Artificial Black Holes, again

[vanesch]

Well, according to my research, the impacts have to be nearly perfect for them to obtain the hypothetical nano black hole. 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 black hole escape velocity. That is, they can be tuned to an energy level that would not be sufficient to create nano black holes, 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 catastrophe scenarios, which are on one side BASED upon speculative, and less speculative theories in order to even make the catastrophe scenario initially potentially plausible, but then DENYING the same theories which are then used to show that the catastrophe 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]

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!

Remember, momentum is conserved.

No, really? So that was what I should have remembered for my quantum field theory exam last Thursday :uhh:

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.

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

Why would they?

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!

 

[Rach3]

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 black hole. 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]

SpaceTiger, I attempted to setup your equation in post #28, however I obtain a large value for $$\tau_b$$?

You're using the conventional Planck length for the horizon radius. TeV mass black holes only appear in theories with extra dimensions that modify the Planck quantities. See here:

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

 

[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

 

[vanesch]

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

Didn't check everything, but this is weird: the hole radius DECREASES with increasing energy ??

 

[Orion1]

Didn't check everything, but this is weird: the hole radius DECREASES with increasing energy ??

Affirmative, setting the threshold energy equivalent to the Planck Energy results in a Planck Radius:

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

$$E_b = E_p$$

$$E_b = \sqrt{\frac{\hbar c^5}{G}}$$

$$r_h = \hbar c \sqrt{\frac{G}{\hbar c^5}} = \sqrt{\frac{\hbar G}{c^3}}$$

$$r_h = r_p$$

$$r_h = \sqrt{\frac{\hbar G}{c^3}}$$

This is called a 'quantum black hole'.

According to my research, the Planck Mass is the maximum producible mass of a 'quantum black hole'. Meaning that any particle accelerator or cosmic event within this quantum threshold is not capable of generating a more massive quantum singularity, except by spherical absorption or accretion.

Interesting to note, that if 'quantum black holes' can exist as naked singularities, then a Planck Mass can also exist as a naked singularity.

 

[vanesch]

Affirmative, setting the threshold energy equivalent to the Planck Energy results in a Planck Radius:

Ah, yes, understood ; you adapt G in the classical formula of a BH in order for the Planck energy to come out equal to 1 TeV. Yes, then the schwarzschild radius is indeed the Planck radius (up to a factor 2 I think).

Next point, your tau_b is the time constant needed to EAT ONE SINGLE IRON NUCLEUS, right ? So this BH eats one single iron atom every 3 hours, if I'm not mistaking ? (and on the sun, one proton every 15 seconds).

Not so worrysome, right ?

 

[rcgldr]

Why don't neutrons or protons behave like mini black holes? Can matter get even denser than a single neutron or proton?

 

[jarvis]

This is a very entertaining thread, in the funny nothing of consequence sort of way! It has been like daytime television. I can read page one, then come back later and read page 6, and I have not missed a beat! Anecdotal arguments, lucky for us, are not sufficient to cease all fundamental high energy physics in the world. It reminds me of the people who thought we would set the Earth's atmosphere on fire by detonating a nuclear device. By the way, when the great name of "string theory" is invoked, which of the five mathematically self consistent versions are you referring to? The one that we have a chance at doing experiments to support? Wait, that doesn't answer the question does it, still left with five.

This is all in good fun of course, no offense is intended towards anyone!

 

[tehno]

Why don't neutrons or protons behave like mini black holes? Can matter get even denser than a single neutron or proton?

electrons/positrons are "denser".

 

[rcgldr]

electrons/positrons are "denser".

OK, can a single electron exhibit the behaviour of a very tiny black hole? Hmm, they do capture and release photons.

 

[Orion1]

$$\tau_b$$ is the 'mean time' interval for nuclear reaction occurence or the time required to absorb 1 particle. This is the amount of time required for a single quantum black hole to reaction with a single iron nucleus or with a single proton.

The 'particle reaction rate' is the reciprocal of the 'mean time'.

$$\lambda_b = \frac{1}{\tau_b} = \frac{dn}{dt}$$

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

Based upon this particle rate, and presuming this rate is constant, how much time would be required for a single quantum black hole to consume 1 m^3 of Terra?

$$t_a = \frac{n_e}{\lambda_b} = \frac{1}{\sigma_c v_e} = \frac{1}{\pi} \left( \frac{E_b}{\hbar c} \right)^2 \sqrt{\frac{r_e}{2 G m_e}}$$

$$t_a = \frac{1}{\pi} \left( \frac{E_b}{\hbar c} \right)^2 \sqrt{\frac{r_e}{2 G m_e}}$$

$$t_a = 7.309 \cdot 10^{32} \; \text{s m}^{-3}$$ - 2.317*10^25 years*m^-3

Based upon this particle rate, and presuming this rate is constant, how much time would be required for a single quantum black hole to consume Terra?

$$n_t = \frac{m_e}{m_{Fe}}$$

$$t_e = \frac{n_t}{\lambda_b} = \left( \frac{m_e}{m_{Fe}} \right) \frac{1}{\lambda_b}$$

$$t_e = 7.951 \cdot 10^{53} \; \text{s}$$ - 2.521*10^46 years


Reference:
https://www.physicsforums.com/showpost.php?p=1005179&postcount=75

 

[vanesch]

$$\tau_b$$ is the 'mean time' interval for nuclear reaction occurence or the time required to absorb 1 kg.

This is then a strange notation, because:

(density x sigma x velocity) is normally the rate, per unit of time, of ONE SINGLE INTERACTION (of which there are "density" items per unit of volume).

 

[Orion1]

your tau_b is the time constant needed to EAT ONE SINGLE IRON NUCLEUS, right ? So this BH eats one single iron atom every 3 hours, if I'm not mistaking ? (and on the sun, one proton every 15 seconds).

(density x sigma x velocity) is normally the rate, per unit of time, of ONE SINGLE INTERACTION (of which there are "density" items per unit of volume).

Affirmative, that is correct.
$$\lambda = n \sigma v$$

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

$$t_e = 7.951 \cdot 10^{53} \; \text{s}$$ - 2.521*10^46 years


Reference:
https://www.physicsforums.com/showpost.php?p=1005179&postcount=75

 

[Orion1]

The Planck mass...

However, the multiple dimensions postulated by string theory would make gravity many orders of magnitude stronger at small distances. This has led some string theorists to predict micro black hole production at upcoming colliders.

Current predictions for the behavior of a black hole with a mass less than Planck mass are inconsistent and incomplete.

I am enquiring as to what the string theory predicted 'orders of magnitude stronger' value is for G at small distances?

$$m_p$$ - Proton mass

Gravitational Coupling Constant:
$$\alpha_g = \frac{G m_p^2}{\hbar c}$$

Gravitational 'Constant':
$$G = \frac{\hbar c \alpha_g}{m_p^2}$$

Strong Gravitational Coupling Constant:
$$\alpha_g = 1$$

Strong Gravitation:
$$G_s = \frac{\hbar c}{m_p^2} = 1.130 \cdot 10^{28} \; \text{Nm}^2 \text{kg}^{-2}$$
$$t_e = \frac{4}{3} \left(\frac{E_b}{\hbar c} \right)^2 \sqrt{\frac{r_e^7}{2 G_s m_e}}$$
$$t_e = 6.110 \cdot 10^{34} \; \text{s}$$ - 1.937*10^27 years

Combining terms:
$$t_e = \frac{4 m_p E_b^2}{3} \sqrt{\frac{r_e^7}{2 m_e (\hbar c)^5}}$$

Reference:
http://en.wikipedia.org/wiki/Quantum_black_hole
http://hyperphysics.phy-astr.gsu.edu/hbase/forces/couple.html

 

[IMP]

If they were able to make a small black hole, and it got "loose" and fell to the center of the Earth, the pressures at the Earths core would force material into it so fast that even a very small one would gobble us up very fast. I am not sure what the exact pressure is at the Earths core but it could force material through even a very small "hole" very quickly. I do agree that once it gobbled up the Earth, it would just continue to orbit the Sun, and the Moon would still orbit the black hole as if it were the Earth...

 

[vanesch]

If they were able to make a small black hole, and it got "loose" and fell to the center of the Earth, the pressures at the Earths core would force material into it so fast that even a very small one would gobble us up very fast. I am not sure what the exact pressure is at the Earths core but it could force material through even a very small "hole" very quickly. I do agree that once it gobbled up the Earth, it would just continue to orbit the Sun, and the Moon would still orbit the black hole as if it were the Earth...

No, you should read this thread.

First of all, a black hole that falls to the center of the earth, wouldn't stop there, but would continue falling up on the other side, just to plunge in again, and on and on, because there's no "friction" on the black hole.

Second, there have been posted in this thread a lot of calculations of the speed at which it would gobble up matter.
Don't forget that the black hole we're talking about here IS MUCH MUCH SMALLER THAN A PROTON. As such, pressures on *atomic* level (such as in the center of the earth) matter little: the black hole travels most of the time in the empty space between nucleae.
A way to calculate the probability of hitting a nucleus (and somehow imagining that it would gobble up the entire nucleus, which is MUCH MUCH bigger than the black hole itself - which is a worst-case scenario) is done by calculating the "cross section" of the black hole and its probability to cross a nucleus on its voyages through the earth. We know its speed (just falling), and knowing the cross section and the density of nucleae, we can estimate how many nucleae it could eat per unit of time.

For a classical black hole, the calculation is done in the link provided by Pervect in this post:
https://www.physicsforums.com/showpost.php?p=1001414&postcount=12

for a MUCH LARGER black hole, about the size of a proton, weighting a billion tons (figure that! A black hole *the size of a proton* weights a billion tonnes ; we're talking here about black holes that weight 10 TeV or 10^(-24) kg - go figure how small it is !)

For more exotic calculations which are more severe, orion made some, and arrived at a time to eat the Earth ~ 10^46 years.

All this in the following rather un-natural hypotheses:
- no Hawking radiation (which would make the black hole evaporate almost immediately)
- production of black hole EXACTLY IN THE CENTER OF GRAVITY of the collision (no remnant particles)
- very high production rate, producing billions of black holes per second.

 

[MelissaSweet]

Hi guys. Just a few quick questions:

Your calculations seem to be based on a constant rate of absorption, is this right? Wouldn't the absorption rate increase exponentially? In your cross section, are you looking only at the Schwarzschild radius? Doesn't gravity extend far beyond? Someone mentioned that the scientists failed to mention the effect that conservation of momentum has on nanoblackholes. Is that right? If they missed this very basic concept what else might they be missing?

 

[Orion1]

Current predictions for the behavior of a black hole with a mass less than Planck mass are inconsistent and incomplete.

One problem with calculating a constant rate of absorption, is the fact that a quantum black hole's horizon radius decreases with increasing mass. Therefore the horizon radius becomes a function of its mass:

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

This means that the cross section and reaction rate decreases as the quantum black hole mass increases.

However, I can determine what the upper limit of my equation is:

$$E_b = E_e = m_e c^2$$

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

$$t_e = \frac{4m_p}{3} \sqrt{\frac{(m_e c)^3 r_e^7}{2 \hbar^5}}$$

$$t_e = 6.874 \cdot 10^{131} \; \text{s}$$ - 2.180*10^124 years

An exponentially decreasing reaction rate should be even longer than this.

An equation demonstrating an exponentially decreasing cross section and reaction rate would probably show that the time required to absorb the Earth is infinite.

Is this infinite?, close enough...

 

[vanesch]

Hi guys. Just a few quick questions:
Your calculations seem to be based on a constant rate of absorption, is this right? Wouldn't the absorption rate increase exponentially?

Yes, that is correct, but it won't change the conclusion very much (it will change the result by a few orders of magnitude).
As has been exposed (see link by pervect), even a billion ton black hole would need 10^28 years to eat the earth. But first, our nano 10^(-24) kg black hole needs to grow to a billion ton black hole and will thus have to eat about ~10^38 atoms. It is still smaller than the size of a proton during all that time.
The more pessimistic calculation by Orion (using more dimensions, and hence a higher effective G constant for the nano black hole) would become rather complicated, because this effective G constant would SHRINK as the nano black hole grows, and leaves its "quantum domain" to become more and more a classical black hole. So although its mass would increase, its effective cross section wouldn't rise proportionally.

In your cross section, are you looking only at the Schwarzschild radius? Doesn't gravity extend far beyond?

Yes, but the "cross section" is the quantified probability of ABSORPTION, not simply of interaction. The moon interacts gravitationally with the earth, but isn't ABSORBED by the earth. So anything much farther away from the BH than the Schwarzschild radius will simply undergo a deflection (talking classically). This interaction is extremely small: don't forget that outside of the Schwarzschild radius, the gravitational effect of a BH is the same as any other mass. So you'd get the gravitational attraction of a mass of 10^(-24) kg, which is normally utterly neglegible.

Also, there has been made a crude assumption: that is, when a nano black hole encounters an iron nucleus, that it eats the ENTIRE nucleus, even though the nano BH is much much much smaller than the nucleus. But this is probably entirely wrong: it would only eat at most a gluon or a quark, meaning that it would leave most of the mass of the nucleus behind (which would probably undergo a desintegration into another nucleus and a few pions or so).

Someone mentioned that the scientists failed to mention the effect that conservation of momentum has on nanoblackholes. Is that right? If they missed this very basic concept what else might they be missing?

No, the point was something different. Some people argued that eventual nano black holes produced in cosmic rays (of much higher energy than the LHC accelerator will produce) have high momentum wrt the earth, and hence will just fly once through the earth, so the fact that these collisions are regularly happening is no proof that nano black holes aren't dangerous.
That reasoning is correct: indeed, even if we underwent showers of nanoblack holes, they would at most eat one or two iron atoms before having traveled through the Earth and fly off in the blackness of space.
So the observation that cosmic rays exist, is no proof of the "safety" of nanoblack holes, is entirely correct.

However, the reasoning ALSO applies to the eventual nanoblack holes produced at the LHC. It is only in the case that they are produced in the exact center of gravity of the two colliding particles that they don't have any momentum left and hence fall to the earth. But this is a highly exceptional case, because colliding protons, at these energies, must rather be seen as the collision of two bags of potatoes, the real interactions being between the potatoes (quarks and gluons), and not between the entire bags. So normally, such collisions produce a lot of "debris" together with an interesting interaction (such as the production of a nano BH). It is what renders the experimental observation a pain in the a**: between miriads of uninteresting tracks in one and the same event, you have to find those three or four tracks which indicate something interesting. There is a priori no reason for any correlation between the debris, and the interesting interaction (this has already been established for many years in lower-energy interactions ; I did my PhD on part of the problem for instance). So there is no reason to assume that this interaction happens in the center of gravity of the bag of potatoes, it is rather in the center of gravity of the two potatoes who do the interaction. Now, this center of interaction usually has high momentum wrt the center of gravity of the interacting protons, so the resultant product (in casu a nano BH) also.
In that case, it flies right off the reaction event, through the earth, or through the sky, into outer space.

And, honestly, the possibility that all these exotic processes happen (only predicted by very exotic and speculative theories) is way more dubious than the (also speculative, but way more down to earth) prediction that Hawking radiation really happens. In fact, all these speculative theories which open the possibility of the production of nano BH, ALSO predict Hawking radiation.

And if this is true, a nano black hole will go POOF even before leaving the detector.

So the entire reasoning is flawed. Current established physics says that NO black holes will be produced at the LHC. One needs to switch to speculative theories to open up even their possibility. And those same speculative theories (just as well as a small extrapolation of currently established physics) foresee Hawking radiation. So it is a bit aberrant to speculate on the production of nano BH using these theories, and refute them at the same time when considering Hawking radiation, no ?

 

[Quaoar]

No, the point was something different. Some people argued that eventual nano black holes produced in cosmic rays (of much higher energy than the LHC accelerator will produce) have high momentum wrt the earth, and hence will just fly once through the earth, so the fact that these collisions are regularly happening is no proof that nano black holes aren't dangerous.

I'm going to have to disagree on this point. True, most of the black holes produced by cosmic rays would escape, but you must realize that every time there is an event, many many many particles are produced in the shower (~10^11, from what I've read). I would imagine that since these events happen millions of time a year across the globe, at least one black hole would come out of a collision with a small enough kinetic energy as to not escape the Earth's gravitational pull. So, coupled with the fact that a black hole takes so long to become the size of a single proton, it's POSSIBLE that there are some floating in and out of the Earth right now, as we speak.

 

[MelissaSweet]

Hi again, my friends and I came up with a few more questions. We hope they're not too naive:

Yes, but the "cross section" is the quantified probability of ABSORPTION, not simply of interaction. The moon interacts gravitationally with the earth, but isn't ABSORBED by the earth. So anything much farther away from the BH than the Schwarzschild radius will simply undergo a deflection (talking classically). This interaction is extremely small: don't forget that outside of the Schwarzschild radius, the gravitational effect of a BH is the same as any other mass. So you'd get the gravitational attraction of a mass of 10^(-24) kg, which is normally utterly neglegible.

Isn't your angular momentum effect limited by the Earth's own angular momentum? Therefore wouldn't classical gravity work to grow the nanoblackhole because mass falls to the center of the Earth in a classical way?

No, the point was something different. Some people argued that eventual nano black holes produced in cosmic rays (of much higher energy than the LHC accelerator will produce) have high momentum wrt the earth, and hence will just fly once through the earth, so the fact that these collisions are regularly happening is no proof that nano black holes aren't dangerous.
That reasoning is correct: indeed, even if we underwent showers of nanoblack holes, they would at most eat one or two iron atoms before having traveled through the Earth and fly off in the blackness of space.
So the observation that cosmic rays exist, is no proof of the "safety" of nanoblack holes, is entirely correct.

So that snubabooba guy was right? Isn't that scary by itself?

However, the reasoning ALSO applies to the eventual nanoblack holes produced at the LHC. It is only in the case that they are produced in the exact center of gravity of the two colliding particles that they don't have any momentum left and hence fall to the earth. But this is a highly exceptional case, because colliding protons, at these energies, must rather be seen as the collision of two bags of potatoes, the real interactions being between the potatoes (quarks and gluons), and not between the entire bags. So normally, such collisions produce a lot of "debris" together with an interesting interaction (such as the production of a nano BH). It is what renders the experimental observation a pain in the a**: between miriads of uninteresting tracks in one and the same event, you have to find those three or four tracks which indicate something interesting. There is a priori no reason for any correlation between the debris, and the interesting interaction (this has already been established for many years in lower-energy interactions ; I did my PhD on part of the problem for instance). So there is no reason to assume that this interaction happens in the center of gravity of the bag of potatoes, it is rather in the center of gravity of the two potatoes who do the interaction. Now, this center of interaction usually has high momentum wrt the center of gravity of the interacting protons, so the resultant product (in casu a nano BH) also.
In that case, it flies right off the reaction event, through the earth, or through the sky, into outer space.

We seem to agree that colliding bags of potatoes might be very messy but the largest mess would occur at the center of the interaction. Are you saying this isn't right?

And, honestly, the possibility that all these exotic processes happen (only predicted by very exotic and speculative theories) is way more dubious than the (also speculative, but way more down to earth) prediction that Hawking radiation really happens. In fact, all these speculative theories which open the possibility of the production of nano BH, ALSO predict Hawking radiation.

And if this is true, a nano black hole will go POOF even before leaving the detector.

That's reassurring but isn't it also speculative? We read the article about the possible nanoblackhole at the RHIC. Do you have more information on it? Was it observed to completely evaporate? Did it leave the detector?

So the entire reasoning is flawed. Current established physics says that NO black holes will be produced at the LHC. One needs to switch to speculative theories to open up even their possibility. And those same speculative theories (just as well as a small extrapolation of currently established physics) foresee Hawking radiation. So it is a bit aberrant to speculate on the production of nano BH using these theories, and refute them at the same time when considering Hawking radiation, no ?

We don't know we're just college students. We think ignoring problems is stupid but we don't know enough to think about this critically. We're wondering if the scientists are similarly handicapped. Snubbabubba apparently found a weakness in their arguments. Can we safely assume they're right otherwise?

 

[ZapperZ]

That's reassurring but isn't it also speculative? We read the article about the possible nanoblackhole at the RHIC. Do you have more information on it? Was it observed to completely evaporate? Did it leave the detector?

Which article?

Most people only read Wilczek's first essay on this and that's all they get, while ignoring a second paper that analyzed this in detail and came to the conclusion that "...The authors estimate the parameters relevant to black-hole production and find that they are absurdly small..."[1] So what black hole? How could it leave a detector when it doesn't even have any appreciable chance of being formed in the first place? And the fact that RHIC's stuctural integrity hasn't changed since Day 1 is ample proof that these black holes never occured.

Zz.

1. R.L. Jaffe et al., Rev. Mod. Phys. v.72, 1125 (2000).

 

[vanesch]

I'm going to have to disagree on this point. True, most of the black holes produced by cosmic rays would escape, but you must realize that every time there is an event, many many many particles are produced in the shower (~10^11, from what I've read). I would imagine that since these events happen millions of time a year across the globe, at least one black hole would come out of a collision with a small enough kinetic energy as to not escape the Earth's gravitational pull. So, coupled with the fact that a black hole takes so long to become the size of a single proton, it's POSSIBLE that there are some floating in and out of the Earth right now, as we speak.

True. One should indeed compare the "integrated luminosity" of 4 billion years of cosmic rays with 10 years of LHC operation.

 

[vanesch]

Isn't your angular momentum effect limited by the Earth's own angular momentum? Therefore wouldn't classical gravity work to grow the nanoblackhole because mass falls to the center of the Earth in a classical way?

I don't understand a word if what you're saying

So that snubabooba guy was right? Isn't that scary by itself?

No, he wasn't right, because that's by far not the entire argument.
In fact, the argument of the high-energy cosmic ray collisions was used for ANOTHER potential catastrophe: the phase-transformation of the vacuum.
According to certain theories, our vacuum is just one of many possible, and maybe not even the most stable one. Just as with supercooled water, a "seeding event" might induce a phase transformation. A high energy collision might just do that, and blow the entire universe as we know it, apart (making it go through a phase change). So switching on the LHC might just blow the universe apart... and it was against THIS argument that it was argued that many more high energy collisions occur every day in cosmic rays without the universe blowing apart.
It wasn't an argument against that other catastrophe on small scale: the black hole that eats the earth.

We seem to agree that colliding bags of potatoes might be very messy but the largest mess would occur at the center of the interaction. Are you saying this isn't right?

Indeed, this isn't right. It may sound strange, but at high energies, the potatoes in the bag have different energies and momenta (although they all move at essentially lightspeed). So individual potatoe-potatoe collisions all have entirely different centers of gravity (this is where the potatoe bag analogy breaks down in fact - so it was probably not appropriate to use it in the first place, my appologies). In the real potatoe bag, there's a relationship between the momenta of the potatoes and their energies, because they all have to go at the same "bag speed". But relativisitically, this doesn't hold anymore (the bag goes essentially at light speed, as do all the components). So it is as if there were *independent* potatoes flying around. As such, you see that the center of gravity of the potatoe potatoe collisions has nothing to do with the center of gravity of the bag-bag collisions.

That's reassurring but isn't it also speculative? We read the article about the possible nanoblackhole at the RHIC. Do you have more information on it? Was it observed to completely evaporate? Did it leave the detector?

I don't know the details. Me thinks that if they have some indication of it, that is in the data of the remnants (the Hawking explosion). Because otherwise *they wouldn't have noticed it*. It would not have left the slightest trace in the detector (at most eaten up one or 2 atoms of the detector material).

We don't know we're just college students. We think ignoring problems is stupid but we don't know enough to think about this critically. We're wondering if the scientists are similarly handicapped. Snubbabubba apparently found a weakness in their arguments. Can we safely assume they're right otherwise?

[sarcastic mode on]

Of course not. Scientists are a dangerous lot, wanting to destroy the world in their quest for fame Most of the time, they don't have kids themselves, and are blinded by their silly faith in their own ideas. We should all put them in camps !

(uh, not so irrealistic, what I write, in fact :tongue2: )

 

[MelissaSweet]

Sorry guys, we tried to come up with some good questions but I guess not. Would you guys be so kind as to remove my posts? Um would you remove your responses too?

 

[vanesch]

Sorry guys, we tried to come up with some good questions but I guess not. Would you guys be so kind as to remove my posts? Um would you remove your responses too?

Eh, no, what would be the point of a forum if each time one should remove questions and responses ?

 

[Orion1]

The most it could do is take the nucleon's entire mass, but realistically, it would probably only take a fraction of the total mass energy -- perhaps a quark or gluon.

it would only eat at most a gluon or a quark, meaning that it would leave most of the mass of the nucleus behind (which would probably undergo a desintegration into another nucleus and a few pions or so).

Strong Gravitation:
(Quantum BH strong nuclear reaction with a proton)
$$t_p = \frac{4 E_b^2}{3} \sqrt{\frac{m_p r_p^7}{2 (\hbar c)^5}}$$

$$t_p = 3.362 \cdot 10^{-16} \; \text{s}$$

 

[vanesch]

Strong Gravitation:
(Quantum BH strong nuclear reaction with a proton)
$$t_p = \frac{4 E_b^2}{3} \sqrt{\frac{m_p r_p^7}{2 (\hbar c)^5}}$$

$$t_p = 3.362 \cdot 10^{-16} \; \text{s}$$

Yes, but that is only when the BH is *gravitationally captured* by the proton (as it was gravitationally captured by the earth)...

 

[Cane_Toad]

Sorry for the novice post, but could somebody discuss or point me at an explanation of how a mini-black hole is possible, given that

1) I thought you needed enough mass to overcome subatomic particles' resistance to compaction

2) the [cosmic ray] particle collisions I've heard about are many orders of magnitude smaller than what seems to be required

3) even if you had a particle that was energetic enough to have such a huge mass, wouldn't/couldn't it already be a mini-black hole before any collisions?

If there is a better place to post novice questions, please let me know.

 

[vanesch]

Sorry for the novice post, but could somebody discuss or point me at an explanation of how a mini-black hole is possible, given that
1) I thought you needed enough mass to overcome subatomic particles' resistance to compaction

According to "standard" physics (in casu general relativity the way we know it in 3+1 dimensions), you are right, it is not possible to have a mini-black hole with just some 14 TeV energy available at most.
However, there are several *speculative* theories out there, which say that the universe has more than 3 + 1 dimensions. The effect of this is that at small scales, gravity is a much stronger force than it is in the standard theory. In fact, the idea is that gravity in so many dimensions is as strong as, say, electromagnetism, but because at our large scale, we only see a few dimensions, it only LOOKS to us as a weak force.
Once gravity becomes much stronger, it is easier to form black holes, and 14 TeV might be sufficient.
Now, these same theories also predict (well, they don't predict much anything, but suggest :-) Hawking radiation, which is huge for a tiny black hole, so the "formation + evaporation" of a mini black hole should be something like a very spurious event, a glitch.

So in the hypothetical case that these speculative theories are right, and that mini black holes can form (in contradiction to standard theory), they also say that they'd explode almost immediately in a rain of particles (as if they didn't form in the first place). All this is thus, speculative. But the aim of these experiments is of course to explore new territory, and to verify whether some speculative ideas might be right.

 

[Cane_Toad]

...
In fact, the idea is that gravity in so many dimensions is as strong as, say, electromagnetism, but because at our large scale, we only see a few dimensions, it only LOOKS to us as a weak force.
Once gravity becomes much stronger, it is easier to form black holes, and 14 TeV might be sufficient.
...

I've heard a little about this, but I'm curious what is different about this situation that would allow that larger n-dimension gravity cross section to begin interacting with our space where it wasn't immediately before the event?

 

[Orion1]

$$t_a(r) = \frac{n_e}{\lambda_b} = \frac{1}{v_e \sigma_c(r)}$$

Schwarzschild radius:
$$t_a(r) = \frac{1}{v_e \sigma_c(r)} = \frac{1}{\pi} \sqrt{\frac{r_e}{2Gm_e}} \left( \frac{c^2}{2Gm_b} \right)^2$$

$$t_a(m_b) = \frac{c^4}{4 \pi m_b^2} \sqrt{\frac{r_e}{2G^5m_e}}$$

$$t_a = \frac{c^4}{4 \pi} \sqrt{\frac{r_e}{2G^5m_e}} \int_{m_p}^{m_e} \frac{1}{m_b^2} \; dm_b = \frac{c^4}{4 \pi} \sqrt{\frac{r_e}{2 G^5 m_e^3}}$$

$$t_a = \frac{c^4}{4 \pi} \sqrt{\frac{r_e}{2 G^5 m_e^3}}$$

Time required to absorb 1 m^3 of Terra:
$$t_a = 6.844 \cdot 10^{16} \; \text{years}$$

 

[eclipsed78]

"Don't forget that the black hole we're talking about here IS MUCH MUCH SMALLER THAN A PROTON. As such, pressures on *atomic* level (such as in the center of the earth) matter little: the black hole travels most of the time in the empty space between nucleae.
A way to calculate the probability of hitting a nucleus (and somehow imagining that it would gobble up the entire nucleus, which is MUCH MUCH bigger than the black hole itself - which is a worst-case scenario) is done by calculating the "cross section" of the black hole and its probability to cross a nucleus on its voyages through the earth. We know its speed (just falling), and knowing the cross section and the density of nucleae, we can estimate how many nucleae it could eat per unit of time."

ya we are dealing with much denser material that has enormous pressure that is moving too at high speed which gives our gravity on the planet. Last time I checked, molecules are in constant movement too and the center of the planet is iron, which is much larger then one proton. Any calculations done are not taking into acount of any of these variables, and I am not impressed with caluculations that only take into account the size of a MBH and a proton. Gravity is what the cern is studing and how it works if BH are made and HR is correct. Yes the implications of knowing what the higgs particle is would allow more study on maybe making antigravity devices but, if HR is wrong, we can not know for sure how long we would have before the MBH became the size of the earth. If we know there is a possiblility (lets say 1/10^1094856306 from what we think and know about physics today) of HR being wrong, when it is wrong we go oh that's how it works and it should have been wrong all along. How could have anyone thought that in this crazy universe that entagled particles could be in exsitance? QT is weird, it makes sense only when we observe it and make note of it. These observations then become logical due to everyone being taught the observations. Come to think of it maybe a MBH not have RH should be logical too. hmmm. The point is no one has or will be able to give prove that HR is existent until this experiment is done.

Russian rulett is what we are playing.

As for the calculations for how long a BH would devour the earth, take into acount that the core spins at a very high speed, high temperatures cause ALOT of molecular movement, and not simply calcualting one proton radius or only one type of nulcious, because there are heavier elements in the earth.

Planing how long the Earth would be destroyed is one thing, and if it took alog time then why not, but if it is not possible to calculate it due to the enormous amouts of variables and I am sure I have not thought of them all, then the question goes back to should they be allowed to conduct this experiment on earth? Why not wait and do it on the moon? B/c little minded over zelous book worms want everything right now, and can not think of anything but themselves and their "life's work". There is more to life than physics, and maybe putting all of this money that is used for the cern into finding a cure for aids would be more worthwhile than pulling that trigger with at least one bullet with our planets name on it. Sorry to all you little minded book worms, i ment no affence I am sure your lifes work is very important.