Fringe : Season 3 : Episode 11 : “Reciprocity”
Inexplicably, the government and Massive Dynamic have decided to assemble The Machine in order to learn more about it (and absolutely not destroy the universe which was probably Walternate’s plan all along). I don’t think I’ll be able to comment very much on First People technology, being completely made-up as it is.
Do humans put out an unique “electromagnetic signature”? Well, back in Power Hungry (season 1, episode 5) the Fringe team encountered somebody with a vastly amplified one and stated that human fields are normally far too weak to detect. All living things produce weak bioelectromagnetic fields due to the movements of ions, but it is not known whether they are unique to individuals.
Is Peter’s DNA on file? Even if blood typing is quick and DNA sequencing isn’t, the FBI should have been able to match the blood to Peter within a few days.
When Olivia shows up to help Astrid read through Fauxlivia’s files, the molecule shown on the screen behind her is theobromine. Theobromine is a mild stimulant found in cocoa (and hence chocolate), and is structurally similar to caffeine. Perhaps Walter is sill experimenting with chocolate milk?