Four years ago, Fermilab accelerator physicist Arden Warner watched national news of the BP oil spill and found himself frustrated with the cleanup response. “My wife asked ‘Can you separate oil from water?’ and I said ‘Maybe I could magnetize it!’” Warner recalled. “But that was just something I said. Later that night while I was falling asleep, I thought, you know what, that’s not a bad idea.” Sleep forgone, Warner began experimenting in his garage. With shavings from his…