Rapid big bang expansion

[blike]

The other day I was having a conversation with a staunch creationist about the big bang theory. He stated that it is his personal belief that the universe reached it's present size in less than 10,000 years. He also claims that the universe is no longer expanding, we're just seeing old light. Finally, he says that there is no way we could tell the difference between an expansion that took place rapidly over the course of a few thousand years and a continuous, long-term (billions of years) expansion. Now, I'm inclined to say that something in the red-shift would tip us off to a rapid expansion. But this is way out of my arena. I'm just curious to see what our resident cosmologists have to say.

[Xyph]

Galaxies billions of light years away would have to have moved at over a million times the speed of light. Plus, the faster things are moving away from us, the greater the red shift.

 

Things moving at the speed of light would be red shifted to infinity, I think. I'm not sure what this would mean in a practical sense, with these ridiculously superluminal galaxies, but we probably wouldn't even be able to observe anything more than 10000 light years away. It would definitely have very noticeable effects on what we're seeing now.

[Severian]

There is nothing physical which would prevent this. After all, this is what is thought to happen in the period of inflation. He is also correct in saying that we don't have up to date information on the movements of galaxies since it takes a lot of time for the light to reach us. (As I am typing this, the sun might have vanished, and it would take 8 minutes for me to notice!)

 

However, the idea that we would not be able to tell the difference is just ridiculous. We have amazingly accurate galactic surveys (e.g. http://www.mso.anu.edu.au/2dFGRS/ ) which would look completely different if the expansion had been recent.

[Cap'n Refsmmat]

It's very easy to tell the rate of expansion and how it has changed over the years, giving us a quick estimate of how much it has expanded since The Beginning and how long it would have to be for it to reach its present size.

 

First, you measure the redshift of a star just a million or so light-years away, so you know just how fast it was receding a million years ago. Then you do the same measurement on a star a few million more light-years away, and you get even further "back in time" as you go. Rinse and repeat.

 

I recommend that you read The Fabric of the Cosmos as it explains most bits of current quantum physics, as well as this sort of thing.

[RyanJ]

Red shift is the key killer in this theory. Measring redshift accuratly as can be done today, allows us to show how long the light from some very distant objects (Billions of lightyears away) took to get where by the ammount ot has been shifted to the red spectrum as it moves away from us.

 

I also agree with Cap'n Refsmmat - The Fabric of the Cosmos would help you a lot here (Your creationist friend should try reading this too ) also, Brain's other book The Elegant Universe also covers things along these lines too

 

The two books are well worth the money and the reading, he really does a good job at explaining complex concepts with an easy language style and covers a lot of topics too

 

Cheers,

 

Ryan Jones

[bascule]

Big Bang Cosmology predicted the Cosmic Microwave Background. Does he have any other explanation for it other than "God put it there (to confuse us and lead those evil demonic scientists down the wrong path)?"

 

Have you tried explaning to him that the Catholic Church accepts the validity of the Big Bang Theory/Inflation and teaches it in their schools?