It's long been thought that, if there were to be life somewhere out there in the void of space, it would probably be composed of more or less the same stuff that living things on earth are made of. If you're alive on this planet, chances are you've got a lot of carbon in you. Living matter seems to follow a few specific chemical patterns, and despite the diversity of elements in our physical vicinity, we living things are made up of only a few.
But the universe is big. Absurdly big. And who's to say we've pinned down exactly what life can and can't be? Our conception of intelligent life includes some sort of consciousness like our own, but need that consciousness run on a similarly organic organism? Couldn't there be, somewhere in the vastness, something very much like life but made of entirely different materials from life as we know it?
Scientists are now trying to figure out just that. We already had our conceptions of life rocked a little bit when NASA discovered arsenic in living bacteria at the bottom of a lake. An element previously thought to be toxic to all life was found to be metabolized by a very specific kind of living thing. Now, scientists are attempting to recreate biological life using completely inorganic materials--and they've experienced an interesting degree of success.
Researchers at the University of Glasgow have built new cells out of metal. The idea of life made out of metal might make you think of robots (or specifically The Iron Giant), but these scientists aren't interested in constructing computers that replicate sentience. They're starting from scratch, going down to the basic unit of life: the cell. By bonding metallic elements with oxygen and phosphorus, the team has created cell-like bubbles that can self-assemble and filter their surroundings with a porous membrane. They simulate cell function fairly accurately despite containing no carbon whatsoever.
The scientists are hoping to create metallic cells that can carry out processes like photosynthesis and replication. They'd need to imbue the cells with some kind of DNA analog for the latter to occur, but it may yet be possible. If the cells could use each other as a template, they might just split off into more bubbles autonomously. And if they could figure out a way to harvest energy from light, we might just have made something very similar to life itself in a lab.
So far, the cells are just porous bubbles, like tiny metal models of the real thing. But if scientists figure out a way to get them to function like real cells autonomously, it could mean that our search for life in the universe just got a lot more expansive. We'd no longer need to limit our definition of living things to organic material. We might not need to look for water or oxygen as definite harbingers of life. If metal cells could evolve on their own, who's to say what sort of creatures could arise from them?