* Astronomy

Splitting the quark
If quarks are made of preons, then stars made of the stuff should be detectable.
Are there pea-sized objects as heavy as the Moon out there in space? Perhaps so, if quarks, the constituent particles of atoms, are themselves made up of still smaller particles.
Fredrik Sandin and Johan Hansson of Luleå University of Technology in Sweden say that these hypothetical particles, called preons, might exist in super-dense chunks left over from the beginning of the Universe. Their work predicts that these heavy objects should be detectable with current astronomical techniques. This helps to turn a highly speculative hypothesis into a testable idea.
If preon nuggets exist, they might account for a significant proportion of the mysterious dark matter known to make up a big chunk of the tangible mass of the Universe.
 Its been long known that matter has a Russian-doll nature. Atoms are made of protons and neutrons (together called hadrons), along with lighter electrons. In turn, hadrons consist of particles called quarks, of which there are six varieties. In addition, there are six varieties of fundamental particles related to the electron, called leptons.
In 1974, physicists Jogesh Pati and Abdus Salam speculated that a small family of particles they called preons could explain the proliferation of quarks and leptons. In 1999, Hansson and his coworkers proposed that three types of preons would suffice to build all the known quarks and leptons23.
Then in 2005, Hansson and his student Sandin went on to explore whether some matter could have got stuck at the preon stage, rather than condensing into quarks or hadrons4. They predict that it could. Such lumps of preons would be even denser than quark stars or neutron stars. Neutron stars, for comparison, are thought to compact the mass of our Sun into a ball the width of Long Island in New York.

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