Physicist: Deep…
It depends on how entangled God is with the rest of us. If He can make the observation, and then keep a completely straight face forever (never leak any information about the result in any way), then His mighty observation would not collapse the wave, from our perspective.
That’s why sparrows can be in so many places! (Matthew 10:29)
When you hear about “observations”, in the context of quantum mechanics, it usually takes the form of some smart-looking, glasses-wearing, dude saying things like “a particle is in a ‘super-position’ of states until someone observes it, and then suddenly it’s in only one state”. The misconception here is that the universe as a whole (which includes people and Gods and whatnot) is in one state, and only tiny things can be in many states.
The traditional thought experiment for talking about this is “Schrödinger’s Cat”. Schrödinger puts his cat into a purfectly information-proof box, so that there’s no way to see what’s going on inside. Also, he rigs up something deadly that has some chance of killing the cat in the next day or so. Before the box is opened, the cat is both alive and dead, but afterward the cat is either alive or dead. The cat undergoes “wave function collapse”.
This is a metaphor for, for example, the photons in the double slit experiment. Each can demonstrably go through both slits, but if you determine which slit a photon goes through, then it only goes through one.
Unfortunately, this has been taken as a rallying cry for a lot of bad physics. A better thought experiment (and one which gets closer to explaining the answer to the question) is “Schrödinger’s Graduate Student”.
Repeat the cat in a box experiment, but this time Schrödinger finds that, overcome by quantum grief, he cannot bring himself to open the box. Instead, he goes out for tea or something and has a graduate student complete the experiment for him. Once done, the student then finds Schrödinger and reports the results.
But, since Prof. Schrödinger hasn’t observed the graduate student yet, from his perspective the cat and student are still in a super-position of states. The only difference is that now they’re entangled. They’re in a combination of the “dead-cat/horrified-student” and “living-cat/cautiously-optimistic-student” states. When the student finally reports the results to Schrödinger, then the cat/student wave function collapses (from his perspective).
In practice of course, there’s information leaking all over the place. Considering all of the different paths that information can take: chemicals, air movement, stray photons, gravity, etc. it’s really hard to construct “information-proof-anythings”. If someone on the far side of the planet sneezes you’ll be entangled with that event within moments. That’s not saying as much as it sounds like it is. Essentially, you don’t have to worry much about “big and nearby” events (like sneezing on Earth) being in multiple states.
So, say there’s a God, and say that he/she/it/they/we observes every quantum event. As far as each of us are concerned, unless God somehow conveys the information (burning bush, cheeky glance) he’ll/she’ll/it’ll/they’ll/we’ll be in the same position as the graduate student was before he delivered the results to Schrödinger.
So, in order to keep a quantum event many-stated and quantumy (from our perspective), all that an all-seeing God needs to do is play it cool, and not reveal any clues, whatsoever, about that event.
I think it was in an article by Paul Davies that said that one of the confusions about quantum mechanics is that it mixes information with physical stuff. That seems similar to what you are saying–although I’m not sure if you agree. Davies says that the wave function is information. It is not the case that the world is composed of wave functions. One can’t go out and measure a wave function. All one can measure is the collapsed result, i.e., the actual stuff.
If I’m understanding Davies correctly and if I’ve explained it properly, that seems like a nice way of by-passing the QM paradoxes. It isn’t that the cat is both dead and alive. It’s that the cat is possibly both dead and alive and that there is no way of knowing until one looks.
I’m concerned, though, that this explication sounds too easy. If it were that easy why does QM seem so paradoxical?
How would this apply to the double slit experiment. It would require that the wave, which we want to think of as information must physically pass through both slits, thereby interfering with itself. Is that a problem? If one propagates the wave in the context of two slits and computes its transition in time, it would go through both slits and interfere with itself. Again, though, that seems too easy. So what am I missing?
You’re right, it isn’t that easy.
There’s a very powerful statement called “Bell’s Theorem” (proven) which says that the universe cannot be “locally real”.
“Locality” basically means that no effects travel faster than light.
“Reality” means that the universe, and everything in it, exists in only one state.
This is extremely hand-wavy and incomplete, but:
If relativity (which implies locality) holds, then things can exist in multiple states. Quantum mechanical randomness stems from the many-stateness of things (there’s no way to predict what state something is in when it’s in several). Most physicists who’ve spent some time looking at the problem choose locality.
What you’re describing (with “information” scouting ahead) is a good summary of Bohm’s pilot-wave theory. It abandons the locality assumption, and embraces the reality assumption. Unfortunately, the best, paradox free, but unfortunately mind-bending, choice is to abandon the reality assumption, which puts you right in the middle of the “Many Worlds” camp.
OK, omniscient God is entangled with all events. So when Schrödinger sees the burning bush, God has collapsed the wave function of the universe! Neat trick, being both all-knowing and all-powerful
If God defines reality and exists outside of time (locality), then is Bell’s theorem conserved?
By looking at the bush, Schrödinger (on his own) collapses the bush’s wave function from his perspective. From a larger perspective, he and the bush are still in many states, but entangled (like the grad student).
You don’t need a God to look at stuff on your behalf.
In order to approach a problem like the Almighty Corolary to Bell’s Theorem from a theoretical perspective, I’d need to know what “outside of time” means, the nature of the interaction, and how the reality-defining is done.
But, considering that the Bell inequality can be experimentally verified, you can chuck all that and say, yes; Bell’s theorem holds.
How quickly do things become entangled? To continue with the grad student example, I’m thinking of a scenario where the grad student takes a measurement while the Professor is on the other side of the planet. Is there a sphere of entanglement that spreads out at the speed of light as soon as the grad student makes a measurement? Or could the grad student somehow selectively entangle the Professor by some other means while leaving his roommate across town unentangled?
They become entangled as fast as they can interact, so the speed of light is the upper bound. Any means that Schodinger’s Grad Student can use to interact with Schrodinger’s Professor, and not with Schrodinger’s roommate will work.
But, in general it’s very difficult to not interact at all with something as big as people, as close as a planet or less away.
I accept that the wave nature of a photon is statistical –a probability wave rather than a physical wave. Max Born re-interpreted the “matter-wave” ideas of de Broglie and Schrodinger as mathematical wave functions, but certainly there must also be a physical wave nature to light, as electromagnetic waves are dealing with physical forces, i.e., charge, and do not propagate merely probabilistically. (I am guessing.) I have searched through answers to the same question in the Physics Forum, but the varied answers only seem to confirm confusion. So, what is the relation of a probability wave to a physical force wave? And can this be explained for a non-scientist with limited math skills?
i am a musician and a philosopher and i love maths but all i know is how to do triangles, but as a philosopher i could say that only when we liberate the consciousness we can be, we can fully be, then we can define but we can play the game endlessly without defining, and this in spirituality would be never pointing at anyone because then like that you set them free, it can be that one who redeems you, either a witness who said saw nothing or by the grace of god, so as to say, they both act as intercessors, and then you become a free person, instead of being defined by ego, your granted favor to be forgiven turns you into a spiritual being part of the quantum ocean,
Shroedingers Cat. Try this.
Lets not forget that inside the box the cat is either dead or not regardless of Shroedigers later observation. Can it really only become dead from Shroedigers frame of reference whan the observation is made?
Lets go back into the box. The cat dies and begins to decay. Shroediger opends the box and the cat ‘dies’ upon his observation is the classic interpretation. Since the cat is already decayed then causality has been breached with the cat decaying before it died!
The Shroediger cat example therefore confuses uncertainty with relativity for most people.
There must be some valid debate about precisely when the cat died but not about whether it was dead before the box was opened as it clearly was.
This argument reapplied to the original example means that the only valid observation to be made is that the cat is dead and it died while it was in the box.
The principle of being both alive and dead violates causality as life must precede death even if only be a vanishingly small degree.
Sounds like you’re landing on exactly why Schrodinger’s cat is so strange. The cat really is both alive and dead, with both of the histories necessary to back that up.
Of course, Schrodinger was originally talking about particles being in super-positions of states (several states at the same time), but he used a clearly impossible cat example because it’s easy to write off particles as strange, but harder to write of more intuitive objects (like cats).
Actual super-position requires the thing in question to be completely isolated from the observer in question. Not a single stray photon (or at least, not many). If you were to try this experiment in reality, you’d find that it’s impossible (with current technology) to isolate a cat-sized-thing enough for any weird quantumy things to happen.