Let's say that the number density of galaxies in the universe is, on average, 3 × 10–68 galaxies/m3. If astronomers could observe all galaxies out to a distance of 1010 light-years, how many galaxies would they find? (Note that there are 1016 meters in 1 light-year.)

They would find galaxies.

Explanation:

Given that,

The number of density of galaxies in the universe is 3×10⁻⁶⁸ galaxies /m³.

Assuming that, the astronomers are observing at the center of sphere.

So, they can observe the sphere of space whose radius 10¹⁰ light years.

1 light year = 10¹⁶ meters

10¹⁰ light years =10¹⁰ .10¹⁶ meters

                         =10²⁶meters

The volume of the space is

=

m³

m³.

The number of galaxies

= Volume of the space × density

galaxies

= galaxies

They would find galaxies.

moving ball hits still ball. mover stops, hit ball moves. momentum transfer.