Dark Matter, Parallel Worlds, and Bizarro Neighbors

It turns out that it is very likely that an unseen world is occupying the same space that we do.  What goes on there?  Are there Bizarro humans living with Bizarro pets in Bizarro homes, working at Bizarro jobs, just like we do?

Astronomers who have studied the motion of galaxies and clusters of galaxies have noticed that such large astronomical objects rotate too fast for the amount of matter inferred by their size, distance, and luminosity.  Further, in order for the universe to be flat, as it is observed, there must be much more matter than is currently visible.  In fact, by some estimates, observable matter only accounts for less than 1% of the mass of the universe.  The rest, therefore, must be dark – hence the name “dark matter.”  Many varieties of dark matter have been proposed, including exotic dark matter consisting of various high energy loose particles such as neutrinos and theoretical particles called WIMPs (weakly interacting massive particles).  Also in the menu of candidates for dark matter are big chunky masses called MACHOs (massive compact halo objects – don’t astronomers have a great sense of humor?), which include brown dwarfs, planets, or black holes.  Certain studies of the structure of the early universe, however, have demonstrated that MACHOs can not account for more than a fraction of the total dark matter.

As a result, WIMPs are winning the battle.  Anomalous scientific results from Results from ATIC (Advanced Thin Ionization Calorimeter in Antarctica, PAMELA (an Italian space mission called a Payload for AntiMatter Exploration and Light-nuclei Astrophysics), and INTEGRAL (a European Gamma Ray satellite, INTErnational Gamma-Ray Astrophysics Laboratory) ) are starting to narrow down the kinds of particle that could be responsible.  See Kaluza-Klein particles for more (also see New Scientist article).

Interesting, this has some fascinating implications.  The fact that WIMPs don’t interact means we don’t even know they are there.  Because the measurements imply that they are integrated into our space just like ordinary matter is, they are effectively right next to us and we have no way of detecting them.

But what form are they in?  Is it a sea of particles?  Or do they clump like ordinary matter?  The answer appears to be the latter.  According to Hubble data, dark matter clumps at all magnitudes (see Science Daily article), which means it looks pretty much like ordinary matter.

What does all this mean?  All indications are that there is tons (figuratively speaking) of invisible, undetectable material existing right in our own space.  In fact, by all accounts, there is about 7 times as much as our common ordinary matter.  For all we know, there are dark desks, dark Volvos, and dark versions of Donald Trump’s hair.