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Other options include neutrinos , theorized particles called axions or even normal matter like black holes and brown dwarf stars that are just too faint to see . All technical applications of luminescence and other linear and nonlinear matter and radiation interactions close out the range of interest of the Division . It is no laughing matter . " To laugh at things that are not a laughing matter ( 9 ) . research and discussions take place with regard to the doctrine of evolution in as far as it inquires into the origin of the human body as coming from pre-existent and living matter . The weak interactions of WIMPS are why , even though dark matter particles have mass and obey the laws of gravity , they do not clump into galaxies and stars like normal matter . The Union argues that the matter is not excluded by section 7121 ( c ) ( 2 ) because it is a contractual matter that cannot be appealed to OPM . This is about as dense as you can get and still have more or less normal matter . This turns out to be substantially more than the calculated mass of normal matter ( in the form of stars , planets , gas and dust ) and thus indicates the presence of ' dark matter ' - a form of matter about which little is yet known .