Artificial Black Holes, again

[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}
[/Color]

 

[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.

 

[ZapperZ]

Sorry to all you little minded book worms, i ment no affence I am sure your lifes work is very important.

What in the world are you ranting about, especially for your FIRST post here on PF that is rife with over-generalizations?!

First of all, stop with the over-speculation, especially when YOU haven't done the calculations yourself. Secondly, even the SUGGESTION that such particle collisions would generate black holes is itself highly speculative in the first place! So why are you attacking the uncertainty of what would happen if a black hole was created but totally ignoring that the creation of such black holes is also full of uncertainty in the first place?

I've seen a lot of silly hysteria regarding this because I was at Brookhaven when Wilczek wrote the initial article about the possible creation of black holes at RHIC. These people who can't work their way out of a simple QM text started writing petitions to stop RHIC's operation based on Wilczek's article, while totally ignoring his followup article that made a more careful calculations and predicted the extreneous circumstances for such a scenario to happen.

When you based something out of ignorance, then you will have demigods who will use scare tactics to stop something. This is the worst possible way of doing anything, not just physics. And if you think there is zero worth in the pursuit of basic knowledge, I'd like to see you live without your modern electronics when your identical clone stopped the research on quantum mechanics back in the early 1900's because he too didn't see anything worthwhile in it for mankind.

Zz.

 

[Cane_Toad]

Russian rulett is what we are playing.

If you think about it for a minute, we are so screwed three ways to Sunday by potential cataclysms that have real and fairly defined probabilities of wiping us all off the earth: global warming, atlantic conveyor shutdown, global ice-age, earthquakes, volcanos, super-volcanos, global magnetic field shutdown, asteroid collision, hemoragic viruses, small pox, super-tsunamis. This is not to mention small time threats like terrorists with dirty bombs, air dispersed viruses, and rampaging fembots after our mojo.

People will go after easy targets like a single institute or facility, because going after problems that have daunting political inertia like global warming, etc. has less chance of reward (i.e. getting their way). Better to spend your worry cycles on real threats, or better yet, just keep your eyes on the road, and tune into a good tune. :-)

 

[magnetar]

I am waiting for LHC!

 

[paw]

I am waiting for LHC!

Me too! Dispite the overwhelming risk.

 

[pervect]

We did that ages ago. The poster didn't listen to the answer.

 

[MountainSnake]

I for me think that we should give them a BIG BANG in the form of 100 tons of TNT right in the middle of the CMS detector and blow all this wasting money, pointless, risky nonsense.

 

[beeport]

Wisdom, or lack there of

This is an informative and highly academic thread. Let me say I'm quite impressed with the level of knowledge displayed here. I'm am not a physicist, I can only say I have studied basic physics in college. I guess I would be considered one the ignorant by some of you. I generally am supportive of scientific inquiry, but I would like to point out that most experiments do not conceivably involve the complete distruction of the only place we have to live. I understand there are those that don't believe there is a risk in the CERN experiments. What is troubling to us ignorant people is that there is disagreement among those who supposedly are not ignorant.
The question to me is wether the scientific community has the wisdom and fortitude to admit even to themselves that they are not infallable. If you doubt that there is any possiblity that those of you who support these experiments could be wrong and are in fact risking the future of an entire planet, take a look at this ...

http://www.timesonline.co.uk/tol/news/uk/article1626728.ece

Let's not forget there is an enormous investment of time, money and reputation invested in the CERN project. History tells us very clearly that such an investment is sufficient to create many blind eyes. And what will happen if we discover in the future that a black is eating the Earth and its source could traced to CERN. What then, do you think an apology would cover it? There seems to be an intentional ignoring of the context of the conversation on the part of those who claim there is little risk. Wisdom would give you the ability to see that there are risks not worth taking.

 

[ZapperZ]

Do yourself a favor and read this:

http://physicsworld.com/cws/article/indepth/30679

Why are people ignoring the FACT that we already have tons of even higher energy collisions than the one that we will get with the LHC? Why is this evidence completely ignored? Do you see any black holes forming that are swallowing the Earth after all these million (billions?) of years?

Zz.