The lesson is not to try to be too small:

https://www.quantamagazine.org/how-renormalization-saved-particle-physics-20200917/

"Only by using a technique dubbed “renormalization,” which involved carefully concealing infinite quantities, could researchers sidestep bogus predictions. The process worked, but even those developing the theory suspected it might be a house of cards resting on a tortured mathematical trick.

“'It is what I would call a dippy process,” Richard Feynman later wrote. “Having to resort to such hocus-pocus has prevented us from proving that the theory of quantum electrodynamics is mathematically self-consistent.”

"Justification came decades later from a seemingly unrelated branch of physics. Researchers studying magnetization discovered that renormalization wasn’t about infinities at all. Instead, it spoke to the universe’s separation into kingdoms of independent sizes, a perspective that guides many corners of physics today.

***

"Today, Feynman’s “dippy process” has become as ubiquitous in physics as calculus, and its mechanics reveal the reasons for some of the discipline’s greatest successes and its current challenges. During renormalization, complicated submicroscopic capers tend to just disappear. They may be real, but they don’t affect the big picture. “Simplicity is a virtue,” Fendley said. “There is a god in this.”

"That mathematical fact captures nature’s tendency to sort itself into essentially independent worlds. When engineers design a skyscraper, they ignore individual molecules in the steel. Chemists analyze molecular bonds but remain blissfully ignorant of quarks and gluons. The separation of phenomena by length, as quantified by the renormalization group, has allowed scientists to move gradually from big to small over the centuries, rather than cracking all scales at once.

"Yet at the same time, renormalization’s hostility to microscopic details works against the efforts of modern physicists who are hungry for signs of the next realm down. The separation of scales suggests they’ll need to dig deep to overcome nature’s fondness for concealing its finer points from curious giants like us.

“'Renormalization helps us simplify the problem,” said Nathan Seiberg, a theoretical physicist at the Institute for Advanced Study in Princeton, New Jersey. But “it also hides what happens at short distances. You can’t have it both ways.'”

Comment: Quantum theory is as weird as ever, but it works. The universe is based on quantum mechanics, which tells us God works in mysterious ways. We are bright folks who always want to know how it works. Hopefully we'll figure it out.

Using electrons and photons as a starting point, n o one knows as of yet:

https://aeon.co/essays/is-everything-made-of-particles-fields-or-both-combined?utm_sour...

"Physicists deftly shift between different pictures of reality as it suits the task at hand. The textbooks are written to teach you how to use the mathematical tools of physics most effectively, not to tell you what things the equations are describing. It takes hard work to distil a story about what’s really happening in nature from the mathematics. This kind of research is considered ‘philosophy of physics’ when done by philosophers and ‘foundations of physics’ when done by physicists.

***

"Unfortunately, it’s not immediately clear what replaces the atoms of the periodic table in the standard model. Are the fundamental building blocks of reality quantum particles, quantum fields, or some combination of the two?

***

"On 8 August, at the 2019 International Congress on Logic, Methodology and Philosophy of Science and Technology in Prague, I joined four other philosophers of physics for a debate – tersely titled ‘Particles, Fields, or Both?’ Mathias Frisch of the Leibniz University Hannover opened our session with a presentation of the debate between Einstein and Ritz (see his Aeon essay, ‘Why Things Happen’). Then, the remaining three speakers defended opposing views – updated versions of the positions held by Einstein, Ritz, and Faraday.

***

"The part of the standard model that describes electrons and the electromagnetic field is called ‘quantum electrodynamics’, as it is the quantum version of classical electrodynamics. The foundations of the two subjects are closely linked.

***

"In my contribution to the debate, I advocated a different point of view on quantum electrodynamics. Following Faraday, I argued that we should get rid of particles and just have fields. However, I don’t think the electromagnetic field alone is enough. We need another field as well: the Dirac field. It is this field that represents the electron (and also the antiparticle of the electron, the positron).

"In classical electrodynamics, this approach replaces the point electron particle with a spread-out lump of energy and charge in the Dirac field. Because the charge is spread out, the electromagnetic field that is produced by this charge will not get infinitely strong at any point in space. That makes the self-interaction problem less severe. But it is not solved. If the electron’s charge is spread out, why don’t the various parts of the electron repel one another so that the electron rapidly explodes? That’s something I’m still working to understand.

***

"If you think of electrons as particles, you’ll have to think of photons differently – either eliminating them (Lazarovici’s story) or treating them as a field (Hubert’s story). On the other hand, if you think of electrons as a field, then you can think of photons the same way. I see this consistency as a virtue of the all-fields picture.

"As things stand, the three-sided debate between Einstein, Ritz and Faraday remains unresolved. We’ve certainly made progress, but we don’t have a definitive answer. It is not yet clear what classical and quantum electrodynamics are telling us about reality. Is everything made of particles, fields or both?

"This question is not front and centre in contemporary physics research. Theoretical physicists generally think that we have a good-enough understanding of quantum electrodynamics to be getting on with, and now we need to work on developing new theories and finding ways to test them through experiments and observations.

"That might be the path forward. However, sometimes progress in physics requires first backing up to reexamine, reinterpret and revise the theories that we already have. To do this kind of research, we need scholars who blend the roles of physicist and philosopher, as was done thousands of years ago in Ancient Greece."

Comment: We still don't know the real basis of the reality that was created by......fill in your blank, and most cosmological physicists don't care because the equations work just fine in unexplained ways. It would be nice to know and there might be reasonable explanation instead of so much confusion. The Creator works in very mysterious ways.

Weird as it sounds superposition does it:

https://www.quantamagazine.org/quantum-mischief-rewrites-the-laws-of-cause-and-effect-2...

"Over the last decade, quantum physicists have been exploring the implications of a strange realization: In principle, both versions of the story can happen at once. That is, events can occur in an indefinite causal order, where both “A causes B” and “B causes A” are simultaneously true.

***

"The possibility follows from the quantum phenomenon known as superposition, where particles maintain all possible realities simultaneously until the moment they’re measured. In labs in Austria, China, Australia and elsewhere, physicists observe indefinite causal order by putting a particle of light (called a photon) in a superposition of two states. They then subject one branch of the superposition to process A followed by process B, and subject the other branch to B followed by A. In this procedure, known as the quantum switch, A’s outcome influences what happens in B, and vice versa; the photon experiences both causal orders simultaneously.

***

"With the emerging frameworks, “we can make predictions without having well-defined causality,” Brukner said.

***

"The operational question is: In quantum gravity, what can we, in principle, observe? Hardy thought about the fact that quantum mechanics and general relativity each have a radical feature. Quantum mechanics is famously indeterministic; its superpositions allow for simultaneous possibilities. General relativity, meanwhile, suggests that space and time are malleable. In Einstein’s theory, massive objects like Earth stretch the space-time “metric” — essentially the distance between hash marks on a ruler, and the duration between ticks of clocks. The nearer you are to a massive object, for instance, the slower your clock ticks. The metric then determines the “light cone” of a nearby event — the region of space-time that the event can causally influence.

***

"What we normally think of as causal relationships — such as photons traveling from one region of the sky to another, correlating measurements made in the first region with measurements made later in the second region — act, in Hardy’s formalism, like data compression. There’s a reduction in the amount of information needed to describe the whole system, since one set of probabilities determines another.

"Hardy called his new formalism the “causaloid” framework, where the causaloid is the mathematical object used to calculate the probabilities of outcomes of any measurement in any region. He introduced the general framework in a dense 68-page paper in 2005, which showed how to formulate quantum theory in the framework (essentially by reducing its general probability expressions to the specific case of interacting quantum bits).

***

"In “the most beautiful experiment” done so far, according to Rubino, Jian-Wei Pan at the University of Science and Technology of China in Hefei demonstrated in 2019 that two parties can compare long strings of bits exponentially more efficiently when transmitting bits in both directions at once rather than in a fixed causal order — an advantage proposed by Brukner and co-authors in 2016. A different group in Hefei reported in January that, whereas engines normally need a hot and cold reservoir to work, with a quantum switch they could extract heat from reservoirs of equal temperature — a surprising use suggested a year ago by Oxford theorists.

***

"In a key paper in 2019, Magdalena Zych, Brukner and collaborators proved that this situation would allow Alice and Bob to achieve indefinite causal order.

***

"A “quantum equivalence principle” analogous to the equivalence principle that, a century ago, showed Einstein the way to general relativity. One way of stating Einstein’s equivalence principle is that even though space-time can wildly stretch and curve, local patches of it (such as the inside of a falling elevator) look flat and classical, and Newtonian physics applies. “The equivalence principle allowed you to find the old physics inside the new physics,” Hardy said. “That gave Einstein just enough.”

***

"But ultimately quantum gravity must be specific — answering not just the question “What can we observe?” but also “What exists?” That is, what are the quantum building blocks of gravity, space and time?

***

"Hardy thinks his causaloid framework might be compatible with loops or strings, potentially suggesting how to formulate those theories in a way that doesn’t envision objects evolving against a fixed background time. “We’re trying to find different routes up the mountain,” he said. He suspects that the surest route to quantum gravity is the one that “has at its heart this idea of indefinite causal structure.'”

Comment: all of this is at the quantum level of reality, not our level. Only we see causality

We don't really know it:

https://bigthink.com/starts-with-a-bang/reality-objective-exist/?utm_source=mailchimp&a...

"...there had previously been a set of assumptions that came along with our notion of reality that are no longer universally agreed upon, and chief among them is that reality itself exists in a fashion that’s independent of the observer or measurer. In fact, two of the greatest advances of 20th century science — relativity and quantum mechanics — specifically challenge our notion of objective reality, and rather point to a reality that cannot be disentangled from the act of observing it. Here’s the bizarre science of what we know, today, about the notion of objective reality.

***

"Does this mean that there is no such thing as objective reality? Not necessarily; there could be an underlying reality that exists whether we measure it or not, and our measurements and observations are just a crude, insufficient way to reveal the full, true character of what our objective reality actually is. Many people believe that this will someday be shown to be the case, but so far — and this advance was just awarded 2022’s Nobel Prize in Physics — we can place very meaningful constraints on what just type of “reality” exists independent of our observations and measurements. To the best that we can tell, the real outcomes that arise in the Universe cannot be divorced from who is measuring them, and how.

"It isn’t the job of science, contrary to popular belief, to explain the Universe that we inhabit. Instead, science’s goal is to accurately describe the Universe that we inhabit, and in that it’s been remarkably successful. But the questions that most of us get excited about asking — and we do it by default, without any prompting — often involve figuring out why certain phenomena happen. We love notions of cause-and-effect: that something occurs, and then later on, as a consequence of that first thing occurring, something else happens because of it. That’s true in many instances, but the quantum Universe can violate cause-in-effect as well in a variety of ways. (my bold)

"One such question that we cannot answer is whether there is such a thing as an objective, observer-independent reality. Many of us assume that it does, and we build our interpretations of quantum physics in such ways that they admit an underlying, objective reality. Others don’t make that assumption, and build equally valid interpretations of quantum physics that don’t necessarily have one. All we have to guide us, for better or for worse, is what we can observe and measure. We can physically describe that, successfully, either with or without an objective, observer-independent reality. At this moment in time, it’s up to each of us to decide whether we’d rather add on the philosophically satisfying but physically extraneous notion that “objective reality” is meaningful."

Comment: The reality we experience is not the underlying reality. Note my bold. Science tells us what God did, but not how. dhw always wants to know the how. Good luck!!! This essay is filled with examples of how to answer quantum mechanics with great value.

Still no solution for it:

https://www.scientificamerican.com/article/quantum-theorys-measurement-problem-may-be-a...

"In textbook quantum theory, before collapse, the system is said to be in a superposition of two states.

"This collapse-inducing process is the murky source of the measurement problem: it’s an irreversible, one-time-only affair—and no one even knows what defines the process or boundaries of measurement. What amounts to a “measurement” or, for that matter, an “observer”? Do either of these things have physical constraints, such as minimal or maximal sizes?

"Quantum Theory's 'Measurement Problem' May Be a Poison Pill for Objective Reality
A core mystery of quantum physics hints that objective reality is illusory—or that the quantum world is even weirder than expected.

"At the heart of this bizarreness is what’s called the measurement problem...the measurement causes the system’s multiple possible states to randomly “collapse” into one definite state. But this accounting doesn’t define what constitutes a measurement—hence, the measurement problem.

"Attempts to avoid the measurement problem—for example, by envisaging a reality in which quantum states don’t collapse at all—have led physicists into strange terrain where measurement outcomes can be subjective.

" In a recent preprint, the trio proved a theorem that shows why certain theories—such as quantum mechanics—have a measurement problem in the first place and how one might develop alternative theories to sidestep it, thus preserving the “absoluteness” of any observed event.

"But their work also shows that preserving such absoluteness comes at a cost many physicists would deem prohibitive. “It’s a demonstration that there is no pain-free solution to this problem,” Ormrod says. “If we ever can recover absoluteness, then we’re going to have to give up on some physical principle that we really care about.”

"Holding on to absoluteness of observed events, it turns out, could mean that the quantum world is even weirder than we know it to be.

"Gaining a sense of what exactly Ormrod, Venkatesh and Barrett have achieved requires a crash course in the basic arcana of quantum foundations.

"In textbook quantum theory, before collapse, the system is said to be in a superposition of two states, and this quantum state is described by a mathematical construct called a wave function, which evolves in time and space. This evolution is both deterministic and reversible: given an initial wave function, one can predict what it’ll be at some future time, and one can in principle run the evolution backward to recover the prior state.

"This collapse-inducing process is the murky source of the measurement problem: it’s an irreversible, one-time-only affair—and no one even knows what defines the process or boundaries of measurement. What amounts to a “measurement” or, for that matter, an “observer”? Do either of these things have physical constraints, such as minimal or maximal sizes? And must they, too, be subject to various slippery quantum effects, or can they be somehow considered immune from such complications? None of these questions have easy, agreed-upon answers
"Given the example system, one model that preserves the absoluteness of the observed event—meaning that it’s either heads or tails for all observers—is the Ghirardi-Rimini-Weber theory (GRW). In GRW, quantum systems can exist in a superposition of states until they reach some as-yet-underdetermined size, at which point the superposition spontaneously and randomly collapses, independent of an observer. Whatever the outcome—heads or tails in our example—it shall hold for all observers.

:But GRW, which belongs to a broader class of “spontaneous collapse” theories, seemingly runs afoul of a long-cherished physical principle: the preservation of information....By postulating a random collapse, GRW theory destroys the possibility of knowing what led up to the collapsed state—which, by most accounts, means information about the system prior to its transformation becomes irrecoverably lost. “[GRW] would be a model that gives up information preservation, thereby preserving absoluteness of events,” Venkatesh says.

***

"So if a theory is Bell nonlocal, it implicitly acknowledges the free will of the experimenters. “What I suspect is that they are sneaking in a free choice assumption,” Wiseman says.

"This is not to say that the proof is weaker. Rather it would have been stronger if it had not required an assumption of free will. As it happens, free will remains a requirement. Given that, the most profound import of this theorem could be that the universe is nonlocal in an entirely new way. If so, such nonlocality would equal or rival Bell nonlocality, an understanding of which has paved the way for quantum communications and quantum cryptography.

"In the end, only experiments will point the way toward the correct theory, and quantum physicists can only prepare themselves for any eventuality."

Comment: the universe is non-local. Any theory must include that concept. This dense quantum theorizing may not compute with all readers but it the basis of our reality.