What is meant by the word “expanding” when scientists say that the Universe is expanding? Is this about physical matter, gasses, or creation of new galaxies, or something else?
In: Physics
They aren’t talking about matter, they’re talking about space itself. A common analogy is when you bake a loaf of bread that has raisins or something in it; the raisins all move apart when the bread bakes because the bread itself expanded. If you were tiny and on one of the raisins, it would appear that all of the other raisins were moving away from you. That would be true no matter which raisin you were on. That’s essentially what you see in real life when you look at other galaxies, they’re all moving away from us because space is expanding.
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