how do we know the universe is expanding and will do this till infinity?
In: 2
Imagine a bouncing buoy on a still pond. It makes ripples in circles. If you push this buoy away from yourself, those ripples become further apart by the time they hit you, because each time it bounces, it covered a slight bit of distance away from you before making the next bounce. If it was moving towards you, the ripples would be closer together for the opposite reason.
Stars make ripples and those ripples are light. If they are moving closer they will have compressed ripples (higher frequency). If they are moving further, we see less frequent ripples than we should see if it was stationary. We can confirm how much we ‘should’ see through a whole bunch of different ways.
Whether this will happen forever or not in reality is not yet known. Some theory says yes it will continue forever. From our perspective, it would seem as if were speeding up away from the buoy until we were going to fast the ripples couldn’t ever reach us because we’re moving faster than the ripples themselves.
Latest Answers