Skip to 8:59 for the animation. I found this useful, as a physical illustration of spin 1/2.
Opening salvo of rambling
I’ve got some insomniacal 3 am ravings to share (one of those “it seemed like a good idea at the time” moments).
I’ve been thinking about physics again. Revisiting deep underlying ideas after a hiatus of nearly two decades. That’s a story in itself. I once thought that I was going to be a professor of physics, making famous theoretical discoveries. The I totally whiffed at grad school. Not that I was failing classes or anything so mundane as that; rather I hated it and I sucked at it, and I hated it and sucked more and more until I couldn’t mentally handle the unhappiness anymore. I dropped out after my first year. Didn’t even make it through a measly second year to grab a masters as a consolation prize.
In retrospect, I dropped out not because the program was too hard (though it was I think) but because theoretical physics—as a whole discipline—was too hard. I felt like a failure even before I started, because I realized how impossible it was going to be to solve the world’s physics questions. When I dropped grad school, I also dropped physics. Didn’t think about it anymore, didn’t follow the news, forgot everything I knew.
Perhaps more relevantly, I let go of my physics ego. I no longer considered myself smart at physics, and so I let go of all pretense. In so doing, I also may have let go of some of the assumptions and scientific biases that creep into one’s view of a subject, which are difficult to ever extirpate and which inextricably color every idea and thought and view that one has about a subject ever afterwards.
Well anyway, after twenty years of not paying any attention to theoretical physics, and no longer having even the slightest claim to expertise in it or ego about it, I’ve started thinking about it again. Someone offered Karen a pristine paperback set of Feynman’s lectures and I’ve started reading them again. And surprisingly I find that I went so far away from physics for so long that I can look at the most basic principles in a completely fresh, almost infantile light. I no longer look at the most basic material and feel like a failure for not remembering it. I don’t experience that ego-comfort-driven tendency to dismiss the “easy” stuff, to gloss over the basics as intellectually below me, or sufficiently understood that I can ignore it.
Instead, I find myself questioning even the most basic of claims. And my latest fractured philosophizing over the past few months has yielded some surprising epiphanies. Personal epiphanies, really, as I doubt that my vague mental victories can ever be translated into useful (testable) hypotheses that are useful to other scientists. But in my head (at least at a sleepless 3 AM), some of these thoughts are “eureka” sorts of moments that seem so self-evidently correct, so obvious and elegantly explanatory, that I can’t help but think that I’m onto something. And I’m not drunk or high either!
The thing about the state of physics, on this May 22, 2022, is that we have far more data than we have understanding. We don’t lack for information and evidence; we lack the explanations that put it all into a sensible context. The shameful truth is that we humans simply do not understand the newest physics information that we have collected. And by “newest” I’m including every important theoretical discovery since special relativity, including special relativity. It’s all right in front of us now–tons of data–and yet no one has figured out what it means. Quantum mechanics remains a blight on our collective intelligence, in that the best explanation anyone has generated so far is paraphrased as “we aren’t supposed to understand it.” Which itself is a stunning self-admission of failure, almost a collective capitulation which has stood now for nearly century.
My entrance point for recent revelations is Time. All of our physics is inextricably wrapped up with Time, as a foundational, fundamental entity. It’s enshrined in our most basic equations, some of the first that we ever study in school, and then we build up our edifice of physics on that foundation. The problem is that Time is not foundational, in/to the laws of universe. Time is a construct, an emergent property that filters (and blinds us) to reality. If one yanks out that foundation, of Time as a fundamental, absolute quantity of the universe, then all of modern physics needs to be re-imagined from the bottom up. The problem isn’t so much of using incorrect math, and it’s not a question of being incorrect in any of the calculations that cap our best physics discoveries. Rather, from the time we’re first introduced to physics (and, I will argue, from our sensory experience of the universe from birth) Time is an underlying mental and cognitive cornerstone that is almost impossible to remove and restart without.
Time is a sort of cognitive illusion. Not the sort of illusion that doesn’t exist, but the sort of illusion that derives from a limited viewpoint. It’s as if we have a filter the prevents us from seeing the universe the way it truly is. The filter is, of, course, an inbuilt consequence of the “way the universe is”. It’s not some sort of filter special to humans, or “consciousness” or any of that bullshit. Let me see if I can explain my recent “revelations”, if that’s not being too presumptuous.
My most important point, from which much else derives, is this: the notion that there is a “present” moment, a “now”, and that the past is behind us and done and gone and the future is yet-to-be, is… wrong. The “present-sense” that we experience is naturally caused by the way the universe works, but it is absolutely wrong. All of the universe, past, present, and future, is equally extant, all at the same time, forever, simultaneously. That last sentence makes me cringe, because I cannot avoid using “time words” to try to dispel the notion of time. “Time” is so fundamental to our thinking and our perception that I cannot even find words to avoid it.
Imagine a movie of your entire life, if you will. Picture yourself moving and talking and acting, from birth through death, as one continuous reel of existence. All of that is equally “true” or “extant” in the universe. There is no present, Now moment that is more true or real than all other moments. Grab the “you” of ten years ago, yank them out of the movie of your life, and ask them what moment it is, and they will answer “now”. All of the yous, from all of the movie, all think that it is the present moment. And all of them are equally correct. You, the reader, reading this “now,” have no more accurate a claim to “now” than the you from ten years ago. The you of ten years ago is every bit as alive and true and real as you are “now”—and they also think it is “now” for them, and they are equally correct in our universe.
The history of human exploration and discovery has been ever successive abandonment of human-centric falsehoods. We once thought we occupied a central position in a flat land until we learned that it was a round earth. We once though the earth was the center of a solar system of celestial bodies orbiting us. We once though the solar system was the one-and-only special set of bodies, surrounded by dots of light orbiting us. We once thought the galaxy was a one-and-only phenomenon of collected stars, until we realized there were other galaxies. We once thought our planet was the only one in the universe. Inevitably, our underlying assumption that we’re the only life in the universe is equally incorrect—but naturally we will stubbornly cling to that human-centric belief until some alien shows up, in the flesh, to reveal our shortsightedness.
So, too, with time. Really, the notion that we live at the one and only, current, “now” moment is a similarly ridiculous idea. And I need not rely solely on philosophy or the elegance of my explanations. Special relativity—that by now ancient and supposedly fully-understood aspect of “modern physics”, says so. Special relativity tells us that the sense of time experienced by observers moving relative to each other is different. Each observer senses their own time as accurate, but equally validly observes the other as having slow time. More compellingly: special relativity says that the two observers will disagree on the “now”. They will not agree on the simultaneity of different events. They each have a firm belief in what the “present moment” is, and they are not in agreement. It is not that one is wrong and the other right. The truth is that there is not one present moment, for anyone. There is no absolute time; there is no “now”.
That, alone, can still be brushed under the metaphorical carpet, perhaps as a quirk of measurement, or some hand-wavy dissatisfying argument that their length measuring devices have also changed, so it all works out. But if you really strip down all of physics, back to the beginning, and allow yourself to be appropriately skeptical of everything, then the only courageous conclusion that one can reach is that our entire reliance on absolute Time, with us in a special Now moment, is suspect. Flawed.
The second law of thermodynamics is cunningly simple—just statistics!—and yet the implications of it are not well appreciated in my opinion. Entropy is a mover and shaker in my revelations. When a box of gas particles is opened, the gas expands to fill the room. It does not do so because of any underlying rules to the particle motion. The rules of particle motion alone lack an explanation—a reason—a drive—that explains the emerging macroscopic tendencies of systems. Mere statistics applied to that motion does so. The gas expands to fill the room because of the humongously larger number of ways that the gas can fill the room, in comparison to the number of ways that it can remain in the box forever once the top has been opened. There is a natural sequence, or chronology, to the changes in position that happen to the macroscopic collection of gas particles. And for now I can even admit a chronology—a timeline—without requiring a “present moment” in that timeline. That’s one key aspect of my argument. I am not really arguing that Time “doesn’t exist” (though I will argue eventually that time is a limited and largely fallacious filter). For now I’m just arguing that there is not a privileged “present”. The gas does not “know” to expand into the room.
Here’s the rub: humans can only form memories of reduced entropic states. We can have a memory of the gas being in the box, because it was at a state of reduced entropy. We can “know” that the gas once was in the box—hence form a memory of it—but we cannot “know” the gas filling the room. Our neurons themselves are subject to the same entropy limitations, and this is also part of it. Our memory is “one-sided” so to speak—it can only contain knowledge about “one half” of time—the past—and so we have a false illusion that we occupy the edge of the “now” which is ever forward-moving into the future. It’s a misconception, is what it is. Every “you” from the movie reel of your life has the same misconception; every you there ever was also thinks they reside in the “now” are are on the bleeding edge of the future. Memory only exists because of entropy changes. Memory is our mechanism for perceiving time. We can form memories of the past; we cannot form memories of the future. That is a circular statement, but I can come up with no simpler single sentence to capture my notion. Our feeling that we exist in the “now” is an illusion arising from memory, and the nature of entropy. This is the so-called “arrow of time” though I think that metaphor almost does more harm than good, in terms of explanatory power.
Also notable: our notion of time only arises from macroscopic phenomena. This “arrow of time” arises when huge numbers of particles interact—which is really the only life we know. Every experience we have, every event we observe, every action we take, is all dependent on so many particles, that we almost never encounter the small-particle way that the universe works, at a fundamental level. Everything we know is based on huge statistics, obvious “direction” to the chronology of particle interactions, because of the multitude.
We can contrive tiny little interactions, amongst just a few particles, in physics laboratories, with great effort. And when we do so, our entire edifice of physics understanding is called into question. We are confused by the way things seem to work, at that scale. The primary reason we are confused, is because we are still trying to apply a flawed sense of time to the scene. Our in-built bias and illusion of Time and Now that arises from the macroscopic world of countless particle interactions blinds us to the universe’s reality.
A related misconception we have grown up with, as physicists, is that a particle is a mass, and it can have a velocity, but somehow that velocity is an changeable attribute of the particle, that can evolve through time (e.g. based on its interactions with other particles or fields, say). So, here we encounter the word “time” again, already. Our notion of velocity is inextricably dependent on our notion of time—which is flawed.
As an aside, it is nearly impossible to convey meaning on this subject without using incorrect language that involves “time” words. Because we lack the proper words. This is one of those linguistic examples in which our words perhaps originated from human ideas, but our words also now limit our thinking, by failing to provide adequate signifiers to break out of our biases. Our fundamental understanding of the universe is so inextricably tied to time, and wrong ideas about it, that we’re going to have a hell of a… time… trying to write sensible thoughts without sounding like some superstitious mystical (enlightened?) guru.
So, time to return to the point: we think of a particle and it’s velocity as somehow “separate”. We can change the velocity of the particle, and the mass is still the mass. The mass is the main thing, and the velocity is one of many attributes of it.
Not so. The velocity IS the particle. The mass and the velocity of the particle, together, are the particle. The velocity is not separate. The fact that we think of it, or conceive it, as separate, is another failure of perception on our part. Naturally, it has to do with our hangups on time. The whole history of the particle, which includes naturally its velocity as well, IS the particle. The particle should be thought of as a continuous world-line of existence, in which the velocity of it is as fundamental and inextricable from its nature, as is its mass. And the reason for this, the reason I bring it up now, that is, is that our perception of the velocity as being somehow separate from the particle itself is another cognitive failure, or illusion, or limiting filter is perhaps the best analogy here. Because Time is a cognitive filter that negatively affects our accurate perception of the universe. The bad-filter-of-Time also makes us think incorrectly about velocity, and really motion overall of course, but specifically velocity, because a more fundamental way of thinking about a particle is by momentum. Momentum is both mass and velocity, and momentum is the particle in a more fundamental way than thinking of mass and velocity separately, and, oh, yeah, I have to multiply them together to get momentum. We see velocity as separate from the mass… but it’s really not. It’s because we don’t see properly. The particle IS its velocity, every bit as much as it “is” its mass. The velocity seems to stretch it out through Time… and of course we’re wrong about time.
This is born out, in a way, but some of our very first physics principles. Newton’s law states that force is the time rate of change of momentum, not velocity. But already, in our very first F=dp/dt equation that we teach from student’s first exposure to physics, inextricably conjoins time into the equation.
The question is: how do we build up a physics that involves particles interactions, and the notion of “change”, without using time? We need to build a physics out of which time can be extracted as a dependent variable, as a phenomenon that emerges from a more fundamental underlying edifice that does not require absolute time and “now” as a starting point.
I can generate a metaphor for our cognitive hang-ups about time. Imagine a set of blue-filtered glasses, which only pass the color blue to your eyes. And imagine you’re observing a rainbow colored wall which is continuously changing color. I can create a color-changing pattern on that wall which will give your blue-filtered perception the idea that a single blue line is moving down an otherwise unfeatured blank wall, all while in the “real world” the whole wall is filled with swirls of complicated color. Your limited brain sees one thing moving down the wall. Our time filter is like that. It squashes a full-rainbow universe into a single-particle entity moving in isolation.
Another metaphor in my mind’s eye. Imagine a soliton-like lump rises from a flat plane. Imagine that the lump is squishy and deformable. If I squeeze it between my flat hands, I can squish it down to a thin line in one axis, and it metaphorically looks like a “point” particle. But in so squishing in one axis, I have squeezed it out along the other direction, directly towards me and away from me, making it look way wider and less point-like in that axis. After releasing it, I can squish it along the other axis, if I wish, but then I’ve made it wide again in the original axis. I can’t simultaneously squish it into a “point” on both axes.
This is a metaphor for our “uncertainty” principle, where we cannot simultaneously know the position and momentum of the particle to arbitrary precision. Here again we see that the “particle” is constituted by its mass and velocity; they are aspects of the same particle–a particle is both of these things together. And here we also have our first glimpse of the “texture” of time in a way that moves beyond the statistical arrow of thermodynamics. Here we are treating with the “time” of a single particle, which removes all aspects of the statistics of the wider world. Which also means that we have moved beyond memory, and beyond the incorrect conceit of the “now” and are observing a naked particle and what “time” means when there’s no ensemble of particles with which to engage in copious statistical interactions.