I am a political scientist, but often in my spare time I prefer to think about science and philosophy rather than politics. So I’m not an expert on the material I’m writing about today, and welcome any corrections or modifications!
Today, while digging mini-trenches in our never-ending yard project, I tried to get my mind around the question of what makes up the universe. There is a delightful irony in thinking of these things while struggling to shovel rocky dirt in rainy cool weather with an aching back and painful fingers. Because as starkly real as that work and those pains are, reality itself almost seems unreal.
The average distance between the nucleus of an atom and the electrons “orbiting” it is about 100,000 times the diameter of the nucleus. That means that even every day solid objects are almost all comprised of empty space. Moreover, the electrons themselves are tiny point particles, existing as part of a probability wave until detected and forced to occupy a single position.
The nucleus of most large particles (hadrons) is made up of quarks — almost all of reality that we experience consists of up and down quarks, and electrons. Electrons have electrical charge, while quarks have color charge (nothing to do with color, that’s the name given to this ‘strong force’ of nature). Particles are also posited as carrying the force that keeps reality together. For electrons this particle is a photon (which we experience as light), and for quarks it is a gluon. These “force carriers” have the attributes of being both a particle and wave, existing in a field. All the stuff of reality — light, particles, even macro objects like human beings — exist as both a particles and waves.
So the universe is made up of electrons and quarks, and most of what we experience are up and down quarks. There also exists strange, charmed, top and bottom quarks, as well as numerous other particles that are made up of different combination of quarks with different color charge and spin — and every particle has an anti-particle — but that’s not the stuff that makes up most of what we experience. These other particles exist in cosmic rays, perhaps stars, and in tiny amounts in nature (thanks to quantum probabilities everything that can exist or happen does — at the quantum level). Humans have seen the impact of these particles in what is created in particle accelerators, but in general our universe seems composed of very basic particles.
Of course, “particle” may be the wrong term. Certainly things like photons are only ripples in fields. Traveling at the speed of light they have no mass and experience no time. That doesn’t sound like anything “real,” even if we experience photons on our space time. The photon seems to be some kind of particle that we experience in space time, but may also exist outside space-time.
So think about it – space and time is an entity that was created at the big bang (what came before may not be sensical within a space-time framework). When physicists came up with quantum electro dynamics, they did to do so with a method called “renormalization.” They measured the the mass and charge of existing particles, and did the calculations backwards, getting rather absurd starting energies/masses for those particles. They had to incorporate a vast number of vacuum fluctuations in order to account for the predictions of the Heisenberg uncertainty principle that now and then for a brief period of time particles will appear out of nowhere. It works in measurements as precise as we can measure, and is universally accepted due to that fact.
Beyond that, to explain the weak force of nature in the same way the strong force was explained (the strong force is through quantum chromo dynamics, analogous to quantum electro dynamics, but involving quarks rather than electrons), a new particle has been theorized (and no science has had more success in correctly predicting new phenomena of nature than particle physics) called the Higgs boson. This particle is essentially thought to be everywhere – it’s really a field, particles are disturbances in fields. The higgs field is what gives particles mass, just as color and electro-magnetic fields give color and charge.
The difficulty in connecting quantum theory with relativity in a complete manner suggests that quantum theory, in all its mathematical complexity, may be hinting at a border between space-time and whatever is outside space-time. The hints seem to be that there is intense energy available to space-time at the quantum level, with reality itself perhaps more ripples in the stream (or disturbances in fields) than solid and absolute. It may well be that the hard and fast nature of space-time that we experience is an illusion based on how our senses operate. Indeed, think of insects who have no clue about the worlds of politics, religion, marriage, social custom, etc, that go on all over their world. That is something outside their capacity to perceive. While their limits may be biological within space-time, ours could be the result of the need to operate effectively in space-time.
So what makes up the universe? Mostly empty space (again, even within the most solid of objects), forces (gravity, the electro-magnetic weak force, and the strong nuclear force), and at a fundamental level, quarks, electrons, photons and gluons. But since these particles are a weird particle/wave mix, they aren’t so much “things” as disturbances in fields. One theory puts forth tiny ‘strings’ with different vibrations as the fundamental stuff of the universe. The forces themselves and the nature of how they interact seems to come from quantum fields and probabilities that require measurement (or consciousness) in order to actualize one of a myriad of probable realities.
Add to that quantum tunneling (the idea particles can be actualized outside the confines of where they should be — the equivalent of a person falling through a solid wall) exists and our sun’s capacity to produce energy requires it, and non-locality (a change in a particle can impact another distant particle immediately, violating the laws of Newtonian physics which would require some kind of communication, which would take time,) and its clear we know little about the true nature of reality. In fact, there are so many paradoxes and apparent contradictions in modern physics that the whole theory might get thrown out as weird and impossible were it not for the reality that these models work in the real world to achieve practical results.
I remain struck by the “non-reality” of reality. Atoms that are 99.999% empty space. The forces that put the world in motion seem to come from nowhere. They include things like photons that experience no time or space, but we experience them in time and space (and they, like neutrinos which zip through our body by the hundreds of trillions every second, have no mass.) Particles and forces that are ripples in probability fields (as Max Born called early quantum field theory) which seem themselves to have no certain form. I mean, if one were inside a video game as a character, this is how it might look. Or, ideas and spirit could be more the stuff of reality than matter. At a fundamental level, we just don’t know those things. That’s what makes learning about and thinking about this kind of question fun!