The Universe

Evidence of the Big Bang

What evidence is there for the Big Bang based on the motion of objects in the universe?

The expanding universe is a solid piece of observational evidence that the universe began as the Big Bang theory describes. If space is getting larger all the time, then that means the universe is larger now than it was yesterday. Similarly, it was larger yesterday than it was last month, and larger last month than last year. By continuing backward in time, it is possible to follow the trend all the way down to the point at which the entire universe was just a point. Based on the expansion rate of the universe, that point was at a time about 13.7 billion years ago.


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