Creating a Quantum Superposition of Living Things 321
KentuckyFC writes "Having created quantum superpositions of photons, atoms, and even molecules, scientists are currently preparing to do the same for larger objects — namely viruses. The technique will involve storing a virus in a vacuum and then cooling it to its quantum-mechanical ground state in a microcavity. Zapping the virus with a laser then leaves it in a superposition of its ground state and an excited one. That's no easy task, however. The virus will have to survive the vacuum, behave like a dielectric, and appear transparent to the laser light, which would otherwise tear it apart. Now a group of researchers has worked out that several viruses look capable of surviving the superposition process, including the common flu virus and the tobacco mosaic virus. They point out that after creating the superposition, scientists will be able to perform the Schrodinger's Cat experiment for the first time, which should be fun (but less so for the virus)."
Re:Viruses don't live (Score:4, Interesting)
Is this necessary? (Score:5, Interesting)
I was under the impression that there was nothing to be gained by doing the schrodinger's cat experiment. The idea is that in collapsing the probability wave of any object, the "observer"-object (really anything that the collapsing object interacts with, conciousnes not required!) essentially becomes a superposition of states. This forms an outward expanding wave of super position with the individuals caught within the wave observing it as collapsed and those outside the event observing all those that interact with the superpositions becoming superpositions themselves.
For example scientist-A is in an isolated box and has a cat in an isolated box. The cat is a superposition either dead or alive, is definately one or the other when he opens the box. Let's say for him, the cat is dead when he opens it and that makes him sad. However the scientist-B, outside the larger box which contains scientist-A can now say that the box is filled a superposition of A-with dead cat (sad scientist), and A-with live cat (happy scientist). This is because scientist-B does not know the result of scientist-A opening the box,only that room now contains a superposition of a sad or happy man with a dead or live cat. Only when B opens this larger box does it the superposition of A collapse for scientist B. Now B is in the same position - he is now be a superposition of states of scientist-B seeing sad-man with dead cat, and scientist-B seeing happy-man with live cat. So the idea is that ALL quantum events function in this way. Performing this on any object, be it virus or molecule or cat. Of course because the real world has no such isolation boxes, these wavefronts of collapse and local superposition happen continuously and undetectably.
So what will happen is they'll go through all this difficulty to superpose two states. Then view the virus, seeing it in one state - all the while oblivious that they are now intertwined with that superposition to an outside observer.
Schroedinger's cat? (Score:4, Interesting)
Re:Schroedinger's cat? (Score:5, Interesting)
No, a real cat and a real box are too tightly coupled to the rest of the world to actually create a superposed state. The common layman's understanding treats a superposition as sort of an "I don't know" state, but that's not accurate. If you made a Schrodinger's cat-killing box, certainly you wouldn't know if the cat was alive until you opened the box, but you wouldn't end up constructing a superposed quantum state.
One consequence of a superposition being a real state (rather than an "I don't know") is that you can perform tests that show an object must have been in a superposed state, beyond simply opening many cat-boxes and observing that half are dead and half are alive. It's fair to call this "observing that the object is in a superposed state", but it conflicts with the quantum-mechanical definition of "observation" that involves collapsing the wavefunction. They certainly can't quantum-mechanical-observe the superposed state directly -- but that's not what they're saying.
Fascinating (Score:3, Interesting)
But what will doing this show? I'm not a physicist, although the topic in very interesting to me. I sort of understand why it is useful in quantum computing but what effect would this have on the virus? Would it interact with other matter/organisms differently? Would it return to its normal state upon removal from the vacuum/cold or would it stay in this quantum superposition? What are the applications of this research aside from recreating Schrodinger's cat (they aren't nicknaming the virus the T-Virus are they...)?
It's semantics, so debate is pointless (Score:4, Interesting)
The definition of life is somewhat squishy, even in Biological fields, but still, technically, viruses are not living as they do not exhibit many traits that living creatures do (eg. homeostasis, metabolism, growth, asexual or sexual reproduction, etc).
In common language, and philosophically speaking, the argument for calling a virus living could be made, but it's all just semantics.
Wikipedia has an interesting article on life and its varying definitions throughout time: http://en.wikipedia.org/wiki/Life [wikipedia.org]
Re:There is only... Super Virus! (Score:5, Interesting)
Virii is not a word. The plural is 'viruses.'
Whether viruses are life is still a matter of some debate. They have genes, reproduce, and evolve, but have no metabolism of their own and do not reproduce by division. They require a host cell in order to reproduce, but so do some bacteria. It's a fuzzy line.
ShroÃdinger (Score:2, Interesting)
Shroedinger's point with the cat experiment was to explain how stupid it would be to take the quantum model for something that could work at human scale.
Too bad people took it seriously, as if the quantum model was more than what it is: a model.
Re:Viruses don't live (Score:3, Interesting)
virus DNA, eg, can not only be frozen solid for millions of years, but it can be CRYSTALIZED!
Do THAT to a tadpole, why dontchya!
Ok, viruses are not animals, like tadpoles.
But human sperm and ova can be frozen and then used for reproduction. So... are they alive, or not?
Plant seeds and insect eggs can lie dormant for years and then sprout or hatch when conditions are right. Are they alive, or not?
The question of whether viruses are living things is far from clear-cut.
Re:Viruses don't live (Score:5, Interesting)
Oh? Just the other day, we were talking about how much cell division is like fork(): it's not just the pure code that's forked, but the state of all globals and open file descriptors, too. There's more to reproduction than just our DNA, there's all that "running VM" stuff going on, too: an infected cell that reproduces is likely to result in two infected cells, even if that's not part of the cell's normal DNA; a cell with a chemical imbalance will likely pass that on to its new sibling. Some cloning methods rely on injecting one cell's DNA into another -- like running a program in both a test and production environment, care should be taken to think about the whole situation when diagnosing problems, not just the DNA/code itself. See? More similarities.
Comparing & contrasting (via "like") is not the same as saying the two are the same (via "equals"). Commonalities, when they can be found, are informative because (most) humans have the power of inductive reasoning. You're welcome to point out the important differences so we can avoid coming to undue conclusions in one or the other field.
Re:Is this necessary? (Score:3, Interesting)
Uh, forgive me for not understanding QM, but how exactly would we *know* that the cat is in a superposition of states? As soon as we check, they would collapse, no?
Unless of course we can cause the probability wave of the cat state to interfere with itself in some way not classically explainable, but I have a hard time thinking of a way to do that.