This: Something tangible becomes the intangible. So in essence, a BH is a place of increasing negative existence.
Hard to believe.
So science wants me to believe the opposite of what appears?
There's a BH in the center of every galaxy.
So galaxies exist because the gravity of BHs formed them?
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Tidal Force......Pffff.
As said, that is nothing but gravity gradient.
Gravity is g = GM/d²
Gradient is -2GM/d^3
When d goes to 0, the gradient blows to infinity.
It is already damn high at the event horizon d= Rs= 2GM/c²
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We must have a 'Cosmic Connection' as I was, indeed, reading the February issue of Hi-Fi World, in which Noel Keywood continues to extol the virtues of valve amplifiers and criticises loudspeakers that peak in the upper midband and treble just to create 'showroom appeal'.
Noel Keywood seems to die his hair. Looks a bit weird. 😀
Not many people know this, but in 1850 a battle royal was fought between the Vector men, and the William Hamilton's Quaternion troops. I have always detested Vectors.
IMO, it was unfortunate that the Quaternion and Octonion people lost. 😱
Quanta Magazine
Thus giving us a 150 years of deep confusion. Even when David Hilbert was asked what he would like to know in 500 years time about Mathematics, he said he wanted to know if the Riemann Hypothesis had been solved. I like tough problems.
A whole galaxy of Maths is based on the Riemann Hypothesis being true. But we can't (currently) prove it. 😕
I am pretty comfortable with infinity. 1/0 an' all that. One of my better Maths teachers (Quint) set us a 100 integrals to solve during the Summer Holidays. I started with No. 100 and worked backwards. How hard can it be? Cracked it pretty quickly using complex variable. Old Quint gave me a glowing report. "The brilliance and conciseness of Steve's solutions frequently impress me." 😀
Not many people know this, but in 1850 a battle royal was fought between the Vector men, and the William Hamilton's Quaternion troops. I have always detested Vectors.
IMO, it was unfortunate that the Quaternion and Octonion people lost. 😱
Quanta Magazine
Thus giving us a 150 years of deep confusion. Even when David Hilbert was asked what he would like to know in 500 years time about Mathematics, he said he wanted to know if the Riemann Hypothesis had been solved. I like tough problems.
A whole galaxy of Maths is based on the Riemann Hypothesis being true. But we can't (currently) prove it. 😕
I am pretty comfortable with infinity. 1/0 an' all that. One of my better Maths teachers (Quint) set us a 100 integrals to solve during the Summer Holidays. I started with No. 100 and worked backwards. How hard can it be? Cracked it pretty quickly using complex variable. Old Quint gave me a glowing report. "The brilliance and conciseness of Steve's solutions frequently impress me." 😀
A black hole with the mass of the Sun would have an event horizon radius of approximately 3km.The differential acceleration across a 2m human at a distance of 100km from the event horizon would be approximately 50,000 times the acceleration due to gravity at the surface of the Earth. I feel some spaghettification coming on! 😱
The interesting thing is that, as the mass of the black hole becomes larger, the differential acceleration actually becomes less.
A supermassive black hole with a mass of 100 Suns would have an event horizon radius of approximately 300 million km. The differential acceleration across a 2m human at a distance of 100km from the event horizon would then be far less than he/she would experience on the surface of the Earth. 😎
No, small galaxies were the first to form when the universe was young.
The first black holes were formed when individual stars in these galaxies died and collapsed in on themselves. These stellar mass black holes sank to the centre of gravity i.e. to the heart of the galaxy in which they formed.
Galaxies subsequently grew larger by colliding and merging with each other. The black holes at the centres of the galaxies collided and merged as well to eventually produce supermassive black holes.
Yes.
Here is a proof: Assuming a Schwartzchild BH, the gravity gradient at the event horizon is
- c^6 / 4 G² M² ( from post #5043 )
One can see the gradient becomes less, when the mass becomes larger.
A BH also cools as it gets larger. It’s counter intuitive because a big BH is far more massive and obviously from the energy perspective there’s a lot more gone into it. DrPhysicsA covers this in his YouTube lecture
I think there's just a whole lot of stuff that we haven't really figured out yet.
Not a mathematician or physicist by any stretch of the imagination, but it seems clear to me we're lacking a whole lot of insight in the actual "ongoings" of the universe.
Edit:
Meanwhile, might I suggest the title track "Cosmic Coincidence" from my album?
Partly inspired by pulsar beats and sattelites, the great expance and general wonderment. No samples.
Not a mathematician or physicist by any stretch of the imagination, but it seems clear to me we're lacking a whole lot of insight in the actual "ongoings" of the universe.
Edit:
Meanwhile, might I suggest the title track "Cosmic Coincidence" from my album?
Partly inspired by pulsar beats and sattelites, the great expance and general wonderment. No samples.
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Just wait until we've got quantum gravity (QG) all figured out. There'll be no stopping us then!
Quantum gravity - Wikipedia
P.S. Here's a suggestion for the name of your next title track: Quantum Quandary 😎
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Must be her accent! 😎
And she contributes copious content to keep you captivated:
Channel Trailer 2020 - YouTube
And she contributes copious content to keep you captivated:
Channel Trailer 2020 - YouTube
Sabine Hossenfelder is a German author and theoretical physicist who researches quantum gravity: Sabine Hossenfelder - Wikipedia
That would suggest she supplies YouTube content we can trust!
It appears you are not the only one who appreciates her talents . . .
That would suggest she supplies YouTube content we can trust!
It appears you are not the only one who appreciates her talents . . .
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I agree, this is a conundrum, people in this thread are (correctly) quoting scientists as saying contradictory things about the insides of black holes.
I want to grill some high-fallutin' scientist about this. They say "we can't know what goes on inside the event horizon," (which is clear because nothing can exceed the speed of light in a vacuum, and the event horizon is where something would have to exceed that speed for it to come out), on the other hand "they" say all the mass goes to the center, collecting in a point of zero size called the singularity, based on the mathematical term for a point of a function where one divides by zero.
"Backing up" to something that's NOT a black hole but close to it, in a neutron star (named because with this much gravity the electrons are pushed into the protons and they become neutrons along with the neutrons that were already there, so it's all neutrons) the mass can be such that the escape velocity is 99 percent of the speed of light, but it's still considered to be a sphere with every part of it having neutrons packed next to one another. Add in just a "little bit more" matter and the escape velocity exceeds 100 percent of the speed of light, and then they claim all those neutrons are suddenly squished together into a teeny tiny point. HOW do they know this?
"They" surely have some good reason for saying this, but I haven't discovered anything other than an appeal to authority.
Fortunately, you don't have to worry about the (ahem, alleged) singularity to explain this.
This may have been explained, but what grows is the amount of mass in a black hole, and with more mass it has more gravity, so the distance from the center where the escape velocity reaches the speed of light also grows.
Indeed.
Boggled about "Volume of a black hole", I found a paper where it is said the inside volume depends of the chosen metric for the space inside. Then they calculate different volumes using different metrics.
My understanding is: We don't know, the inside volume of a BH is not defined, it does not exist.
Why don't they say so ?
It seems to me, people are not able to say: "I do not know" ...and this is getting worse.
I'll need to look into it, not making promises. 🙂
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Yep, it's becoming more important to portray themselves as knowledgeable, that they have some kind of understanding or grip on the theory that helps solidify their positions.
It's a lot easier (and cheaper) than saying: "We got to figure out what's happening here."
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Kaffiman, I thought your last track "Silence" was very soothing...
I have been following Loop Quantum Gravity: Quanta Magazine.
Very good hour-long lecture at the Royal Institution on LQG. Jim Baggott explains it to kids, which is about my level:
Why Space Itself May Be Quantum in Nature - with Jim Baggott - YouTube
Bottom line, is that General Relativity falls on its face with Quantum Theory, because you can't actually know Energy, Momentum and Position and Time simultaneously. So Lee Smolin has hatched up LQG.
The lecture slightly lost me at the crucial point of what LQG really is after a gentle introduction, but I have a notion it's about spin. Lee thinks we have to abandon the idea of Space and presumably the Metric. His colleagues think that Time has to go. Other people think LQG fails to deal with Special Relativity since the "Spin Foam" must change shape with velocity.
I don't see that as a problem, since a sphere is still a sphere under Relativity. The good news is the troublesome singularity in a Black Hole disappears. 😎
I have been following Loop Quantum Gravity: Quanta Magazine.
Very good hour-long lecture at the Royal Institution on LQG. Jim Baggott explains it to kids, which is about my level:
Why Space Itself May Be Quantum in Nature - with Jim Baggott - YouTube
Bottom line, is that General Relativity falls on its face with Quantum Theory, because you can't actually know Energy, Momentum and Position and Time simultaneously. So Lee Smolin has hatched up LQG.
The lecture slightly lost me at the crucial point of what LQG really is after a gentle introduction, but I have a notion it's about spin. Lee thinks we have to abandon the idea of Space and presumably the Metric. His colleagues think that Time has to go. Other people think LQG fails to deal with Special Relativity since the "Spin Foam" must change shape with velocity.
I don't see that as a problem, since a sphere is still a sphere under Relativity. The good news is the troublesome singularity in a Black Hole disappears. 😎
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