Quark Stars 243
BigGar' writes "Astronomers seem to have discovered a new type of star. It would lie between a neutron star and and a black hole in the hierarchy of stars and consist of quark matter. Further observations with the Chandra X-ray telescope will be needed to confirm the results."
Re:Well... (Score:2, Informative)
Anyways, they are just guessing at this point.
Re:"Up" quarks and "down" quarks. (Score:5, Informative)
Well the up quark, like any quark, is not as cleanly defined as the word "particle" might indicate. The up quark and the properties associated are not just a measure of how much "mass" or "spin" has been shoved into a sphere called the quark. The properties of quarks actually come from an extremely complex cloud of virtual particles that pop into and out of existence in close proximity to the area we call the quark. There seem to only be a few stable configurations of energy, spin, and charge that can result in a quark. The properties of the quarks seem to result from some intrinsic properties defining the way these virtual particles can interact, so you can't just put a little more of something into a quark, because that would require changing the rules of the interactions. Unfortunately, the precise details of all of the above is still a subject of some speculation, since no one quite knows for sure all the virtual particles that can pop in and out and all of their properties.
Re:How does this fit in with String theory? (Score:3, Informative)
Actually it's that statement you just made that doesn't fit with String theory. String theory predicts that black holes can retain information about the structure of objects that are sucked into them. If this turns out to be true, then they can't be regarded as large elementary particles, since elementary particles must be indistinguishable from each other.
Re:Well... (Score:3, Informative)
Interestingly.. (Score:3, Informative)
Re:black holes etc. (Score:3, Informative)
Why? One way of looking at the vacuum is that it is filled with virtual particles. A group of virtual particles can "borrow" energy to spring into existence, and then annihilate after a short period of time, returning the borrowed energy to the vacuum. The time scale they are allowed to exist is governed by Heisenberg's uncertainty relation. (E*t>=h-bar.) For massive particles like electrons, it's a short period of time.
If, during their short existence, the electric field can do more work on the particles than their borrowed energy, the "debt" to the vacuum can be "repaid", and the particles can become real.
Re:Of all the billions of stars to choose... (Score:3, Informative)
Also, you've fallen prey to a terrible, terrible fallacy that afflicts even good astronomer: the dreaded Selection Effect. How do you think they "happened" to come across this odd object? Almost certainly, because they were already studying the nebula and remnant. In other words, it's not out of the many billions of stars that they chose. It was out of the much much smaller pool of SNRs.
It only gets speculative at the edges (Score:2, Informative)
Sure prevailing theories influence what we look for, the way we look for it (instrument design) and the questions we ask of our observations. But that does not mean that there might be no substance to the scientific concensus.
One thing that is blindingly obvious from any perusal of the last couple of centuries of human history is that the rise of the scientific method has provided a potent tool to tamper with the world with.
While I certainly don't claim any ability to turn off my knowledge of such theories when looking at the world, I do see them rendering many things sensible which without them would demand special explanation
The example I like best is the theory of plate tectonics which renders sensible a host of observations and phenomena, such as volcanos and earthquakes, and ultimately has been shown by increasingly accurate measurement to account for the observed relative movement of adjacent tectonic plates.
When it comes to data from distant galaxies or from the subatomic realm, my confidence relies on little more than simple extrapolation from what I can observe directly with my own senses through the clear breadth gained by using even simple telescopes and microscopes to there being no sign of discontinuity as the power of such instruments is scaled up.
Are there any radical thinkers left? someone perhaps not starting from Newton or Einstein's work and trying to move it forward, but someone with NO preconsceptions, NO ingrained ideas, and NO outside influences?
Without language, it is going to be worse than hard for anybody to think too deeply in these areas, so it doesn't make any more sense to try to set up such a straw man than to try to ascertain the cosmology of an elephant.
Yet it remains important to remind ourselves just how much evil has been perpetarated by those who believed they knew the authoritative truth.
So how far can we go in discarding preconceptions and looking again with an open mind? And might anybody actually do it if they could?
Here I can only go from personal experience, although an experience I suspect at least a few have shared. As an already mature adult, I reached a point where things clearly were not working the way I had long assumed they would, so I consciously put aside my preconceptions and tried to start from scratch to find out how the world really works.
Now I'm first to admit it is nigh on impossible to put every detail behind you, most especially not deep personal values, likes and dislikes, but at least for me it was possible to have a sincerely fresh look at how the world works.
And while I certainly didn't find something which would overturn the bulk of mainstream science, I did identify useful patterns that extend way beyond the then traditional scope of science
Re:Quark Matter is Not New (Score:1, Informative)
whether anyone knows how to apply it to massive collapsing stars, and
it doesn't surprise me if no one ever tried.
Look at http://www.aip.org/pt/vol-53/iss-8/p22.html People have been working on high density QCD quite a bit in the last few years. These are real calculations. It actually turns out that QCD is much simpler in the high density regime. (the other area where it is currently tractable is the high energy regime).
But even without these calculations, for at least 10-20 years people have speculated (in a qualitative sort of way) that Pauli blocking may cause Kaons, pions, or hyperons to become stable in heavy neutron stars. The "quark matter" as the article calls it
is the newer idea. You could probably have guessed that people have thought about it, because otherwise why would they be proposing it as a solution to a problem that has barely been observed? What we have seen is a low temperature and a small radius. "Exotic matter" is an obvious explanation, but it is a convenient blank that is filled in by whatever exotic matter may exist in bound state at high densities. But this is far from a conclusive observation.
Not so fast.... (Score:5, Informative)
I am one of the authors of a competing paper [uchicago.edu] on RX J1856 that was published yesterday, as well as a co-discoverer of the pulsar [harvard.edu] in 3C58. In my opinion these results, while definitely a possibility are certainly very preliminary. And in fact, there are other possibilities that make quite a bit more sense.
In the case of RX J1856, there is a ~15% chance that the lack of pulsations (one of the biggest reasons for suspecting a quark star) is simply the result of an unfortunate emitting geometry or viewing alignment. Given that there are ~7 objects known that are similar to RX J1856, having at least one of them in this 15% seems quite likely to me -- and avoids having to invoke a new form of "star stuff".
As for 3C58, the neutron star cooling problem can be mitigated (but not completely removed) by assuming a larger age for the supernova remnant (and therefore the neutron star) -- which expansion measurements and pulsar timing measurements also suggest.
In other words, there are simpler explanations for the facts. Although those explanations certainly wouldn't get as much press...
Re:Quark Matter is Not New (Score:2, Informative)
The basic idea behind strange quark matter is really easy to understand, and has very little to do with quantum chromodynamics, and everything to do with thermodynamics. If you have two kinds of fermion (up, down) and squeeze them together (gravity), they'll reach a certain energy state determined by Fermi-Dirac statistics - the Pauli exclusion principle. If you thrown in another type of fermion (strange), and apply the same pressure, you'll get more particles in the same space because there are now more states for the fermions to occupy without running into the Pauli exclusion principle. A strange quark can have exactly the same energy as an up as a down, because they are still different. There are now three quarks occupying a certain energy level instead of two.
There are many very interesting implications of this which aren't mentioned in any article I've seen, including the possibility of exothermic reactions from such a ball of strange quark matter. That's sekrit code talk for something very exciting and far out which I won't mention explicitly because I'm not a crackpot. No, really! Witten and Fitch said it first anyway.
The theory is there. Now it'll be interesting to see if we can make any of this stuff in an accelerator.
Now let's see how this gets modded, since I'm the only person on
Re:What's the physics behind this? (Score:3, Informative)
Degeneracy is a fundamental feature of the quantum theory of fermions. It isn't an "approximation of other forces". The concept of a force is only applicable at a higher level. Quantum theory is concerned with interactions.
Black holes exist because as a neutron star gets bigger, additional neutrons require more and more energy. All the low energy states are occupied. Soon the neutrons have more energy than you see in an accelerator, and they can react to form other particles. Particles that aren't neutrons won't compete with neutrons for the higher energy states.