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mathematic

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Posts posted by mathematic

  1. There aren't too many cases to consider. First simplify the problem by looking at 6k rather than 60k. Once you solve it for 6k, just multiply by 10. Between 0 and 199 there are only 3 numbers 2, 20, 22. Between 200 and 1999 there are only 4 numbers 200, 202, 220, 222 (first hit - so the smallest for the original question is 2220). If you want more, just keep on going.

  2. An interesting aside is Cerenkov radiation, where particles going close to the speed of light enter a medium, where the speed of light is slower than the particle speed. The particle will give off radiation in a shape that resembles the shock waves off a supersonic aircraft.

  3. According to this site, given the observed abundances of Deuterium, 3-Helium, & Lithium, Primeval Nucleosynthesis could have occurred, at almost any temperature, T < 500 MK, with next-to-no discriminative sensitivity beyond that. What is the cosmic abundance of neutrons (which would discriminate) ??

     

    primordialnucleosynthes.jpg

    The nucleosynthesis occurred for T > 500 MK (NOT <). The cosmic abundance of FREE neutrons is 0.

  4. For baryons the general idea is that there are decay processes which are slightly different for anti-matter as compared to matter. These seem to fall in category of CP violation. There are no such processes for electrons or positrons.

  5. After the big bang pair production resulted in (among other things) positron-electron pairs. Positrons do not decay, so they can be removed only by annihilation with electrons. Where did the surplus electrons come from?

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