(September 11, 2014 at 2:48 pm)sswhateverlove Wrote: Umm... I think this person is confused. May want to check your source. Both "darks" are assumed to explain why the expansion is accelerating and not slowing down.
Wrong.
Dark matter is assumed to explain the gravitational effect of objects such as galaxies that don't appear to have enough luminous matter to explain the gravitational interaction with other objects.
(September 11, 2014 at 2:48 pm)sswhateverlove Wrote: Yes, I agree about them both being "placeholder" names because they have not actually been observed, so they cannot claim them to be "matter" or "energy". Neil Degrasse Tyson actually said they would be better off labeled "Fred" and "Wilma" because we know nothing about what theyactually are.
With all due respect to Tyson, "dark energy" and "dark matter" are better names because they actually serve to describe the properties that those unknown "things" have - both are so far not directly observable (dark), and one (dark matter) interacts gravitationally like ordinary baryonic matter, and the other (dark energy) behaves like, well, energy.
