Ultra Massive Black Holes......

[tahaadi]

Looking at the size and amount of matter inside black holes, our own very existence and our life looks completely meaningless.
Nihilism is now making sense for me.

[vulcanlogician]

Looking at the size and amount of matter inside black holes, our own very existence and our life looks completely meaningless.
Nihilism is now making sense for me.

I fail to see how the mass of a black hole relates to the meaningfulness of one's life. If meaning is measured by the pound, sure, every human life that was ever lived is meaningless when stood before the massiveness of one of these cosmic giants.

But there are other metrics by which to gauge the meaningfulness of things. Mass is by far the crudest.

[Anomalocaris]

Yes, but the black star hypothesis also counts as a (still) plausible alternative explanation for observations, so it satisfy as a legitimate reason why actual black holes MIGHT not exist.

OK, I took a closer look at the reasoning for 'black stars'. As far as I can see, the distinction between them and 'true' black holes is that they do not have singularities or event horizons. Instead, they are 'frozen' at what would be the event horizon boundary. This, by the way, is expected to happen in the formation of a black hole because of observer effects concerning time dilation near an event horizon.

Again, truthfully, the difference seems minimal. We expect BHs to form via collapse and thereby be subject to the observer effect. From the view of a distant observer, they will *look* like a black star. Since, from the view of a distant observer, there will *always* be matter outside of the event horizon and since the infall takes an infinite amount of time, there is no real difference between a BH and a black star. This is doubly true if the EH and singularity are 'smoothed over' due to quantum effects.

As far as I can see, this is a distinction without an observable difference, which means there is no difference at all.

Time dilation if I am not mistaken only affects free falling towards event horizon.   Dark star applies to collapse at less than freefall speeds. Black star in effect suggests that it is possible no true black holes can ever form.

[Peebothuhlu]

At work.

*Raises hand*

Uhm..... about that 'Spin' thing?

Can you point to the original article?   There is no minimum spin for black holes. Black holes possesses whatever angular momentum was possessed by its progenitor object and by whatever is carried by everything falling into it.  Since angular mometum had a sign, it is possible for incoming angular momentum to cancel out existing angular momentum.  It in theory is possible for a black hole to have no spin whatsoever.   There is a maximum spin when the black hole forms.  Anymore and the angular momentum would prevent the progenitor object from collapsing into a blackhole.

I don't have the article.

So... the gist goes like this.

Stars, planets etc all rotate due to physics reasons (Yah, my edumacation be gooder.  )

Stars can spin ridonculously fast. The pulsars being examples off the top of my head. Am sure knowledgable people can point to some insanely fast spinning celestial objects.

Now... black holes (The model) aren't solid. They are the effect of something also ridonculous acting on the reality around them.

The thing is that, since black holes aren't 'Solid'. They have a limit to just how fast they (The effect) can warp reality as they rotate. Uhm... as pace distorts?

So... black holes have an upper limit of how fast they can spin.

Stars have a different upper limit to how fast they can spin.

Sorry again if I'm not reading well in my post. Am running of memeory of a New Scientist article.

Hope the ideas help explain my question of.

"How fast can a 'Black Star' spin? How fast can 'Other' stellar bodiesspin? How fast can something that's just a twist in reality effectivly 'Spin'?   What do we see happening when we look out into the cosmos?"

[polymath257]

OK, I took a closer look at the reasoning for 'black stars'. As far as I can see, the distinction between them and 'true' black holes is that they do not have singularities or event horizons. Instead, they are 'frozen' at what would be the event horizon boundary. This, by the way, is expected to happen in the formation of a black hole because of observer effects concerning time dilation near an event horizon.

Again, truthfully, the difference seems minimal. We expect BHs to form via collapse and thereby be subject to the observer effect. From the view of a distant observer, they will *look* like a black star. Since, from the view of a distant observer, there will *always* be matter outside of the event horizon and since the infall takes an infinite amount of time, there is no real difference between a BH and a black star. This is doubly true if the EH and singularity are 'smoothed over' due to quantum effects.

As far as I can see, this is a distinction without an observable difference, which means there is no difference at all.

Time dilation if I am not mistaken only affects free falling towards event horizon.   Dark star applies to collapse at less than freefall speeds.   Black star in effect suggests that it is possible no true black holes can ever form.

Not true. Time dilation would be significant even if there is no event horizon as long as the gravitational field is large enough. The 'frozen' nature of black stars is precisely this effect.

We expect most black holes to form in situations where there is other matter around. So we expect that there will be matter in a deep gravitational well. It seems that the 'evidence' supporting black stars is that there was a photon signal as well as a gravitational wave signal. But that is expected from BH also because of any extra matter around them.

In essence, a BH with matter around it is exactly the same as a black star from all possible observations. The notions are observationally identical.

This makes a distinction with no difference.

[Jehanne]

Time dilation if I am not mistaken only affects free falling towards event horizon.   Dark star applies to collapse at less than freefall speeds.   Black star in effect suggests that it is possible no true black holes can ever form.

Not true. Time dilation would be significant even if there is no event horizon as long as the gravitational field is large enough. The 'frozen' nature of black stars is precisely this effect.

We expect most black holes to form in situations where there is other matter around. So we expect that there will be matter in a deep gravitational well. It seems that the 'evidence' supporting black stars is that there was a photon signal as well as a gravitational wave signal. But that is expected from BH also because of any extra matter around them.

In essence, a BH with matter around it is exactly the same as a black star from all possible observations. The notions are observationally identical.

This makes a distinction with no difference.

As a sidebar, there was an original Star Trek episode in the 1960s, where Captain Kirk mentions a "black star".