# Artificial Black Holes, again

#### ubavontuba

vanesch said:
Yes, but that's highly hypothetical, no ? We already have to live in 10 dimensions...
Maybe you didn't read my other http://news.bbc.co.uk/1/hi/sci/tech/4357613.stm" [Broken] wherein it's claimed that they've already accomplished it.

The scaling up in itself needs a lot of R&D. You don't see this as spectacular breakthroughs, it are many many small improvements in the reliability of the production process and so on which make up the bulk of this research.

For instance, at PSI I remember having heard a talk about research on back-to-back connections between arrays of photodiodes on silicon and the ASIC that does the data selectioning and compression before sending it on an optical fibre. The industrially available techniques didn't have a high enough density of connection points to do this. So a lot of research was done to improve this, and the density was increased 16 fold.
Now that these back-to-back connections are available, the whole sandwich of photodiodes + electronics is used for high resolution medical X-ray imaging. It took 6-7 years of a 10 person R&D group to devellop this.

There are many such examples.
Sure... fine. But, wouldn't it have been a lot cheaper to just tell these same engineers that we want this or that for other applications? Why not just put them to work building better medical imagers, rather than having to develop the technology secondhand?

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#### vanesch

Staff Emeritus
Gold Member
ubavontuba said:
In order for blackholes to form (generally speaking) all of the energy must be expended in the collisions. Glancing blows, that allow for continued momentum of the particles, will not deliver enough energy to compress the particles into blackholes. This is why they expect only a small percentage of each run to form blackholes.
Problem is, at these energies, protons look more like "a bag of potatoes" than a single particle. So it is relatively hard for that ENTIRE bag to collide coherently without some schrapnels escaping. But if that's a worry, one could slightly "untune" one of the beams wrt the other (say, colliding 7.001TeV protons onto 6.999 TeV protons). Then the center of mass of the collision has enough (1 GeV !) kinetic energy left not to be captured by the earth's gravity.

Jupiter wasn't always where it is. Besides, Jupiter's moons suffer more tidal forces than the asteroids, and yet there they are.
Damn, never thought of that ! So it MUST be a particle accelerator fired up by an ancient civilisation...
But that means that that black hole is still there ! Help ! :rofl: :rofl:

#### AlphaNumeric

ubavontuba said:
Sure, but the relative motion frame of the two colliding particles is not the same as the relative motion frame of the earth, in this instance.
A particle accelerator accelerates electrons and protons parallal with the Earth's surface (it's locally flat). Therefore, the resultant particles produced also move in the vague direction of parallal to the Earth's surface (sort of spread out in a cone).

The particles hitting the upper atmosphere do anything from a glancing blow, through to aiming right at the centre of the Earth. Therefore the upper atmosphere reactions cover an enormous spectrum of energies (millions of times stronger than CERN) and also aim at every direction from "parallal to the Earth's surface" through to "aim right at the core".

The atmosphere reactions are higher energy and aim all over the place. Hence the danger from them is much much higher than that of CERN, and since we're still here 4.5 billion years after the Earth formed, the chances of a black hole being formed and swallowing us up seems small.
ubavontuba said:
Not true, a rotating body eaten from within would collapse both outwardly and inward. It's a function of angular momentum (like Hawking radiation).
We'd still see the black hole orbiting around by a mysterious force perturbing the asteroids.
ubavontuba said:
Jupiter wasn't always where it is. Besides, Jupiter's moons suffer more tidal forces than the asteroids, and yet there they are.
No, it's been there about as long as the other planets have.

Besides, the strength of tidal forces relates to how big the object is. A tiny moon wouldn't have too much tidal forces on it, or if it formed far from jupiter than was captured by it's gravity it might be strong enough to survive. If a proto-planet hadn't formed yet, a passing Jupiter might have been enough to shred it and make the asteroids, or shred it into smaller bodies which could survive the tidal forces, giving rise to some of Jupiter's larger moons.

But maybe you're right. Our theories of quantum mechanics and relativity are way off and Earth wasn't the first place in the solar system to develop life, a myterious planet between Mars and Jupiter once harboured life which got destroyed by an artificial black hole when they did 1TeV+ experiments.

That is much more plausable.....

#### ubavontuba

vanesch said:
Problem is, at these energies, protons look more like "a bag of potatoes" than a single particle. So it is relatively hard for that ENTIRE bag to collide coherently without some schrapnels escaping.
Certainly, they expect a spectacular array of parton distribution. Their plan is to collide around a billion particles per second, of which they expect/hope to see a small percentage form nano blackholes. It should indeed be a spectacular particle show.

But if that's a worry, one could slightly "untune" one of the beams wrt the other (say, colliding 7.001TeV protons onto 6.999 TeV protons). Then the center of mass of the collision has enough (1 GeV !) kinetic energy left not to be captured by the earth's gravity.
This is an excellent suggestion, but it would require the loss of some potential energy. I think it'd be a hard sell to the scientists. It'd sure make me happy if they'd modify their experiments thusly, though.

Damn, never thought of that ! So it MUST be a particle accelerator fired up by an ancient civilisation...
Just so we're clear. I did not ever speculate so wildly. All I asked is a question. Specifically: "...how do we know that the asteroid belt wasn't the result of a black hole orbiting the center of mass of a former planet?"

Aren't there rules here against this type of speculation?

But that means that that black hole is still there ! Help ! :rofl: :rofl:
Perhaps, perhaps not. If a planet didn't collapse around a mini blackhole exactly evenly, the mini blackhole could easily be flung away in the ensuing melee.

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#### ubavontuba

AlphaNumeric said:
A particle accelerator accelerates electrons and protons parallal with the Earth's surface (it's locally flat). Therefore, the resultant particles produced also move in the vague direction of parallal to the Earth's surface (sort of spread out in a cone).
Right, but with little or no relative momentum to the earth's center of mass.

The particles hitting the upper atmosphere do anything from a glancing blow, through to aiming right at the centre of the Earth. Therefore the upper atmosphere reactions cover an enormous spectrum of energies (millions of times stronger than CERN) and also aim at every direction from "parallal to the Earth's surface" through to "aim right at the core".
Sure, but with great relative momentum to the earth's center of mass. They don't strike the earth and magically lose their momentum. Remember, momentum is conserved. If they form nano blackholes, they'll procede away from or through the earth... friction free.

The atmosphere reactions are higher energy and aim all over the place. Hence the danger from them is much much higher than that of CERN, and since we're still here 4.5 billion years after the Earth formed, the chances of a black hole being formed and swallowing us up seems small.
If you'd just apply basic Newtonian Mechanics to what you are writing, you'd see that regardless of the odds of one forming, the odds of one sticking around are virtually zero. Therefore, this argument is meaningless.

We'd still see the black hole orbiting around by a mysterious force perturbing the asteroids.
No, it's been there about as long as the other planets have.
Not true, the collapse of a planet around a mini blackhole isn't necessarily evenly distributed. If a planet didn't collapse around a mini blackhole exactly evenly, the mini blackhole could easily be flung away in the ensuing melee. The blackhole might have a different or eccentric orbit, or might even have achieved solar escape. It'd be so small, It could easily be virtually undectable.

Besides, the strength of tidal forces relates to how big the object is. A tiny moon wouldn't have too much tidal forces on it, or if it formed far from jupiter than was captured by it's gravity it might be strong enough to survive. If a proto-planet hadn't formed yet, a passing Jupiter might have been enough to shred it and make the asteroids, or shred it into smaller bodies which could survive the tidal forces, giving rise to some of Jupiter's larger moons.
Aren't Jupiter's moon orbits too circular for this to be the case? Don't captured bodies tend to have eccentric orbits? Also, why do the asteroids exist in the wide array of sizes they do then? Shouldn't they be more uniform?

But maybe you're right. Our theories of quantum mechanics and relativity are way off and Earth wasn't the first place in the solar system to develop life, a myterious planet between Mars and Jupiter once harboured life which got destroyed by an artificial black hole when they did 1TeV+ experiments.

That is much more plausable.....
See above response to Vanesch.

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#### franznietzsche

ubavontuba said:
Just so we're clear. I did not ever speculate so wildly. All I asked is a question. Specifically: "...how do we know that the asteroid belt wasn't the result of a black hole orbiting the center of mass of a former planet?"

How do we know it wasn't a vogon destructor fleet?

Or the Klingons?

Or supernova jet that was so narrow as to leave the rest of the solar system unharmed?

Or another Star passing through the solar system disk?

I'm not being wildly speculating, no sirree.

ubavontuba said:
Aren't Jupiter's moon orbits too circular for this to be the case? Don't captured bodies tend to have eccentric orbits? Also, why do the asteroids exist in the wide array of sizes they do then? Shouldn't they be more uniform?
Why do asteroids in exist in a wide array of sizes? Are all rocks equally strong?

Further why would the size of the asteroids be dictated by tidal forces? The planet breaks up due to tidal forces along weak lines in the rock. Why would they be uniform?

Which moons of Jupiter have circular orbits? You mean ALL 63 KNOWN moons of jupiter have nearly perfect circular orbits? Now that's amazing. 29 of those moons are less than 4 kilometers across. Aside from the Galilean moons and the Amalthea moons (which are only the first 8 and have eccentricities all on the order of 0.001), almost all have eccentricities greater than .15, most greater than .25 and a few as great as .44, one even as great as 0.60. Pluto's eccentricity is only 0.248. Highly circular orbits indeed.

#### Rach3

ubavontuba said:
It'd be so small, It could easily be virtually undectable.
"Virtually" undectable? A borderline case? Tell me, how do you propose to detect an order-of-TeV (10^-24 kg) mass by it's graviational effects? You seem to be missing the essential point here - this is an order-of-magnitude issue. This is 40 orders-of-magnitude from being an issue. Assuming this thing will even exist (huge assumption), and that it won't instantly evaporate (another huge assumption), then we have a totally inert object which will capture particles gravitationally on an astrophysical time scale (assuming it even survives).

Regarding your last post, extremely-relativistic objects do not fall to the earth. Orbital speeds are on order of 10^4 m/s. Relativistic speeds are on order >10^8 m/s. It escapes like a knife through butter.

#### Rach3

Question for the experts - if the black hole is formed from a collision of hadrons, will it interact via the strong force? I can't imagine what qcd looks like in a black hole...

#### ubavontuba

franznietzsche said:
How do we know it wasn't a vogon destructor fleet?

Or the Klingons?

Or supernova jet that was so narrow as to leave the rest of the solar system unharmed?

Or another Star passing through the solar system disk?

I'm not being wildly speculating, no sirree.
I like your enthusiasm! That's the spirit!

All I'm saying is that the CERN scientists use the evident here-ness of solar system bodies as proof for the safety of this experiment. I'm just pointing out one not-here-ness. I don't see it as being any weaker than their arguments (especially considering that they seemed to forget about the law of conservation of momentum).

Why do asteroids in exist in a wide array of sizes? Are all rocks equally strong?

Further why would the size of the asteroids be dictated by tidal forces? The planet breaks up due to tidal forces along weak lines in the rock. Why would they be uniform?
Ah, then you think it WAS a planet that broke up, versus a void orbit caused by Jupiter's gravity? Sorry, I don't see Jupiter as being capable of actually breaking a planet at that distance. Flinging it away? Maybe. But chopping it into itty bitty pieces?

Which moons of Jupiter have circular orbits? You mean ALL 63 KNOWN moons of jupiter have nearly perfect circular orbits? Now that's amazing. 29 of those moons are less than 4 kilometers across. Aside from the Galilean moons and the Amalthea moons (which are only the first 8 and have eccentricities all on the order of 0.001), almost all have eccentricities greater than .15, most greater than .25 and a few as great as .44, one even as great as 0.60. Pluto's eccentricity is only 0.248. Highly circular orbits indeed.
Generally speaking, the non-Gallilean moons are quite small and are obviously captured asteroids, as are Mars' moons. Most have retrograde orbits. The Galilean moons orbits are only elliptical due to Laplace resonance. Where's the evidence that they are caused by Jupiter's ability to "shred it (a proposed proto-planet) into smaller bodies which could survive the tidal forces, giving rise to some of Jupiter's larger moons."

How does Io survive these amazing chopping forces of Jupiter?

#### ubavontuba

Rach3 said:
"Virtually" undectable? A borderline case? Tell me, how do you propose to detect an order-of-TeV (10^-24 kg) mass by it's graviational effects?
Apparently you missed the fact that we were discussing the concept of one eating a planetary core, thus embuing it with some significant mass.

You seem to be missing the essential point here - this is an order-of-magnitude issue. This is 40 orders-of-magnitude from being an issue. Assuming this thing will even exist (huge assumption), and that it won't instantly evaporate (another huge assumption), then we have a totally inert object which will capture particles gravitationally on an astrophysical time scale (assuming it even survives).
That'd be nice, but what about the planetary core's own internal pressure and it's effects?

Regarding your last post, extremely-relativistic objects do not fall to the earth.
Where did I write that?

Orbital speeds are on order of 10^4 m/s. Relativistic speeds are on order >10^8 m/s. It escapes like a knife through butter.
My point exactly. Thereby belying the CERN scientists assumption that the existence of solar objects is proof that no harm can come to us by the creation of artificial nano blackholes. If they form natuarally, they don't stick around long enough to cause any harm regardless.

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#### franznietzsche

ubavontuba said:
I like your enthusiasm! That's the spirit!

All I'm saying is that the CERN scientists use the evident here-ness of solar system bodies as proof for the safety of this experiment. I'm just pointing out one not-here-ness. I don't see it as being any weaker than their arguments (especially considering that they seemed to forget about the law of conservation of momentum).

Ah, then you think it WAS a planet that broke up, versus a void orbit caused by Jupiter's gravity? Sorry, I don't see Jupiter as being capable of actually breaking a planet at that distance. Flinging it away? Maybe. But chopping it into itty bitty pieces?
Ah, then you like putting words in my mouth. You asked why, if a planet was broken by jupiter, wouldn't the asteroids be the same size. I replied to that. I was not stating that I thought a planet formed and was subsequently broken up.

Generally speaking, the non-Gallilean moons are quite small and are obviously captured asteroids, as are Mars' moons. Most have retrograde orbits. The Galilean moons orbits are only elliptical due to Laplace resonance. Where's the evidence that they are caused by Jupiter's ability to "shred it (a proposed proto-planet) into smaller bodies which could survive the tidal forces, giving rise to some of Jupiter's larger moons."

How does Io survive these amazing chopping forces of Jupiter?
Io is literally turning itself inside out because of the tidal, not chopping, forces.

I never supported the comment that captured chunks of rock gave rise to some of Jupiter's larger moons. I object to your comment that 1) Asteroids should suddenly be the same size, and 2) that jupiter's moons mostly have circular orbits.

I think this thread has been just been a progression of greater and greater crackpottery, and should simply be locked.

#### ubavontuba

franznietzsche said:
Ah, then you like putting words in my mouth. You asked why, if a planet was broken by jupiter, wouldn't the asteroids be the same size. I replied to that. I was not stating that I thought a planet formed and was subsequently broken up.
No, I asked; "Also, why do the asteroids exist in the wide array of sizes they do then? Shouldn't they be more uniform?" in regards to an assumption that a proto-planet hadn't ever formed.

Io is literally turning itself inside out because of the tidal, not chopping, forces.

I never supported the comment that captured chunks of rock gave rise to some of Jupiter's larger moons.
Why do you think I do? That concept came from someone else (AlphaNumeric).

Aside to Alphanumeric: Why haven't the numerous smaller moons formed up into larger ones too?

I object to your comment that 1) Asteroids should suddenly be the same size, and 2) that jupiter's moons mostly have circular orbits.
Where did I write; "Asteroids should suddenly be the same size"? As for circular orbits, I was refering to the "larger" (Galilean) moons mentioned by AlphaNumeric.

I think this thread has been just been a progression of greater and greater crackpottery, and should simply be locked.
I agree. The "experts" here haven't answered any of my questions, and have resorted to crackpot rhetoric to suppress them.

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#### Rach3

ubavontuba said:
Apparently you missed the fact that we were discussing the concept of one eating a planetary core, thus embuing it with some significant mass.
Did you miss the fact, frequently repeated in this thread, that the timescale for 'eating' even a single proton is an astronomical timescale? Or the part where a 10^9 ton black hole was shown to be harmless? (It's also microscopic, if you do the math.)

That'd be nice, but what about the planetary core's own internal pressure and it's effects?
Yes, what about them? We've already mentioned that the mass density is on the order of unity that of solids at STP. I.e., insignificant.

My point exactly. Thereby belying the CERN scientists assumption that the existence of solar objects is proof that no harm can come to us by the creation of artificial nano blackholes. If they form natuarally, they don't stick around long enough to cause any harm regardless.
The same argument applies equally well to accelerator-produced black holes. Their mass is SMALL compared to the energies involved, so they must invariably be highly relativistic. Not that it would make any difference.

#### Orion1

Classical GR cross section...

Classical GR Planck Singularity cross-section

$$m_{Fe} = 9.274 \cdot 10^{-26} \; \text{kg}$$ - Iron nucleon mass (35.1% Terra composition)

$$m_e$$ - Terra mass
$$r_e$$ - Terra radius

$$\tau \sim \frac{1}{n \sigma v}$$

$$n_e = \frac{3 m_e}{4 \pi m_{Fe} r_e^3}$$

$$\sigma_c = \frac{\pi \hbar G}{c^3}$$

$$v_e = \sqrt{\frac{2 G m_e}{r_e}}$$

$$\tau_b = \frac{1}{n_e \sigma_c v_e} = \left( \frac{4 \pi m_{Fe} r_e^3}{3 m_e} \right) \left( \frac{c^3}{\pi \hbar G} \right) \left( \sqrt{\frac{r_e}{2G m_e}} \right)$$

Combining terms:

$$\tau_b = \frac{4 c^3 m_{Fe}}{3 \hbar} \sqrt{\frac{r_e^7}{2 G^3 m_e^3}}$$

Reference:
https://www.physicsforums.com/showpost.php?p=1001445&postcount=14
https://www.physicsforums.com/showpost.php?p=1002158&postcount=28

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#### vanesch

Staff Emeritus
Gold Member
Rach3 said:
Question for the experts - if the black hole is formed from a collision of hadrons, will it interact via the strong force? I can't imagine what qcd looks like in a black hole...
If it is a classical black hole, it can only interact through gravity. If it is not a classical black hole, then who's going to say how it interacts...

#### vanesch

Staff Emeritus
Gold Member
ubavontuba said:
My point exactly. Thereby belying the CERN scientists assumption that the existence of solar objects is proof that no harm can come to us by the creation of artificial nano blackholes. If they form natuarally, they don't stick around long enough to cause any harm regardless.
Yes, but you're forgetting that this is only ONE of the arguments. Let's put all the arguments in a row:

- first of all, the LHC is not built to make black holes, contrary to what one sometimes might read in speculative articles. However, because the LHC is going to explore higher (a factor 10 about) per nucleon energies, new scenarios are not excluded (one of the reasons to build the machine is to explore a new region of course).

- the energies that will occur in the LHC are much lower than the highest energies occuring naturally in cosmic rays

- in the hypothetical case that black holes might form, normally they should evaporate through Hawking radiation

- in the hypothetical^2 case that Hawking radiation doesn't happen, normally they would have some remnant momentum, by far strong enough to have them escape the earths gravity (just as with cosmic ray generated hypothetical black holes)

- in the hypothetical^3 case where they'd form in EXACTLY the center of gravity of the collision (highly unlikely), and Hawking radiation doesn't happen, then they'd be captured by the earth, and they'd eat a proton every year or so according to classical estimations.

People figure that we're now in lala land and that we can take that risk. Others, with safety belts on their sofas, might not agree.

#### ubavontuba

Rach3 said:
Did you miss the fact, frequently repeated in this thread, that the timescale for 'eating' even a single proton is an astronomical timescale? Or the part where a 10^9 ton black hole was shown to be harmless? (It's also microscopic, if you do the math.)
That's right. Perhaps you missed my first post in this thread wherein I stated we're probably safe. However, that safety is relatively reliant on our theories being correct, and no one really knows that our theories hold true beyond the event horizon. I'm not saying the experiments are inherently dangerous and I'm not saying the experiments shouldn't be conducted. I'd just like the experiments to be performed in a "can't miss" secure way.

Yes, what about them (planetary core's own internal pressure and it's effects)? We've already mentioned that the mass density is on the order of unity that of solids at STP. I.e., insignificant.
Perhaps it is insignificant, perhaps not. Should the nano blackhole have the ability to absorb whole particles (not known that they wouldn't), then they'd essentially become a drain in which the internal pressures can fllow into, right?

The same argument applies equally well to accelerator-produced black holes. Their mass is SMALL compared to the energies involved, so they must invariably be highly relativistic. Not that it would make any difference.
Highly relativistic in quantum scales? Don't these two theories come to odds here?

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#### ubavontuba

vanesch said:
Yes, but you're forgetting that this is only ONE of the arguments. Let's put all the arguments in a row:

- first of all, the LHC is not built to make black holes, contrary to what one sometimes might read in speculative articles. However, because the LHC is going to explore higher (a factor 10 about) per nucleon energies, new scenarios are not excluded (one of the reasons to build the machine is to explore a new region of course).
Really? That's not what the http://www.cerncourier.com/main/article/44/9/22" says. Are they lying then?

- the energies that will occur in the LHC are much lower than the highest energies occuring naturally in cosmic rays
Sure, but why does that matter? According to CERN it doesn't matter because:
CERN Courier said:
It should be stated, in conclusion, that these black holes are not dangerous and do not threaten to swallow up our already much-abused planet. The theoretical arguments and the obvious harmlessness of any black holes that, according to these models, would have to be formed from the interaction of cosmic rays with celestial bodies, mean that we can regard them with perfect equanimity.
Don't you think if conservation of momentum is considered, this argument is generally baseless?

- in the hypothetical case that black holes might form, normally they should evaporate through Hawking radiation
"Should" is not the same as "will".

- in the hypothetical^2 case that Hawking radiation doesn't happen, normally they would have some remnant momentum, by far strong enough to have them escape the earths gravity (just as with cosmic ray generated hypothetical black holes)
Maybe, maybe not. Remember they're intent is to make thousands at a time. Can you guarantee that none will not have escape velocity? You, yourself suggested they weaken one beam for an added measure of safety. I concurred.

- in the hypothetical^3 case where they'd form in EXACTLY the center of gravity of the collision (highly unlikely), and Hawking radiation doesn't happen, then they'd be captured by the earth, and they'd eat a proton every year or so according to classical estimations.
How can you so easily trust "classical calculations" with something that's so poorly understood?

People figure that we're now in lala land and that we can take that risk. Others, with safety belts on their sofas, might not agree.
Since the world is shared by all, shouldn't everyone's opinion count?

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#### vanesch

Staff Emeritus
Gold Member
ubavontuba said:
Really? That's not what the http://www.cerncourier.com/main/article/44/9/22" says. Are they lying then?
It's a *hypothetical* article.

Don't you think if conservation of momentum is considered, this argument is generally baseless?
Yes, but the argument ALSO goes for production in an accelerator, because normally, there's no reason why the momentum should come out 0, as there will always be remnants.

Maybe, maybe not. Remember they're intent is to make thousands at a time. Can you guarantee that none will have not have escape velocity? You, yourself suggested they weaken one beam for an added measure of safety. I concurred.
Yes, but it is a silly argument, because the probability of having one with 0 momentum coming out with "untuned" beams is the same as for tuned beams, because no such collision will not have any remnants. So one needs the remnants to perfectly balance in order for the hole to be "at rest" in the lab frame.

How can you so easily trust "classical calculations" with something that's so poorly understood?
Well, if there are scientific arguments AT ALL to say that black holes are to be produced, and if you are using scientific arguments to say that they will eat the earth, then one is allowed to use the same kind of argument to refute it, no ?
If one can use hypothetical arguments (as of now, they ARE hypothetical) to say that black holes are going to be produced in the first place, then why can one NOT use LESS hypothetical arguments to show that they will not cause any harm ? The classical theory of black holes (on which you base yourself to even call them black holes and to even think it might eat the earth) is much more solid than the HYPOTHETICAL arguments that they might be produced (namely the necessity of the universe to be at least 10-dimensional). Hawking radiation, although hypothetical, is nevertheless based upon thermodynamics mixed with some quantum ideas and classical GR, and is as such LESS hypothetical than the theory that says that BH will form in the first place.

Since the world is shared by all, shouldn't everyone's opinion count?
No, only the opinion of people knowing what they talk about should count. Know what ? Two days ago, next to where I'm working, they opened a new research center on nanotechnology, Minatec:
http://www.minatec.com/minatec_uk/index.htm [Broken]

Well, at the day of its official opening, there have been demonstations by people opposed to it for various hilarious reasons...

http://biotech.indymedia.org/or/2006/05/5127.shtml

I agree that scientists shouldn't be reckless, but one shouldn't be demonstrating against one's own ignorance either, and disrupt the work of people knowing what they are doing.

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#### ubavontuba

vanesch said:
It's a *hypothetical* article.
Sure, but obviously considered seriously.

Yes, but the argument ALSO goes for production in an accelerator, because normally, there's no reason why the momentum should come out 0, as there will always be remnants
.

Well, according to my research, the impacts have to be nearly perfect for them to obtain the hypothetical nano blackhole. If they're perfect and the beams are equal, there really will be no relative momentum to the earth.

Yes, but it is a silly argument, because the probability of having one with 0 momentum coming out with "untuned" beams is the same as for tuned beams, because no such collision will not have any remnants. So one needs the remnants to perfectly balance in order for the hole to be "at rest" in the lab frame.
See above. Also, beam differentials can be sufficient to virtually gaurantee nano blackhole escape velocity. That is, they can be tuned to an energy level that would not be sufficient to create nano blackholes, if escape velocity is not met. However, this may reduce the energy too much to create them to begin with.

Well, if there are scientific arguments AT ALL to say that black holes are to be produced, and if you are using scientific arguments to say that they will eat the earth, then one is allowed to use the same kind of argument to refute it, no ?
If one can use hypothetical arguments (as of now, they ARE hypothetical) to say that black holes are going to be produced in the first place, then why can one NOT use LESS hypothetical arguments to show that they will not cause any harm ?
Because producing them or not isn't nearly so imporatnt as the consideration of safety. If a young kid is playing with a handgun and he told you he unloaded it, would you believe it to be safe? Assurances of safety aren't always sufficient. The gun may indeed be safe, but are you willing to take the risk?

The classical theory of black holes (on which you base yourself to even call them black holes and to even think it might eat the earth) is much more solid than the HYPOTHETICAL arguments that they might be produced (namely the necessity of the universe to be at least 10-dimensional). Hawking radiation, although hypothetical, is nevertheless based upon thermodynamics mixed with some quantum ideas and classical GR, and is as such LESS hypothetical than the theory that says that BH will form in the first place.
I'd agree wholeheartedly with this, save it's thought they've already done this at the RHIC.

No, only the opinion of people knowing what they talk about should count.
Well I live in a democracy, and in a democracy even the less astute have a say in their fate (as they should).

Know what ? Two days ago, next to where I'm working, they opened a new research center on nanotechnology, Minatec:
[URL]http://www.minatec.com/minatec_uk/index.htm[/url

Well, at the day of its official opening, there have been demonstations by people opposed to it for various hilarious reasons...

http://biotech.indymedia.org/or/2006/05/5127.shtml
Maybe they're hilarious, maybe not. However I feel it is the institution that is responsible for easing the minds of the protesters. Remember, people once thought it was stupid to protest for environmental protections too.

I agree that scientists shouldn't be reckless, but one shouldn't be demonstrating against one's own ignorance either, and disrupt the work of people knowing what they are doing.
But do they? Aren't scientists the first to state that they're conducting these experiments because they DON"T know what will happen?

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#### vanesch

Staff Emeritus
Gold Member
ubavontuba said:
Well, according to my research, the impacts have to be nearly perfect for them to obtain the hypothetical nano blackhole. If they're perfect and the beams are equal, there really will be no relative momentum to the earth.
Could you elaborate on this ? You mean it is only when there is entire coherence between the different parton interactions of the two protons that a black hole can form ? This must be a totally coherent diffractive phenomenon ?

See above. Also, beam differentials can be sufficient to virtually gaurantee nano blackhole escape velocity. That is, they can be tuned to an energy level that would not be sufficient to create nano blackholes, if escape velocity is not met. However, this may reduce the energy too much to create them to begin with.
Well, I have no idea of the precision by which the two beams are equal. But it would be fun if you could work out what would be the needed "untuning" for the COM.
Let's do it:
the mass of two 7 TeV protons colliding is essentally 14 TeV, or
14 TeV * 1.6 10^(-19) / c^2 = 2.5 10^(-23) kg

Giving this mass a velocity of 11200 m/s (escape velocity) comes down to a momentum of this mass of 2.78 10^-19 kg m/s, which is very non-relativistic of course. In eV units, we need to multiply by c and divide by e, to find: 522 MeV untuning is sufficient. I even wonder if they can tune the beams to such an accuracy: we're talking about 0.004% of the total beam energy here.

But do they? Aren't scientists the first to state that they're conducting these experiments because they DON"T know what will happen?
Well, there's a difference between expecting eventually some new stuff to happen, and totally out-of-the-blue catastrophy scenarios, which are on one side BASED upon speculative, and less speculative theories in order to even make the catastrophy scenario initially potentially plausible, but then DENYING the same theories which are then used to show that the catastrophy will not happen, finally.

Why not putting up scenarios for ultrasound ripping apart the spacetime continuum, so that sudden singularities will open up a corridor that enables space invaders to take over earth, and feed on humans ?
I would propose, based upon that, to ban immedately any research on piezo-electric sound transducers...

Honestly, both scenarios sound just as crazy.

#### AlphaNumeric

ubavontuba said:
Right, but with little or no relative momentum to the earth's center of mass.
They are moving at 99.9999% the speed of light, while the Earth is moving at ~0.00001% the speed of light. Is that a big enough different for you? They have LOADS of momentum (for an subatomic object) when taken in the Earth's reference frame! If they didn't, the particle accelerator would be useless, it'd not be accelerating anything!
ubavontuba said:
Remember, momentum is conserved.
No, really? So that was what I should have remembered for my quantum field theory exam last Thursday :uhh:
ubavontuba said:
If you'd just apply basic Newtonian Mechanics to what you are writing, you'd see that regardless of the odds of one forming, the odds of one sticking around are virtually zero. Therefore, this argument is meaningless.
So is your about the black holes perhaps to be had at CERN, they've shedloads of momentum to move through the Earth. Even if the colliding beams are untuned by 0.0001% the resultant black hole would sail through the Earth without thinking twice.
ubavontuba said:
Aside to Alphanumeric: Why haven't the numerous smaller moons formed up into larger ones too?
Why would they?
ubavontuba said:
But do they? Aren't scientists the first to state that they're conducting these experiments because they DON"T know what will happen?
That's what experiments are for, to check what we hope will happen will happen. Are you saying any kind of electronic research should be stopped incase the energy involved triggers a castestropic black hole or sends out a signal aliens hear and then come to invade us?

Won't someone think of the children!!

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#### Rach3

ubavontuba said:
Highly relativistic in quantum scales? Don't these two theories come to odds here?
No, SR is not in conflict with QM.

Well, according to my research, the impacts have to be nearly perfect for them to obtain the hypothetical nano blackhole. If they're perfect and the beams are equal, there really will be no relative momentum to the earth.
You claim to be doing research in string theory...

#### SpaceTiger

Staff Emeritus
Gold Member
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#### Orion1

Classical GR Terra micro-singularity cross-section:

$$m_{Fe} = 9.274 \cdot 10^{-26} \; \text{kg}$$ - Iron nucleon mass (35.1% Terra composition)

$$m_e$$ - Terra mass
$$r_e$$ - Terra radius
$$E_b$$ - 1 Tev energy

$$\tau \sim \frac{1}{n \sigma v}$$

$$n_e = \frac{3 m_e}{4 \pi m_{Fe} r_e^3}$$

$$r_h = \frac{\hbar c}{E_b}$$

$$\sigma_c = \pi \left( \frac{\hbar c}{E_b} \right)^2$$

$$v_e = \sqrt{\frac{2 G m_e}{r_e}}$$

$$\tau_b = \frac{1}{n_e \sigma_c v_e} = \left( \frac{4 \pi m_{Fe} r_e^3}{3 m_e} \right) \left[ \frac{1}{\pi} \left( \frac{E_b}{\hbar c} \right)^2 \right] \left( \sqrt{\frac{r_e}{2G m_e}} \right)$$

Combining terms:

$$\tau_b = \frac{4 m_{Fe}}{3} \left(\frac{E_b}{\hbar c} \right)^2 \sqrt{\frac{r_e^7}{2 G m_e^3}}$$

$$\tau_b = 12331.540 \; \text{s}$$ = 3.425 hrs.

$$m_p$$ - Proton mass
$$m_{\odot}$$ - Sol mass
$$r_{\odot}$$ - Sol radius

Classical GR Sol micro-singularity cross-section:
$$\tau_b = \frac{4 m_p}{3} \left(\frac{E_b}{\hbar c} \right)^2 \sqrt{\frac{r_{\odot}^7}{2 G m_{\odot}^3}}$$

$$\tau_b = 15.722 \; \text{s}$$

Oh no!, micro-singularity radiation has seeded the Earth and the Sun with some black-holes!, we must all evacuate this solar system immediately!!!

Reference:
https://www.physicsforums.com/showpost.php?p=1001445&postcount=14
https://www.physicsforums.com/showpost.php?p=1002158&postcount=28
https://www.physicsforums.com/showpost.php?p=1004506&postcount=64

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