An atom to a black hole exists in space. So the space inside would expand, unless the strong force is not effected by space-time. I wonder if the size of quark is expanding. Right now we think they are fundamental, but I am not so sure. Actually not so sure if particles exist or if they are the observable effect of a vibrating dimensional string.
Even though the fabric of space is expanding throughout the Universe, our atoms remain the same size.
On small scales, such as the atom, the electromagnetic and nuclear forces dominate and overcome the expansion of space.
On larger scales, such as individual galaxies, gravitational forces dominate and overcome expansion.
It's only on the largest scales of all, such as the vast distances between galactic clusters, that expansion wins the battle against gravity.
The expansion of the Universe only has any effect where another force - whether gravitational, electromagnetic or nuclear - hasn't yet overcome it.
As Black Holes become more massive, their density decreases.
The maths was explained earlier in the thread, but suffice it to say that N times the mass would drop the density by a factor of N squared. For example, 10 times the mass results in 1/100th of the density.
A Black Hole of three times the Sun’s mass will have an event horizon radius of about 9 km. That means it has a huge density, about two quadrillion grams per cubic cm (2 x 10^15).
A Black Hole of a billion times the Sun's mass (like the ones in the centres of galaxies) would have an event horizon 3 billion km in radius - roughly the distance of Neptune to the Sun. The density would drop by a factor of 1 x 10^18. That would give it a density of roughly 1/1000 of a gram per cc - and that’s the same as the density of air!
I read it here: Ten Things You Don'''t Know About Black Holes | Discover Magazine
It's unknown Physics beyond the event horizon. What is at the centre is really conjecture because we can't see in.
When we talk about the density of a Black Hole we normally mean its mass divided by the volume enclosed within the event horizon - that's all we can say about its density as seen from outside.
If you read my link above, you will learn that, at some point, the collapsing core will be smaller than an electron. It’ll eventually reach a size called the Planck Length.
The Planck length is approximately the size of a Black Hole where quantum and gravitational effects are at the same scale - or so I read! Planck length - Wikipedia
When we talk about the density of a Black Hole we normally mean its mass divided by the volume enclosed within the event horizon - that's all we can say about its density as seen from outside.
If you read my link above, you will learn that, at some point, the collapsing core will be smaller than an electron. It’ll eventually reach a size called the Planck Length.
The Planck length is approximately the size of a Black Hole where quantum and gravitational effects are at the same scale - or so I read! Planck length - Wikipedia
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I found this relating to primordial black holes:
Quantum Black Holes - Scientific American
So, that's probably the best description of the centre of a Black Hole you can get!
Quantum Black Holes - Scientific American
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Okay. I do get that it's math. However my question refers to the ultimate physical condition at that point. The "fabric" of spacetime represents a domain comprised of gravitational forces observable physically, no? So what would we observe if for example the entire universe all of a sudden became a black hole? I mean if all matter were gathered together in one giant mass.
There is no answer to such an extremely hypothetical question.
What goes on at the centre of a Black Hole, of whatever size you care to imagine, is pure conjecture - our current theories of Physics break down in such extreme conditions.
I can accept that we currently don't know everything about how the Universe actually works and perhaps we'll never know!
That's all I am able to say - it's sleepy time!
What goes on at the centre of a Black Hole, of whatever size you care to imagine, is pure conjecture - our current theories of Physics break down in such extreme conditions.
I can accept that we currently don't know everything about how the Universe actually works and perhaps we'll never know!
That's all I am able to say - it's sleepy time!
So, it is possible (!?) that the bigger black holes do not, in fact, get "less dense". But rather that there is some unknown phenomenon that is eventually causing a decrease in gravity relative to mass.
I present to you the following thought: It could be that gravity reaches a point of saturation, sort of like there is an absolute zero in temperature, there could be an absolute limit in gravity.
But up to this point, we do not have any mathematical theories that can support this.
Using sound waves or electromagnetic waves as an analogy for gravitational waves is problematical.
Sound and electromagnetic waves are vibrations which travel through spacetime, whereas gravitational waves are warpings in space time.
However, LIGO ( Laser Interferometer Gravitational-wave Observatory) can translate the interference that gravitational waves cause in the laser beams bouncing between its detection mirrors into sound waves that we can hear.
The result is a 'chirp' representing the arrival of the gravitational waves.
The video in this link reveals the 'sound' of two black holes colliding:
Video | The Sound of Two Black Holes Colliding | LIGO Lab | Caltech
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