Is the universe expanding? If so how do you know?

Question

Just curious.

Answer 1

Yes. Read below.
http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/ExpandUni.html

Answer 2

Yes, it is the nature of the universe to expand.

Over the last hundred years, the expansion of the universe has been a subject of passionate discussion, engaging the most brilliant minds of the century. Like his contemporaries, Albert Einstein initially thought that the universe was static: that it neither expanded nor shrank. When his own Theory of General Relativity clearly showed that the universe should expand or contract, Einstein chose to introduce a new ingredient into his theory. His "cosmological constant" represented a mass density of empty space that drove the universe to expand at an ever-increasing rate.

When in 1929 Edwin Hubble proved that the universe is in fact expanding, Einstein repudiated his cosmological constant, calling it "the greatest blunder of my life." Then, almost a century later, physicists resurrected the cosmological constant in a variant called dark energy. In 1998, observations of very distant supernovae demonstrated that the universe is expanding at an accelerating rate. This accelerating expansion seemed to be explicable only by the presence of a new component of the universe, a "dark energy," representing some 70 percent of the total mass of the universe. Of the rest, about 25 percent appears to be in the form of another mysterious component, dark matter; while only about 5 percent comprises ordinary matter, those quarks, protons, neutrons and electrons that we and the galaxies are made of.

Answer 3

Because all galaxies that we observe in the universe are moving away from us. We know it by the wavelength of light. The wavelenght of the light of a galaxy becomes 'more red' (redshift) as the galaxy is moving faster away from us. Also we know distances of galaxies by other ways (stars with distinctive brightness). So we find that more far is a galaxy, faster it is moving away from us.

So we are as in a cake that is heating, the 'cake' universe inflates !

Answer 4

astronomers can tell becaus ethe distance between objects in space are growing greater, so the only answer they have for this is that the universe is expanding.

Answer 5

Clever people have told me it is, and I can see no reason why they would wish to lie. They aren't trying to sell me anything.