Dark matter remains one of physics’ missing puzzle pieces. Only about 4 % of the universe is made up of“ normal” matter. Do we live in a universe that is not 100 % full?
M. M.
L. R.
I’ m not sure what a full universe would be! Clearly there is a lot of empty space in the universe— on the whole it is not very dense and the temperature is very low. One definition of 100 % full as you say would be that the universe contains critical density— the density in which it is flat. That does indeed seem to be the case.
What about the dark energy?
M. M.
L. R.
The dark energy is truly mysterious— more mysterious than dark matter in my opinion. It is energy that is spread throughout the universe but is not carried by matter. It doesn’ t clump under gravitational influence. Instead it drives an acceleration of the expansion of the universe. It is not surprising in some sense that such energy should exist— it is completely allowed.
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Dark matter remains one of physics’ missing puzzle pieces. Only about 4 % of the universe is made up of“ normal” matter. Do we live in a universe that is not 100 % full?
M. M.
L. R.
I’ m not sure what a full universe would be! Clearly there is a lot of empty space in the universe— on the whole it is not very dense and the temperature is very low. One definition of 100 % full as you say would be that the universe contains critical density— the density in which it is flat. That does indeed seem to be the case.
What about the dark energy?
M. M.
L. R.
The dark energy is truly mysterious— more mysterious than dark matter in my opinion. It is energy that is spread throughout the universe but is not carried by matter. It doesn’ t clump under gravitational influence. Instead it drives an acceleration of the expansion of the universe. It is not surprising in some sense that such energy should exist— it is completely allowed.