We love reading the advances of real scientists doing real research. It puts us in our place when we’re feeling all smart — here are people actually advancing knowledge and doing stuff for real! — and at the same time we get to learn some really cool stuff.
For example: It was January of 2000, and we were sitting in a Hell’s Kitchen Dunkin’ Donuts, just looking out the window, thinking about this and that, when suddenly we had an epiphany: What if the wave function was a real thing, and we just saw the sliver of it that coincided with our own dimension?
You have to understand, this was back before we got married and had kids, and so we occasionally had what was called “free time.” (We’re not sure what it’s called these days, it’s been so long since we had any.) How it worked was, we had “free time,” which we spent pursuing various hobbies like motorcycling, playing in bar bands, and the like. We had gone to the Dunkin’ Donuts after a lackluster rehearsal with an acting company we were with at the time (another hobby), and our mind must have turned to quantum physics — which had been a mild hobby of ours ever since John Crowley showed us that Omni article on string theory back in our freshman year of high school. The more we learned about it, and all the spooky nonsensical impossible stuff that apparently was really being observed, the more we dove into it. By 2000, we’d written off string theory as hopeless, and were waiting for some brilliant scientist to come up with something like Garrett Lisi did some years later. We weren’t contributing anything, of course; just trying to understand the current state of knowledge.
So anyway, what our epiphany was, was that it seemed you could explain a lot of that spooky nonsensical impossible stuff if you thought of things like photons and electron as not being particles or waves or whatever, and instead thought of them as wavelike things rippling or oscillating in a higher dimension, and what we saw was nothing more than the points where they intersected our 4-dimensional reality. You need more dimensions for the math, but you only need 5 to explain it.
Take the standard 2-slit experiment. You shine a beam of photons at a screen with two slits on it, and on the far wall you’re going to get an interference pattern as the two sets of waves from each slit interact with each other (as in the hastily-photoshopped image at the top). If you shoot individual photons through a single slit, you get just a single patch of light on the far wall. If you shoot individual photons at the two-slit screen, the same interference pattern builds up as if each photon had interfered with itself, and found a spot on the far wall in that interference pattern. It makes no sense if the photon only exists in our 4-dimensional world, and yet it happens.
But if you think of the photon as something one dimension higher, it’s easy to contemplate.
(Note: what follows is not science, but only what occurred to us as we sipped our hot chocolate that day.)
Think of a 3-dimensional sphere. If you only experienced 2 dimensions, you’d only see it as a circle, because the circle is what would intersect your plane. If the ball entered your plane, moved across it, and exited the other side, then you’d see a tiny circle appear out of nowhere, grow to its largest circumference, and then shrink back to nothingness. You’d have no explanation for where it came from or why it did what it did, but someone in a 3-D world would see it clearly.
So you and I are in a 4-D world (length, width, height and time). Imagine the photon as a wave in the 5th dimension. Imagine a circular wave, much like at the bottom of the picture above, with the source of the photon at its center. We are not seeing the whole wave, though, because our universe is only a 4-D plane intersecting that 5-D world. What we see is not the wave, but the point at which it intersects our plane. The point we actually experience is like a little dot of energy moving along the wave’s path.
That 5-D photon acts like a circular wave (well, not quite, more in a second) that hits the two slits, coming out as two more waves that interact. But the photon that we see in our 4-D world is a single particle that travels a path through one of the holes, then veers back and forth along the interfered-with path, until hitting the far wall. It looks as though it interfered with itself because it really did, just not in our dimension.
Now it might be that certain directions of travel were more likely than others. The photon might have been aimed at the center of the screen, but it could have gone off to the side or even backwards. But because it was aimed that way, it’s a lot more likely that it went in that direction. So the wave is sort of concentrated in that direction where the probabilities are strongest, and thinner where the probabilities are weakest. (This is simply a mental image here, but it makes the point.) When our 4-D plane intersects paths that are more likely — or perhaps, when such a path is more likely to be intersected by our 4-D plane — we’re more likely to see the event.
So think of that wave of thicker and thinner probabilities as a wave function. If it’s a real thing that really exists in higher dimensions, then it would explain why we see that bizarre 2-slit behavior of single photons.
It would also explain quantum entanglement, where two particles interact and their shared relationship remains tight, no matter how far across the universe you separate them. If you affect one, the other will feel it. It makes no sense in a 4-D world, but if they’re both part of the same wave function in the higher dimensions, it’s not a problem at all. Time and distance are not obstacles to be overcome. It would explain why photons don’t experience time. It would explain a lot of things.
It’s a pretty simple idea, really.
So anyway, that was our little epiphany. Maybe we did a little math to toy with it later, but nothing too serious. We did speak of it to actual physicists, but those conversations usually ran something like “Yeah, but that would require the wave function to be a real thing.” “Right, that’s what I’m saying.” “But it isn’t. It’s just a statistical thing that explains reality. It’s not the reality itself.” “Oh, right.” And then they’d point out some of the numerous (and probably still very true) reasons why our dilettante-ish musings were not only wrong, but unoriginal and long-since discredited.
So it was with a little extra pleasure that we just read an awesome paper just posted online by Matthew F. Pusey, Jonathan Barrett, and Terry Rudolph, entitled “The Quantum State Cannot Be Interpreted Statistically.” Suffice it to say, it is mind-blowing. Nature reports that reaction in the physical community is excited, to say the least: “I don’t like to sound hyperbolic,” the magazine quotes physicist Antony Valentini as saying, “but I think the word ‘seismic’ is likely to apply to this paper.” The paper’s conclusion?
That the wave function is a real thing, and not just a statistical construct.
They got there by process of elimination, sort of. If the wave function were only a statistical helper, then quantum states that are not entangled would be able to act just as if they were entangled. That’s not what happens at all. They have to be entangled for it to work. And that means the only remaining option is that the wave function really is a real thing.
Quantum states are the key mathematical objects in quantum theory. It is therefore surprising that physicists have been unable to agree on what a quantum state represents. There are at least two opposing schools of thought, each almost as old as quantum theory itself. One is that a pure state is a physical property of system, much like position and momentum in classical mechanics. Another is that even a pure state has only a statistical significance, akin to a probability distribution in statistical mechanics. Here we show that, given only very mild assumptions, the statistical interpretation of the quantum state is inconsistent with the predictions of quantum theory. This result holds even in the presence of small amounts of experimental noise, and is therefore amenable to experimental test using present or near-future technology. If the predictions of quantum theory are confirmed, such a test would show that distinct quantum states must correspond to physically distinct states of reality.
If these guys are right, it could be a very big deal in our understanding of the universe. If you just think of all the real-world things that work precisely because of spooky quantum physics (cell phones, MRI machines, Blu-ray, pretty much everything in your kid’s letter to Santa), just think of what more we can accomplish as we learn even more. Though really, the understanding alone is more than enough.
Now, what they have concluded and what we imagined a dozen years ago are not the same thing. They did real science and careful analysis. We were a crank who had a brain fart. While we casually doodled waves and stuff on a napkin, they did actual math:
We can’t even claim to have made a heuristic proposal (academicspeak for “I haven’t done the math, but if I’m right I want the credit”).
So no, we are not comparing what we thought up and what these guys have accomplished.
We’re just really happy that they did!