When?

When was the Universe created?

It's about 15 to 20 billion years ago.

We know from studies of radioactivity of the Earth and Sun that our solar system probably formed about 4.6 billions years ago, which means that the Universe must be at least twice that old, because before our solar system formed, our Milky Way galaxy had to form, and that probably took several billions years by itself. It would be reasonable to guess that the Universe is at least twice as old as our Sun and Earth. However, we can't do radioactive dating on distant stars and galaxies. The best we can do is balance a lot of different measurements of the brightness and distance of stars and the red shifting of their light to come up with some ballpark figure. The oldest star clusters whose age we can estimate are about 12 to 15 billions years old. So it seems safe to estimate that the age of the Universe is at least 15 billion years old, but probably not more than 20 billion years old. This matter is far from being settled by astrophysicists and cosmologists, so stay tuned. There could be radical new developments in the future.