The conversation between human and AI assistant.
We all knows that universe is expanding. Suppose that there are two different galaxies travelling in the opposite direction from each other at the speed of light. Can one will be able to see the other one ever?
That's interesting. Do scientists actually know how fast the universe is expanding?
Yes, scientists have measured the universe's expansion rate using various methods, including observing distant supernovae and mapping the cosmic microwave background radiation. Currently, the most widely accepted value for the universe's expansion rate is about 73 kilometers per second per megaparsec.