'Normal' matter has atomic nuclei formed with 'up' and 'down'quarksplugin-autotooltip__plain plugin-autotooltip_bigQuarks
Following theoretical calculations, particle accelerator experiments in the 1970s confirmed that quarks are responsible for the internal structure of protons and neutrons. ( 3 quarks each, in different configurations, see :Electron / Quark charge balance).
Again, as calculations predicted, six 'flavours' of quark have now been experimentally identified (ref.. It's confirmed, however, that there are six types of quark - one of which is known as the 'strange' quark.
Multiple observations have shown that in isolation they spontaneously decay into 'up' quarks - in line with current theory.
In the mid 70s and early 80s, two nuclear physicists, Arnold Bodmer and Edward Witten proposed separately that it might be theoretically possible for stable matter to exist if its nuclei were built from roughly equal numbers of 'up', 'down' and 'strange' quarks.
This is the so-called Strange Matter Hypothesis.
Theoretical particles formed in this way have been given the name Strangelets - but, in theory, combinations of strange matter particles could be stable at any size, and it has been proposed that entire 'Neutron Stars' could be formed from strange matter.
To date, no strange matter has ever been observed - either in high-energy nuclear experiments or as a result of cosmic ray bombardment.
Nevertheless, many physicists agree on the theoretical possibility that it could exist.
Further technical details Rutgers University (holden)
( Note that Strange Matter has recently been proposed as a possible candidate for an explanation of Dark Matterplugin-autotooltip__plain plugin-autotooltip_bigDark Matter
"The nature of the dominant component of galaxies and clusters remains unknown."
Source : Measuring the dark matter equation of state (Mon. Not. R. Astron. Soc. 415, L74–L77)"
In the 1930s, astronomical observations of galaxy rotations showed that the outer regions were rotating (about the galaxy's 'centre') at the same speed, or faster, than the central regions. Subsequent calculations referring to the galaxy's mass, and thus its internal gravitational attractions, showed that i… )