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First real Black Hole image - 10 April 2019


Elendirs
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Just now, QuantumT said:

Yes, I've also read that. But what about the volume/size of the singularity itself?

The singularity [where our laws of physics and GR break down] exist at the Planck/quantum level, as in all BH's. 

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1 minute ago, QuantumT said:

Yes, I've also read that. But what about the volume/size of the singularity itself?

I think a singularity in any black hole doesn't really have a size nor volume.

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22 minutes ago, StringJunky said:

Is the bright bit/ring actually a sphere and not a disc?

It's a disk: the accretion disk. Or at least the brightest, inner part. In the case of M87 we are almost aligned with the axis of rotation, which is why the ring is nearly symmetrical.

But if you see it from side on, it doesn't;t appear to be a disk, because gravitational lensing (see also: Interstellar).

25 minutes ago, beecee said:

That's the one. I was just about to try and watch it (if I can find some headphones!)

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2 minutes ago, beecee said:

The singularity [where our laws of physics and GR break down] exist at the Planck/quantum level, as in all BH's. 

1 minute ago, koti said:

I think a singularity in any black hole doesn't really have a size nor volume.

Even if it is incredibly small, it still has volume, right? Just not something tangible.

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Just now, koti said:

I think a singularity in any black hole doesn't really have a size nor volume.

Any mathematical singularity of infinite density and spacetime curvature, is not really viable and rejected by cosmologists and physicists today. The singularity defined by where our laws break down, certainly does exist, at the quantum/Planck level.

1 minute ago, QuantumT said:

Even if it is incredibly small, it still has volume, right? Just not something tangible.

Yes, as defined by the quantum/Planck level.

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7 minutes ago, QuantumT said:

Even if it is incredibly small, it still has volume, right? Just not something tangible.

As far as I know, our current knowledge of particle physics and quantum mechanics cannot determine whether a singularity has volume. Most probably the question whether it has volume or not might not be relevant at all since volume is a region occupied in space and this becomes something differnt for a singularity with the extreme spacetime curvature. I would presume that on the quantum level the region of a singularity is non zero volume but we can never measure that from our outside reference frames.

 

Edited by koti
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16 minutes ago, QuantumT said:

What is the estimated size of the M87* singularity?

Do you mean singularity? That has zero size (and doesn't;t really exist).

The event horizon has a diameter of about 250 Astronomical Units (about 4x1010 km) ... if my calculation is correct!

 

 

8 minutes ago, QuantumT said:

Even if it is incredibly small, it still has volume, right? Just not something tangible.

The singularity is the centre of the black hole (so not visible, even if it existed) and has zero size. 

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4 minutes ago, Strange said:

The singularity is the centre of the black hole (so not visible, even if it existed) and has zero size. 

So you're telling me that the very "thing", that powers a black hole, isn't physical at all? Has no volume?

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Just now, QuantumT said:

So you're telling me that the very "thing", that powers a black hole, isn't physical at all? Has no volume?

That is not the thing that powers a black hole. It is the point at which the mathematics fails to produce meaningful results. It probably failed to match reality before that.

What "powers" a black hole is its mass (and angular moment and electric charge). That's all.

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6 minutes ago, QuantumT said:

So you're telling me that the very "thing", that powers a black hole, isn't physical at all? Has no volume?

Heres something to put it all into perspective, there are more Hydrogen atoms in a teaspoon of water than there is tea spoons of water in all Earth's oceans. A Hydrogen atom size is 10^-9 m and the Planck length starts at 10^-34 m:
 

Planck_scale.gif

Since the singluarity is below Planck length territory where the concept of left/right up/down straight/backwords stop to have meaning, the very question if a singularity has volume has no meaning. 

Edited by koti
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2 minutes ago, QuantumT said:

So you're telling me that the very "thing", that powers a black hole, isn't physical at all? Has no volume?

GR tells us that once the Schwarzchild radius [EH] is reached, further collapse is compulsory. That in itself infers to a singularity of infinite density and spacetime curvature. But at the same time, GR fails us at the quantum/Planck level. So most cosmologists today, reject the concept of infinite density and curvature, which suggests that the mass collapses to at least the quantum/planck level, or the minimum size possible.

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4 minutes ago, beecee said:

...which suggests that the mass collapses to at least the quantum/planck level, or the minimum size possible.

And there we don't really have a basis of defining space not to mention volume so we probably can't even use the concept of "occupy" or "volume". 

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4 minutes ago, koti said:

Heres something to put it all into perspective, there are more Hydrogen atoms in a teaspoon of water than there is tea spoons of water in all Earth's oceans. A Hydrogen atom size is 10^-9 m and the Planck length starts at 10^-34 m:
 

Planck_scale.gif

Since the singluarity is below Planck length territory where the concept of left/right up/down straight/backwords stop to have meaning, the very question if a singularity has volume has no meaning. 

Yeah I know the Planck scale and particle and atom sizes. I used to have fun by explaining it to my friends. Their jaws would drop.

But it is new to me that so much matter can become so dense in a singularity.

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1 minute ago, QuantumT said:

But it is new to me that so much matter can become so dense in a singularity.

We don't know if it can! 

The matter might be concentrated in something the size of a house. Or it might be evenly distributed throughout the black hole. We just don't know. 

 

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Just now, QuantumT said:

But it is new to me that so much matter can become so dense in a singularity.

It's totally off charts to everybody. Our current state of physics cannot explain the true nature of black hole singularities, certainly to me its completely mind blowing.

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7 minutes ago, koti said:

It's totally off charts to everybody. Our current state of physics cannot explain the true nature of black hole singularities, certainly to me its completely mind blowing.

Yep. We need a throw of quantum gravity to give us a better clue to what might be going on. The only quantum model of black holes I am aware of so far is from string theory: https://en.wikipedia.org/wiki/Fuzzball_(string_theory)

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7 minutes ago, Strange said:

We don't know if it can! 

The matter might be concentrated in something the size of a house. Or it might be evenly distributed throughout the black hole. We just don't know. 

 

My knowledge is limited but it would seem extremely exotic that matter which forms structures all over the universe like stars, planets, houses, animals would suddenly decide that its capable of squashing itself into a region so small its undefined, keep its mass and not rip the universe into oblivion. Not a very scientific statement, I know...but common.

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13 minutes ago, Strange said:

We don't know if it can! 

The matter might be concentrated in something the size of a house. Or it might be evenly distributed throughout the black hole. We just don't know. 

 

Agreed that observationaly, we can never really be able to confirm what size the matter that makes up a BH will conform to. But I believe that GR does tell us that when the Schwarzchild radius is reached, that nothing [that we know] can stop further collapse. Current logic with regards to infinity status, tells us that any mathematical point singularity is rejected. Which leaves the quantum/Planck level where we know that GR fails us. Wouldn't that tell us that the favourable/probable collapse is at this quantum/Planck level?

Edited by beecee
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28 minutes ago, Strange said:

Not familiar with this one, will read up on this now, thanks!

Edit: From the wiki link above:


"At 3.9 billion M (a rather large super-massive black hole), a fuzzball would have a radius of 77 astronomical units—about the same size as the termination shock of our solar system's heliosphere—and a mean density equal to that of the Earth's atmosphere at sea level (1.2 kg/m3)."

It's a long shot but assuming the below image is semi-correct it just might render the fuzzbal theory correct because the distances seem to add up:



 

imageproxy.png

Edited by koti
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39 minutes ago, koti said:

It's a long shot but assuming the below image is semi-correct it just might render the fuzzbal theory correct because the distances seem to add up:

Sadly, that can't tell us whether or not the fuzzball theory is correct or not because the overall size is the same in both cases.

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That black hole at the center of Messier 87 has a mass of 6.5 billion solar masses.

One wonders if any of those 6.5 billion suns had planets which supported intelligent life.

It would be a real bummer if the astronomers of an alien society had to inform their population that in the distant future their sun and the planet that this alien society occupys are going to be sucked into their galaxy's black hole and annihilated. 

 

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