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Confessions of a Theoretical Physicist

185 points by signa11 2y ago

deleted 2y ago
[deleted]
nyc111 2y ago
“Yet these are concepts that reify a certain approximate sketch of the structure of the world. Physicists once thought that these categories were fundamental and real, but we now understand them as necessarily inexact because they ignore the finer details that our instruments have just not been able to measure.“
FeepingCreature 2y ago
Sure, quarks and leptons are maybe a high-level concept that masks a more messy underlying reality, but surely quarks and leptons are less messy than dogs? There is an arrow of progress in the development of physical theories. I don't see a reason why a perfect description should not be possible.
- infogulch 2y ago
  Even wrong theories can be useful in some contexts, Newtonian gravity for example. Take it to an extreme: say quarks aren't useful at all for science, but are a useful conceptualization pedagogically, it can still be worth.
  - danbruc 2y ago
    Even wrong theories can be useful in some contexts, Newtonian gravity for example. Newtonian gravity is not wrong, it is pretty good model of gravity in a certain region of the parameter space.
    - moi2388 2y ago
      Right. Well, by the same logic my theory of gravity isn’t wrong: everything falls at 9m/s. It’s not wrong, it’s just a pretty good model of gravity in a certain region of the parameter space. Except of course, that it is wrong.
      - danbruc 2y ago
        Everything falling at a constant speed of 9 m/s takes this probably a bit too far, on Earth this will only be true for tens of milliseconds before the speed is of by a few percent. Had you said every objects accelerates with 9.81 m/s², that would be a pretty good theory of gravity on the surface of Earth, probably still the dominant theory for solving gravity related problems on Earth. Your example reminds me more of the difference between Aristotelian and Newtonian physics. Aristotle - looking at the world around him - thought that the natural state of motion is being at rest and that it requires a force to make an object move. Newtonian physics realizes that this is not the case, that without forces objects keep moving instead of coming to rest, that Aristotle lacked a proper understanding of the role of friction. To come back to gravity, space flight probably still heavily uses Newtonian gravity and it works, for that reason alone I would not call it wrong. Objects falling at a constant 9 m/s seems to have much less practical use and does not even get the most important characteristic of gravity - that it accelerates objects - right, so I will agree with you and call it wrong.
      - FeepingCreature 2y ago
        The difference is that the region your theory of gravity is a good model in, is not inhabited, whereas the region that Newtonian gravity is a good model in is the one where most of us spend most of our time.
        moi2388 2y ago
        You spend time in a region where the propagation of gravity is instantaneous? Cool.
    - tines 2y ago
      It seems that different people often use "not wrong" to mean two different things. Some people are using the word to mean "useful as far as it's meant to be," like you. Some people, like the GP, are using it to mean "the truth." It's important to clarify what you mean when you're discussing, otherwise there's heat and not much light.
      - danbruc 2y ago
        In case of physics we do not really have access to the later kind, every theory is a current best guess that might at any time turn out to be only approximately correct or under certain circumstances. General relativity is almost certainly not the truth, the universe probably has no singularities hiding behind event horizons, but does it help us to call it wrong? There is reality and there is series of better and better mathematical models of reality and all of them are wrong in the strict sense until we eventually find the final theory but even then it is not clear that we could even recognize that we have arrived at the destination. In the end a binary characterization as right or wrong does not make too much sense for physical theories, they occupy a continuum of correctness.
        tines 2y ago
        I somewhat agree with you, but I think it's very important to distinguish between the two meanings, because different points on the continuum of correctness cause you to come to completely opposite conclusions about the nature of the universe. A bit of quantity leads to a totally different quality. In other words, truth and usefulness are continua, but they are two different and orthogonal continua, and going right on one may mean going left on the other. My view of the universe is going to be totally different if Newtonian mechanics is the "truth", versus if something like quantum mechanics is the "truth." The former depicts a totally deterministic and knowable-in-principle clockwork universe, whereas the latter has randomness and ignorance that cannot be removed even in principle. Quantum mechanics may not be the whole truth, but it's certainly so different that it shows earlier approaches to be not just incomplete but totally incorrect about their fundamental assumptions, even if they can be used to make useful predictions. Quantum mechanics isn't just more useful, it's more true, whereas Newtonian mechanics might be more useful than some other theory, but actually less true in some sense.
    - nathan_compton 2y ago
      Counterpoint: Newtonian Gravity could be considered profoundly wrong since it presupposes a structure for space and time which is fundamentally wrong. What I mean is that ontologically Newtonian Gravity is a total non-starter, implying the existence of relations which are simply totally absent in this universe.
- CoastalCoder 2y ago
  > but surely quarks and leptons are less messy than dogs? I dunno, I'd rather clean up an accident from a dog than from a particle accelerator.
lokimedes 2y ago
Physics is an empirical inquiry into the structure, composition and dynamics of the observable usensorium we inhabit. I find it just short of hybris to entertain any promise that the outcome can be more than a metaphor of the underlying reality. The whole quagmire of “the measurement problem” in quantum mechanics seems to largely come from misunderstanding Bohr’s philosophical objections on this difference between a theory of the measurable and the interpretation of the theory’s internal mechanics as evidence of the true reality it models. Givens that twentieth century physics (apart from General Relativity) is based on Bohr’s foundation, no wonder people get confused. The mathematization of physics hasn’t helped either. That Bell’s theorem “proves” something is language applicable to a mathematical structure, not to the physical world itself.
- elashri 2y ago
  Why can't you just shut up and calculate? /s
  - lokimedes 2y ago
    Exactly
  - DiscourseFan 2y ago
    formulas are meaningless without concepts
- gpderetta 2y ago
  c.f. "The unreasonable effectiveness of mathematics in the natural sciences" (https://www.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf https://www.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf)
  - DiscourseFan 2y ago
    > It is even possible that some of the laws of nature will be in conflict with each other in their implications, but each convincing enough in its own domain so that we may not be willing to abandon any of them. We may resign ourselves to such a state of affairs or our interest in clearing up the conflict between the various theories may fade out. We may lose interest in the "ultimate truth," that is, in a picture which is a consistent fusion into a single unit of the little pictures, formed on the various aspects of nature. Mathematics alone cannot reflect on its conditions of possibility, and mathematical physics is as inept in that domain. The reason why the quantum physics vs. general relativity thing can't be resolved is not because we don't have the right math, its because to overcome it requires a paradigm shift away from the mathematization of physics, and to actually gain a familiarity with the conceptual apparatus that engendered these theories.
sanxiyn 2y ago
I mean, leptons are definitely real, not just concepts. An electron is a lepton, and an electron surely exists? You can spray individual electrons. If an electron is just a concept, it is in a sense that a tiger is just a concept, and in a sense it is, but that is not very useful thing to say.
- anatoly 2y ago
  An electron is just an excitation of the electron field, a vast probabilistic something that's ever-present everywhere in the universe, with a different complex-number amplitude (not observable directly) at each and every point. Sometimes that vagaries of its ever-changing amplitudes cause it to locally coalesce into something that looks like an individual electron if you squint at it in the right manner, and that vision persists until a strong enough interaction with another vast and nebulous field shatters the illusion, at least in the tiny corner of the probabilistic multiverse your local version of your consciousness brazenly imagines to be the objective reality. What kind of existence is that? (Well, the only kind on offer, really.)
  - goatlover 2y ago
    An existence that mistakenly took fundamental reality to consist of point particles instead of fields. But we still found out about fields and quantum mechanics.
    - dist-epoch 2y ago
      We don't know that fields are real. We just know that the mathematical language of fields is the most convenient and concise to describe the experimental results we see.
      - goatlover 2y ago
        As a starting pint, the magnetic field can be shown to be real with metal filings. Whether fields are the fundamental building block is another matter.
BrandoElFollito 2y ago
I am an ex-physist who stopped after his PhD in particle physics. I love physics but while money does not bring happiness, it is better to cry in a Mercedes than on a bike (this is not true, I just laughed when I first read it). I went through the stages of OP (on a way smaller scale, I do not have his experience) and I think this is awesome. You continuously go from "oh yeah, now I get it" to "crap". This always have you on the bleeding edge between "this si physics, I know that" and "yes, but what if...". To me this is the essence of knowledge though curiosity. I started my PhD on a specific topic and at some point I was a bit stuck (not panic mode stuck but pissed off stuck). I had dinner with a friend, we were discussing about my work (she is also a physicist) and she off-handly suggested something. And bam! my world changed. The direction of the thesis changed. I added an extra thesis director because what I was about to do was a world where the hands of men did not step on yet. I thanked her profusely for her help in the thesis and suggested a joined publication (which she did not want to take because she was not interested and asked me to stop stalking her :)) And this is how science moves: because of eureka moments under the shower or at dinner or because someone thought "hmmm..." (looking at you Nikola Tesla). So the fact that this guy doubts about what the world is, and that he is a theoretical physicist (so hopefully will not switch to some insanities) is awesome.
- kaiwen1 2y ago
  Off topic, but eureka moments are my favorite go-to evidence for the absence of free will. No one chooses to have a eureka moment. They just arrive. And not just those moments, but every thought in every moment. They all just arrive, none are choosen.
  - futuramaconarma 2y ago
    That's not evidence But I agree there's no free will and anybody who believes it also believes in magic and god
    - mettamage 2y ago
      I experience having mo free will whenever I am in the break of a meditation retreat. During those breaks it’s sometimes quite easy to observe my thoughts, given that I focus 10 hours per day on making my internal chatter very very quiet. The most fascinating thing to me is how subtle body sensations lead to thoughts and vice versa.
thewanderer1983 2y ago
It's refreshing to me to read articles like this. In the current climate of consensus science, and settled science. Here is someone well versed in Physics, and the Philosophy of it. Reminding people that we need to be humbled again.
openrisk 2y ago
Do we care about "real" reality if we can, more or less, make sense of some of its manifestations through our senses? That there is something deeper and unknowable and "informationally huge" seems obvious. We didn't bring quarks or quasars into existence, we "discovered" them as and when we extended our senses far enough using technologies (which are themselves a result of us becoming comfortable enough with our immediate reality, as a sort of positive feedback loop). There is every reason to suspect that this deeper reality does not stop where our technologically extended abilities peter out. Our imperfect and tentative understanding when reaching the extremes of scales (of time, space, complexity, etc) is perfectly understandable. Why should a finite carbon brain be able to map out a coherent and finite model of something much, much bigger than itself. On the other hand over millennia of brainstorming (literally) we have collected some interesting datapoints about this deeper reality: it is not "malicious", and somehow it agrees to be mapped by us (mathematically), even if in disconnected parts. In fact this benevolent aspect of deeper reality has made us unusually cocky. Imagine the existential angst if the universe changed its laws at whim. We'd be back to praying. E.g., that gravity remains stable for a while so that we don't drift into space. This premature self-assuredness explains repeated scientific episodes of proclaiming "we have explained everything". This also feeds the sterile chase of "a theory of everything". In fact the limits of our understanding are in front of our eyes, everywhere. We haven't really explained a single phenomenon in the so called "complexity science" domain. Deeper reality is all around us and the most dramatic and impactful scientific revolutions are still ahead of us.
- DiscourseFan 2y ago
  >Deeper reality is all around us and the most dramatic and impactful scientific revolutions are still ahead of us. Maybe
- graycat 2y ago
  > Why should a finite carbon brain be able to map out a coherent and finite model of something much, much bigger than itself. Have asked that and have a guess: Darwin-style selection rewarded getting some rational understanding of the most important parts of nature -- fire, rock tools, clean water, agriculture, staying warm in winter, basic geometry, bows and arrows, the Pythagorean theorem, levers, wheels, boats, etc. -- we encountered. Well, it so happens that in this universe such "rational understanding" is enough to understand basic math, physics, chemistry, biology, ... back to the Big Bang, the 3 K background radiation, cells, reproduction, nutrition, diseases and immunity, .... I gave up on the US education physics community when my teachers couldn't give a valid proof of Stokes' theorem, explanation of Young's double slit, or the beginnings of quantum mechanics. So, now I have several polished treatments of each of Stokes' theorem, Maxwell's equations, and special relativity. Got a good background in probability (Neveu, Poincaré recurrence, martingales, etc.), enough to get a good path through thermodynamics. From Rudin, etc., got enough solid Fourier theory to check carefully the uncertainty principle in physics (doubt that what physics does there is fully justified) -- also carefully treated in a great course in "Analysis and Probability". For differential geometry, an Andrew Gleason student gave me some lectures and explained that the keys are the inverse and implicit function theorems, proved in a book by W. Fleming and just exercises in a Rudin book -- local nonlinear versions of what is easy in linear algebra. So, now I attack physics as a curious amateur! I do remember a remark from a good mathematician: "Physics abuses its students." Well, they can abuse me no longer, and I can still do high quality study of physics.
_hark 2y ago
I'm in the final year of my PhD, and I feel very lucky to be working on the question of what it means for an explanation to be "good". The closest thing to a satisfactory resolution of the question of "reality" in theories, to me, is Dennet's Real Patterns [1] It may well be that multiple explanations are consistent with the most basic phenomena. The criterion for the reality of the theory is whether it does better than random (its predictive power, equivalently how well it can compress the observational data). We can try to find the simplest explanation, but we can never know if we have it [2]. We can stop thinking of theories as being real or not in a binary sense, and merely ask how well they compress the data. Of course, different theories can achieve the same compression by compressing different aspects of the data! Your pattern can look like my noise :-) Luckily and interestingly, the physics of the macroscopic world is in many cases effectively independent of the underlying microscopic rules [3], with the details of the microscopic physics being screened off as complexity emerges. Personally, I like to think of abstraction as a kind of hierarchy of hardware + software: at each level, some useful ontology is picked out for stable patterns to emerge (e.g. the software of "fluids" emerging from the hardware of quantum "particles"). Layers of software at one level become the hardware substrate for the next rung up the abstraction ladder. Luckily, we get to choose the software that runs on us, so don't forget to vote this fall ;) [1]: https://ruccs.rutgers.edu/images/personal-zenon-pylyshyn/class-info/FP2012/FP2012_readings/Dennett_RealPatterns.pdf https://ruccs.rutgers.edu/images/personal-zenon-pylyshyn/cla... [2]: https://en.wikipedia.org/wiki/Kolmogorov_complexity https://en.wikipedia.org/wiki/Kolmogorov_complexity [3]: https://en.wikipedia.org/wiki/Effective_field_theory https://en.wikipedia.org/wiki/Effective_field_theory
- jll29 2y ago
  > what it means for an explanation to be "good" Chomsky coined the technical term "explanatory adequacy" for that, which is used/recognized among linguists and psychologists.
- mikepalmer 2y ago
  > We can stop thinking of theories as being real or not in a binary sense, and merely ask how well they compress the data. Of course, different theories can achieve the same compression by compressing different aspects of the data! Your pattern can look like my noise :-) Love this, thanks for these insights.
dakiol 2y ago
I didn’t know that Physics was about understanding reality (sure, from a romantic perspective yeah). I always thought it was about making our lives better (like any other branch of science). I believe we will never find out what’s the real nature of reality. That doesn’t mean we should stop doing science, though: it makes human live better. I believe that the “meaning of life” is not about the answer (science telling us what’s the actual meaning) but about the discovery process we embrace: knowing beforehand that we’ll never understand everything and nevertheless keep waking up every day to do the job.
- jajko 2y ago
  Understanding reality makes our lives significantly better. No room for primitive religions leading us to stagnation or even reversal, when we can understand very well what sun, moon and stars are, why they move as they do, or why lightning happens and why weather patterns are what they are. Understanding of reality via physics gave us all electronics too, including one I use to write this and one you use to read it. That's a noble goal on its own, no need to meddle with that. Pursuit of meaning of life is completely different topic, for different folks, no need to try to mix those two. Plus its very subjective - tons of folks already found it or simply don't care about it.
  - hnfong 2y ago
    > Understanding reality makes our lives significantly better. Of course on the whole understanding makes our lives better, but if you're asserting this for everything, it's probably some kind of a survival bias. The understandings that aren't really useful are often forgotten, while the useful ones are passed down through generations. It's actually very easy to get caught in understanding niche topics that genuinely find very little application.
    - mistermann 2y ago
      Is all potentiality that exists unlocked and harvested? Is science even looking in all the right places? Can a mind on science even care about such things (or better: to what degree do individual and a culture/society of minds on science have the ability to care (have non-constrained curiosity))? In my experience, something about the mind makes it think it is able to know the correct answer to these questions, which is a remarkable but little studied phenomenon.
bjornsing 2y ago
I could have been a theoretical physicist, but got out after my master’s. Subconsciously I think I had already come to this (the OP’s) conclusion then. Since then I’ve worked a bit in statistics and machine learning. There’s a saying in this field that captures my subconscious conclusion well: “all models are wrong, but some models are useful”. I’ve often said that I would have loved to do a PhD in physics in 1910, but less so in 2010. The models physicists found in the 20th century were extraordinarily useful. I have little hope that I will see anything comparable in my lifetime. Don’t get me wrong: More models will undoubtedly be found, and there’s beauty and honor in that work. But they will most likely all be “wrong”, and far less useful than e.g. the models that let us harness nuclear reactions.
- sigmoid10 2y ago
  That depends a bit on the field. If you were doing particle physics (in particular using earth-borne accelerators), the second half of the 20th century would probably be best. But if you're into astroparticle or cosmology, the best time is literally right now. The 21st century has been one giant thing after another thanks to Sudbury, WMAP and Planck, the EHT, LIGO, the Pulsar Timing Array and tons of other experiments. When it comes to understanding the universe as a whole, there is no better time to work in physics than today. Similar goes for quantum and condensed matter, albeit with a focus on real world applications rather than understanding the universe.
  - bjornsing 2y ago
    I’m into usefulness. And I’m not convinced by your argument. I still doubt very much that I will see any new models as useful as those that transformed the world in the 20th century. I’d love to be wrong though.
    - sigmoid10 2y ago
      Usefulness usually means real world use. It took the theory of general relativity 70 years before we saw a real world application make use of it. The theory that led to modern hard drives (GMR) went from new fundamental physics in the late 80s to full commercial use within a decade. Things like the blue LED (1990s) or frequency combs (early 2000s) were even faster and can be found truly everywhere now (unlike GR). There are far more useful models out there than the high level overview stuff you might get from an intro to fundamental physics class. And even if you're into explaining the universe rather than improving day to day life, as I said, there's tons of stuff going on right now if you're in the right field.
swayvil 2y ago
We do not craft models of reality because reality and models have any kind of intrinsic connection. We craft models of reality because we value models. That is arguably very funny.
TheOtherHobbes 2y ago
So this is the new zeitgeist. Between AI, quantum fundamentals, disinformation, and a few other less obvious trends, "reality" is going to get less and less concrete and more and more contextual and non-binary.
jeroenvlek 2y ago
Ultimately, we're all just living in an episode on Rick & Morty's galactic cable TV
efitz 2y ago
Humans are not “generally intelligent”; our intelligence is extremely well adapted to being a hominid family animal in a tribe or clan in a savannah habitat with large predators and hostile members of our own species lurking about. Our senses and brains are well suited to reasoning about and making decisions in environments at “human” scales. By that, I mean that humans don’t receive relativistic, atomic or quantum phenomena directly with our unaided senses, and therefore our brains never developed intuition for these phenomena. So it’s no surprise at all that our intuition completely fails us at those scales. Again, our intelligence is not “general”; it’s hominid.
- snovv_crash 2y ago
  We also fail horrifically at recognising exponential growth, or understanding its implications.
  - mettamage 2y ago
    Exponential growth is pretty rare in nature, right? Linear growth or fuzzy up and down growth/swings seems way more commonplace
    - snovv_crash 2y ago
      COVID was an example of nature, and peoples' poor understanding of exponential growth.
      - GuB-42 2y ago
        Epidemics generally follow a logistic curve, like most "exponential" processes. It looks exponential at first, but at some point, it decays. COVID is no exception. It is now in "fuzzy up and down" mode. True, unbounded exponential processes don't exist in nature. There is a simple explanation about why not: assuming the speed of light is the speed limit of causality and we don't have weird things like warp gates, then the influence of something cannot go further than a sphere around it expanding at the speed of light. The volume of this sphere of influence increase following a cubic function. Now, if an exponential process happen withing that sphere, for example a population growth, it will run out of space at some point, because an exponential function will always beat a cubic (or any polynomial) at some point. The fastest growth possible is cubic, not exponential.
flowingfocus 2y ago
Yes, our models are never complete. As someone here already wrote: "all models are wrong, some are useful". What makes me optimistic here is that since the enlightenment we have a good track record with arriving at better and better models. In the language of David Deutsch: We are arriving at better and better explanations, where the quality of an explanation is determined by rigidity ("how hard it is to vary") and reach ("in how many situations does it apply"). His books "The Fabric of Reality" is a great book by the way, he describes how the theories of evolution, quantum physics, epistemology and the theory of computation are connected with each other. The bit about good explanations is from "The Beginning of Infinity", also a very good read.
- sampo 2y ago
  From 1954 to 1975, theoretical physics created the standard model of particle physics. Experimental verification of the theory continued through 1980s and 1990s, and finally the Higgs boson in 2011. But if we follow the dictionary definition of scientific theory "A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed" or "a hypothesis confirmed by observation, experiment etc.", then after the 1970s, theoretical physics about the fundamental building block of reality hasn't really been theoretical physics, but rather hypothetical physics. They have worked on lots of theories (or rather: hypotheses) that they have not been able to test and verify experimentally.
alexpc201 2y ago
Most likely, the nature of consciousness and reality are rigged in such a way that we cannot use our consciousness to decipher them. Any progress in that direction is useless and, at this point, almost ridiculous.
librasteve 2y ago
Thanks to Vijay for a thought provoking post. I like the juxtaposition of quantum gravity and neuroscience. I think that it carries two messages, one trivial and one deep. The trivial one is that physics builds on the human nature to build concepts. Both a jaguar and a quark are ideas that we extract from our perceptions, that we share with others and that help us to model and predict the world - quarks just need a more expensive microscope like the LHC. Sure eagles and prawns may have slightly different versions of concepts since they have different colour perception, but only marginally so. A practical fellow like a physicist will be clear that when the concepts can make measurable predictions they are worthwhile (we call this meta concept "real"). It is not possible to store the full state of or compute the evolution of anything macroscopic to full precision - such as the positions and momenta of all the particles in a table. So concepts are the only things we can know about reality. They argue that we may never be able to attain the deep underlying reality - either because it is theoretically unattainable or that we will continue to be resource limited. I contend that this dichotomy is false. It just may never be possible to attain deep underlying reality. The best we can do until we get there is to find some probabilistic rules that work in a pragmatic sense and to refine these tools over time. [That's pretty much a restatement of the Copenhagen interpretation of 1922]. The deep one is that we are probably looking down the wrong end of the telescope. As far as I can tell (from popular neuroscience) is that our ability to model the perceptual / conceptual processes and how they compose into intelligence remains in the dark ages. But, given that we each have 70 billion neurones or so, there is a lot of classical physics going on in our heads to make these concepts and we have practically no hard, proven theories about how this works. We are doing layers of pattern recognition and extraction and feedback that allows us to avoid being eaten by Jaguars. So let's get a proper theory of intelligence. One that let's us work out which aspects of quantum mechanics are philosophically necessary to sustain our subjective experience of space and time. With a substrate with branching / collapsing features. Where time has an arrow with memory in the past and uncertainty in the future. Where cause and effect are loosely coupled. Where there is a notion of free will. Some endnotes: - The quantum measurement problem is perhaps a limit of this theory - Perhaps the notion of computational reducibility is a stab in this direction [Wolfram] - Probably all you need is emergence for this and not a quantum brain [Penrose]
- 2y ago
throw7 2y ago
Science is an open system. Everything is open to being "wrong"/"updated". There is nothing that grounds the system. You must be always open that your prediction of unobserved things will be wrong. To actually believe that science will one day solve the great mystery of the universe is scientism.
- jfactorial 2y ago
  Is there any stronger tool for rational truth seeking than the scientific method? Observe. Hypothesize with falsifiable statements. Form experiments that could disprove the falsifiable statements. Observe. Publicly make falsifiable statements to peers capable and incentivized to disprove them. How can this fail to lead us to truth that is as close to objective as possible? What greater method exists?
  - bubblyworld 2y ago
    This is a little bit out there from a rationalist point of view, but I think there are domains in which not all of the requisite concepts for the scientific method actually exist. An example that comes to mind is the nature of conscious experience - having spoken to a lot of meditators, for instance, I'm convinced that there really are commonalities to it that you can experience yourself by sitting down and paying attention. But I don't think there's anything to really falsify here, because there's nothing to measure! You can't tell someone "here's this totally objective way you can pick apart your conscious experience into a bunch of statistics, and when you do change X I predict you'll see the statistics vary like Y". You can kinda just point their brain in a direction and hope that they experience it for themselves. Another example, I think, is domains that are under optimisation pressure or control of some kind (like an ecosystem, or much more simply a thermometer). There was a post on HN a few days ago about causality, and how the standard statistical methodologies for determining causality kinda break down when you start measuring systems like this. Correlation is not causation, but in these systems causation no longer necessitates correlation either! Perhaps a different kind of epistemology would be useful here too. Anyway, not sure this is making sense. Would be curious to hear your thoughts.
  - NemoNobody 2y ago
__rito__ 2y ago
The Indian Philosopher that is gravely missing from the article is Nagarjuna. The kinds of questions the author raises, the path he is treading on, will benefit from the study of Shunyata Philosophy of Madhyamika school, especially Nagarjuna. I am not alone in thinking this. I was surprised to see Carlo Rovelli talking about it in multiple occasions. Heres one [0]. Nyaya and Madhyamika Philosophies still have many lessons that are not yet discussed in the spotlight. [0]: https://m.youtube.com/watch?v=CgIfNuZs56w https://m.youtube.com/watch?v=CgIfNuZs56w
ziofill 2y ago
I am a theoretical physicist, and I am very much in tune with the author. Take quantum mechanics (my field), it is clear that even though we have a working model of it, it doesn't explain how nature instantiates it. Entanglement is a prime example of this: I know exactly how to describe it, but nobody has a clue of how it works. In other words, physics is a mostly coherent and certainly useful story about reality, but it isn't grounded on "bedrock" reality, rather on our perception of it.
- BobaFloutist 2y ago
  Correct me if I'm wrong, but I think of entanglement as less forming an actual binding relationship to two particles, and more as setting them up exactly the same way. So it's not that you have two magnetic marbles and rotating one rotates the other, it's that you're rolling two dice with identical parameters and can expect that at any given slice of time they'll be doing the same thing. Is that incorrect?
  - nathan_compton 2y ago
    Entanglement is neither a bond between two objects nor a setting up of two objects in the same way. Entanglement derives from the fact that quantum mechanical systems have properties which are non-local with respect to the "process" of measurement that do not depend on the physical size of the system in question. Its actually suspect to say that "particles" are entangled at all - the entanglement is a property of the wave function in which the particles identities are (with respect to the quantity that is entangled) indistinct.
    - mikepalmer 2y ago
      Agree, "spooky action at a distance" isn't spooky at all if you just accept it as physical!
      - nathan_compton 2y ago
        I don't personally think that there is any action at a distance at all.
jebarker 2y ago
I'm not a physicist. An idea from physics that I recently learned and found very unnerving was that the solid objects we see and feel in the world are actually mostly empty space. We just see them as solid because of the way light interacts with the particles. So in a sense our visual and tactile perception of the world is just one representation of the underlying reality and you can imagine there being infinitely many other possible representations. I'm just crudely saying the same thing as the author I think, but I wanted to emphasize how uncomfortable this makes me. In some sense it feels like being a prisoner in a perceptual cell you can't escape from surrounded by a reality you'll never know. Having philosophy as a counterpoint (in my case dabbling in Buddhism) has been essential to keep me calm and relaxed.
- biggoodwolf 2y ago
  You're a brain in a bucket. What is the nature of the bucket is up for debate
  - goatlover 2y ago
    Your brain is part of a nervous system that extends throughout the "bucket". Body and brain aren't really separate.
    - jebarker 2y ago
      I think the bucket is bigger than just your body.
- nathan_compton 2y ago
  This is more of an intellectual parlor trick than anything else. Like literally what else could "solid" mean besides "that which we call solid based on our perception." When you say that matter is "mostly empty space" you are really writing is a sentence which implicitly uses two definitions of solid in one place without distinguishing between them.
  - jebarker 2y ago
curation 2y ago
The book Sublime Object of Ideology (Zizek) and a second volume due soon attempts an interdisciplinary reframing of the theory of everything - working with Quantum Physicists and Material Hegelian/Lacanian philosophy. I am a philosopher who works with theoretical physicists.
- NemoNobody 2y ago
  Philosophy is the science of ideas. Ideas are the basis for all understanding - it is good that you are you there, this topic is inherently the realm of philosophy. Theoretical physicists must be very focused on theory to frame a "Theory of Everything" - what they kno will get in the way. The Theory of Everything is just our modern way of saying "God" - they occupy the same position in our lives and society. We need to understand and it needs to make sense to us rn, in this time and space - like religion once did. Even if incorrect, believing that we have a Theory of Everything is necessary. We have killed God and now find it necessary to create an idea that can encompass the void where God once was. Functionality is key. I doubt the physicists ability to be objective. This is easily explained by adapting God into a Creator of a Game, us to fully uploaded VR Players, reality to the engine, mechanics and programming - all executed as science has already identified with the laws of the universe, etc. A future version of Microsoft could easily hypothetically make this game. We already are testing reality to determine if it is a hologram. I believe Stanford already declared it more likely we live in a simulation than it isn't - bc someday, if we can, we will totally make an exact copy of reality - maybe this it. Maybe we are dead and chose to upload ourselves here. Perhaps Musk is right and we are the NPCs of an alien game... All of those things are far more likely than a spontaneous universe, coming into existence without cause, creating the universe for no reason and only time + chance allowing for what we call reality. Far far more faith is needed to believe this not a created thing. I find it almost illogical that this being the simplest and most likely conclusion, that it is ignored. Where is the objectivity? A working model is all we need to move forward - we can figure out later if it's right or not. I'll bet a seriously considered hypothetical" reality as a construct" would explain a lot of stuff. You need include the placebo effect, how reality knows when I look at it and how only 60 some % of a society need believe something for all of them to declare it true - the collective unconscious, not as defined now - the NYT crossword experiment collective unconscious, the Theory of EVERYTHING must be all of that. Purely philosophically I can account for much of reality - including ideas, what they are, how we have them, how they evolve and what they do. I'm not sure everything can actually be accounted for outside of a construct - I can't rn and I've tried. I wish you all the best of luck.
wigster 2y ago
i can't read that due to the bobbing header. atrocious design.
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michael9423 2y ago
How can he be sure he's a theoretical physicist if he doesn't know reality exists at all? The truth is, instead of reality, he would be better off questioning theoretical physics, which indeed does not exist outside the heads of academia. His "questioning of reality" only happens philosophically (in other words, it is an academic farce), once he gets up to do some grocery shopping he sure knows what to buy so he can eat in order to survive. There is your objective reality. Humans understand reality if they do not bury their heads in the sand. But academia can get in the way.
analog31 2y ago
Disclosure: I'm not a theoretician, but just an old industrial physicist who helps design measurement equipment. What I've noticed is that most physicists are aware of the great epistemological puzzles, and may even have briefly dabbled in them, but also tend to ignore them if there's work to be done. There's a lot of pleasure and utility to be gained from just finding a hard problem and working on it, maybe even solving it, or inventing something. When people find out that I'm a physicist, and ask me about those puzzles, I usually plead ignorance. I'm not dismissive of them, or anti-intellectual, but I think you shouldn't let them be an obstacle to the enjoyment of physics, either as a spectator or practitioner.
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aristofun 2y ago
There is little doubt left that materialistic reality (what people and even physicists usually mean when they say “reality”) is not the fundamental nature of reality. This is the main philosophical, scientific and even cultural challenge today.
- zdyn5 2y ago
  Little doubt? By tautological reasoning sure…
- zdyn5 2y ago
  Sorry I had misread your line - somehow the “not” didn’t register. Can’t remove/edit my previous comment for some reason.
micheles 2y ago
I remember when I took my course of "Theoretical Physics" (so called, it was an Introduction to Quantum Field Theory in actuality) and I realized that particles do not exist. It was quite an enlightenment. Particles are a convenient description of Quantum Fields in the perturbative regime, but what Quantum Fields are is not known, not even at the mathematical level. When you live at frontier of knowledge, as a Theoretical Physicists, reality becomes fuzzy. But that's life.
mikepalmer 2y ago
Near the end: "I believe that the quest to understand the reality of the universe must contend with the truncations imposed by the perceptual and cognitive limitations of the mind." Totally agree with him. Interestingly AGI will have different limitations. In fact different AGIs (transformers vs something not yet invented; or an AGI with an huge encyclopedic memory vs one without; or ones with different limitations of compute; etc. This touches on computability with limited or unlimited resources.) will have different limitations and be literally unable to understand each others' versions of reality.
ngcc_hk 2y ago
There is some discussion below about evil, part of my study. There could evil as judgement, as nature, as action, as consequences or as being. One starting point is somehow someone can judge a being, a thought, an action and a consequence as evil. Is killing … it depends upon context so much … or should we just back to I or God or whoever think it is evil itbis evil? Action if assume above seems easy. I or some beings know it is evil or not and act on it. It is an evil act. It is when consequence are considered it is really complicated. It can change over time as an evil act can have good consequence in certain place and time. Nature as evil or not is part of one major Buddha sect - Tien Tai claim Buddha has evil in its nature forever just not do it (if … ) Evil as a being like God? The problem of evil in the religion context has a much wider issue one has to consider.

185 points by signa11 2y ago

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“Yet these are concepts that reify a certain approximate sketch of the structure of the world. Physicists once thought that these categories were fundamental and real, but we now understand them as necessarily inexact because they ignore the finer details that our instruments have just not been able to measure.“

FeepingCreature 2y ago

Sure, quarks and leptons are maybe a high-level concept that masks a more messy underlying reality, but surely quarks and leptons are less messy than dogs? There is an arrow of progress in the development of physical theories. I don't see a reason why a perfect description should not be possible.

infogulch 2y ago
Even wrong theories can be useful in some contexts, Newtonian gravity for example. Take it to an extreme: say quarks aren't useful at all for science, but are a useful conceptualization pedagogically, it can still be worth.
- danbruc 2y ago
  Even wrong theories can be useful in some contexts, Newtonian gravity for example. Newtonian gravity is not wrong, it is pretty good model of gravity in a certain region of the parameter space.
  - moi2388 2y ago
    Right. Well, by the same logic my theory of gravity isn’t wrong: everything falls at 9m/s. It’s not wrong, it’s just a pretty good model of gravity in a certain region of the parameter space. Except of course, that it is wrong.
    - danbruc 2y ago
      Everything falling at a constant speed of 9 m/s takes this probably a bit too far, on Earth this will only be true for tens of milliseconds before the speed is of by a few percent. Had you said every objects accelerates with 9.81 m/s², that would be a pretty good theory of gravity on the surface of Earth, probably still the dominant theory for solving gravity related problems on Earth. Your example reminds me more of the difference between Aristotelian and Newtonian physics. Aristotle - looking at the world around him - thought that the natural state of motion is being at rest and that it requires a force to make an object move. Newtonian physics realizes that this is not the case, that without forces objects keep moving instead of coming to rest, that Aristotle lacked a proper understanding of the role of friction. To come back to gravity, space flight probably still heavily uses Newtonian gravity and it works, for that reason alone I would not call it wrong. Objects falling at a constant 9 m/s seems to have much less practical use and does not even get the most important characteristic of gravity - that it accelerates objects - right, so I will agree with you and call it wrong.
    - FeepingCreature 2y ago
      The difference is that the region your theory of gravity is a good model in, is not inhabited, whereas the region that Newtonian gravity is a good model in is the one where most of us spend most of our time.
      - moi2388 2y ago
        You spend time in a region where the propagation of gravity is instantaneous? Cool.
  - tines 2y ago
    It seems that different people often use "not wrong" to mean two different things. Some people are using the word to mean "useful as far as it's meant to be," like you. Some people, like the GP, are using it to mean "the truth." It's important to clarify what you mean when you're discussing, otherwise there's heat and not much light.
    - danbruc 2y ago
      In case of physics we do not really have access to the later kind, every theory is a current best guess that might at any time turn out to be only approximately correct or under certain circumstances. General relativity is almost certainly not the truth, the universe probably has no singularities hiding behind event horizons, but does it help us to call it wrong? There is reality and there is series of better and better mathematical models of reality and all of them are wrong in the strict sense until we eventually find the final theory but even then it is not clear that we could even recognize that we have arrived at the destination. In the end a binary characterization as right or wrong does not make too much sense for physical theories, they occupy a continuum of correctness.
      - tines 2y ago
        I somewhat agree with you, but I think it's very important to distinguish between the two meanings, because different points on the continuum of correctness cause you to come to completely opposite conclusions about the nature of the universe. A bit of quantity leads to a totally different quality. In other words, truth and usefulness are continua, but they are two different and orthogonal continua, and going right on one may mean going left on the other. My view of the universe is going to be totally different if Newtonian mechanics is the "truth", versus if something like quantum mechanics is the "truth." The former depicts a totally deterministic and knowable-in-principle clockwork universe, whereas the latter has randomness and ignorance that cannot be removed even in principle. Quantum mechanics may not be the whole truth, but it's certainly so different that it shows earlier approaches to be not just incomplete but totally incorrect about their fundamental assumptions, even if they can be used to make useful predictions. Quantum mechanics isn't just more useful, it's more true, whereas Newtonian mechanics might be more useful than some other theory, but actually less true in some sense.
  - nathan_compton 2y ago
    Counterpoint: Newtonian Gravity could be considered profoundly wrong since it presupposes a structure for space and time which is fundamentally wrong. What I mean is that ontologically Newtonian Gravity is a total non-starter, implying the existence of relations which are simply totally absent in this universe.
CoastalCoder 2y ago
> but surely quarks and leptons are less messy than dogs? I dunno, I'd rather clean up an accident from a dog than from a particle accelerator.

lokimedes 2y ago

Physics is an empirical inquiry into the structure, composition and dynamics of the observable usensorium we inhabit. I find it just short of hybris to entertain any promise that the outcome can be more than a metaphor of the underlying reality. The whole quagmire of “the measurement problem” in quantum mechanics seems to largely come from misunderstanding Bohr’s philosophical objections on this difference between a theory of the measurable and the interpretation of the theory’s internal mechanics as evidence of the true reality it models. Givens that twentieth century physics (apart from General Relativity) is based on Bohr’s foundation, no wonder people get confused. The mathematization of physics hasn’t helped either. That Bell’s theorem “proves” something is language applicable to a mathematical structure, not to the physical world itself.

elashri 2y ago
Why can't you just shut up and calculate? /s
- lokimedes 2y ago
  Exactly
- DiscourseFan 2y ago
  formulas are meaningless without concepts
gpderetta 2y ago
c.f. "The unreasonable effectiveness of mathematics in the natural sciences" (https://www.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf https://www.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf)
- DiscourseFan 2y ago
  > It is even possible that some of the laws of nature will be in conflict with each other in their implications, but each convincing enough in its own domain so that we may not be willing to abandon any of them. We may resign ourselves to such a state of affairs or our interest in clearing up the conflict between the various theories may fade out. We may lose interest in the "ultimate truth," that is, in a picture which is a consistent fusion into a single unit of the little pictures, formed on the various aspects of nature. Mathematics alone cannot reflect on its conditions of possibility, and mathematical physics is as inept in that domain. The reason why the quantum physics vs. general relativity thing can't be resolved is not because we don't have the right math, its because to overcome it requires a paradigm shift away from the mathematization of physics, and to actually gain a familiarity with the conceptual apparatus that engendered these theories.

sanxiyn 2y ago

I mean, leptons are definitely real, not just concepts. An electron is a lepton, and an electron surely exists? You can spray individual electrons. If an electron is just a concept, it is in a sense that a tiger is just a concept, and in a sense it is, but that is not very useful thing to say.

anatoly 2y ago
An electron is just an excitation of the electron field, a vast probabilistic something that's ever-present everywhere in the universe, with a different complex-number amplitude (not observable directly) at each and every point. Sometimes that vagaries of its ever-changing amplitudes cause it to locally coalesce into something that looks like an individual electron if you squint at it in the right manner, and that vision persists until a strong enough interaction with another vast and nebulous field shatters the illusion, at least in the tiny corner of the probabilistic multiverse your local version of your consciousness brazenly imagines to be the objective reality. What kind of existence is that? (Well, the only kind on offer, really.)
- goatlover 2y ago
  An existence that mistakenly took fundamental reality to consist of point particles instead of fields. But we still found out about fields and quantum mechanics.
  - dist-epoch 2y ago
    We don't know that fields are real. We just know that the mathematical language of fields is the most convenient and concise to describe the experimental results we see.
    - goatlover 2y ago
      As a starting pint, the magnetic field can be shown to be real with metal filings. Whether fields are the fundamental building block is another matter.

BrandoElFollito 2y ago

I am an ex-physist who stopped after his PhD in particle physics. I love physics but while money does not bring happiness, it is better to cry in a Mercedes than on a bike (this is not true, I just laughed when I first read it). I went through the stages of OP (on a way smaller scale, I do not have his experience) and I think this is awesome. You continuously go from "oh yeah, now I get it" to "crap". This always have you on the bleeding edge between "this si physics, I know that" and "yes, but what if...". To me this is the essence of knowledge though curiosity. I started my PhD on a specific topic and at some point I was a bit stuck (not panic mode stuck but pissed off stuck). I had dinner with a friend, we were discussing about my work (she is also a physicist) and she off-handly suggested something. And bam! my world changed. The direction of the thesis changed. I added an extra thesis director because what I was about to do was a world where the hands of men did not step on yet. I thanked her profusely for her help in the thesis and suggested a joined publication (which she did not want to take because she was not interested and asked me to stop stalking her :)) And this is how science moves: because of eureka moments under the shower or at dinner or because someone thought "hmmm..." (looking at you Nikola Tesla). So the fact that this guy doubts about what the world is, and that he is a theoretical physicist (so hopefully will not switch to some insanities) is awesome.

kaiwen1 2y ago
Off topic, but eureka moments are my favorite go-to evidence for the absence of free will. No one chooses to have a eureka moment. They just arrive. And not just those moments, but every thought in every moment. They all just arrive, none are choosen.
- futuramaconarma 2y ago
  That's not evidence But I agree there's no free will and anybody who believes it also believes in magic and god
  - mettamage 2y ago
    I experience having mo free will whenever I am in the break of a meditation retreat. During those breaks it’s sometimes quite easy to observe my thoughts, given that I focus 10 hours per day on making my internal chatter very very quiet. The most fascinating thing to me is how subtle body sensations lead to thoughts and vice versa.

thewanderer1983 2y ago

It's refreshing to me to read articles like this. In the current climate of consensus science, and settled science. Here is someone well versed in Physics, and the Philosophy of it. Reminding people that we need to be humbled again.

openrisk 2y ago

Do we care about "real" reality if we can, more or less, make sense of some of its manifestations through our senses? That there is something deeper and unknowable and "informationally huge" seems obvious. We didn't bring quarks or quasars into existence, we "discovered" them as and when we extended our senses far enough using technologies (which are themselves a result of us becoming comfortable enough with our immediate reality, as a sort of positive feedback loop). There is every reason to suspect that this deeper reality does not stop where our technologically extended abilities peter out. Our imperfect and tentative understanding when reaching the extremes of scales (of time, space, complexity, etc) is perfectly understandable. Why should a finite carbon brain be able to map out a coherent and finite model of something much, much bigger than itself. On the other hand over millennia of brainstorming (literally) we have collected some interesting datapoints about this deeper reality: it is not "malicious", and somehow it agrees to be mapped by us (mathematically), even if in disconnected parts. In fact this benevolent aspect of deeper reality has made us unusually cocky. Imagine the existential angst if the universe changed its laws at whim. We'd be back to praying. E.g., that gravity remains stable for a while so that we don't drift into space. This premature self-assuredness explains repeated scientific episodes of proclaiming "we have explained everything". This also feeds the sterile chase of "a theory of everything". In fact the limits of our understanding are in front of our eyes, everywhere. We haven't really explained a single phenomenon in the so called "complexity science" domain. Deeper reality is all around us and the most dramatic and impactful scientific revolutions are still ahead of us.

DiscourseFan 2y ago
>Deeper reality is all around us and the most dramatic and impactful scientific revolutions are still ahead of us. Maybe
graycat 2y ago
> Why should a finite carbon brain be able to map out a coherent and finite model of something much, much bigger than itself. Have asked that and have a guess: Darwin-style selection rewarded getting some rational understanding of the most important parts of nature -- fire, rock tools, clean water, agriculture, staying warm in winter, basic geometry, bows and arrows, the Pythagorean theorem, levers, wheels, boats, etc. -- we encountered. Well, it so happens that in this universe such "rational understanding" is enough to understand basic math, physics, chemistry, biology, ... back to the Big Bang, the 3 K background radiation, cells, reproduction, nutrition, diseases and immunity, .... I gave up on the US education physics community when my teachers couldn't give a valid proof of Stokes' theorem, explanation of Young's double slit, or the beginnings of quantum mechanics. So, now I have several polished treatments of each of Stokes' theorem, Maxwell's equations, and special relativity. Got a good background in probability (Neveu, Poincaré recurrence, martingales, etc.), enough to get a good path through thermodynamics. From Rudin, etc., got enough solid Fourier theory to check carefully the uncertainty principle in physics (doubt that what physics does there is fully justified) -- also carefully treated in a great course in "Analysis and Probability". For differential geometry, an Andrew Gleason student gave me some lectures and explained that the keys are the inverse and implicit function theorems, proved in a book by W. Fleming and just exercises in a Rudin book -- local nonlinear versions of what is easy in linear algebra. So, now I attack physics as a curious amateur! I do remember a remark from a good mathematician: "Physics abuses its students." Well, they can abuse me no longer, and I can still do high quality study of physics.

_hark 2y ago

I'm in the final year of my PhD, and I feel very lucky to be working on the question of what it means for an explanation to be "good". The closest thing to a satisfactory resolution of the question of "reality" in theories, to me, is Dennet's Real Patterns [1] It may well be that multiple explanations are consistent with the most basic phenomena. The criterion for the reality of the theory is whether it does better than random (its predictive power, equivalently how well it can compress the observational data). We can try to find the simplest explanation, but we can never know if we have it [2]. We can stop thinking of theories as being real or not in a binary sense, and merely ask how well they compress the data. Of course, different theories can achieve the same compression by compressing different aspects of the data! Your pattern can look like my noise :-) Luckily and interestingly, the physics of the macroscopic world is in many cases effectively independent of the underlying microscopic rules [3], with the details of the microscopic physics being screened off as complexity emerges. Personally, I like to think of abstraction as a kind of hierarchy of hardware + software: at each level, some useful ontology is picked out for stable patterns to emerge (e.g. the software of "fluids" emerging from the hardware of quantum "particles"). Layers of software at one level become the hardware substrate for the next rung up the abstraction ladder. Luckily, we get to choose the software that runs on us, so don't forget to vote this fall ;) [1]: https://ruccs.rutgers.edu/images/personal-zenon-pylyshyn/class-info/FP2012/FP2012_readings/Dennett_RealPatterns.pdf https://ruccs.rutgers.edu/images/personal-zenon-pylyshyn/cla... [2]: https://en.wikipedia.org/wiki/Kolmogorov_complexity https://en.wikipedia.org/wiki/Kolmogorov_complexity [3]: https://en.wikipedia.org/wiki/Effective_field_theory https://en.wikipedia.org/wiki/Effective_field_theory

jll29 2y ago
> what it means for an explanation to be "good" Chomsky coined the technical term "explanatory adequacy" for that, which is used/recognized among linguists and psychologists.
mikepalmer 2y ago
> We can stop thinking of theories as being real or not in a binary sense, and merely ask how well they compress the data. Of course, different theories can achieve the same compression by compressing different aspects of the data! Your pattern can look like my noise :-) Love this, thanks for these insights.

dakiol 2y ago

I didn’t know that Physics was about understanding reality (sure, from a romantic perspective yeah). I always thought it was about making our lives better (like any other branch of science). I believe we will never find out what’s the real nature of reality. That doesn’t mean we should stop doing science, though: it makes human live better. I believe that the “meaning of life” is not about the answer (science telling us what’s the actual meaning) but about the discovery process we embrace: knowing beforehand that we’ll never understand everything and nevertheless keep waking up every day to do the job.

jajko 2y ago
Understanding reality makes our lives significantly better. No room for primitive religions leading us to stagnation or even reversal, when we can understand very well what sun, moon and stars are, why they move as they do, or why lightning happens and why weather patterns are what they are. Understanding of reality via physics gave us all electronics too, including one I use to write this and one you use to read it. That's a noble goal on its own, no need to meddle with that. Pursuit of meaning of life is completely different topic, for different folks, no need to try to mix those two. Plus its very subjective - tons of folks already found it or simply don't care about it.
- hnfong 2y ago
  > Understanding reality makes our lives significantly better. Of course on the whole understanding makes our lives better, but if you're asserting this for everything, it's probably some kind of a survival bias. The understandings that aren't really useful are often forgotten, while the useful ones are passed down through generations. It's actually very easy to get caught in understanding niche topics that genuinely find very little application.
  - mistermann 2y ago
    Is all potentiality that exists unlocked and harvested? Is science even looking in all the right places? Can a mind on science even care about such things (or better: to what degree do individual and a culture/society of minds on science have the ability to care (have non-constrained curiosity))? In my experience, something about the mind makes it think it is able to know the correct answer to these questions, which is a remarkable but little studied phenomenon.

bjornsing 2y ago

I could have been a theoretical physicist, but got out after my master’s. Subconsciously I think I had already come to this (the OP’s) conclusion then. Since then I’ve worked a bit in statistics and machine learning. There’s a saying in this field that captures my subconscious conclusion well: “all models are wrong, but some models are useful”. I’ve often said that I would have loved to do a PhD in physics in 1910, but less so in 2010. The models physicists found in the 20th century were extraordinarily useful. I have little hope that I will see anything comparable in my lifetime. Don’t get me wrong: More models will undoubtedly be found, and there’s beauty and honor in that work. But they will most likely all be “wrong”, and far less useful than e.g. the models that let us harness nuclear reactions.

sigmoid10 2y ago
That depends a bit on the field. If you were doing particle physics (in particular using earth-borne accelerators), the second half of the 20th century would probably be best. But if you're into astroparticle or cosmology, the best time is literally right now. The 21st century has been one giant thing after another thanks to Sudbury, WMAP and Planck, the EHT, LIGO, the Pulsar Timing Array and tons of other experiments. When it comes to understanding the universe as a whole, there is no better time to work in physics than today. Similar goes for quantum and condensed matter, albeit with a focus on real world applications rather than understanding the universe.
- bjornsing 2y ago
  I’m into usefulness. And I’m not convinced by your argument. I still doubt very much that I will see any new models as useful as those that transformed the world in the 20th century. I’d love to be wrong though.
  - sigmoid10 2y ago
    Usefulness usually means real world use. It took the theory of general relativity 70 years before we saw a real world application make use of it. The theory that led to modern hard drives (GMR) went from new fundamental physics in the late 80s to full commercial use within a decade. Things like the blue LED (1990s) or frequency combs (early 2000s) were even faster and can be found truly everywhere now (unlike GR). There are far more useful models out there than the high level overview stuff you might get from an intro to fundamental physics class. And even if you're into explaining the universe rather than improving day to day life, as I said, there's tons of stuff going on right now if you're in the right field.

swayvil 2y ago

We do not craft models of reality because reality and models have any kind of intrinsic connection. We craft models of reality because we value models. That is arguably very funny.

TheOtherHobbes 2y ago

So this is the new zeitgeist. Between AI, quantum fundamentals, disinformation, and a few other less obvious trends, "reality" is going to get less and less concrete and more and more contextual and non-binary.

jeroenvlek 2y ago

Ultimately, we're all just living in an episode on Rick & Morty's galactic cable TV

efitz 2y ago

Humans are not “generally intelligent”; our intelligence is extremely well adapted to being a hominid family animal in a tribe or clan in a savannah habitat with large predators and hostile members of our own species lurking about. Our senses and brains are well suited to reasoning about and making decisions in environments at “human” scales. By that, I mean that humans don’t receive relativistic, atomic or quantum phenomena directly with our unaided senses, and therefore our brains never developed intuition for these phenomena. So it’s no surprise at all that our intuition completely fails us at those scales. Again, our intelligence is not “general”; it’s hominid.

snovv_crash 2y ago
We also fail horrifically at recognising exponential growth, or understanding its implications.
- mettamage 2y ago
  Exponential growth is pretty rare in nature, right? Linear growth or fuzzy up and down growth/swings seems way more commonplace
  - snovv_crash 2y ago
    COVID was an example of nature, and peoples' poor understanding of exponential growth.
    - GuB-42 2y ago
      Epidemics generally follow a logistic curve, like most "exponential" processes. It looks exponential at first, but at some point, it decays. COVID is no exception. It is now in "fuzzy up and down" mode. True, unbounded exponential processes don't exist in nature. There is a simple explanation about why not: assuming the speed of light is the speed limit of causality and we don't have weird things like warp gates, then the influence of something cannot go further than a sphere around it expanding at the speed of light. The volume of this sphere of influence increase following a cubic function. Now, if an exponential process happen withing that sphere, for example a population growth, it will run out of space at some point, because an exponential function will always beat a cubic (or any polynomial) at some point. The fastest growth possible is cubic, not exponential.

flowingfocus 2y ago

Yes, our models are never complete. As someone here already wrote: "all models are wrong, some are useful". What makes me optimistic here is that since the enlightenment we have a good track record with arriving at better and better models. In the language of David Deutsch: We are arriving at better and better explanations, where the quality of an explanation is determined by rigidity ("how hard it is to vary") and reach ("in how many situations does it apply"). His books "The Fabric of Reality" is a great book by the way, he describes how the theories of evolution, quantum physics, epistemology and the theory of computation are connected with each other. The bit about good explanations is from "The Beginning of Infinity", also a very good read.

sampo 2y ago
From 1954 to 1975, theoretical physics created the standard model of particle physics. Experimental verification of the theory continued through 1980s and 1990s, and finally the Higgs boson in 2011. But if we follow the dictionary definition of scientific theory "A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed" or "a hypothesis confirmed by observation, experiment etc.", then after the 1970s, theoretical physics about the fundamental building block of reality hasn't really been theoretical physics, but rather hypothetical physics. They have worked on lots of theories (or rather: hypotheses) that they have not been able to test and verify experimentally.

alexpc201 2y ago

Most likely, the nature of consciousness and reality are rigged in such a way that we cannot use our consciousness to decipher them. Any progress in that direction is useless and, at this point, almost ridiculous.

librasteve 2y ago

Thanks to Vijay for a thought provoking post. I like the juxtaposition of quantum gravity and neuroscience. I think that it carries two messages, one trivial and one deep. The trivial one is that physics builds on the human nature to build concepts. Both a jaguar and a quark are ideas that we extract from our perceptions, that we share with others and that help us to model and predict the world - quarks just need a more expensive microscope like the LHC. Sure eagles and prawns may have slightly different versions of concepts since they have different colour perception, but only marginally so. A practical fellow like a physicist will be clear that when the concepts can make measurable predictions they are worthwhile (we call this meta concept "real"). It is not possible to store the full state of or compute the evolution of anything macroscopic to full precision - such as the positions and momenta of all the particles in a table. So concepts are the only things we can know about reality. They argue that we may never be able to attain the deep underlying reality - either because it is theoretically unattainable or that we will continue to be resource limited. I contend that this dichotomy is false. It just may never be possible to attain deep underlying reality. The best we can do until we get there is to find some probabilistic rules that work in a pragmatic sense and to refine these tools over time. [That's pretty much a restatement of the Copenhagen interpretation of 1922]. The deep one is that we are probably looking down the wrong end of the telescope. As far as I can tell (from popular neuroscience) is that our ability to model the perceptual / conceptual processes and how they compose into intelligence remains in the dark ages. But, given that we each have 70 billion neurones or so, there is a lot of classical physics going on in our heads to make these concepts and we have practically no hard, proven theories about how this works. We are doing layers of pattern recognition and extraction and feedback that allows us to avoid being eaten by Jaguars. So let's get a proper theory of intelligence. One that let's us work out which aspects of quantum mechanics are philosophically necessary to sustain our subjective experience of space and time. With a substrate with branching / collapsing features. Where time has an arrow with memory in the past and uncertainty in the future. Where cause and effect are loosely coupled. Where there is a notion of free will. Some endnotes: - The quantum measurement problem is perhaps a limit of this theory - Perhaps the notion of computational reducibility is a stab in this direction [Wolfram] - Probably all you need is emergence for this and not a quantum brain [Penrose]

2y ago

throw7 2y ago

Science is an open system. Everything is open to being "wrong"/"updated". There is nothing that grounds the system. You must be always open that your prediction of unobserved things will be wrong. To actually believe that science will one day solve the great mystery of the universe is scientism.

jfactorial 2y ago
Is there any stronger tool for rational truth seeking than the scientific method? Observe. Hypothesize with falsifiable statements. Form experiments that could disprove the falsifiable statements. Observe. Publicly make falsifiable statements to peers capable and incentivized to disprove them. How can this fail to lead us to truth that is as close to objective as possible? What greater method exists?
- bubblyworld 2y ago
  This is a little bit out there from a rationalist point of view, but I think there are domains in which not all of the requisite concepts for the scientific method actually exist. An example that comes to mind is the nature of conscious experience - having spoken to a lot of meditators, for instance, I'm convinced that there really are commonalities to it that you can experience yourself by sitting down and paying attention. But I don't think there's anything to really falsify here, because there's nothing to measure! You can't tell someone "here's this totally objective way you can pick apart your conscious experience into a bunch of statistics, and when you do change X I predict you'll see the statistics vary like Y". You can kinda just point their brain in a direction and hope that they experience it for themselves. Another example, I think, is domains that are under optimisation pressure or control of some kind (like an ecosystem, or much more simply a thermometer). There was a post on HN a few days ago about causality, and how the standard statistical methodologies for determining causality kinda break down when you start measuring systems like this. Correlation is not causation, but in these systems causation no longer necessitates correlation either! Perhaps a different kind of epistemology would be useful here too. Anyway, not sure this is making sense. Would be curious to hear your thoughts.
- NemoNobody 2y ago

__rito__ 2y ago

The Indian Philosopher that is gravely missing from the article is Nagarjuna. The kinds of questions the author raises, the path he is treading on, will benefit from the study of Shunyata Philosophy of Madhyamika school, especially Nagarjuna. I am not alone in thinking this. I was surprised to see Carlo Rovelli talking about it in multiple occasions. Heres one [0]. Nyaya and Madhyamika Philosophies still have many lessons that are not yet discussed in the spotlight. [0]: https://m.youtube.com/watch?v=CgIfNuZs56w https://m.youtube.com/watch?v=CgIfNuZs56w

ziofill 2y ago

I am a theoretical physicist, and I am very much in tune with the author. Take quantum mechanics (my field), it is clear that even though we have a working model of it, it doesn't explain how nature instantiates it. Entanglement is a prime example of this: I know exactly how to describe it, but nobody has a clue of how it works. In other words, physics is a mostly coherent and certainly useful story about reality, but it isn't grounded on "bedrock" reality, rather on our perception of it.

BobaFloutist 2y ago
Correct me if I'm wrong, but I think of entanglement as less forming an actual binding relationship to two particles, and more as setting them up exactly the same way. So it's not that you have two magnetic marbles and rotating one rotates the other, it's that you're rolling two dice with identical parameters and can expect that at any given slice of time they'll be doing the same thing. Is that incorrect?
- nathan_compton 2y ago
  Entanglement is neither a bond between two objects nor a setting up of two objects in the same way. Entanglement derives from the fact that quantum mechanical systems have properties which are non-local with respect to the "process" of measurement that do not depend on the physical size of the system in question. Its actually suspect to say that "particles" are entangled at all - the entanglement is a property of the wave function in which the particles identities are (with respect to the quantity that is entangled) indistinct.
  - mikepalmer 2y ago
    Agree, "spooky action at a distance" isn't spooky at all if you just accept it as physical!
    - nathan_compton 2y ago
      I don't personally think that there is any action at a distance at all.

jebarker 2y ago

I'm not a physicist. An idea from physics that I recently learned and found very unnerving was that the solid objects we see and feel in the world are actually mostly empty space. We just see them as solid because of the way light interacts with the particles. So in a sense our visual and tactile perception of the world is just one representation of the underlying reality and you can imagine there being infinitely many other possible representations. I'm just crudely saying the same thing as the author I think, but I wanted to emphasize how uncomfortable this makes me. In some sense it feels like being a prisoner in a perceptual cell you can't escape from surrounded by a reality you'll never know. Having philosophy as a counterpoint (in my case dabbling in Buddhism) has been essential to keep me calm and relaxed.

biggoodwolf 2y ago
You're a brain in a bucket. What is the nature of the bucket is up for debate
- goatlover 2y ago
  Your brain is part of a nervous system that extends throughout the "bucket". Body and brain aren't really separate.
  - jebarker 2y ago
    I think the bucket is bigger than just your body.
nathan_compton 2y ago
This is more of an intellectual parlor trick than anything else. Like literally what else could "solid" mean besides "that which we call solid based on our perception." When you say that matter is "mostly empty space" you are really writing is a sentence which implicitly uses two definitions of solid in one place without distinguishing between them.
- jebarker 2y ago

curation 2y ago

The book Sublime Object of Ideology (Zizek) and a second volume due soon attempts an interdisciplinary reframing of the theory of everything - working with Quantum Physicists and Material Hegelian/Lacanian philosophy. I am a philosopher who works with theoretical physicists.

NemoNobody 2y ago
Philosophy is the science of ideas. Ideas are the basis for all understanding - it is good that you are you there, this topic is inherently the realm of philosophy. Theoretical physicists must be very focused on theory to frame a "Theory of Everything" - what they kno will get in the way. The Theory of Everything is just our modern way of saying "God" - they occupy the same position in our lives and society. We need to understand and it needs to make sense to us rn, in this time and space - like religion once did. Even if incorrect, believing that we have a Theory of Everything is necessary. We have killed God and now find it necessary to create an idea that can encompass the void where God once was. Functionality is key. I doubt the physicists ability to be objective. This is easily explained by adapting God into a Creator of a Game, us to fully uploaded VR Players, reality to the engine, mechanics and programming - all executed as science has already identified with the laws of the universe, etc. A future version of Microsoft could easily hypothetically make this game. We already are testing reality to determine if it is a hologram. I believe Stanford already declared it more likely we live in a simulation than it isn't - bc someday, if we can, we will totally make an exact copy of reality - maybe this it. Maybe we are dead and chose to upload ourselves here. Perhaps Musk is right and we are the NPCs of an alien game... All of those things are far more likely than a spontaneous universe, coming into existence without cause, creating the universe for no reason and only time + chance allowing for what we call reality. Far far more faith is needed to believe this not a created thing. I find it almost illogical that this being the simplest and most likely conclusion, that it is ignored. Where is the objectivity? A working model is all we need to move forward - we can figure out later if it's right or not. I'll bet a seriously considered hypothetical" reality as a construct" would explain a lot of stuff. You need include the placebo effect, how reality knows when I look at it and how only 60 some % of a society need believe something for all of them to declare it true - the collective unconscious, not as defined now - the NYT crossword experiment collective unconscious, the Theory of EVERYTHING must be all of that. Purely philosophically I can account for much of reality - including ideas, what they are, how we have them, how they evolve and what they do. I'm not sure everything can actually be accounted for outside of a construct - I can't rn and I've tried. I wish you all the best of luck.

wigster 2y ago

i can't read that due to the bobbing header. atrocious design.

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michael9423 2y ago

How can he be sure he's a theoretical physicist if he doesn't know reality exists at all? The truth is, instead of reality, he would be better off questioning theoretical physics, which indeed does not exist outside the heads of academia. His "questioning of reality" only happens philosophically (in other words, it is an academic farce), once he gets up to do some grocery shopping he sure knows what to buy so he can eat in order to survive. There is your objective reality. Humans understand reality if they do not bury their heads in the sand. But academia can get in the way.

analog31 2y ago

Disclosure: I'm not a theoretician, but just an old industrial physicist who helps design measurement equipment. What I've noticed is that most physicists are aware of the great epistemological puzzles, and may even have briefly dabbled in them, but also tend to ignore them if there's work to be done. There's a lot of pleasure and utility to be gained from just finding a hard problem and working on it, maybe even solving it, or inventing something. When people find out that I'm a physicist, and ask me about those puzzles, I usually plead ignorance. I'm not dismissive of them, or anti-intellectual, but I think you shouldn't let them be an obstacle to the enjoyment of physics, either as a spectator or practitioner.

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aristofun 2y ago

There is little doubt left that materialistic reality (what people and even physicists usually mean when they say “reality”) is not the fundamental nature of reality. This is the main philosophical, scientific and even cultural challenge today.

zdyn5 2y ago
Little doubt? By tautological reasoning sure…
zdyn5 2y ago
Sorry I had misread your line - somehow the “not” didn’t register. Can’t remove/edit my previous comment for some reason.

micheles 2y ago

I remember when I took my course of "Theoretical Physics" (so called, it was an Introduction to Quantum Field Theory in actuality) and I realized that particles do not exist. It was quite an enlightenment. Particles are a convenient description of Quantum Fields in the perturbative regime, but what Quantum Fields are is not known, not even at the mathematical level. When you live at frontier of knowledge, as a Theoretical Physicists, reality becomes fuzzy. But that's life.

mikepalmer 2y ago

Near the end: "I believe that the quest to understand the reality of the universe must contend with the truncations imposed by the perceptual and cognitive limitations of the mind." Totally agree with him. Interestingly AGI will have different limitations. In fact different AGIs (transformers vs something not yet invented; or an AGI with an huge encyclopedic memory vs one without; or ones with different limitations of compute; etc. This touches on computability with limited or unlimited resources.) will have different limitations and be literally unable to understand each others' versions of reality.

ngcc_hk 2y ago

There is some discussion below about evil, part of my study. There could evil as judgement, as nature, as action, as consequences or as being. One starting point is somehow someone can judge a being, a thought, an action and a consequence as evil. Is killing … it depends upon context so much … or should we just back to I or God or whoever think it is evil itbis evil? Action if assume above seems easy. I or some beings know it is evil or not and act on it. It is an evil act. It is when consequence are considered it is really complicated. It can change over time as an evil act can have good consequence in certain place and time. Nature as evil or not is part of one major Buddha sect - Tien Tai claim Buddha has evil in its nature forever just not do it (if … ) Evil as a being like God? The problem of evil in the religion context has a much wider issue one has to consider.