- What are the three different components of the energy density of the universe

Question

- What are the three different components of the energy density of the universe today? If a universe consisted of only one of these components (matter, radiation, dark energy) how would their expansion histories be different?

- Associated with above, how does the density of all three components change with the scale factor R of the universe. You will be required to either draw or recognize graphs of this and the above. And the below.

- How does the matter density impact the expansion history of the universe? If the matter density changes (either up or down) what happens to the expected age of the universe (under the assumption that the Hubble constant is always the same today.) What type of universe(s) would expand forever? What type of universe(s) would eventually stop? What type of universe(s) would recollapse upon themselves?

Explanation / Answer

SOLUTION:-1.

The Universe is made up of three things. as the Universe is getting bigger, the energy density from matter and radiation would be getting smaller, but vacuum energy density would remain the same. Another name for vacuum energy is the cosmological constant. A cosmological constant eventually controls the time evolution of an expanding universe, because its energy density stays the same while those of matter and radiation are getting smaller.

VACUUM

MATTER

PHOTONS (radiation fields) in the current time only 4% of the density is provided by ordinary number, proton, neutron, electron., but 23% of total energy is provided by dark matter. . and 73 % of density is reuired by dark matter as related to electric field.

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