Creating a Black Hole: Possible?

[J20gU3]

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

First of all wouldn't 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.

Anyway what's your opinion.

 

[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.

 

[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.

 

[chroot]

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 $1.4 \cdot 10^{-27} m$:

http://www.google.com/search?hl=en&q=(2+*+G+*+1+kg)/(c^2)&btnG=Google+Search

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

 

[J20gU3]

Wouldnt you need a part hollow iron. If you had a solid piece wouldn't it make it hard to collapse in on its self.

And that's big.

 

[chroot]

The type of matter is not relevant 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

 

[Aki]

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

 

[J20gU3]

i wouldn't of thought so, they may be trying but even for a baby black hole u need a huge mass first.

 

[da_willem]

i wouldn't of thought so, they may be trying but even for a baby black hole u need a huge mass first.

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.

 

[NanoTech]

they are creating very very small black holes, 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.

 

[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.

 

[NanoTech]

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

 

[premjan]

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

 

[Nereid]

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).

 

[Nereid]

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.

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, traveling 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.

 

[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?

 

[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.

 

[Nereid]

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?

 

[Chronos]

Way short, IMO

 

[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 haven't seen mini-holes, as you noted. It is one of the things that makes me think the standard model is very accurate.

 

[Chronos]

Ok, I looked it up. The reigning cosmic ray champion is about 3E20 ev, which works out to 3E11 GeV. Only 8 OOM short of a Planck mass.

 

[Nereid]

Thanks Chronos.

... and 'only' ~ 5 (yes, FIVE!) OOM above what the LHC will achieve with Pb nuclei. €x billion, and nature casually delivers cosmic rays many thousands of times more energetic ... for free.

 

[tony873004]

Wouldn't creating a mini-black hole start a runaway affect. Even if the black hole were only 1kg compressed to 1.4e-27, everything it touched would be sucked into it. It would probably sink to the middle of the Earth where it would eventually eat the Earth from the inside out until the black hole was the mass of the Earth.

Or could it safely be contained?

 

[Chronos]

Assuming a mini black hole was stable [did not evaporate due to hawking radiation], its gravitational sphere of influence would be so tiny it would virtually take forever to consume the earth.

 

[!Live_4Ever!]

Well.. if our EArth was a size of our thumb nail, wouldn't Earth become a black hole?

Hmm question is.. how do we do that... :uhh:

 

[Billy T]

Assuming a mini black hole was stable [did not evaporate due to hawking radiation], its gravitational sphere of influence would be so tiny it would virtually take forever to consume the earth.

I'm far from an expert, but do not agree.

Seem to me, that no mater where the mini BH is on Earth, it would not sit on lab table etc. Instead it would consume the atoms in contact with it's "no escape" surface. It might even gain mass fast enough to resist evaporation.

Also seems clear to me that it would soon fall to the center of the Earth, eating whatever was obstructing its passage on the way down.

I think that there is ample pressure, Browian motion, etc. there at center of the Earth to bring matter to it, even if it does not have large enough mass to gravitionally pull matter towards it rapidly at first.

Consequently, I think if one is created (fortunalely this seems to be well beyound man's capacity) that mini BH would rapidly have the mass of the Earth.

Please correct me where I error.

 

[Billy T]

Magnetic monopole black holes?

Again I'm no expert, but it is my understanding the in the early history of the universe, magnetic monopoles should have been copiously made yet none have been definitely observed. (There is one experiment with superconducting ring that had a current step, for no explained reason, whose magintude matches that a monople passing thru would have created, but this observation is not reproducible.)

Monopoles are increadable heavy. I forget the best estimates (and they vary) but if memory serves each has about 10^15 to 10^21 times the mass of a proton. Some claim that they are massive and dense enough to have collapsed into mini BHs and then evaporated away etc. and that is why we don't see them. I am not very happy with this idea, as my understanding of BHs is that in addition to mass and angular momentun, any net electrical charge would also be externally observable, as is the also inverse square law gravity. Thus I think their monopole field can't be lost by evaporation. (All this is too complex for me to understand.)

What seems much more probable to me as explanation as to why we don't see them is that an S one and a N one combined to form initially a "monopole Hydrongeic like atom." I think their great mass makes this atom have very small size and consequently be very short lived, due to quantum tunnel effects. Thus, I have no problem with all the monopoles having been converted to non magnetic BHs and then evaporating away.

This and a whole lot more (many other types of BHs and physics in general) is discussed in Dark Visitor - Visit www.darkvisitor.com to learn more, including how to read entire book for free. Dark Visitor is a recruting tool, trying to attract more students to the study of physics, by hidding all the physics in it in a scary story of cosmic disaster, that may be true.

Any comments?

 

[selfAdjoint]

seems clear to me that it would soon fall to the center of the Earth, eating whatever was obstructing its passage on the way down.

Wouldn't it oscillate in the classical "linear orbit through the center of the earth" fashion? Then as the Earth rotates it would eat more and more, till soon the hollowed out remains of Earth would collapse into the event horizon and be lost.

 

[Billy T]

Wouldn't it oscillate in the classical "linear orbit through the center of the earth" fashion? Then as the Earth rotates it would eat more and more, till soon the hollowed out remains of Earth would collapse into the event horizon and be lost.

Yes I think so, but as it is gaining zero momentum mass on the way down, it would not be the standard oscillation (in an impossible evacuated tube) from one side of the Earth to the other but some "damped" oscillation.

 

[omagdon7]

If I had to randomly guess I'd say the Cosmic Guru of the year was correct and whatever you read (your explanation sounds very disjointed and convoluted i.e. sci-fi) is incorrect.

 

[SpaceTiger]

Black holes of 1 kg in size have evaporation times of about $$10^{-16} s$$ and event horizons of about $$10^{-25} cm$$. How likely do you suppose it is that something that small will run into something else in that amount of time? If you want to get the answer for a different mass, just multiply the quoted evaporation time by $$M^3$$ and event horizon by $$M$$, where M is in kilograms.

Chronos is right, mini-black holes evaporate very quickly and very rarely accrete matter. Note that the numbers I quote above are assuming GR is valid on those scales. It very well may not be.

 

[Billy T]

Black holes of 1 kg in size have evaporation times of about $$10^{-16} s$$ and event horizons of about $$10^{-25} cm$$. How likely do you suppose it is that something that small will run into something else in that amount of time? If you want to get the answer for a different mass, just multiply the quoted evaporation time by $$M^3$$ and event horizon by $$M$$, where M is in kilograms.

Chronos is right, mini-black holes evaporate very quickly and very rarely accrete matter. Note that the numbers I quote above are assuming GR is valid on those scales. It very well may not be.

If your numbers are correct (see later question), I would agree. But I would not want to near 1 Kg turning entirely into energy!

My question is based on my assumption that you are assuming "vacuum polarization" as the mechanism leading to the evaporation. In the lab, at atmospheric pressure, is their creation of electron / positron pairs at the same rate as in vacuum? If not, and you are basing your numbers on the asumption there is, then I hesitate to agree.

I am not an expert, but the experts do call it "vacuum polarization."

 

[SpaceTiger]

I am not an expert, but the experts do call it "vacuum polarization."

If it is different, I can assure that it's not nearly that many orders of magnitude different. Besides, even if you could get it to live forever, it would almost never run into anything at that size.

 

[Billy T]

If it is different, I can assure that it's not nearly that many orders of magnitude different. Besides, even if you could get it to live forever, it would almost never run into anything at that size.

I think you are right, but not completely ready to throw in the towel yet.

Certainly 10^25cm is small, but even many OOM larger, the gravitational field of a 1kg BH must be greater than the Earth's gravity at the surface (to lazy to do calculations) Thus near by atoms and molecules would fall towards the BH, not to the Earth. It is not completely clear to me, yet, that the 1kg BH does not eat significant numbe of oxygen (A=16) Nitrogen, and "table atoms". I note also that when it eats one member (only) of the electron/positron pair, the BH only need suppy mass equal to 0.5Mev for the other now long lived member of the pair. A proton is roughly 1000Mev of mass. Thus eating only one oxygen molecule would give mass increase of 32,000Mev, or compensate for BH eating 64,000 members of the vacuum polarization pairs.

A nice fat "table molecule" say a celelose molecule, would surely permit BH to gain mass even if it ate a million "half members" of vacuum polarization pairs between each eating of one of these "fat molecules."

Again you are probably right, but it is not yet clear to me that your are.

 

[Billy T]

Another thought occurred to me: The gravitational gradient at no escape surface of 1kg BH must be so strong that it could often happen that it eats both members of the vacuum polarization pair. In which case the BH does not lose any mass by this event. In what fraction of the vacuum polarization events does this "no mass loss, eat both" occur? How frequent are vacuum polarization events (per CC of air)?
Your 10^-16 sec and 1kg implies that they are "dam frequent" in vacuum, so frequent it seems hard to believe, but intuition is useless in these things, so again, you may be right. Where did the 10^-16sec for life time of 1kg BH come from?