Defending Young-Earth Creationism Scientifically

[JonDarbyXIII]

This weekend I was talking with a Christian about evolution, and when I said something about the age of the universe, I caught an ever-so-subtle eye roll from him. He didn't comment on that, but having a strange feeling, I had to ask, "Wait.... exactly how old do you think the universe is?"

"Well the genealogies of the Bible add up to about 6,000 years, so I figure that's about right."

I've never fully understood how it is that some people can truly believe this. I've heard the arguments of 'apparent age,' and I know that they always fall back on 'science is often wrong,' but despite claims to the contrary, I've never seen any genuine scientific evidence that the earth could really only be 6,000 years old. I once read a book of essays from 50 PhDs on why they believe in a literal young-earth creation. Each essay boiled down to 'the Bible says it and that's what I believe despite the evidence.' One even acknowledged that by by excising everything in the Bible that conflicted with science, he was left with shreds of paper that weren't recognizable as a book. His conclusion: "I believe it anyway."

So this is primarily to the theists... What scientific evidence is there for a young-earth creation?