From: eripe.dk@gmail.com   
      
   On Monday, July 20, 2015 at 5:49:09 PM UTC+7, Harri Tavaila wrote:   
   > 20.7.2015 10:08, Greg Goss kirjoitti:   
   > > eripe  wrote:   
   > >   
   > >> Thats 1400 times the mass of our sun.   
   > >>   
   > >> So my new hypothesis is that there is no special dark matter, there is   
   just dark planets. We just dont have the tools to detect them.   
   > >   
   > > This is the "MACHO" hypothesis - "Massive compact halo objects".  The   
   > > distribution of dark matter is slightly different than the   
   > > distribution of matter we can detect, thus "halo".   
   > >   
   > > In the early days of dark matter theorizing, this was contrasted (and   
   > > names were chosen to emphasize the contrast" to a neutrino-ish   
   > > particle known as the "Weakly interacting massive particle" or "WIMP".   
   > >   
   > > Neither theory is accepted anymore, but I don't know enough cosmology   
   > > to say why.   
   >   
   > Actually WIMP is indeed still going strong. It has merely had to accept   
   > additional limitations as to the nature of potential candidates (exotic,   
   > non-baryonic particles).   
   >   
   > As to MACHO; the strongest objection comes from the observed amount of   
   > deuterium in the universe.   
   >   
   > Stars do not produce deuterium - if anything they consume it. Therefore   
   > it is assumed that all deuterium was produced during the early days of   
   > Big Bang.   
   >   
   > This (and the amount of helium produced during the BB nucleosynthesis)   
   > sets rather strict limits to the density of baryonic matter in the early   
   > universe. It appears that the density and hence the mass is way too   
   > small to account for the observed effects of the dark matter.   
   >   
   > This doesn't however rule out some more exotic forms of MACHO's: if the   
   > objects do not consist of matter as we know it (primordial black holes   
   > maybe?) there would still be room for them.   
   >   
   > However attempts to observe the gravitational lensing of such objects   
   > has been negative (early days though). If they were sufficiently small,   
   > maybe - but then one again has to come up with the answer to the   
   > question: what are they.   
   >   
   > H Tavaila   
      
   Hmm   
   What if the MACHO's are frozen balls of hydrogen? Hydrogen freezes at 14 K,   
   wouldnt that lock up the deuterium too, so we cant observe it?   
      
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