Black hole in LHC?

dmitrrr

While discussing LHC one safety argument is, that mini black holes
would evaporate via Hawking radiation. I can't get clear picture from
Hawking's original paper
[S. W. Hawking, Commun. math. Phys., 43, 199 (1975),
(downloadable from Wikipedia)]. Can there be a contradiction?
Namely on page 207 is written:
"no particles on j^{-}" but on page 208 is written:
"the wave... propagate... out on j^{-}".
In the "particle description" the wave function corresponds
to particles. So on page 208 there are particles on j^{-}.

humanino

No. The safety argument is that BH should already be produced in the atmosphere from cosmic rays, but we are still here. This is different from "how to calculate what would happen if they don't evaporate".

dmitrrr

I agree, that the energy of a single particle from cosmic ray can be much larger
than energy of a single particle in LHC, it calms.
But there remains a concern. Namely
intensity of cosmic rays is incomparably less than in LHC.
In LHC very many particles will hit the unit area of target in one second, and as result
much more energy will hit the unit area in unit of time.
So, there could be unknown non-linear effect, which will give a BH.

Vanadium 50

Only if you call this unknown non-linear effect "magic".

First, there is no target at the LHC. There are colliding beams. That's why it's called the Large Hadron Collider. Next, there are a series of discrete interactions, occurring every 25 ns. Are you trying to tell us that somehow space "remembers" that previously there was a collision there?

ZapperZ

I think that you need to give the committee that reviewed the LHC safety a lot more credit for intelligence than this. After all, the notion of "luminosity" is a very common parameter in particle colliders. You need to look at the safety report and show that the issue that you have brought up has been ignored. Till then, your complain is rather moot.

Zz.

Varnick

Particle collisions like those in the LHC happen naturally, they just aren't observed by huge detectors. Thus, if the LHC were likely to produce dangerous black holes, we would have seen this naturally occurring, no?

jms5631

The energy levels produced in the LHC are only going to be a fraction of those energies produced in nature everyday from events such as gamma ray bursts and cosmic ray collisions. In a very real sense, we already use the universe as a veritable collider whose vast size amplifies the effects of cosmic events, and observe the effects of extraordinarly high energy occurances, to which the LHC pales in comparison. The fact of our continued existence is a strong confirmation of LHC's safety. However, additional safety concerns have been probed and reviewed in the CERN safety report which is exceptionally comprehensive.

buffordboy23

In this scenario, the colliding particles have vastly different momenta, so if a black hole forms, its velocity is likely always greater than the escape velocity of earth.

For the LHC I would imagine that the colliding protons have a greater probability of creating a black hole whose velocity is less than earth's escape velocity, since the colliding protons will have momenta of about the same magnitude and approach from nearly opposite directions in terms of the stationary LHC frame. I think the probabilities of such a result would be very small, but possible. Does this make sense?

If this is true, I am not too concerned since the black hole would be extremely tiny and will have little gravitational effect on its immediate surroundings; its essentially a black hole with total mass no more than two protons.

H0T_S0UP

Well suppose many small black holes are created and collide. Could that pose a problem? Also couldn't it be beneficial if the LHC created microscopic black holes. That way they could be studied with very little risk.

ZapperZ

Actually, it does. However, after chatting with a few people who worked on the Atlas detector, they all have concluded that it will be very difficult to distinguish signatures of the creation of "blackholes" versus other events. I had a Q&A session with Tom LeCompte, was recently appointed to be the science coordinator (assistant for the first year) of Atlas. You may read both parts of my session with him here.

http://physicsandphysicists.blogspot...ome-atlas.html
http://physicsandphysicists.blogspot...-atlas_21.html

In the second part, he addressed my question if such blackholes can be identified if created at Atlas.

Zz.

Topher925

Are black holes really thought of actually existing? I always thought of them as still being theory, although a highly supported theory. After all do we really have any cognitive proof that black holes really do exist other than mathematics based on empirical assumptions?

Vanadium 50

Do you mean micro-BHs? No, nobody knows if they exist. Odds are they don't.

If you mean astronomical BHs, there are a number of objects that are known to be too heavy to be neutron stars or too dense to be anything but a BH.

enisys

Hello, I understand that our equations have demonstrated that the microscopic black holes capable of being created at the LHC would quickly evaporate, but I was curious as to whether or not those conclusions were strongly based on the assumption that black holes are infinitely dense. If black holes happen to NOT be infinitely dense, would the results be much different??

Orion1

I have already calculated how much time is required for a classical 'stable' micro-singularity to consume one Iron nucleus in Terra's core at 1 Tev:
[tex]\boxed{\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}}}[/tex]

[tex]\tau_b = 12331.540 \; \text{s}[/tex] = 3.425 hrs.

Time required for a classical 'stable' micro-singularity to consume one proton in Sol's core at 1 Tev:
[tex]\boxed{\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}}}[/tex]

[tex]\tau_b = 15.722 \; \text{s}[/tex]

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?

[tex]\boxed{t_e = \frac{4}{3} \left(\frac{E_b}{\hbar c} \right)^2 \sqrt{\frac{r_e^7}{2 G m_e}}}[/tex]

[tex]t_e = 7.951 \cdot 10^{53} \; \text{s}[/tex] - 2.521*10^46 years

BH horizon radius as function of energy:
[tex]r_h(E_b) = \frac{\hbar c}{E_b}[/tex]

Theoretical upper limit:
[tex]\boxed{t_e = \frac{4m_p}{3} \sqrt{\frac{(m_e c)^3 r_e^7}{2 \hbar^5}}}[/tex]

[tex]t_e = 6.874 \cdot 10^{131} \; \text{s}[/tex] - 2.180*10^124 years

[tex]\boxed{t_a = \frac{c^4}{4 \pi} \sqrt{\frac{r_e}{2 G^5 m_e^3}}}[/tex]

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

Note that if such an event were possible, the Universe would have generated trillions of such particles.

Reference:
classical stable micro-singularity absorption cross-section - Orion1 #75
classical stable micro-singularity absorption cross-section - Orion1 #83
classical stable micro-singularity absorption cross-section - Orion1 #90
classical stable micro-singularity absorption cross-section - Orion1 #104

Rascalking

Hey everyone. Sorry if this topic has been played to death, but like many, I'm having pretty high anxiety about the start up of the LHC in a few weeks. Just got engaged, new job, life is really starting for me. I'm afraid it might be cut short cause of this thing. Theres so much speculation about what this machine can bring, and I'm actually seeing more doomsdayers on the internet then people with faith in the project. So, I decided to come to the most rational message board I could think of. A Physic board, since the whole machine is one giant physics experiment. I keep seeing article after article that offers a counterargument to the "its safe" theory. This one specifically caught my attention:

http://arxiv.org/PS_cache/arxiv/pdf/...808.1415v1.pdf

If this machine is "so safe" why are all these distinguished scientists fighting so hard against it? Some of these guys ARENT nutballs. So....is this really safe? Like I said, sorry if this has been discussed before but if I could get some reassurance from you guys, it'd be great cause I've definitely been losing lots of sleep over it.

Gear300

don't worry...what happens will happen when it happens...life is only life...do not mourn over it...do not obsess over it

Vanadium 50

Which distinguished scientists?

Which ones? They all seem like nutballs to me. Particularly those who are advocating violence - see ZapperZ's blog for an interesting response.