A bunch of scientist-bloggers are complaining about McCain's criticism of Obama's planetarium earmark. These scientists are dead wrong. Pork-barrel spending is a threat to science. It circumvents peer review and allocates money based on politics rather than merit. Moreover, it opens the way for money to be diverted from science altogether and into other areas. I wrote about science pork back in the early '90s and the problem has not gotten better since.