The Laws Underlying The Physics of Everyday Life Are Completely Understood

Not sure why people don’t make a bigger deal out of this fact. Physicists (and scientists more generally) are infamous for making grandiose claims about how close we are to Figuring It All Out, only to be shocked by some sort of revolutionary discoveries soon thereafter. Personally I have no idea how close we are to a comprehensive theory of absolutely everything. But I do know how close we are to having a comprehensive theory of the basic laws underlying the phenomena we encounter in our everyday lives — without benefit of fancy telescopes or particle accelerators or what have you. Namely, we already have it! That seems to be worth celebrating, or at least remarking upon, but you don’t hear it mentioned very much.

Obviously there are plenty of things we don’t understand. We don’t know how to quantize gravity, or what the dark matter is, or what breaks electroweak symmetry. But we don’t need to know any of those things to account for the world that is immediately apparent to us. We certainly don’t have anything close to a complete understanding of how the basic laws actually play out in the real world — we don’t understand high-temperature superconductivity, or for that matter human consciousness, or a cure for cancer, or predicting the weather, or how best to regulate our financial system. But these are manifestations of the underlying laws, not signs that our understanding of the laws are incomplete. Nobody thinks we’re going to have to invent new elementary particles or forces in order to understand high-Tc superconductivity, much less predicting the weather.

All we need to account for everything we see in our everyday lives are a handful of particles — electrons, protons, and neutrons — interacting via a few forces — the nuclear forces, gravity, and electromagnetism — subject to the basic rules of quantum mechanics and general relativity. You can substitute up and down quarks for protons and neutrons if you like, but most of us don’t notice the substructure of nucleons on a daily basis. That’s a remarkably short list of ingredients, to account for all the marvelous diversity of things we see in the world.

A hundred years ago it would have been easy to ask a basic question to which physics couldn’t provide a satisfying answer. “What keeps this table from collapsing?” “Why are there different elements?” “What kind of signal travels from the brain to your muscles?” But now we understand all that stuff. (Again, not the detailed way in which everything plays out, but the underlying principles.) Fifty years ago we more or less had it figured out, depending on how picky you want to be about the nuclear forces. But there’s no question that the human goal of figuring out the basic rules by which the easily observable world works was one that was achieved once and for all in the twentieth century.

You might question the “once and for all” part of that formulation, but it’s solid. Of course revolutions can always happen, but there’s every reason to believe that our current understanding is complete within the everyday realm. Using the framework of quantum field theory — which we have no reason to doubt in this regime — we can classify the kinds of new particles and forces that could conceivably exist, and go look for them. It’s absolutely possible that such particles and forces do exist, but they must be hidden from us somehow: either the particles are too massive to be produced, or decay too quickly to be detected, or interact too weakly to influence ordinary matter; and the forces are either too weak or too short-range to be noticed. In any of those cases, if they can’t be found by our current techniques, they are also unable to influence what we see in our everyday lives. We have very little idea how big the region of our understanding is, compared to all that there is to be understood; but we know that it’s bigger than what we need to understand to make sense of the world we see with our unaided senses.

That’s pretty amazing. Science will certainly push forward along the frontier of phenomena that are too big or small or subtle to be detected without delicate instruments, as well as along the much more jagged and unpredictable frontier of how the basic laws play out in complicated ways. But getting the basic laws right is an extremely impressive accomplishment, especially for good old human beings who have only been doing science systematically for a few centuries. Way to go, human beings!

(See follow-up posts here and here.)

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70 Responses to The Laws Underlying The Physics of Everyday Life Are Completely Understood

  1. bittergradstudent says:

    One caveat: To my understanding, we haven’t ruled out things like non-local hidden variable theories or time-symmetric quantum mechanics. While unlikely, these things could very well have low-temperature consequences that affect things like brain function (not that I’m saying that they DO, but it’s possible).

    There’s still much not understood about quantum entanglement, either over macroscopic distances or human-scale times, at least, to my understanding.

  2. Maldoror says:

    On the one hand you say:

    The Laws Underlying The Physics of Everyday Life Are Completely Understood

    and then you qualify this with

    We certainly don’t have anything close to a complete understanding of how the basic laws actually play out in the real world.

    I think this answers the question in your first sentence.

  3. wolfgang says:

    >> The Laws Underlying The Physics of Everyday Life Are Completely Understood

    we can finally tell if our experience is real or based on a simulation (a la Matrix) ?
    so should i take the red or the blue pill?

  4. eukaryote says:

    A complete understanding of consciousness is not going to come from any physical laws as they are currently understood. This problem is on a wholly different level than curing cancer or developing high temperature superconductivity.
    It doesn’t seem totally certain though that consciousness has any causal role in the physical Universe, so I it may be possible to forgo an explanation of it, and just ignore it when putting together a mathematical description of the world. However, that seems unlikely to me that it has no causal connection to the rest of physical reality.

  5. Joseph Smidt says:

    Very interesting article Sean. I think you are 100% correct and think this is a very honest analysis of the whole situation.

  6. maneesh says:

    What if this idea was brought about during the time of Einstein , Copernicus, or Newton or Darwin. They all thought beyond their everyday life, even when apparently they didn’t have to, for the times they lived in. Space travel is our next frontier and that break through depends on our understanding the mysteries of fundamental particles and other ‘theories of everything’.

    Colonizing other solar systems with today’s technology is as ‘distant’ as it was to the Polynesians who colonized the remote islands in the Pacific using hand built canoes and stars to guide them. We must not satisfy ourselves with the accomplishments to date but look beyond. Fundamental research into ‘theory of everything’ will provide the next technology break through to accomplish that.

  7. Anthony McCarthy says:

    When you say “All we need to account for everything we see in our everyday lives are a handful of particles,” you are talking about only those things you take into account that can be explained that way, as of to date, I would imagine. In that would lie the unstated and often unconsidered necessity of regarding knowledge as contingent. But those questions are far, far from being “all we need to account for in everything we seen in our everyday lives.

    There isn’t any way to reduce enormous parts of human experience to fit into that framework. Just assuming that everything in our experience is a manifestation of the interactions of those particles is certainly a statement of materialist faith, it’s not anything that has been reliably established in science. I’m becoming more convinced that it accounts for a good part of the decidedly unreliable, would be science allegedly explaining behavior. Materialism has been the mainstream faith of a large part of psychology just about from the beginning, with a few heretics along the way. You can read the resulting wreckage in the bone yard of discontinued psychology, much of which was “founded” in “science” that was quite well accepted in its time. I doubt that the dubious use of images from MRIs is going to do much to change that, especially considering the criticism of that much touted advance.

    I’d like to repose that question. Is there a single object of which physics has a comprehensive and exhaustive knowledge?

  8. Anthony McCarthy says:

    Since someone mentioned evolution, which is, beyond question, the most thoroughly documented phenomenon in science, the idea that more than a tiny fraction of it is known to date seems to be very unlikely. Consider the length of time that evolution is presently known to have been in progress, more than three billion years and compare that to the length of time that the modern science of evolutionary biology has been existence, since the publication of The Origin of Species is a good place to measure that. So it’s been about a hundred fifty years that people have been scientifically studying it. Then consider the number of organisms which constitute the units of evolution, which is certainly a number that would be many times greater than three billion. And consider how many aspects of the lives of those organisms are relevant to the problem, and not only as individuals but in their environments. And then consider the incredibly tiny amount of that information available for review in any depth. To think that we have anything close to a comprehensive knowledge of even the general mechanisms of evolution would seem to be rather unlikely. I’d include that in things that might be relevant to our everyday lives, though hardly as relevant to them as the enormously complex topic of climate change.

    I’m beginning to think I’m spying a sort of “materialism in the gaps”.

  9. Amos Zeeberg (Discover Web Editor) says:

    Interesting idea. I wonder if, in part, scientists don’t want to talk about how much we know because (consciously or subconsciously) they don’t want to take away from the excitement of what lies ahead. For instance, if you hammered this point home in every news article, would that decrease the likelihood that legislators will fund another, more expensive particle collider? “Well, what’s the point, the physicists have already figured out what makes all this stuff work.”

    I guess it’s the same reason for many scientists’ rejection of John Horgan’s End of Science thesis.

  10. onymous says:

    Fundamental research into ‘theory of everything’ will provide the next technology break through to accomplish that.

    No, it won’t. Space travel will never be easy. We will probably never colonize other planets. Understanding the physics of new particles that are more massive than the electroweak scale will never have techonological consequences. Science fiction has lied to you.

  11. Doug says:

    Wow, this posting really brought out the kooks…

    “materialist faith”? You mean not arbitrarily making up things that we have no evidence for the existence of?

  12. PTM says:

    We cannot explain atomic nuclei – QCD is too hard doesn’t cut it.

    We do not know how to interpret QM.

    IMHO we do not even understand electrons and photons properly – I bet there is much more to them then the probabilistic picture.

    Finally past generations had good reasons to celebrate the progress of physics, currently we are mostly stuck.

  13. Ellipsis says:

    I don’t think you can say we understand why there are 3 dimensions of space and one of time, to be more specific, why the Minkowski metric is the vacuum expectation value of the metric.

    That is most definitely the physics of everyday life, our 3+1 dimensional world affects everyone, and it really is not understood.

  14. CanuckRob says:

    Do we have any understanding of time? In particular why does it seem to “flow” to our perception but there is no sign of that in our physics. Is it because the apparent passage of time is just something our brains or consciousness makes up or is it a lack of understanding of what time is?

  15. Anthony McCarthy says:

    Doug, materialism isn’t science, it’s an ideology. You have to believe it, you can’t know it. If you then use it to make assertions about the natural universe, those are statements of faith.

    You know, scientists could save themselves a lot of bother by not opening up issues like this but once they’ve done that, they can’t avoid people discussing it. You almost might get the feeling they haven’t though them through very far.

  16. Anthony McCarthy says:

    Amos Zeeberg, sometimes you come to an end that’s just a dead end because you can’t get any farther. Eventually you’re going to come to the limits of your ability. When I read Horgan’s description of the collider necessary to verify stuff on the Planck scale, I wondered if it might run up against the limits in computers Feynman talked about. I don’t know but I would imagine it might be something to think about.

    And that’s not to mention the budgetary limits. My sister in law, the aquatic biologist, will declare war if that project gets funding.

  17. max says:

    I think that saying that the underlying laws of everyday physics are completely understood is taking it a bit too far. I certainly agree with the more moderate statement that all everyday phenomena can, with enough computational power, be described with extreme accuracy using only the laws of modern physics (the problem of consciousness being the big exception, as others have noted above). However, that doesn’t mean that we understand those laws, or even that the laws describe nature as it really exists independently of our observations. To truly understand even the most basic laws of physics — to understand why these laws exist in the first place and what bits of matter they act upon — will definitely require a theory of everything. Maybe this is being too semantic though.

  18. Anthony McCarthy says:

    max, back when thinking through the previous Hawking session, on extraterrestrials, his statement about how “other life” might be extremely different from our form and have arisen under greatly different conditions, one of the issues was if it was possible that they would have an entirely different means of making the physical universe comprehensible to themselves. If we’re going to start making assumptions about our species having a theory of everything, it’s at least interesting to wonder if it’s going to be the only possible theory of everything. And if that’s the case, would it be possible to have more than one theory of everything. Among the proud claims that are currently all the rage is that some of us are not anthropocentric in our thinking, but isn’t the idea that our species could come up with the one and only possible ToE a bit humanish? What if they sense something we can’t?

  19. jpd says:

    “All we need to account for everything we see in our everyday lives are a handful of particles”
    i’ll point you to
    “More Is Different”
    by P. W. Anderson

  20. spyder says:

    for that matter human consciousness

    Though there is tremendous progress being made; for example this resume!

    Wow, i see the thread hog is back, willing again to gobble up time and space. I guess the 12000+ (because i wanted to see what it was) words he spewed back on the Hawking thread were somehow insufficient to construct a reasonable point.

  21. Anthony McCarthy says:

    spyder, it’s not my fault that you guys wanted to go through the entire, badly thought out and ill considered program of the new atheism. I’d thought it through and I wasn’t about to pretend I hadn’t. I was relieved when Gordon didn’t pursue neuroscience as I’ve got better things to do than go through the rest of it.

    I’ll make a deal, if Sean will answer the question I put to him, I won’t post another comment here. Is there a single object that physics knows comprehensively and exhaustively?

  22. cmt says:

    I think maybe this post goes a little too far, but I almost agree with it. Aside from the usual caveats about how knowing the rules doesn’t mean you can predict what happens, there are two points I want to make:

    1) There are classes of models that are so difficult to solve computationally that I’m not sure it makes much sense to say that they are solvable. Anything with a severe sign problem, protein folding, certain disordered and glassy statistical systems, etc.

    2) Also, though it may *not* happen, it seems possible that our understanding of how measurement works in quantum mechanics could be fine-tuned a bit. I still don’t understand how to tell when an observer is big enough to collapse a wave function. Maybe that is just me, though.

  23. max says:

    Anthony, I suppose when I said “a theory of everything” I really meant “the theory of everything.” There are undoubtably many different theories that can describe the universe to arbitrary accuracy, and these theories will be different based upon who comes up with them and what their particular cultural or sensorial backgrounds emphasize, but there should be only one theory that describes the way the universe actually works. That is, you can have a theory that models the universe but whose components don’t physically exist (think epicycles and Ptolemy, for example), or you can have a theory whose components are in a one to one correspondence with fundamental bits of physical reality. Such a theory should be unique. Now, whether or not that theory is even theoretically obtainable is separate question.

  24. xponen says:

    What the OP says, (posted by Sean), is true. We know everything that is to know about physical law. -We know how sub-atomic particle are related to each other (by quark), and we know how atoms are related to each other (by sub-atomic particle), and we know all the force that made up the universe!

    The things that is TO KNOW NOW is “how things can work from being a simple law of physics into a complex thing, that produces novel physical law”. Complex interaction is the thing that caused novel thing to appear in our everyday life. -For example; High-T Superconductor is caused by atomic arrangement and not due to some exotic particle; and the brain is also caused by complex interaction (of electrical wave and ‘memresistive’ circuit), not some exotic physic.

    The underlying mechanism was soo complex, such that we can only see the surface, and what it does was like magic (literally).

  25. Sean says:

    Anthony @ 21: “No.”

    Thanks for commenting.