Quark Matter

[bagel_bytes]

Let me begin by making note that this is my first post and I'm asthmatic so please don't make me run away.

Anyway, I have been researching neutron stars for the past few days and the possibility for quark de-confinement to take place at their cores...inevitably leading to a quark star. Now since neutrons are thought to basically be stripped of their constituent particles (up,down quarks?) I've been wondering what implications this has for Dark Matter.

I've read that solid proof of quark stars/matter would have outstanding ramifications in terms of dark matter but I haven't been able to find out why...these particles couldn't exist outside of the enormous pressure of neutron stars, correct?

Any help would be appreciated.

 

[docm]

You're describing strangelets, or free strange matter fragments (Wiki page....)

Likelihood: slim, but scary if such a fragment, even a tiny one, found its way here. Strange matter is theorized to come with either a positive or negative charge. If positive it would be repelled by 'normal' matters positive nuclei, but if negative it would be attracted to and "eat" normal matters nuclei and in so doing increase its own mass. A quantum mechanical version of Pac-Man.

Ramifications: other than cataclysm if one of significant size hit Earth, it would have a huge impact on dark matter theories.

 

[bagel_bytes]

Thanks for the reply...

Given the extreme ratio of matter and dark matter, do you think strangelets could account for the amount of presumed dark matter, even if it were for the sake of argument, 1%?

 

[Gravity_Ray]

Thanks for the reply...

Given the extreme ratio of matter and dark matter, do you think strangelets could account for the amount of presumed dark matter, even if it were for the sake of argument, 1%?

There is no proof that I can find that shows there is such a thing as a "strangelets", so considering it for dark matter is a bit premature. Even the Strange matter hypothesis hasn’t been proven yet. I think these types of hypothesis are more a theoretical brain experiment than anything else. But maybe one day there will be proof positive if the neutron stars are made of strange matter or nuclear matter. It seems that evidence is pointing at nuclear matter, in which case we probably don’t need to worry about a stangelets.

Interesting subject though, it was a good read. Thanks for bringing it up.

 

[neilsox]

Apparently our atom smashers have not yet succeeded in producing individual quarks, so the quark and quark stars remains a hypothesis. When and if they advance to well established main stream theory, we can theorize their connection to dark matter, if any. Second and third order hypothesis get very speculative, and can go too many places for reasonable analysis. I presume dark matter and stranglets are also hypothesis rather than well founded theory. Neil

 

[ramparts]

*le sigh*

We've been having (or at least, I've been having) a similar discussion in another thread. Quarks are an integral and, so far as we know, inseparable part of the standard model of particle physics, a model which has been extremely well-tested. Just saying quarks are a "hypothesis" and are somehow different than, say, an electron or a proton (have you ever seen one?) is just not robust, unless you have a mathematical model which reproduces all of the successes of the standard model but doesn't include quarks. No one's come up with one, and there's the rub.

Moreover, you should examine your standards of knowledge. Why is the particular act of producing an individual quark in a particle collider what it would take for us to "know" that quarks exist, rather than just hypothesize them? That seems pretty arbitrary; a particle collider doesn't allow you to actually "see" a particle, it just gives you data which are consistent with a particle having been produced. But we already have tons of data consistent with quarks existing; they're just not data of the individual-quark-produced-in-an-accelerator variety. Which would certainly be nice but, as I said, doesn't strike me as the One Criterion for being sure that quarks exist.

 

[ramparts]

Cool. So that was my epistemology post. Here's my science post. Figure it's not a bad idea to split them up... you're making some fairly arbitrary distinctions, and also listing things together which really shouldn't be listed together. Yeah, quark stars and strangelets are totally speculative. We don't have any compelling theoretical reason to believe either of these should exist, just that they're possible, and we don't have any experimental evidence (direct or indirect) supporting the existence of either. So they remain speculative. Quarks (and, for that matter, dark matter) are, as I said in my last post, things without which a lot of very precise data wouldn't make a whole lot of sense. That right there is pretty darn suggestive.

You're drawing a solid line between hypothesis and well-founded theory which is a lot fuzzier than you seem to think. Yes, strangelets are firmly hypothetical, and Maxwell's equations are well-founded theory. I'm fine saying that. Those are at the extremes. But in between it's not nearly so solid, and rarely does something go from being "hypothetical" to "well-founded theory" - they're just not categories which are very strictly defined. Physicists will rather talk - or at least think - about these things in terms of probability p of being correct. Most physicists would say there's something like a p=1-10^n probability (where n is some large number - so a probability of p=0.999.......) that gravity follows an inverse square law on local scales and in weak fields. They might say that there's a probability of p=0.9 or 0.95 or so that dark matter is some non-baryonic particle, depending on who you ask. The probability of strangelets being real would be more like p=0.1 or lower, and that number will go up if and when we have some more data which are best explained by invoking strangelets.

My point is that there's no cutoff value of p that makes something go from being speculation to established theory. It's a fine line. Our discussions are better when they reflect that and take into account what we do and don't know, then simply saying that x is hypothetical and therefore shouldn't come into our theories until it's become "well-established."

Oh, and I'm getting back into epistemology. Darn..... oh well

 

[neilsox]

Thanks Ramparts: You are obviously much better founded in the math than I can ever hope to be, now that I am age 78. Have we found experimental, or observation evidence for a sufficient percent of the math, that we can with confidence combine several concepts lacking non math evidence with confidence that the conclusions aren't garbage? It seems to me that astronomy and off planet physics are much more likely to go off on a wrong tangent than electronics, mining or medicine. We are likely aware of things we knew, until recently, that turned out to be wrong, even in the hard sciences. Finding compelling evidence of a free quark in a collider experiment, would I think, increase confidence significantly. Is it sufficient that the equations work together flawlessly like a properly completed cross work puzzle? Admittedly multiple solutions to a cross word puzzle have rarely been found. Neil

 

[ramparts]

Well, to answer your main question, yeah: we're very confident in the conclusion that quarks exist. There's too many experimental data which they explain, and even more which are explained well by the standard model of particle physics, of which quarks are an integral part.

But more importantly: what I was trying to get across in my last (admittedly long) posts was that there really isn't this distinction between "math evidence" and "non-math evidence," at least not any time in the last couple of centuries. I mean, we already did the physics dealing with stuff we can actually see a few hundred years ago, everything since has been testing mathematical theories. Have you ever seen an electron? Or a photon? Have you seen an electric field? All of these are mathematical constructs which work extremely well to fit a huge array of data, so we can be almost 100% sure that they're right. The same applies to finding a particle in an accelerator, we don't actually pick it up and say "oh, look! a quark," we produce a particle and get data which are consistent with the particle having been produced.