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RE: Uncle K
June 10, 2015 at 12:40 pm
(June 10, 2015 at 12:59 am)Neimenovic Wrote: (June 9, 2015 at 4:12 pm)Pyrrho Wrote: Uncle K
Uhhh, yea....sorry about that Alex 
You are more influential than you seem to realize. "Uncle K" is a great designation. It conveys a sense of affection, as well as suggesting that he is the teacher rather than the student, but without it being a formal teaching relationship. And that is what we have here. You have gotten to some truth with that. I think it is safe to say that you did not randomly select that designation, but had some sense of its rightness when you created the designation.
I also like it because one typically thinks of an uncle as being older than the nephew or niece, and I am pretty sure that he is significantly younger than I am.
It also is interesting in that the designation has the potential to be partially pleasing to him, while possibly being partially displeasing. But it is not as if it were a disrespectful thing to say to someone (at least not to a man; if he were a woman, of course, we would go with "Aunt K").
"A wise man ... proportions his belief to the evidence."
— David Hume, An Enquiry Concerning Human Understanding, Section X, Part I.
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
June 10, 2015 at 12:42 pm
(This post was last modified: June 10, 2015 at 12:42 pm by Alex K.)
I could change my username to that and be even more anonymous. Or would that have a creepy vibe?
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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RE: - (Ask a particle physisicist)
June 10, 2015 at 2:11 pm
(June 10, 2015 at 7:28 am)Alex K Wrote: Jesus, I'm drowning in saccharine harmony here! Can't we fight a little over who made what contribution? 
The trouble is, it is all there in the earlier posts of this thread. How can I take credit for explaining some bit of physics when anyone can look at the earlier pages and see that it was you doing it? I don't even have to be particularly honest to not do that, just not incredibly stupid.
It would also be problematic if someone asked me to explain anything again. It is much easier and smarter for me to say that I had nothing to do with such explanations. Very often, honesty really is the best policy.
(June 10, 2015 at 12:42 pm)Alex K Wrote: I could change my username to that and be even more anonymous. Or would that have a creepy vibe?
It would depend on what you decide to post afterwards. If you start saying things like, "little girl, why don't you come over and sit on Uncle K's lap," that would have a creepy vibe to it. On the other hand, it has a creepy vide regardless of your name, so maybe it would not matter.
I suppose if you are wanting to flirt with anyone, you had better not go with "Uncle K," as that would have a creepiness, as it would be giving the idea that you are flirting with your niece or nephew, even though that is not necessarily what would be going on.
Also, changing your name to "Uncle K" would take all the fun out of calling you "Uncle K." We might then have to start calling you "Alex."
"A wise man ... proportions his belief to the evidence."
— David Hume, An Enquiry Concerning Human Understanding, Section X, Part I.
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
July 27, 2015 at 11:38 pm
So, while the LHC is having a bit of a bumpy start due to certain contaminations in the beam pipe which must be taken care of, people are still analyzing the data from the first run. In those analyses, something interesting has emerged (dyresand already posted about this): one of the less talked-about detectors, LHCb, claims observation of a five quark bound state called a pentaquark. So this is not about discovering a new elementary particle, but about better understanding the strong interaction. It isn't yet clear whether it is a tight bound state of four quarks and an antiquark, ir rather a more loose bound state
http://lhcb-public.web.cern.ch/lhcb-publ...html#Penta
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
July 28, 2015 at 6:44 am
(This post was last modified: July 28, 2015 at 6:48 am by Alex K.)
... a more loose bound state of a quark-antiquark pair and a three quark baryon. What we seem to know is that it somehow is a five quark conglomerate which decays into a proton (up,up,down) and a J/Psi meson (charm, anti-charm). It was suggested that the relatively long (but still unimaginably short) lifetime indicates the second option, i.e. a "bound state of bound states"
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
August 10, 2015 at 12:00 pm
A 5 pack you say....
I ran into a report of this while listening to the FQXi podcast for July.
A couple of questions came to mind...
1) Is there a convention by which you differentiate between particles and aggregates? The 3 quark & 2 quark bundles seem pretty common and discrete, but at what point (or how) do you conclude this is too big to be a particle and call it something else?
2) They mentioned that the pentaquark was "unexpected." I thought you guys had a pretty good handle on what the standard model was going to produce. Is it simply that the solution space for the math is so large that some of it remains unexplored?
FQXi is one of my cherished sources of current physics information for the layperson. Asking perhaps naive questions here is another.
So how, exactly, does God know that She's NOT a brain in a vat? 
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
August 10, 2015 at 12:41 pm
(This post was last modified: August 10, 2015 at 1:01 pm by Alex K.)
Hey Julia,
It makes sense to address your second question first - you're absolutely right, we understand the basic laws of Quantum Chromodynamics governing quarks at these energy scales very well. BUT: the QCD interaction between the gluon and quark fields unfortunately becomes so strong at these low energies that talking about individual gluons doing this or that makes no sense any more. One has a so called strongly interacting system which is super difficult to solve. We know the equations, but solving them to find what they can yield is an art form because of the strength of the interaction.
People try to tackle this by running a statistical simulation of many spacetime points based on the QCD equations (a technique called lattice QCD ), but this already requires massive supercomputing powers for much simpler systems such as a two-quark meson or even a three-quark proton. --- doing that reliably for five quarks? We'll get there, but we're not there yet for quite a few years to come.
I'm not an expert on these bound states, and I wasn't aware of "aggregate" as a specific technical term for hadronic bound states. But it might be. There would be the distinction I mentioned above alluding to the scope of the gluon interactions between the five quarks.
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
August 11, 2015 at 2:04 pm
(This post was last modified: August 11, 2015 at 2:05 pm by JuliaL.)
(August 10, 2015 at 12:41 pm)Alex K Wrote: Hey Julia,
It makes sense to address your second question first - you're absolutely right, we understand the basic laws of Quantum Chromodynamics governing quarks at these energy scales very well. BUT: the QCD interaction between the gluon and quark fields unfortunately becomes so strong at these low energies that talking about individual gluons doing this or that makes no sense any more. One has a so called strongly interacting system which is super difficult to solve. We know the equations, but solving them to find what they can yield is an art form because of the strength of the interaction.
People try to tackle this by running a statistical simulation of many spacetime points based on the QCD equations (a technique called lattice QCD ), but this already requires massive supercomputing powers for much simpler systems such as a two-quark meson or even a three-quark proton. --- doing that reliably for five quarks? We'll get there, but we're not there yet for quite a few years to come.
I'm not an expert on these bound states, and I wasn't aware of "aggregate" as a specific technical term for hadronic bound states. But it might be. There would be the distinction I mentioned above alluding to the scope of the gluon interactions between the five quarks.
Thanks but...
This is too much for me.
I composed a couple more questions.
After chasing into Wikipedia a couple levels on hadrons, confinement, gluon plasma, lattice QCD, I looked back and they looked totally lame.
I'll just lurk and see if anybody else produces enough clarity that I can post without level 5 embarrassment.
My cat likes to watch the pendulum on my long case clock.....
I know how she feels.
So how, exactly, does God know that She's NOT a brain in a vat?
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
August 11, 2015 at 3:01 pm
If it's too much either I explained it badly or you're too ambitious
Come on! Post the questions! 
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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RE: First collisions at the LHC with unprecedented Energy! (Ask a particle physisicist)
September 1, 2015 at 4:53 pm
Here's something that kept me awake the other night.
You are no doubt familiar with some of the various experiments with quantum entanglement. The experiments and their results are strange enough to be sure, but my question isn't really about that.
How are individual entangled (or non-entangled, for that matter) particles observed? (Think back to the 1998 Caltech experiment where an individual photon was "teleported" about a meter. What means is used to make the observations?
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