USA HISTORY

Detailed explanation-1: -Based on large quantities of experimental observation and theoretical work, the scientific consensus is that space itself is expanding, and that it expanded very rapidly within the first fraction of a second after the Big Bang, approximately 13.8 billion years ago. This kind of expansion is known as “metric expansion".

Detailed explanation-2: -But even though the fabric of space is expanding throughout the Universe-everywhere and in all directions-we aren’t. Our atoms remain the same size. So do the planets, moons, and stars, as well as the distances separating them.

Detailed explanation-3: -The energy from the Big Bang drove the universe’s early expansion. Since then, gravity and dark energy have engaged in a cosmic tug of war. Gravity pulls galaxies closer together; dark energy pushes them apart. Whether the universe is expanding or contracting depends on which force dominates, gravity or dark energy.