How do we know that the universe is infinitely expanding?
In: Physics
Think of an ambulance. Racing towards u its higher pitched but as soon as it goes past its lower pitched. Thats the frequency change with speed.
Same with light. If its moving away….more red. If moving towards…..more blue. Everything is pretty much looking red so its all moving away like an expanding bubble.
Thats seriously oversimplified but hope it helps.
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