Comments on: The Earth Will Not Be Sucked Into A Black Hole. But it may coexist with a large number of tiny black holes until the end of time as we know it

By: Ian

Ian — Thu, 26 Jun 2008 06:56:28 +0000

And here I thought the Higgs Bo’sun was the warrant officer onboard the Higgs warship….

By: rpenner

rpenner — Wed, 25 Jun 2008 22:19:09 +0000

Hi, Greg. The referenced paper has appeared in the DOE’s courtroom response to Walter Wagner. The motivation seems similar to a biology paper which is a response to critics claiming splicing indigo-producing genes into bacteria will produce some sort of Communist Revolution. No mechanism was given by the anti-gene-splicer group, but they assert Communism = bad and Communists = wear a lot of indigo dye.I have taken upon myself to “translate” the Giddings-Mangano study into a nearly mathless summary for the masses. By sheerest coincidence it vaguely resembles the format of a deposition.http://www.physforum.com/index.php?showtopic=4830&view=findpost&p=351592You (all) have my permission to reproduce it in whole or in part.

By: Marc Hernandez

Marc Hernandez — Wed, 25 Jun 2008 20:14:51 +0000

I see it as similar to how an automobile engineer studies accidents. Yeah, she could stand on a particular road and wait for one to happen but that is messy and there is a very very low chance she’ll be in the right place at the right time.If she does it in a laboratory she’ll have complete control of the experiment and can run it over and over again.

By: Greg Laden

Greg Laden — Wed, 25 Jun 2008 17:09:37 +0000

Please see the current (latest) post on this blog for a pointer to something you all should read. Which, in turn, has pointers to three or four other items of interest.

By: CS

CS — Wed, 25 Jun 2008 16:59:40 +0000

Also, papers on the arXiv repository, like the one you refer to, a generally meant for other physicists. It was quite readable to me. ;)If articles on the arXiv are meant for a more general audience, they are more likely to be found under the physics section (not the hep-ph section, like this one).

By: CS

CS — Wed, 25 Jun 2008 16:52:38 +0000

I can answer the “why build the LHC if these events happen elsewhere?” question. Generally, when a high energy collision occurs, several particles are created and move away from the collision point at high speed. The idea is to track these particles, identify them, and then reconstruct from their motions what happened in the collision.However, most of these particles are unstable and will decay into other particles. Some of those particles, like muons, will travel relatively far (many meters) before they decay; while others, like the bottom quark, will travel only a tiny fraction of a millimeter before decaying. In the latter case, you see the decay products of the bottom quark; from those decay products, you work back that you have a bottom quark moving with some momentum, then try to work back from that (did the bottom quark come from a top quark that decayed?). Particles like the top quark and Higgs decay extremely quickly, traveling only femptometers (the width of a nucleus) before decaying into something else, so we are not able to track them directly. Instead, there is a complicated process of tracking what you can, determining where and what decayed to produce those tracks, and (if those were intermediate particles) working back from that to figure out where _those_ particles came from. This whole process is called the event reconstruction.Ideally, you want to track and identify all the primary particles (the original products of the collision), but as I said, some of those particles decay way too quickly to see. Then you want to track and identify the secondary particles (products of decays of the primary particles). Oftentimes, these are particles that _also_ decay somewhat quickly, but maybe after traveling a fraction of a millimeter (like the b quark). If you cannot directly detect these, you must track tertiary particles. The lower down you go, the more difficult it is to correctly determine what the primary particles were and there is also the problem that, far enough away from the initial collision, the tracks for primary, secondary, and tertiary particles may be indistinguishable.Because of this, it is extremely important to be able to follow what is going on within a millimeter of the collision point. When you see these big detectors, you generally find, from outside inward, a muon detector (muons tend to travel outside the detector before decaying), an electron/photon detector (these tend to travel some distance, but interact with matter and produce showers of electrons and photons), a hadron detector (for bound states of light quarks, which produce showers of other light quark states), and finally a central tracker. This central tracker likely has a resolution of a millimeter or less around the interaction point (this allows us to determine if b quarks were produced). The whole system, however, only works for collisions that occur in that central, sub-millimeter region. For an example of a detector, see CMS:http://cmsinfo.cern.ch/outreach/CMSdetectorInfo/CMSdetectorInfo.htmlSo, after the long description, the upshot is that the “active” area of these detectors are less than a mm^3. The accelerators will deliver billions/trillions+ of collisions to this region. On the other hand, cosmic rays induce these high energy collisions at a somewhat slower rate, but over the entire volume of the Earth; a volume trillions of time larger than the effective volume of an accelerator detector. The rate of these interactions per mm^3 is tiny, so a detector will never be able to harness cosmic ray collisions effectively. To use cosmic rays as our source for collisions, we would need to build huge numbers of these detectors. Each of these detectors is a sizable fraction of the cost of the accelerator itself, so that becomes prohibitively expensive.There are additional issues as well.Accelerators produce collisions with the center of mass in the same frame as the detector; that means particles will shoot out in all directions and it is relatively easy to distinguish between different tracks. Cosmic ray collisions, however, have a center of mass frame that moves extremely fast relative to us; that means particles produced in the collision will all move in approximately the same direction as the incoming cosmic ray (the trajectories would differ by less than a degree in most cases). Even if you could get a bunch of cosmic rays to collide in your detector, you would need to make that detector much longer and much more sensitive to get the same level of detail as with the accelerator collisions.Finally, accelerators have a somewhat well defined collision energy because the energy of the colliding particles can be controlled (there is some uncertainty in proton colliders because the collisions occur between the quarks and gluons in the protons and there is some variation in how much of the proton’s momentum may be carried by the quark/gluon that collides). The cosmic rays come in with very different energies, varying by many orders of magnitude. That makes interpreting results more difficult and reduces our ability to produce any precision measurements.So, while the universe provides a cheap and abundant source of high energy collisions, we are just unable to use them effectively. Hence, we build accelerators.

By: Theo Bromine

Theo Bromine — Wed, 25 Jun 2008 15:33:32 +0000

How many solar systems do you think have utterly disappeared because all the quantum-range ‘particles’ decided randomly to become some-when else at exactly the same ‘time’???And ‘where’ are they now?And, the LHC is further increasing the risk of this happening, not only by virtue of its particles, but because, according to the late, great Douglas Adams:

“There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.There is another theory which states that this has already happened.”

As for “where” things go when they disappeared, that question brings to mind a quote from Niels Bohr who, when asked regarding a double slit experiment where the electron could be said to be, responded, “To be? To be? What does it mean to be?”

By: Coriolis

Coriolis — Wed, 25 Jun 2008 15:20:24 +0000

I’m in solid state and not high energy so this may be wrong but I think what charlie was saying was that the collisions that will happen in the LHC DO happen all the time with cosmic rays in the upper atmosphere (at least according to current theory, that’s certainly what my high energy friends say). However, it’s impossible to properly measure what’s really happening unless we can do the experiment in the controlled environment of the LHC detector and measure all the crap that spews out of a collision. I think in very simple terms the argument boils down to basically – this type of stuff happens alot. We aren’t dead yet. So it must not be all that dangerous.And no, I don’t think people accept “fully” that Hawking was right about evaporation of black holes. Mainly because he was mixing a classical theory like general relativity with quantum mechanics, and nobody is certain how gravity actually functions in a quantum system. Unfortunately that’s probably the biggest unknown in modern physics, and nobody currently knows how to do quantum gravity. But it sure sounds nice that you can just have pair production and evaporate black holes that way.And I don’t know what you’re talking about at the end, none of these things require a macroscopic quantum effect which is I assume what you mean by a bunch of particles deciding to be something else. Of course we do have systems which have macroscopic quantum effects, like superconductors for example, but what Daniel is simply saying is that when these collisions happen a whole lot of junk comes out which quickly decays into even more junk. For physicists to be able to figure out what the intermediate stuff was (i.e. was it the presumed higgs boson), we’d need to measure *all* of the junk that comes out of a collision. And that’s not possible to do in the upper atmosphere – you need huge detectors all around.

By: Greg Laden

Greg Laden — Wed, 25 Jun 2008 10:51:30 +0000

The assumption is that they should exist but there’s no way apart from the LHC to determine that. Which means…. that the LHC is not merely replicating shit that is flying around all the time. It is designed to produce things that do not normally happen at any regular frequency on or really near the Earth, now.Charlie, ok, I knew about that Hawking thing (it has been a matter of discussion recently because of some bet somebody made). So we now accept pretty much fully that Hawking was right on this? Your explanation makes great sense.Putting in another way, the rate of matter accretion in a tiny black hole …. which exists at a scale where gravity is not the major force (relatively speaking) that it is at the solar-system or planetary or whatever level of size, is very slow. The rate of matter (in the form of enigmatically massless photons, which are presumably popped out of protons or whatever) via the Hawking doppleganger thingie is relatively high.That makes sense. I can’t tell if it is true, but I can totally understand this. Thanks.Daniel: Thanks, that is helpful.It is disconcerting though. The eerie weird stuff that happens at quantum sizes are not supposed to happen anywhere but in massive stars, specially designed equipment, and the minds of physicists.How many solar systems do you think have utterly disappeared because all the quantum-range ‘particles’ decided randomly to become some-when else at exactly the same ‘time’???And ‘where’ are they now?

By: Daniel C. Smith

Daniel C. Smith — Wed, 25 Jun 2008 10:10:52 +0000

The reason we can’t detect the Higgs by watching cosmic ray events is because if it exists at all it has a very, very short lifetime. We won’t even see it directly in the detectors of the LHC. We’ll only see the bits into which it decays. We need to catch all the decay products in the detectors so we can reconstruct the event and be sure that it was a Higgs boson and not something else that decayed into all those bits. As far as I know, you can’t do that by watching the sky.