I’m fairly sure that your eyes work, and if not, I’m glad that you don’t get to hear this in my gravelly-yet-monotone voice. Since your eyes most likely work, I don’t think it will be necessary to direct you to my previous post here, so I shall continue where I left off.
Modern Physicists may be quoted as saying that things may not exist at all times. Let that sink in a bit. Things; you, me, your soda; may not consistently exist, according to some. That is a very fundamental level of “being” upon which they have decided to cast doubt. It is troublesome to me, because these are people that represent not just my field of study, not just my major but to a great many people, they represent science as a whole.
To be clear, there are reasons for thinking this way. All theories must be consistent with reality. What we observe, we have to assume to be true, tacitly. All of our formulations and models must, in the end, agree with all aspects of what we observe. If reality doesn’t work the way that we’ve predicted, we need a damn good reason to keep that prediction around. In physics, the theories are tested with experiments. These experiments are done very very carefully. If an experiment contradicts a theory, the theory is wrong. What is particularly interesting, is that the theories that make people claim these outlandish things do agree with the experiments that have been devised.
***ADVANCED SCIENCE WARNING***
The infamous Double-Slit Experiment illustrates several basic tenets of quantum theory. The experiment goes a little like this:
Scientists set up a laser and shine it at a tiny slit in a screen. On the other side, they set up a backdrop to see the results. As the laser passed through the slit, they found that it diffracted, and the backdrop had a neat little pattern on it.
<= Like this one!
Next, they set up the laser to shine through a double slit, which is nothing more than two slits that are very close to one another. The scientists turned on the laser, and got a different pattern!
<= This one!!!
Now, you may notice that the second pattern is a lot like the first one, but has lots of little bright and dark spots. Well, these are areas of constructive and destructive interference, respectively. This all works because light predominantly acts like a wave.
Well, scientists weren’t quite done with their experiment yet. So they wheel out their electron gun (which is not quite as badass as it sounds, sadly), and shot electrons, one at a time, at the single slit target. One electron goes through, then another, then another, and soon scientists could see that the same diffraction pattern they saw with the laser was appearing on the backdrop.
Even though they had just demonstrated that electrons can have wave-like properties, the scientists weren’t done yet. They took down their single slit target and put up their double slit target. The fired up their electron gun, and one… at… a… time… fired little electrons at it to see what would happen. Several tense minutes later, they had their results: a backdrop with the double slit diffraction pattern on it! Hooray!
This made someone in the group pause for thought. Think about it from the electron’s perspective. You’re flying along, and suddenly you fly through a slit. Being tiny as you are, this causes you to diffract and fly off in a slightly different direction. What should eventually appear is two distinct single slit diffraction patterns. One for each slit in the screen. With the laser, the light could interfere constructively or destructively to form the bright and dark spots. But electrons can’t do that. It seems that electrons could somehow “sense” the second slit, even though it never interacted with it.
There’s several more parts to this experiment that pretty much sequentially blew the minds of scientists, but for now the bottom line is this. The only way for the electron to act as it did is if it interacted with both slits. Since an electron is primarily particulate, the only way it could interact is by travelling through both slits.
An entire mathematical framework was built up around this idea. At its core is the idea that the electron has a wavefunction, and until the wavefunction is collapsed by a measurement, it is in some murky, ill-defined state where it has somehow traveled through both slits in the screen. What is even more problematic is that in order for that to be the case, the electron cannot have a defined path.
Let me say that again: according to the only explanation these scientists had, THE ELECTRON CANNOT HAVE A DEFINED PATH! This means that the electron cannot be said to exist at any particular point along any particular path. Between start and finish, it may or may not exist in any particular place at all!
***END ADVANCED SCIENCE WARNING***
Welcome back all of you who skipped down! The point of all of this is that standard quantum mechanics is a theory that perfectly agrees with experiment, but doesn’t follow some basic logical tenets. Scientists have been very careful in their experiments and produced very particular results, and standard quantum mechanics can explain each of these results splendidly. But at the end of the day, we’re still left with a theory that casts doubt on the very nature of existence.
The most unfortunate part, in my humble opinion, is that there are other formulations of quantum mechanics that also agree with experiment. They, like the standard, perfectly agree with the observations of scientists and experiments. Unlike the standard, they allow for particles that exist at all times in a specific and well-defined way. They have a few problems, but are as glaring as the contradiction of that most obvious observation: THINGS EXIST!
It’s an odd statement to make. It seems obvious, and it is obvious. Every time you open your eyes, you can see a variety of objects. Not only that, but you can go over and feel the objects too. Even if you leave for a while, you can safely assume that everything you left behind still exists. There are literally more than a billion lifetimes worth of experiences that suggest that things actually exist, but even then, it is ultimately an assumption about the way the world works.
This is a problem that has troubled many minds. At its most basic, we have to take the mere existence of things as an assumption. There is no way around this. The problem is illustrated in Godel’s Incompleteness Theorems. In order for the world to make sense, we must assume a few fundamental properties. There are two that I want to reference specifically:
There is sufficient cause for everything.
These are only assumptions about the nature of the universe, but without them, nothing makes sense. I mean that in a very literal way. Logic itself breaks down if we can’t make these sorts of assumptions. If we can’t assume that things exist, then there is nothing to which we can attach any meaning. If we can’t assume that there is causality, then events happen at random. You couldn’t have any measure of control over what happens, and everything you do lacks meaning.
There are reasons for us to assume these things, which I will get into later. For now, I will simply say that I hope nothing here registers as particularly surprising to anyone. These seem like perfectly ordinary assumptions to me, which is why I am particularly troubled that my very own field of science is reporting its results in such a way that makes it seem like these fundamental tenets of logic aren’t true.