Difficult astrophysics questions

Then we studied the structure of Sun
Nuclear reactions in stars
Stellar evolution
The formation of neutron stars and black holes
Types of black holes
Gravitational waves
Radio astronomy
And the CMB radiation.

This is a very difficult question to answer
And many answers have been put forward to try and explain why.
One of the simplest possible reasons is that interstellar travel is very difficult.
Travelling at close to the speed of light
It could still take a lifetime for someone to reach another habitable planet.

While its exact size is still open, it is bound to co-determine empirical reality

Some old and new questions concerning the size and the age of the cosmos arise

The current enigma of early old galaxies supports the prediction of a potentially much larger and older cosmos