JCBQ01 t1_itcun33 wrote
Reply to comment by Akrizek in Scientists have discovered an ultra-bright phenomenon in the distant universe that could have come from a star destroyed by a black hole. by ananovanews
I recall reading that if you apply quantum physics and Roche limit laws upon enstine theories of gravity warping time, I suspect that white holes are akin to the Coronasphere which, in turn, is similar to what solar stars have and that they can eject mass, like solid tangible mass that's not waveforms. Which would fit the theory and be a possible answer to the question as to why science cannot explain fully why some blackholes will randomly eject mass from beyond its event horizon.
So while not as much as "expansive" as you propose but more... reactive... bubble so to speak
Few_Carpenter_9185 t1_itd9h89 wrote
Any light/photons/waves and any mass made of electrons, protons, and neutrons that crosses a black hole's Event Horizon is gone for good*. And in general terms, the region of a black hole's Event Horizon is as black or dark as it gets.
(*There is Hawking Radiation that comes "out" or that originates just a tiny smidgen above the Event Horizon, but it's very small for star-mass and bigger black holes, and really weak. And can be ignored. In this context.)
Stuff gets ejected or shot away from the area very near black holes, and there's enormous amounts of light and radiation produced. Huge jets millions of light years long even. But none of it comes out of the black hole itself.
Example, the jet produced by a supermassive black hole at the center of the M 87 galaxy.
The huge amount of energy around a black hole is produced by the matter falling towards it, but hasn't crossed the Event Horizon yet, creates very strong magnetic fields and other forces that can eject energy/plasma in these jets.
A black hole alone in mostly empty space with nothing nearby is definitely very dark. A spot of perfect darkness surrounded only by a ring of bent light coming past its edge.
If a black hole has matter and energy that's falling into it, dust, gas, a ripped-up star etc. It spirals in forming an accretion disk. And the closer it gets, the faster it's moving. Along the inner edge just above the Event Horizon, the matter is moving along at almost the speed of light.
The particles are all rubbing and colliding extremely violently. They are hot. Very very hot. And there's other effects too. Particles moving at high velocity that are forced to bend or curve their paths or that slow down from collisions with other particles also give up energy and produce photons as well. (Google "Bremsstrahlung radiation")
So while the actual black hole, as defined by the Event Horizon is definitely black, (actually even above the Event Horizon, the exteme gravity bending the light creates a black spherical area) the region around it is about as hot and bright as anything in the Universe can get.
It's like looking directly at the Sun, or worse.
One way to understand how bright and violent the region around the black hole can be is to compare it to how stars produce energy and how efficient they are at it.
A star like our Sun is roughly .7% efficient at mass to energy conversion through the fusion happening at its core. Which relates back to Einstein's famous E=mc² formula.
So if you consider how bright and hot the Sun is, that rather small number of only .7% efficiency at mass-energy conversion is still a lot of energy.
In comparison, the accretion disk that's spiraling into a black hole can be as much as 40% efficient at mass-energy conversion. So about 57 times more efficient than the core of a star.
So that makes black holes, or more correctly, the region just above the black hole, one of the brightest things in the Universe.
This causes a LOT of confusion. Because black holes keep coming up in astronomy news articles about how they're seen in distant galaxies, or are the suspected cause for brilliant flashes seen from billions of light years away.
Further adding to the confusion are artists impressions, or computer graphics of black holes on science and astronomy TV shows. They try to explain some aspects of what is happening, but they all ignore how bright it is. Insanely bright. Because a picture of just blinding light doesn't really explain anything else.
And most images or graphics of black holes also don't explain that the radiation is so strong, depending on the size of the black hole, how much matter is in the accretion disk etc. You may not be able to get any closer than several light years away without dying, unless your spaceship was something like a small moon with several hundred kilometers of ice or rock as shielding.
JCBQ01 t1_itdc5yv wrote
This is true, as such is why im.calling the 'white hole phenomenon' a coronal thing around a black hole we just can't 'see it" because of gravity lensing. But I recall reading that NASA and ESA were stumped that a black hole functionally 'belched' parts of a recently eaten star weeks after they observered it being absorbed (im on mobile so I might need to add the report as an amendment later on.
Few_Carpenter_9185 t1_itdeoho wrote
The Corona analogy is a good one. Because it implies "above" or "just outside", which is exactly what's happening, at least in terms of how a star's Corona is just above or outside the photosphere.
And the photosphere being a stand-in for the Event Horizon etc.
I read the same article, or one on the same subject too about the observation.
I wonder if the "delay" in the "belch" has anything to do with time dialation/relativistic effects of the extreme velocity in the accretion disk, and time running slower in such a strong gravity well.
And the time taken for the belch of star matter took longer from an external reference frame, before magnetic fields or whatever were strong enough to overcome the gravity and eject it etc.
Frankly, the astrophysics and math of that, or if it's even relevant to discussing how it happened, are way beyond me though.
JCBQ01 t1_itdgprm wrote
As I understood it they were using localized frames of reference to get the timings down. But it could be the same effect as to what theoretically happens when two black holes collide that the stars density collided and scraped off some of the holes core. All that I know is they are all confused about it and are excited lol
trackerbuddy t1_itesf0h wrote
Anything that crosses the event horizon is gone for good? I struggle with that because mass and energy can’t be destroyed just changed. Even if an entire star is reduced to a pinhead and can’t ever expand again it still exists, right?
Few_Carpenter_9185 t1_itf6fy1 wrote
Yes, that's correct. It doesn't "disappear".
I meant "gone for good" in pragmatic terms. The black hole's mass/energy definitely increases and its gravitational pull increases with everything that goes in.
I just meant that nothing will be escaping the Event Horizon. Matter can't because the escape velocity is greater than that of light, and nothing with actual mass can go 100% the speed of light no matter how hard it's pushed. Much less even faster. You could take a single electron or neutrino, use every last bit of mass/energy in the Universe as "fuel" to accelerate it, and it can never get to 100% of light speed. Just 99.9999(and a lot of 9's)% of the speed of light.
Massless energy/particles like photons can go no faster or slower than light speed. Since the Event Horizon is where escape velocity exceeds light speed they don't escape either.
One exception or caveat though.
There is Hawking Radiation. It's incorrectly described as the "quantum foam" that's everywhere at very tiny subatomic scales. Where virtual particle/anti-particle pairs pop up and cancel each other out. And some pairs at just the right spot along the Event Horizon are "split" allowing the the one just above the Event Horizon to become "real" and escape, while the other half goes down. And since even a black hole can't violate conservation of mass/energy the "real" particles that escape carries away a tiny bit of mass/energy from the black hole.
And the "quantum foam" is real enough. Very sensitive lab experiments, things with lasers, or devices cooled as low as possible with liquid helium etc. pick up it's faint "static hiss", which can never be eliminated.
But that description is an extreme oversimplification to the point of just being wrong. The "carries away a very tiny bit of mass-energy" part is correct though. Hawking himself owns much of the blame honestly. He was trying to come up with a simplistic explanation that a layperson and the press could understand.
The real mechanism for Hawking Radiation is insanely complicated mind bending math, and a combination of several physical laws, and how they interact under the extreme conditions near a black hole. The Heisenberg Uncertainty Principle, Maxwell's Laws of Black-Body Radiation, the Unruh Effect, and Einsteinian Relativity and what happens from various different reference frames in extremely curved space-time, and more, are all in the mix.
The net result though, is that black holes radiate away a little mass-energy as Hawking Radiation. It's a pittance compared to what they eat currently. And the Hawking Radiation is extremely weak long-wave radio photons from the viewpoint of an external observers reference frame for any stellar mass black hole or larger.
Over a very very long time though, a trillion-quadrillion years (whatever... just a very large exponential number in scientific notation) after the last stars in the Universe have long ago burned out, and there's nothing for the black hole to "eat" it will shrink and evaporate through Hawking Radiation.
The smaller the black hole gets, the "hotter" and shorter the energy, wavelength, or frequency of the Hawking Radiation photons gets, and the more it produces. And it grows at a gradual but exponentially increasing rate. Until it goes up in an enormous flash of gamma rays at the end.
Although, other theories of how the Universe "dies" and "deep time", might make slowly shrinking black holes that eventually go up in a huge gamma ray burst (sometimes called a Hawking Bomb) a moot point, if the expansion of space-time through "Dark Energy" creates the "Big Rip" where even individual subatomic particles cannot stay intact.
But that's all way way way beyond my understanding.
Viewing a single comment thread. View all comments