tutorial 25.1 Astronomy

Why must the universe have no edge?

Because someone near the edge would not see the universe as being the same in all directions.

What is the universe expanding into?

Nothing

How does the expansion of the universe explain Hubble's law?

The wavelengths of light emitted from galaxies far away have expanded to longer wavelengths along with space.

Galaxies farther away from us have a greater cosmological redshift than closer galaxies because:

because their light has been traveling toward us for a longer period of time, getting stretched more as time goes on.

According to the cosmological principle, the universe is

homogeneous and isotropic

The fact that the Universe is homogeneous

indicates that it appears the same no matter where you are located in the Universe.

The fact that galaxies appear to be moving away from us is

not due to their actual motion but rather due to the fact that space itself is expanding

The Big Bang was:

the beginning of the Universe we live in

The terms isotropic means

the same in every direction.

The center of the universe is located

there is no center of the universe.