Sunday, July 9, 2017
The quantum is the world of tiny, very tiny, unfathomably tiny sub atomic particles that make up the fabric of our bodies and the world around us. It is said that “if you think you understand the quantum, then you don’t.” That the behavior of these particles is so bizarre, so weird in relation to the way that things behave in our familiar world of visible objects, that it is just impossible to make any sense of it. The point of this post is to do exactly that, to suggest to you a framework in which not only quantum phenomena, but also phenomena in our familiar visible world, phenomena in the astonomical world of gigantic objects hurtling through space at unfathomable speeds and even the personal world of our internal experience all make some kind of consistent, coherent sense.
In this post I wont be discussing all the weirdness of the quantum, just one important aspect of it; the particle/wave duality. To do that we’ll hone in on the experiment through which the particle/wave duality was first discovered, the double slit experiment. Now please really focus on this so you can appreciate how truly weird this is.
We normally think of light as a wave, and it is, but it has also been found to contain tiny particles, minute packets of energy, that we call photons. In this illustration, light is shone at this wall that contains two slits, and some of that light goes through the slits and photons hit this plate, which is a light sensitive photographic plate; so when a photon hits it, it makes a tiny white dot. As the photons build up a white pattern emerges. If I cover up one of these slits, so the light can only go through the other slit, you would expect to get a band of white, directly in line from the lamp, through the open slit, to the plate. That is what you would expect and that is what you get. And if I expose this other slit, you would expect to get two bands of light in the direct line from the lamp, through either of the two slits and onto the plate. That is what you would expect, but that is not what you get.
What you get is this:
a series of bands of light alternating with bands of darkness. This is called an interference pattern. And it is made when two waves overlap. Waves move in crests and troughs. When a crest emerging from one slit overlaps a crest emerging from the other slit, they make one higher crest and when this higher crest reaches the plate, you get a solid white band. Same with troughs. If troughs from each wave overlap each other, then you get a deeper trough and when it reaches the plate you get another solid white band. But if a crest overlaps a trough, their energies cancel each other out. In that area, no photons reach the plate and you get a dark band. Light, dark, light dark, like that.
So this is weird, but here is something weirder. If I set up a detection device at the slits, so we know which slit the photon is passing through: the first one went through the right slit, the second one went through the left, etc., when we know that, then the interference pattern disappears, the light acts like well behaved particles and we get just the two bands directly in line with the slits. When we know which slit the photon is passing through, we get the two bands; when we don’t know, we get the interference pattern. Now that is very weird.
Okay, weirder than that: If I dim the light so much, and reduce the aperture of the lamp so much that only one photon is being released at a time, say at intervals of ten seconds, and both slits are open, a tiny white dot will appear on the plate every ten seconds and very gradually a pattern will emerge; but that pattern will not be the two band pattern, it will be the interference pattern. What? Hold on! How can one photon, or one wave, interfere with itself, or interfere with another photon that will be making a wave, but hasn’t made a wave yet? That is very, very weird.
Most weird of all: It doesn’t work just with light, but with electrons, protons, neutrons, whole atoms, even molecules consisting of several atoms. When you shoot particles at two slits and you don’t know which slit the particles are passing through, you will get an interference pattern, indicating the intermingling of two waves and not the separate trajectories of two particles.
The atom? The atom? So long thought of as completely indivisible and eternal, the bedrock foundation of the materialist point of view, and then once it was split in the twentieth century only with the release of terrifying powers, enough to decimate whole cities and the release of deadly radiation that threatens all of civilization; this same atom, does what? casually morphs into a fluid wave, maybe two waves, mingles, becomes a particle again? There’s no explosion, no damage. The laboratory is fine, the equipment is fine, the researcher is fine. What’s going on?
Erwin Shrodinger, a prominent physicist, first thought that the wave was an extended form of the particle. If the particle were, say, an electron, the wave would be a stretched out electron. In that case, researchers felt, they should be able to detect fractional electrons. If the particle is stretched out, there should be a tenth of an electron here, a twentieth of it there, etc. Yet no such fractions were ever detected. If you are in the business of detecting electrons, you either detect nothing or you detect a whole electron, with the same mass, the same charge, the same spin as every other electron.
I should note here that all the subatomic particles that we will be discussing have never been seen. They are way, way too small for that. They are detected, but not seen, by detecting a certain mass, a certain spin and a certain charge coming from a precise, discrete area.
So if the wave is not an extended form of the particle, then what is it? There is no agreed upon understanding of what the wave is and no agreed upon explanation for the wave/particle duality. There are methods of calculating, and calculating very accurately, the probabilities of where particles will be if they become waves and create interference patterns; basically, the brighter areas of the pattern would be the areas where a particle would be more likely to show up, and dimmer areas, less so. But these are methods of calculating results, not explanations of how these results are achieved; not explaining in a satisfying way what a wave is, or why it turns into a particle, if it does, or why a particle turns into a wave, if it does, or why in the world it is effected by whether or not we know which slit the particles are passing through.
The field abounds with wild speculations: The wave is a wave of probability. It susses out, like a pathfinder, all the places along the interference pattern where a particle could land, but doesn’t actually move the particle there, itself. Then, how does the particle move from the slits to the plate? Actually, it doesn’t. The particle disappears into another universe when it leaves the slits and reappears at the plate, shuttling back and forth between two universes. Or, each particle lands at every possible landing site on the interference pattern, but in a different universe for each site. Or, there is no wave. The particle simultaneously travels every possible path from the lamp through the slits to the plate, including getting there via the moon and the Andromeda galaxy and is effected by the forces it encounters on each of these journeys, until all other paths are cancelled out except the ones that will bring it to the interference pattern, with more paths leading to the brighter spots and fewer paths leading to the dimmer spots. This one is called the ‘sum of paths’ approach and although it calculates the probable location of particles with great accuracy, it’s author, Richard Feynman, is the very man who said, “If you think you understand the quantum, then you don’t.”
Many prominent scientists have been pondering the particle/wave duality for over a century; Neils Bohr, Werner Heisenberg, Max Planck among them. As brilliant as these men were, they were all looking at the world from a Western perspective which is really, now, the dominant modern perspective of both East and West. And deeply, deeply ingrained in this perspective is the idea that forces are connected to matter, and emanate from matter. That matter, in the form of particles, is the foundational structure of our universe and that everything, including forces, planets, galaxies, even life, consciousness and love, somehow come out of the endless and countless and unguided interplay of these particles.
If you went to school when I did, you learned that civilization and the accumulation of accurate knowledge began in Greece, not quite three thousand years ago, proceeded to Rome , continued from there through a few different European countries until some of those European people came to America at which point some of civilization and real learning spread here as well.
About 2500 years ago Democritus, in Greece, had the idea that the world around us was not made of solid matter, that it was actually divided into tiny bits, way too small to be seen, that he called atoms, from the Greek word atomos, which means indivisible.
Here is an illustration of Democritus’ conception of the atom: