Redefining Reality - The Intellectual Implications of Modern Science

een able to form in that environment, but the energy density
would have made them move so fast that they would not have
to form galaxies.
for galaxies to form because normal matter would have been
overheated and not subject to the requisite gravitational force.
But they posit a different sort of matter that started the process:
dark matter.
Dark matter comes into play in efforts to determine the masses of
galaxies and the universe.
To determine the mass of a galaxy, astronomers have counted
out gravitational effects that would give them the mass of the
galaxy as a whole.
The problem is that these two methods don’t lead to the same
answer. The galaxy as a whole is much more massive than the
sum of the masses of the stars. The gravitational effects of the
galaxy mean that there must be hidden mass.
In 1975, the astronomer Vera Rubin found the same thing by
examining the way galaxies rotated. In order for them to do what
we see them doing, the mass of the galaxy had to be six times more
than the masses of the visible stars in it. The overwhelming amount
of mass in the universe was unobservable by us. What kind of stuff
is it? Physicists have posited that dark matter is made up of weakly
interacting massive particles (WIMPs).
We need such particles to make sense in terms of our best theory
of matter, the standard model. Physicists have played with quarks
and leptons to see if they can come up with the recipe for the
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