Expanding Universe Irony

Hi Michael,

This isn't my field, but I did a bit of reading - here's how I understand it....

To measure the accelerated expanding of the universe, they found a particular type of supernova, Type 1A supernovae, which we can measure our distance from. Essentially, by measuring its brightness, we can measure how far away any particular Type 1A supernova is from us.

Also, if something is further away, it takes the light longer to reach us. So, when we look at supernovae which are further away, we are also looking at supernovae from when the universe was younger.

To measure how fast it is traveling from us, they measure the "red shift" of the supernova. If something is moving away from you, the wavelength you see is "stretched out", which causes it to appear "redder" than it really is. (This is just the Doppler effect, which you may know about from sound waves....)

If you measure the brightness and the redshift of Type 1A supernovae, then you know how far away it is, how far back into the universe you are looking, and how fast it is moving away from us too.

What they found is that the older, further away supernovae were moving away from us more slowly than the newer, closer supernovae. This was the opposite of what was expected. What it suggests is that the "expansion" in the earlier days of the universe was slower than it is today. That is, it suggests that the expansion of the universe has accelerated.

Could the exploding supernovae be what's driving the acceleration of the universe? I'm not an expert in this area, but I think it's unlikely, because of scale.... Although a supernova is pretty big compared to our tiny planet, it is itself extremely tiny compared to the expansion of the universe. The "exploding" supernovae I think are probably way way way too small to make hardly any difference....

Well, that's how I understand it anyhow....

Now - I have a question.... What I want to know is - can the accelerated expanding of the universe explain my expanding waistline???!?! :)

- Dien


Here's an article explaining some of this (the universe, not my waistline)....