Evidence for the expanding universe?

Question

I vaguely remember in school (god i feel old) my physics teacher telling us that the universe is expanding or something. And he also told us something about it making a noise like a racing car (although that may have been something else)

Anyway is this a theory or is there evidence for it?

RickB - you got it exactly as I remember it (pretty much) - are you my physics teacher?? !

Answer 1

The chief piece of evidence for the expansion of the universe is that all distant galaxies have their light red-shifted due to their recession from us, and the farther away they are, the faster they are receding. This was discovered by Edwin Hubble.

http://en.wikipedia.org/wiki/Edwin_Hubble

Answer 2

The red shift of the galaxies, showing they are moving away from us, plus the fact that the shift is greater the farther away the galaxies are, is the evidence Hubble found that indicates the universe is accelerating and expanding.

The expanding universe is a theory because there is validating evidence to support it. If there were no evidence to support it, it would be rightfully called a hypothesis. So called string theory is not a theory because there have been no experiments or observations that validate it. String theory is at best a hypothesis. Most people call it a WAG however.

There is a background "noise" of sorts throughout the universe. If you turn to a TV channel that has no TV signal, you can see (and hear) that noise as so-called snow on the screen and the hissing from the speakers. The hissing does sound a bit like tires rolling over a road.

They used to think the noise was uniform throughout, but not too long ago, astrophysicists discovered there are some small, but significant variations. These variations are significant because they help explain how galaxies and such seemed to form out of the big bang, which they thought, was uniform energy. Apparently it wasn't uniform, as the background variance shows.

Answer 3

He heeee....... The same problem that I had faced and thought about before , the first time when I came to know this fact. But it must always be believed . After all, the Einsteins Theory can never and no one prove wrong.

It was during the 1920's that Edwin Hubble provided the first evidence that we live in an expanding Universe. Hubble discovered that there is a simple relationship between the distance to a remote galaxy and the redshift in the spectral lines from that galaxy. This redshift is know as the cosmological redshift. Hubble's observations showed that the greater the distance to a galaxy, the greater the redshift in its spectral lines. These measurements strongly indicated that galaxies appear to be moving away from us with speeds proportional to their distance. This observation is made in whatever direction you may look in the sky, giving the (false) impression that our solar system is at the centre of the Universe. The net effect of this motion is that as time goes on the galaxies are getting further and further apart. Astronomers describe this as an expanding universe.

A very simple analogy may be drawn with the blowing up of a balloon on which a number of reference points have been marked. The balloon is illustrative of the Universe and the reference points galaxies. As the balloon is inflated each reference point moves further away from the other, so from any reference point within the balloon every other reference point appears to be moving away from the observer. The observer does not have to be at the centre of the balloon to make this observation. Where this analogy breaks down is that, on the skin of the balloon the reference points will expand, as well as the distance between them. In the Universe the expansion takes place in the space between the galaxies. The galaxies themselves do not expand.

A very important consequence for observations which lead us to infer an expanding Universe is that at some point in the past the matter which is becoming increasing distant must have been concentrated all in one place. Astronomers believe that at this point in time, the beginning of the Universe and the beginning of time, all the matter of the Universe was concentrated in an infinitely small volume and was in a state of infinite density. This time can be calculated by a number of different methods. The huge explosion which led to the expansion of the Universe is the event known as the Big Bang.

Answer 4

Another bit of evidence you might use deals with what's called the cosmic microwave background radiation (CMBR) which is basically the temperature left over from the Big Bang event itself. Science has a good idea of what the temperature was at the instant of the Big Bang. We also know that temperature will decrease as its enclosing volume increases, therefore for that Big Bang temperature to cool to almost zero degrees today space must have been expanding ever since.

Answer 5

The evidence that the universe is expanding is based on something called the "cosmological redshift." Basically, the concept is that when things move quickly away from us, they emit lightwaves that have a longer wavelength than if they were "standing still." In visible light, longer wavelengths look more reddish, hence the term "redshift."

We observe this redshift in all distant galaxies, which means they're all receding from us. Furthermore, the farther away the galaxies are, the greater the amount of redshift, which means the faster they're receding. This means that, on large scales, all the galaxies are moving ever farther away from each other; in other words, the universe is expanding.

> something about it making a noise like a racing car ...

The analogy to a racing car refers to the wavelength shift I talked about before; only in the case of the car, it's sound waves rather than light waves. When a racing car recedes from you, it emits sound waves of longer wavelengths than normal. Our ears perceive this as a drop in pitch. That's why racing cars sound like "reeeeeeen" when they're coming toward you, and like "woooooon" when they move away from you. :-) This is called the "Doppler effect."

(p.s. The universe doesn't make this noise. In the case of the universe, it is light, not sound, whose wavelength is shifted.)

> is this a theory or is there evidence for it?

It's a theory AND there is evidence for it. (Remember that, in science, "theory" means an explanation which is based on a large amount of evidence.)

Answer 6

In the most recent issue of Scientific American, there is a picture (drawing) of the Universe (plural-its called something else after some reseachers). Has anyone noticed how much this looks like a New England oil burner? I'm thinking of suing these Universities to get them to pay for my heating bill.

Answer 7

This is a theory exemplified by Einstein's famous E=mc2 equation. This universe emits a very low frequency b-flat. The universe I'm from repeatedly plays The Foundations "Pick me up Buttercup." It's annoying as hell.

Answer 8

EFECT DOPLER= MOVEMENT TO RED =EXPANDING UNIVERS