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IamSmooth

Sun Jun 11 2006, 07:59PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

Have any physics labs been able to create microscopic black holes in the laboratory?

If so, why would their existance be so fleeting; how come they don't take in surrounding matter and continue to grow?

Bjørn

Sun Jun 11 2006, 08:20PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

There have been some reports of possible black hole looking events but you need a very strong imagination to find any evidence.

The size of a laboratory black hole would be so extremely small that gravity would be insignificantly weak in comparison to other forces at play so it probably would make no difference to the behaviour.

Have a look here for one possible reason for small black holes to be short-lived: http://en.wikipedia.org/wiki/Hawking_radiation

Marko

Sun Jun 11 2006, 08:40PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Theoretically a black hole (quantum singularity) can consist of ona two pieces of matter crushed together close enough to be unable to escape their own gravity.
Problem is that here, diameter of 'event horizon' becomes an enormous number of times smaller than for example a proton.

You would need to use some enormous force to crush two protons together, break them into even smaller particles and make the goop small enough for a gravity law F = (m1*m2*G)/d^2 to continue work on its own.

If you try this in real world, for example slaming two protons together with particle accelerators
(using all the power on earth, even more if you need) they would bump together and explode in a bunch of lesse subatomic particles before they were even close to making some kind of singularity.

Actually it seems that such a thing can't happen under any conditions in universe.

I don't know (does somebody else?

) how would such a BH affect surrounding matter or if it would do anything at all.

For a black hole you seem to need some 'critical' mass (one decent star) that will collapse under it's own graviti, to the point where it reaches non-dimensional state, 'falling' into itself as a dot that has no dimensions.

Only thing we see is 'event horison' that is just the line where second cosmic speed reaches speed of light and nothing (matter, energy, it's all the same) can't escape the hole.

'hole' itself has no dimensions (a bit mind boggling, I admit), it has no space and time.
We could (maybe) say that it has completly warped out spacetime from the horizon.

If you could fall into hole (and survive cosmical forces of gravity) you would find yourself in incredibly far 'future' where the hole has evaporated because of hawking radiation and space we know is gone.

I guess that would be pretty scary...

omg omg, whataBS.
I hope some more physics-genius person on this forum can help you much more...

Cesiumsponge

Sun Jun 11 2006, 10:59PM

Registered Member #397 Joined: Wed Apr 19 2006, 12:56AM
Location: Western Washington
Posts: 125

A miniature black hole with the mass of say...several atomic nuclei...will have the exact gravitational pull as several atomic nuclei (not very much at all). It would not really grow unless you force fed it mass because it simply would not have enough gravitational attraction to capture it's own "food". Even random encounters with other gas molecules (for example) in an open environment might be considered extremely rare because atoms are mostly empty space, and the Schwarzschild radius of a black hole with the mass of atomic nuclei would be basically infintesmally small.

Black holes do follow the laws of physics as a body and their gravitational pull is dependant on their mass, which is usually a fraction of the star that existed once before (taking into account radiated mass and energy as the star dies). That is why so much of the "black holes in labs will swallow the Earth" outcry from some of the science-phobic public is silly.

To my knowledge, the necessary situations for the formation of natural black holes is pretty much guided by the Chandrasekhar limit. The only difference is black holes exist where their Schwarzschild radius/event horizon exists outside their surface diameter while ordinary objects do not. For example, I believe the Schwarzschild radius for the Earth is something on the order of 9-10mm in size. If the Earth was compacted under this critical radius (and it would subsequently crush itself into a singularity), it's Schwarzschild radius would exist outside it's own spherical size and be classified as a black hole. However through natural cosmic means, the Earth's gravitational forces will never exceed neutron or electron degeneracy limits required for such fantastic corpses.

As well, in the lab, you would need to collapse atomic material past it's electron and neutron degeneracy limits which is a very large amount of energy. I am not sure if calculations are abound on the Internet or journals, but I believe even the 1TeV particle accelerators would be considered toys when talking this type of energy magnitude. We have just started to probe subatomic particles and black holes appear to be far out there in terms of technological means.

A dimentionless thing isn't too difficult to imagine.
-A cube is three dimensions and can be described with three values of length, width, and height.
-A square is two dimensional and can be described with two values of length and width.
-A line is one dimensional and can be described with a value of it's length.
-A point has no real dimension as it has neither height, length, or width.

Electroholic

Mon Jun 12 2006, 04:00AM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

not really, a square is two dimentional. but you only need 1 parameter to describe it, same as a circle, lol.
Just joking.
and hey a sphere is 3d, but you only need 1 parameter!
sorry for being stupid...

Carbon_Rod

Mon Jun 12 2006, 04:41AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
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Posts: 1155

Well, if the universe were perceived as a Euclidian 3 space then something would appear as 3 dimensional. However n-vector spaces are not always limited to the same classical dimensional restrictions. There are some that suggest our universe is a hypercube â€“ however we could not be fully aware of such a structure.

There have even been proposals suggesting micro black holes form and collapse all the time â€“ err they may not even be perceivable due to violating traditional space-time causality. However, Hawkingâ€™s backward flowing time model suggests a rather interesting contradiction may indeed exist.

In my opinion itâ€™s highly improbable using traditional apparatus of any reasonable scale.

Who knows -- we may finally have a safe place to cleanly dump our garbage.

Cheers,

Marko

Mon Jun 12 2006, 08:16AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Even random encounters with other gas molecules (for example) in an open environment might be considered extremely rare because atoms are mostly empty space, and the Schwarzschild radius of a black hole with the mass of atomic nuclei would be basically infintesmally small.

Yep, you are right.

Such a hole would need to hit another particle to actually eat it, and since it is incredibly small compared to any part of atom such an event would be pretty unlikely.

Quantum Singularity

Mon Jun 12 2006, 04:58PM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

Did someone call me?

I highly doubt that we will see a 'quantum' black hole before seing a regular stellar black hole. On the quantum level - talking about the size of elementary particles - gravity is one of the weakest forces and the nucluer and other forces (repulsion) are much much greater. It would take an enormous amount of power like stated above to force one to happen. Even at that, the closer particles get to each other the stronger the repulsion by the nuclear forces. I have not done any calculations about this but I would guess like said ebove that the Tevetron wouldnt come close.

However, when talking in cosmic terms a black hole is much more possible since over a very long distance gravity is the stongest force. I am not sure if there is any physical proof yet wether or not black holes exist in nature? The last I knew it was highly possible that they were at the center of many galaxies.

Just for clarification: A black hole is a body who's gravitaional pull is so strong that nothing can escape within it event horizon. A singularity is a bit different, and I have heard different ways its explained. But basically it is a point that occupies no space and is infinitely dense. That one is a bit mind boggling. And quantum, like said above, just means on the scale of elementary particles.

IamSmooth

Mon Jun 12 2006, 05:08PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
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Posts: 1567

So let's clear something up, and hopefully those with some advanced physics or astrophysics degree will know the answer...

When a star collapses I believed that it's mass was so great that nothing escapes, but it occupies three dimensions. I contrast this with the "singularity."

So, the question is "is it true that a black hole does not have to be a singularity" as alluded to in the previous reply?

Marko

Mon Jun 12 2006, 05:12PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Just for clarification: A black hole is a body who's gravitaional pull is so strong that nothing can escape within it event horizon. A singularity is a bit different, and I have heard different ways its explained. But basically it is a point that occupies no space and is infinitely dense. That one is a bit mind boggling. And quantum, like said above, just means on the scale of elematary particles.

Black hole occupies no space, and is infinitely dense.

The thing we see as a big black scary thing is generally it's horizon.

A mini black hole out of 2 protons or one in center of galaxy have no physical differences except size. (and you can divide them by size if you wish).

(omg, double post. mod please merge, thanks :) )

[Done but what's wrong with the edit button?]

So let's clear something up, and hopefully those with some advanced physics or astrophysics degree will know the answer...

When a star collapses I believed that it's mass was so great that nothing escapes, but it occupies three dimensions. I contrast this with the "singularity."

So, the question is "is it true that a black hole does not have to be a singularity" as alluded to in the previous reply?

Again, any BH, 2-proton or galaxy center one both are dimensionless and both have horizons
(Schwarzschild radius-es if you wish).

For a horizon you need high enough gravity that it becomes a point where 2nd cosmic speed exceeds speed of light. (so no matter can escape from that point)

If mass is so great that nothing escapes, BH cannot escape it too and turns into a singularity.

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