# Characteristic Parameters and Scales

### Problem 1

Calculate the dark energy density and the cosmological constant value.

### Problem 2

Estimate total number of baryons in the Universe.

### Problem 3

Find dependence of relative density of dark energy $\Omega_\Lambda$ on the redshift. Plot $\Omega_\Lambda(z)$.

### Problem 4

Estimate total number of stars in the Universe.

### Problem 5

Find the ratio of dark energy density to the energy density of electric field of intensity $1\,V/m$. Compare the dark energy density with gravitational field energy density on the Earth surface.

### Problem 6

Estimate the distance between two neutral hydrogen atoms at which the gravitational force of their attraction is balanced by the repulsion force generated by dark energy in the form of cosmological constant. Make the same estimates for the Sun-Earth system.

### Problem 7

Calculate magnitude of physical acceleration.

### Problem 8

How far can one see in the Universe?

### Problem 9

Find age of the Universe.

### Problem 10

Give a qualitative explanation why the age of the Universe in SCM is considerably larger than the age of matter dominated Universe (the Einstein-de Sitter model).