# Creating a black hole.

1. Dec 13, 2004

### J20gU3

Do you think it is possible to create a black hole.

First of all wouldnt you need to create a star. I know that the hydrogen is fused to create energy then it changes to helium. If you had enough deuterium and tritium (i know they have short half lifes so this would need to be a quick process) would you be able to create a chain reaction big enough to make a star.

I also know that you would need to make a star big enough so that when it runs out of fuel (hydrogen) and it turns to helium gravity and preassure become unbalanced and turn into a nuteron star or black hole.

Would this be possible if we had enough and not thinking about the dangers but it would help research into time travle etc etc.

2. Dec 13, 2004

### Grogs

I see a couple of big problems with the star building method. First, you need to get enough material so that it will collapse under its own weight. Theoretically, that's around 3 solar masses, which is certainly nothing to sneeze at. The second problem is that once you get enough mass to set off the proton-proton chain, the nuclear fusion will offset the gravity. (Tritium decays to 3He and then to 2H {Deuterium}, both of which are part of the standard chain - deuterium is stable.) Once started, the star would burn for several million to a few billion years.

If you really wanted to build a black hole by accumulating mass, I think you would be better off using iron. Iron won't produce energy when fused, so 3 solar masses of iron should collapse under its own weight to form a black hole.

I think there might be an easier way though (dragging 3 solar masses of iron together would be tough!) I think that with powerful enough explosives, we may someday be able to implode material in such a way to create a small black hole. The technique would be similar to the way most nukes are detonated today (a sphere of explosives compress a spherical core of plutonium.) In this case, the explosives themselves would probably have to be nukes. If the explosion compresses the central matter to within it's Swarzchild radius, a black hole is created. I doubt we have the technology necessary to do this today or even 50 years from now, but I could see it being accomplished at some point in our future.

3. Dec 13, 2004

### Moore1879

One thing is that a star usually begin with Hydogen-1. Hans Belle predicted this, winning a Nobel Prize. But that still leaves you with getting that much matter.

4. Dec 13, 2004

### chroot

Staff Emeritus
You don't need to create a star. Nor do you need to use materials which normally make up stars. All you need to do is to get enough mass (any kind of mass) inside a small enough radius to satisfy the following criterion:

$$r \leq \frac{2 G M}{c^2}$$

For example, if you have 1 kg of material handy, all you need to do is compact it down to a radius of $1.4 \cdot 10^{-27} m$:

Practically, this is very difficult to do, of course. For comparison, the radius of a hydrogen atom is much, much larger -- about $10^{-10} m$.

- Warren

5. Dec 13, 2004

### J20gU3

Wouldnt you need a part hollow iron. If you had a solid piece wouldnt it make it hard to collapse in on its self.

And thats big.

6. Dec 13, 2004

### chroot

Staff Emeritus
The type of matter is not relevent at all. All you need to do is to put enough matter into a small enough space that its escape velocity exceeds the speed of light. Viola, you have a black hole.

- Warren

7. Dec 14, 2004

### Aki

Aren't they presently creating baby black holes in labs right now?

8. Dec 14, 2004

### J20gU3

i wouldnt of thought so, they may be trying but even for a baby black hole u need a huge mass first.

9. Dec 14, 2004

### da_willem

You only need a huge mass density. But the problem (or I guess we should count ourselves lucky) with baby black holes, is that they evaporate very fast.

10. Dec 14, 2004

### NanoTech

they are creating very very small blackholes, the size of a few protons. the part that is tough, is the sustainability. the minuature black holes created evaporate very very quickly as well. from what i guess, CERN(when finished) will help out with this part of the process.

11. Dec 14, 2004

### Chronos

There is reason to believe you need at least a planck mass to form a black hole [whose schwarzchild radius would be a planck length]. The limit may, however, be lower if certain higher dimensional theories are correct. In that case the Large Hadron Collider at CERN may be able to produce them. At present, none have yet been created of any size in colliders, so far as anyone knows. If the planck mass limit [~10E19 Gev] holds, we will never create one.

Last edited: Dec 14, 2004
12. Dec 16, 2004

### NanoTech

How could we benefit from creating these black holes at CERN?

13. Dec 18, 2004

### premjan

are they sure that they succeeded to create an (even small) black hole? why did it evaporate?

14. Dec 18, 2004

### Nereid

Staff Emeritus
Welcome to Physics Forums premjan!

I too am curious to know why NanoTech thinks mini-black holes have been created in colliders - AFAIK, there's nothing in the data from any collisions that even hints at such production. Further, if they could be made in colliders, there'd be plenty of them formed from UHE cosmic ray collisions with N or O nuclei (in the air) - again, no hints of such in all the CR data.

Mini-BHs would evaporate through Hawking radiation - at least that's the theory. As no one has observed a mini-BH, this theory has not yet been directly tested (although it is consistent with a large body of indirect experimental and observational data).

15. Dec 19, 2004

### Nereid

Staff Emeritus
Good summary Grogs (and a belated welcome to Physics Forums).

I'm not so sure the explosive compression scheme would be feasible, even in 50 years' time. For starters, compressing iron (or similarly 'inert nuclear material') will work just fine ... until electron degeneracy kicks in. At that point, the material - which will be similar to that which comprises white dwarfs - will become dramatically more incompressible, and I doubt that even 'nuclear explosives' will do anything much to compress it further ... after all, that's what happens several times a day (second?) somewhere in the universe - we call this (when we see it) a 'nova' (note to pedants: yes, I'm taking some liberties, and glossing over some important details). Rarely, if ever, does a BH result from a white dwarf nova outburst.

Even if we could find a way to compress a lump of mass against 'white dwarf' electron degeneracy pressure, another dramatic increase in 'incompressibility' awaits us ... when the electrons combine with the protons to form neutrons - which is what neutron stars are - giant nuclei.

Of course, we could - and do - 'compress' a nucleus, even a big one ... and we can do it with the most powerful of hammers - collision with another nucleus, travelling at 0.999999... c! What seems to happen, perhaps because the matter we create is so hot?, is that we make a 'quark-gluon plasma', but not a BH.

So simply pumping more raw energy into already well compressed mass doesn't seem to create densities high enough to form a BH ... and AFAIK the highest densities we think we could create (using our best physics today - the Standard Model) are still many, many OOM too small forr BH production.

16. Dec 21, 2004

### Grogs

Thanks for the welcome Nereid.

You're probably right about today's nukes not having the 'oomph' to create a black hole. I hadn't really thrown any numbers into the calculation. Focusing them precisely enough (smaller than the radius of an atom ) would probably be a huge problem too. It would probably still be easier than dragging 3 SM's of material together, but it's many, many years down the road, if it's possible at all.

For the sake of comparison (to the 1019 GeV number Chronos mentioned), what energies are the latest and greatest supercolliders producing?

17. Dec 21, 2004

### Chronos

RHIC ( Relativistic Heavy Ion Collider )
Name of Institute/Site: BNL
Location: Brookhaven , USA , Americas
Classification of Site: Accelerator under Construction
Type of Accelerator: Collider, Superconducting Technology
Applications: Nuclear Physics, High Energy Physics
Particles used: ions
Beam Energy: up to 100 GeV/nucleon
Beam Current:

LHC ( Large Hadron Collider )
Name of Institute/Site: CERN
Location: Geneva , Switzerland , Europe
Classification of Site: Proposed Project
Type of Accelerator: Storage Ring, Superconducting Technology
Applications: High Energy Physics
Particles used: protons, Pb-ions
Beam Energy: 14 TeV protons, 1150 TeV Pb, center of mass
Beam Current: 540 mA protons

Brookhaven is currently on line. It is a squirt gun compared to the LHC.

18. Dec 21, 2004

### Nereid

Staff Emeritus
So, "1150 TeV Pb" is ~10^6 GeV ... still ~13 OOM short. Whew!

Anybody like to guess how energetic the highest energy cosmic ray observed to date was?

19. Dec 21, 2004

### Chronos

Way short, IMO

20. Dec 21, 2004

### Chronos

Nereid, I am going off the top of my head. I believe even cosmic rays are at least 3 OOM are short of the energies you have in mind. It would explain why we havent seen mini-holes, as you noted. It is one of the things that makes me think the standard model is very accurate.