fission or fusion near event horizon

[Neil9327]

Just an idle question:

 

If a mass of uranium (with neutron source) fell in to a black hole, would the forces/pressures on it shortly before reaching the event horizon be sufficient to make it supercritical and detonate in a nuclear fission explosion?

 

Similarly if you had some deuterium/tritium (without the uranium) and did the same, would you get a fusion thermonuclear bomb?

 

I believe that the approach towards a black hole is to cause elongation and narrowing.

 

Perhaps that could be a way to detect the presence of black holes in the future?

[5614]

That is an interesting idea. A very interesting one...

[insane_alien]

um wouldn't the sheer forces caused by the very steep gravitational gradients pull it apart?

 

i could see how it would work in accretion disks where there is evidence of fusion (x-rays and gamma rays) but that is a LOT of hydrogen falling in. enough to surround the blackhole.

 

i could be wrong though.

[J.C.MacSwell]

Just an idle question:

 

If a mass of uranium (with neutron source) fell in to a black hole' date=' would the forces/pressures on it shortly before reaching the event horizon be sufficient to make it supercritical and detonate in a nuclear fission explosion?

 

Similarly if you had some deuterium/tritium (without the uranium) and did the same, would you get a fusion thermonuclear bomb?

 

I believe that the approach towards a black hole is to cause elongation and narrowing.

 

Perhaps that could be a way to detect the presence of black holes in the future?[/quote']

 

Certainly if the black hole was large enough there would be no discernable effect as it approached the event horizon.

 

Not sure how the tidal forces stretching the mass would lead to detonation on it's own unless it triggered a detonation through a strain gauge or something similar and the mass was an actual "bomb".

[[Tycho?]]

I dont think uranium would undergo fission. Tidal forces would tend to seperate the uranium, making a fission chain reaction less likely. There has to be something causing the uranium to increase in density, so as to get more neutron density. I dont believe a black hole would do this.

 

Fusion is different though. Many large black holes have huge accrection disks; disks of matter falling into the black hole. These can get hot enough to shine in x-rays. Since there is no real pressure on the hydrogen I dont think you'd get too much in the way of reactions, certainly not comparable to a hydrogen bomb. But I'd think at least a bit of it would be fusing.

[5614]

MacSwell: the idea was to have uranium with a neutron source, the idea was that as the uranium entered the black hole it would become denser and so become supercritical and then the neutron source could cause a nuclear reaction.

 

But thinking about it now the side of the uranium nearer the black hole will undergo greater acceleration than the side further from the black hole. This would have an overall effect of stretching ie. decreasing the density of the uranium.

[woelen]

The size of the black hole determines how strong the tidal forces are at the event horizon. For a large black hole, it would hardly be possible to feel these tidal forces and for all black holes of practical size, the tidal forces on atoms are neglectable.

[Neil9327]

The size of the black hole determines how strong the tidal forces are at the event horizon. For a large black hole, it would hardly be possible to feel these tidal forces and for all black holes of practical size, the tidal forces on atoms are neglectable.

 

so does that mean that if you were falling into a large black hole you might not be aware of this until later?

I suppose if you were falling in you would be able to see light coming from within, but not far within the event horizon.

 

I believe I am right in saying that any item, such as a metal coin, would become a (very tiny) black hole if it could be compressed to a small enough size? So if we could compress a nucleus small enough it would become a very tiny black hole with very strong tidal forces, and if we then fired two protons at it it might release some energy?