Question

What is the approximate number of galaxies in the known universe, assuming that the milky way has an average mass and that all of the mass in the known universe is in galaxies? the mass of the milky way is on the order of 1042 kg, and the mass of the known universe is about about 1053 kg?

Answer 1

To estimate the number of galaxies in the known universe, we can use the mass of the Milky Way galaxy as a reference. Assuming all the mass in the known universe is in galaxies, and using the approximate mass of the Milky Way, we can calculate the approximate number of galaxies.

Step-by-step explanation:

To find the approximate number of galaxies in the known universe, we can use the mass of the Milky Way galaxy as a reference. Assuming that all the mass in the known universe is in galaxies, and the mass of the Milky Way is on the order of 10^42 kg, we can estimate the number of galaxies.

From the observations, we know that the mass of the Milky Way is about 8.0 × 10^11 solar masses. The average mass of a star in the Milky Way is about 1.5 times the mass of our Sun. Assuming there are 10^11 stars per galaxy, we can calculate the approximate mass of luminous matter in the known universe.

By multiplying the mass of luminous matter by 2 (to account for electrons) and then by 10^9 (to account for other particles in space), we can estimate the total number of particles in the observable universe.

Answer 2

I think that the correct reporting of the given values are 10⁴² kg for the Milky Way and 10⁵³ kg for the whole universe. That would be logical in that case. Since it is mentioned that each galaxy has the same mass as the Milky Way, then the number of galaxies in the universe are:

Number of galaxies = 10⁵³ kg/10²⁴ kg = 10¹¹ or 100 trillion galaxies