Micro black holes; why wasn't LEP supposed to produce any?
J. J. Lodder
and their collision produces a pure energy state
with all quantum numbers zero, from which anything can come.
So why no 200 GeV micro black holes at LEP?
Nobody thought of whipping up a scare at the time?
Jan
Flip
grain of salt.
* Micro black holes at the LHC appear within a particular "new
physics" scenario, generally extra dimensional models that allow the
higher-dimensional Planck Mass to be on the order of 1 TeV. In other
words, we don't expect black holes within the Standard Model, not at
LEP and not even at the LHC. However, the LHc is different from LEP
because we expect the Standard Model to break down at the TeV scale.
LEP was mainly meant to be a discovery machine to find the Higgs and
SUSY.
* If there were 200 GeV micro black holes, we would have seen them at
the Tevatron.
* The cultural-historical reason: extra dimensional models didn't
become a big thing until around 1998. LEP shut down just as interest
in XD models was ramping up.
Dirk Bruere at NeoPax
> Hi Jan -- this is a bit of a naive response, so please take it with a
> grain of salt.
>
> * Micro black holes at the LHC appear within a particular "new
> physics" scenario, generally extra dimensional models that allow the
> higher-dimensional Planck Mass to be on the order of 1 TeV. In other
> words, we don't expect black holes within the Standard Model, not at
> LEP and not even at the LHC. However, the LHc is different from LEP
> because we expect the Standard Model to break down at the TeV scale.
> LEP was mainly meant to be a discovery machine to find the Higgs and
> SUSY.
>
> * If there were 200 GeV micro black holes, we would have seen them at
> the Tevatron.
>
> * The cultural-historical reason: extra dimensional models didn't
> become a big thing until around 1998. LEP shut down just as interest
> in XD models was ramping up.
Does anybody here seriously expect to see BHs, or is this just String
Theorists crossing their fingers and hoping that something, somewhere,
will turn up to vindicate their efforts?
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.onetribe.me.uk/wordpress/?cat=5 - Our podcasts on weird stuff
harry
> Flip wrote:
>> Hi Jan -- this is a bit of a naive response, so please take it with a
>> grain of salt.
>>
>> * Micro black holes at the LHC appear within a particular "new
>> physics" scenario, generally extra dimensional models that allow the
>> higher-dimensional Planck Mass to be on the order of 1 TeV. In other
>> words, we don't expect black holes within the Standard Model, not at
>> LEP and not even at the LHC. However, the LHc is different from LEP
>> because we expect the Standard Model to break down at the TeV scale.
>> LEP was mainly meant to be a discovery machine to find the Higgs and
>> SUSY.
>>
>> * If there were 200 GeV micro black holes, we would have seen them at
>> the Tevatron.
>>
>> * The cultural-historical reason: extra dimensional models didn't
>> become a big thing until around 1998. LEP shut down just as interest
>> in XD models was ramping up.
>
> Does anybody here seriously expect to see BHs, or is this just String
> Theorists crossing their fingers and hoping that something, somewhere,
> will turn up to vindicate their efforts?
It's not just string theorists. As mentioned in earlier threads, some people
at CERN appear to think that BH's may emerge (although not clear if they can
be detected) and they did a big effort to find out if they may be dangerous
(or to reassure their colleagues that they won't be dangerous?): "this study
finds no basis for concerns that TeV-scale black holes from the LHC could
pose a risk to Earth on time scales shorter than the Earth's natural
lifetime."
- http://arxiv.org/abs/0806.3381
- http://link.aps.org/abstract/PRD/v78/e035009
Harald
Gerard Westendorp
>
> So why no 200 GeV micro black holes at LEP?
Maybe elementary particles *are* black holes, whose Hawking radiation
modes are limited to precisely its decay modes?
Gerard
Dirk Bruere at NeoPax
This seems to be an old idea - did it ever go anywhere?
Phillip Helbig---remove CLOTHES to reply
<dirk....@gmail.com> writes:
> Gerard Westendorp wrote:
> > J. J. Lodder wrote:
> >> So why no 200 GeV micro black holes at LEP?
> >
> > Maybe elementary particles *are* black holes, whose Hawking radiation
> > modes are limited to precisely its decay modes?
>
> This seems to be an old idea - did it ever go anywhere?
What about stable particles, such as the electron? As far as we know,
it will never decay, but according to the Hawking-radiation paradigm, it
should have a (quite high) temperature and emit particles.
Maybe the idea never went anywhere because it doesn't explain enough
stuff to warrant being considered as a hypothesis.
Of course, if the particles in question are truly point particles, then
they are smaller than their Schwarzschild radius, and hence black holes.
The explanation of the absence of Hawking radiation, like many other
things, would, like many other things, then have to wait for a theory of
quantum gravity.
The Schwarzschild radius of, say, an electron is WAY below current
experimental limits, so we can't say for sure if electrons are true
point particles (or even say that they are smaller than their
Schwarzschild radius).
Jeremy Henty
> Gerard Westendorp wrote:
>>
>> Maybe elementary particles *are* black holes, whose Hawking
>> radiation modes are limited to precisely its decay modes?
>
> This seems to be an old idea - did it ever go anywhere?
AIUI there are (at least) two big problems with this idea:
1) General relativity imposes an inequality between the mass and
charge of a black hole (charge <= mass in natural units, I think).
Elementary particles violate this inequality by *many* orders of
magnitude (about 21 orders of magnitude for the electron if you trust
my back-of-the-cortex calculations at 11.45pm).
2) Hawking radiation lets a black hole decay to *all* available
particles. There is no way to restrict the decay mode to what we
observe. In particular, baryon decay is suppressed if strangeness
must be changed. Hawking radiation does not respect conservation of
strangeness (or any other quantum number not associated to a
long-range field) so if it were the mechanism for particle decay there
would be no such suppression.
Disclaimer: my particle physics is *really* rusty. Treat the above as
a prompt for discussion, not an expert's opinion.
Regards,
Jeremy Henty
John Park
> In article <6ks4esF...@mid.individual.net>, Dirk Bruere at NeoPax
> <dirk....@gmail.com> writes:
>
>> Gerard Westendorp wrote:
>> > J. J. Lodder wrote:
>> >> So why no 200 GeV micro black holes at LEP?
>> >
>> > Maybe elementary particles *are* black holes, whose Hawking radiation
>> > modes are limited to precisely its decay modes?
>>
>> This seems to be an old idea - did it ever go anywhere?
>
> What about stable particles, such as the electron? As far as we know,
> it will never decay, but according to the Hawking-radiation paradigm, it
> should have a (quite high) temperature and emit particles.
>
> Maybe the idea never went anywhere because it doesn't explain enough
> stuff to warrant being considered as a hypothesis.
Matt Visser points out that most (neutral) elementary particles have
angular momentum as well as mass, so if anything they would be Kerr
black holes. On this model, a neutrino would be a ring singularity with
the diameter of a small protein molecule. This is not observed....
--John Park
Gerard Westendorp
[..]
> What about stable particles, such as the electron? As far as we know,
> it will never decay, but according to the Hawking-radiation paradigm, it
> should have a (quite high) temperature and emit particles.
Hawking radiation has a temperature that is inversely proportional to
the mass. I calculated the radiation temperature for an electron: 5E53
Kelvin. Pretty hot...
So the radiation quanta radiating from it would have much more energy
than the electron itself. I guess that is what might forbid them. As fas
as I can follow the argument that derives Hawking radiation, it assumes
that the source of the gravitational field is not influenced by
individual quanta of radiation. This would be grossly violated by an
electron sized black hole. It's a bit like an electron orbiting a
nucleus: that also is supposed to decay by emitting radiation, but
because it can only do so in discrete quanta, the radiation stops
altogether when the electron reaches its lowest orbit.
>>> Maybe elementary particles *are* black holes, whose Hawking radiation
>>> > > modes are limited to precisely its decay modes?
>> >
>> > This seems to be an old idea - did it ever go anywhere?
I remember going to a lecture by 't Hoofd related to this (about 5 years
ago, titled "the information paradox for small black holes", in Dutch).
Looking at his online publication list, I cannot find an article that is
clearly about this subject, but I only quickly look at the titles. I
remember it about a new theory he was working on, in which wave
functions sort of can move to the event horizon, live on it for a while,
and move away again, while preserving information. The equations
describing this turned out to be similar to string theory.
Gerard
carlip...@physics.ucdavis.edu
> Matt Visser points out that most (neutral) elementary particles have
> angular momentum as well as mass, so if anything they would be Kerr
> black holes.
As Jerome Henty pointed out, a charged black hole must satisfy an
inequality between charge and mass. A rotating black hole must
satisfy a similar inequality between angular momentum and mass,
M^2>J in Planck units.
For a neutral elementary particle with spin 1/2, this translates into
a requirement that M>(1/\sqrt{2})M_Planck, which is certainly not
satisfied by any known particle.
To the extent that classical GR can be used to describe elementary
particles (a somewhat dubious idea to begin with), all known
particles are *far* past the extemality limits for black holes, and
would have to be described as naked singularities.
(If there's an elementary Higgs, or some other uncharged scalar,
*that* might qualify as a black hole -- except for the fact that we
don't know anything about black holes with masses smaller than
the Planck mass, for which quantum gravity is presumably required
for a description.)
Steve Carlip
John Park
probably said "ring singularity" rather than "Kerr Black hole".
--John Park
Boris Borcic
> (carlip...@physics.ucdavis.edu) writes:
...
>> To the extent that classical GR can be used to describe elementary
>> particles (a somewhat dubious idea to begin with), all known
>> particles are *far* past the extemality limits for black holes, and
>> would have to be described as naked singularities.
> In fairness to Matt Visser, whom I was and am (mis)quoting from memory, he
> probably said "ring singularity" rather than "Kerr Black hole".
Ha, and then quantum entanglement could perhaps get "reduced" to
"classical" paradoxes of naked singularities... :)
Cheers, BB