, 2020 02:56 AM by C C.)
It’s coming from inside the galaxy: First fast-radio-burst source ID’d
https://arstechnica.com/science/2020/11/...ource-idd/
INTRO: Today, researchers are announcing they've solved one of the questions that's been nagging them over the past decade: what exactly produces the weird phenomena known as fast radio bursts (FRBs)? As their name implies, FRBs involve a sudden blast of radio-frequency radiation that lasts just a few microseconds. We didn't even know that FRBs existed until 2007 but have since cataloged hundreds of them; some come from sources that repeatedly emit them, while others seem to burst once and go silent.
Obviously, you can produce this sort of sudden surge of energy by destroying something. But the existence of repeating sources suggests that at least some of them are produced by an object that survives the event. That's led to a focus on compact objects, like neutron stars and black holes, with a class of neutron stars called magnetars being viewed very suspiciously.
Those suspicions have now been borne out, as astronomers have watched a magnetar in our own galaxy sending out an FRB at the same time it emitted pulses of high-energy gamma rays. This doesn't answer all our questions, as we're still not sure how the FRBs are produced or why only some of the gamma-ray outbursts from this magnetar are associated with FRBs. But the confirmation will give us a chance to look more carefully at the extreme physics of magnetars as we try to understand what's going on.... (MORE)
Did a black hole give birth to our universe?
https://www.forbes.com/sites/startswitha...d8080050da
EXCERPT: . . . When you look at the equations that govern a black hole, there’s something remarkable that happens as well. If you start just outside the event horizon and escape to an infinite distance away from the black hole, you’ll find that your distance ® goes from R, the Schwarzschild radius, to infinity: ∞. On the other hand, if you start just inside the event horizon and track your distance from the black hole to the central singularity, you’ll find that same distance ® instead goes from R, the Schwarzschild radius, to zero: 0.
Big deal, right? No, it actually is a big deal, for the following reason: if you examine all the properties of space outside of a black hole’s event horizon, from R to ∞, and compare them to all the properties of space inside the black hole’s event horizon, from R to 0, they are identical at every single point. All you have to do is replace the distance, r, with its reciprocal, 1/r (or, more accurately, to replace all instances of r/R with R/r), and you’ll find that the black hole’s interior is mathematical identical to the black hole’s exterior.
As our understanding of the Universe has improved and been refined over the past few decades, two new discoveries have rocked the foundations of cosmology. The first was cosmic inflation: instead of arising from a singularity, it now appears that the Universe was set up by a rapid, relentless state of constant, exponential expansion that preceded the hot Big Bang. It’s as though there were some sort of field that provided an energy inherent to space itself, causing the Universe to inflate, and only when inflation ended did the hot Big Bang begin.
The second was dark energy: as the Universe expands and becomes less dense, distant galaxies start to recede from us at an accelerating rate. Once again — albeit, with a much smaller magnitude — the Universe behaves as though there’s some sort of energy inherent to space itself, refusing to dilute even as the expansion of space continues. For as long as inflation and dark energy have both been around, people have speculated that there might be a connection.
What might that connection be? Once again, black holes could be the answer. Black holes gain mass as material falls into them, and decay, losing mass, via Hawking radiation. As the size of the event horizon changes, is it possible that this changes the “energy” inherent to the fabric of space to an observer located inside the event horizon? Is it possible that what we perceive as cosmic inflation marks the creation of our Universe from an ultramassive black hole? Is it possible that dark energy is somehow connected to black holes, as well?
And does this mean that, as astrophysical black holes have formed within our Universe, that each one gives rise to its own “baby Universe” somewhere inside of it? These speculations have been around for many decades, but without a definitive or provable conclusion. Nevertheless, many models and ideas abound, and this line of thought continues to be compelling to many who research black holes, thermodynamics and entropy, General Relativity, and the beginning and end of the Universe... (MORE - details)
https://www.youtube-nocookie.com/embed/rFgpKlcpzNM
https://arstechnica.com/science/2020/11/...ource-idd/
INTRO: Today, researchers are announcing they've solved one of the questions that's been nagging them over the past decade: what exactly produces the weird phenomena known as fast radio bursts (FRBs)? As their name implies, FRBs involve a sudden blast of radio-frequency radiation that lasts just a few microseconds. We didn't even know that FRBs existed until 2007 but have since cataloged hundreds of them; some come from sources that repeatedly emit them, while others seem to burst once and go silent.
Obviously, you can produce this sort of sudden surge of energy by destroying something. But the existence of repeating sources suggests that at least some of them are produced by an object that survives the event. That's led to a focus on compact objects, like neutron stars and black holes, with a class of neutron stars called magnetars being viewed very suspiciously.
Those suspicions have now been borne out, as astronomers have watched a magnetar in our own galaxy sending out an FRB at the same time it emitted pulses of high-energy gamma rays. This doesn't answer all our questions, as we're still not sure how the FRBs are produced or why only some of the gamma-ray outbursts from this magnetar are associated with FRBs. But the confirmation will give us a chance to look more carefully at the extreme physics of magnetars as we try to understand what's going on.... (MORE)
Did a black hole give birth to our universe?
https://www.forbes.com/sites/startswitha...d8080050da
EXCERPT: . . . When you look at the equations that govern a black hole, there’s something remarkable that happens as well. If you start just outside the event horizon and escape to an infinite distance away from the black hole, you’ll find that your distance ® goes from R, the Schwarzschild radius, to infinity: ∞. On the other hand, if you start just inside the event horizon and track your distance from the black hole to the central singularity, you’ll find that same distance ® instead goes from R, the Schwarzschild radius, to zero: 0.
Big deal, right? No, it actually is a big deal, for the following reason: if you examine all the properties of space outside of a black hole’s event horizon, from R to ∞, and compare them to all the properties of space inside the black hole’s event horizon, from R to 0, they are identical at every single point. All you have to do is replace the distance, r, with its reciprocal, 1/r (or, more accurately, to replace all instances of r/R with R/r), and you’ll find that the black hole’s interior is mathematical identical to the black hole’s exterior.
As our understanding of the Universe has improved and been refined over the past few decades, two new discoveries have rocked the foundations of cosmology. The first was cosmic inflation: instead of arising from a singularity, it now appears that the Universe was set up by a rapid, relentless state of constant, exponential expansion that preceded the hot Big Bang. It’s as though there were some sort of field that provided an energy inherent to space itself, causing the Universe to inflate, and only when inflation ended did the hot Big Bang begin.
The second was dark energy: as the Universe expands and becomes less dense, distant galaxies start to recede from us at an accelerating rate. Once again — albeit, with a much smaller magnitude — the Universe behaves as though there’s some sort of energy inherent to space itself, refusing to dilute even as the expansion of space continues. For as long as inflation and dark energy have both been around, people have speculated that there might be a connection.
What might that connection be? Once again, black holes could be the answer. Black holes gain mass as material falls into them, and decay, losing mass, via Hawking radiation. As the size of the event horizon changes, is it possible that this changes the “energy” inherent to the fabric of space to an observer located inside the event horizon? Is it possible that what we perceive as cosmic inflation marks the creation of our Universe from an ultramassive black hole? Is it possible that dark energy is somehow connected to black holes, as well?
And does this mean that, as astrophysical black holes have formed within our Universe, that each one gives rise to its own “baby Universe” somewhere inside of it? These speculations have been around for many decades, but without a definitive or provable conclusion. Nevertheless, many models and ideas abound, and this line of thought continues to be compelling to many who research black holes, thermodynamics and entropy, General Relativity, and the beginning and end of the Universe... (MORE - details)
