I may update this as time goes on, and add like more quantum mechanical stuff
I recently watched Oppenheimer. It was a fabulous movie. And watching it rekindled something in me, a love of physics. Of course, since then, that fleeting awe of it has faded away, as the math (a large part of which I did not fully understand), became complete of drudgery, but regardless, I still believe it is beautiful, and I plan on coming back to it in the future.
Using beautiful, a word mainly reserved for descriptions of people, of objects, of beautiful things, rather than beautiful concepts, I believe that quantum mechanics can still be described as beautiful. This is because I view probability as wondrous (you’re telling me you have all this stuff, and can’t be sure? Wow!), and quantum mechanics is probability at its most extreme, probability applied to the fundamentals of the universe and of everything. Stunning.
Additionally, for at least basic quantum mechanics, such as a wavefunction, the math is fairly straightforward.
My main problem, however, is the apparent abstractness of it. While you can build fully functioning, non-abstract (ie applied) stuff with it (e.g. nukes, quantum computers), it still seems very abstract, and very theory-heavy. This abstractness, and reliance on math in an off putting way, caused its luster to die for me, but I believe it is still amazing, if just not for me. I prefer stuff not more concrete, per se, but less purely theoretical, and slightly larger. I prefer stuff at the molecular scale, rather than the 0 mass, infinitesimally small scale. I do feel, however, the need to point out that this loss of beauty happened for me, after only a few hours of looking at it, as after that time, it had already started to get such pure-mathematics, that its abstractness was painful. I was, and as such still am, a beginner into it. But regardless, I believe I should “regale” any reader with my stories of it.
Quantum mechanics is the field of physics which focuses on the particle level, on that of stuff like photons. I will focus here on specifically photons. Photons are, when it comes to physics, non determinate. This means that one equation can’t come up with the exact position of the photon, but rather, how likely it is to have each position. A proof of that which I really liked, is a beam splitter. You shine a homogeneous ray of light, and it splits the ray into two. There is nothing special about each photon in each beam, and nothing physical in the beam splitter that determines “Hey, photon α should go in the reflected beam and photon β should go in the transmitted beam, because blah blah blah”, no. It is simply random chance.
It is also fascinating how simple some of this stuff, covering the fundamental particles, is. I mean, it makes sense, they’re fundamental, but regardless. Take an example in the double slit experiment. Each line has the possibility of being drawn at any possible y on the screen, assuming one photon is passed through at a time, and the y represents y+Δy, then
P(y) ∝|Ψ(x, t)|2,
where Ψ is a wavefunction, at time t and x value x in a 1D plane, and P(y) is the aforementioned probability. It is just so simple, the probability is proportional to the square absolute amplitude of the wavefunction, at x and t. It just makes sense. Beauty.
I also believe I should show what a wavefunction is, and explain its collapse, as that is said a lot in the news and such, but never explained. A 1D wavefunction can be represented by the real part of the equation
Ψ(x, t) = Ψ
where
Ψ0=Aeip
This may seem like a lot, but most of it are just inputs or constants. The variables are as follows:
This can then be graphed as simply a fluctuating chart, at any given time, in accordance with the parts of the wavefunction, which vary by wavefunction. That chart can be interpreted as the possibility of finding the particle at any given x. And a wavefunction “collapses” when it has to “choose” (if we are anthropomorphizing it), which position in will take. The wavefunction, however can still expand.
There are a bunch of other equations and such, which I did not cover here (primarily as I myself don’t even fully understand them), but I 100% recommend that you check out, as, once again it is wondrous. I spent several days just learning about it, even if some stuff went through one ear and out the next. It is nonetheless beautiful, fascinating, everything.