Can physics tell us everything there is to know about the universe?

28 Feb

In the public imagination, physics is well on its way to giving a complete description of the fundamental nature of reality. From the scientific revolution onwards, the development of a rigorous experimental method has allowed continuous progress in understanding the nature of space, time and matter. Of course there is a long way to go; physicists have so far been unable to unify our best theory of the very big, i.e. general relativity, with our best theory of the very small, i.e. quantum mechanics. But at some point, it is supposed, these wrinkles will be ironed out and physicists will proudly present the public with the Grand Unified Theory of everything.

The trouble with this conventional wisdom is that physics, from Galileo onwards, has worked with a very austere vocabulary: its terms express only mathematical and causal concepts. Think about what physics tells us about an electron. Physics tells us that an electron has negative charge. What does physics have to tell us about negative charge? Rough and ready answer: things with negative charge repel other things with negative charge and attract other things with positive charge. Physics tells us that an electron has a certain amount of mass. What does physics have to tell us about mass? Rough and ready answer: things with mass attract other things with mass and resist acceleration. All the properties physics ascribes to fundamental particles are characterised in terms of behavioural dispositions. Physics tells us nothing about what an electron is beyond what it does. If the nature of an electron is exhausted by what physics tells us about it, then an electron is not so much a being as a doing.

More generally, physics provides us with mathematical models which capture the causal structure of the universe.  This is very useful information; it enables us to manipulate nature in all sorts of extraordinary ways, allowing us to build lasers and microwaves, and to fly to the moon. But mathematical models abstract away from the concrete reality of their subject matter.  A mathematical model in economics, for example, abstracts away from the concrete features of real world consumers, such as the nature of their labour and the specific things they buy and sell. Wherever there is mathematical-causal structure, there must be some underlying concrete reality realising that structure. But physics leaves us completely in the dark about the underlying concrete reality of the physical universe.

Contrary to popular opinion, the scientific revolution marks the point when fundamental natural science stopped trying to give a complete description of the universe, and instead focused on formulating useful mathematical models of its causal structure. This limited project has been extraordinarily successful, providing technology which has transformed our society beyond recognition.  Somewhere along the line this impressive record has created in the public mind the conviction that physics is providing us with a complete account of the fundamental nature of the universe.  But physics is successful precisely because it is aiming and succeeding at a much less ambitious task. The truth is that physics tell us nothing about the intrinsic nature of reality, never has done, and – so long as it continues to work with such an austere vocabulary – never will do. 

14 Responses to “Can physics tell us everything there is to know about the universe?”

  1. Tom May 15, 2014 at 8:20 am #

    Fascinating stuff. A couple of questions:

    1. Where (or maybe how) perhaps would suggest science start enquiring about the ‘what it is’ instead of ‘what it does’? Scientists always seem to tout the ability of science to predict accurately as its primary point of value over lines of enquiry like religion and philosophy. Forgive any ignorance on my part, but as I understand it, the scientific method will only ever give us results on how things behave, and isn’t it possible when entertaining the idea of fundamental particles that how it behaves is perhaps our only method of being able to describe what it is. A fundamental particle can’t be defined in reference to any constituent parts so it makes sense to define it in reference to its causal effects.

    2. Is this a widely discussed topic; could you recommend any further reading?


    • conscienceandconsciousness May 15, 2014 at 5:20 pm #

      Thanks for your comment Tom. Are you a Tom I know?

      1. My view is that the only insight we have into the intrinsic nature of the physical universe is via our immediate awareness of consciousness. At the very least we know that the intrinsic nature of our brains is in part constituted by consciousness. It’s meagre data, but on the other hand the existence of consciousness is more certain than any empirical postulation. I think we should build up our picture of the universe based on two sources of data: (A) empirical data, (B) introspective data concerning the existence and nature of consciousness.

      2. The motivation for this stuff is Bertrand Russell’s 1927 book ‘Analysis of matter’. Eddington also defended something similar. The view was completely forgotten about during the 20th century, but is currently enjoying a revival under name ‘Russellian monism’. Derk Pereboom’s ‘Consciousness and the prospects for physicalism’ is a great book, and Galen Strawson’s ‘Real materialism’ is a very vivid account of the view. I’m going to be blogging something on the connection to consciousness this month when I get round to it, but maybe have a look at the first section of my paper ‘The phenomenal bonding solution to the combination problem’ on my website

      David Chalmers has a couple of related forthcoming articles on his website:

      • Tom May 15, 2014 at 6:19 pm #

        Thanks for the swift response! No, I’m sure you don’t know me – I’m an undergrad at Liverpool studying philosophy and maths (so unfortunately I didn’t get to do Mind, Knowledge, and Reality this year).

        And thank you for the reading recommendations, I’ll certainly give them a look. After seeing a lot of ‘science vs philosophy’ debates recently this is a very interesting line of discussion I’ve yet seen referred to.

  2. conscienceandconsciousness May 15, 2014 at 6:53 pm #

    Glad you got something out of it! You may also be interesting the interview in which I talk about this stuff a few posts ago.

  3. James July 17, 2014 at 8:09 am #

    Well written piece, but there’s a lot of problems with the reasons you’re raising an eyebrow at “science’s“ ability to answer a question. I mean firstly it’s not physics that’s the problem; because physics is whatever the universe happens to be. It’s physicists not being smart enough that’s the problem. And i’d like to kindly ask people to stop referring to consciousness on this point because it’s vague, likely nothing to do with it and there’s no reason to believe it’s related. You’re asking what ‘matter’ is, rather than what its properties are. But what is it other than its properties? If you remove all its properties you’re left with nothing. Most of an electrons properties are pretty easily explainable, but some of it is currently arbitrary to us. We’ll find out one day, or we’ll find out we can’t find out one day. But the idea that you need to turn to some other kind of field of work to explain it isn’t really very relevant right now. Thank you. – Guy who was rude on twitter.

    • conscienceandconsciousness July 17, 2014 at 9:09 am #

      If you define physics as ‘the true science of reality’ (what you say above is a little confused, but I think that’s what you mean), then of course there are no limits to physics. But I think a more narrow definition captures the practice of physics from Galileo onward. The reason physics has been so successful is that from the scientific revolution onward it stopped trying to describe all the properties of matter, and just focused on describing its *causal* properties, i.e. what it does. So long as physics continues with the mathematico-causal vocabulary it has worked with the last 500 years, it will be subject to this limitation.

      My claim is not that there must be more to what matter is than its properties. My claim is that there must be more to what matter is that its *causal* properties, i.e. than what it does. It follows that physics does not give us the complete nature of matter.

      It could be that we’ll never know more about matter than what physics has to tell us about. Why should we think creatures evolved to survive not to do science can know everything? That’s consistent with the demonstrable point that there is more to the nature of matter than what physics has to tell us about it.

      I am however more optimistic about the prospects for a broader science that goes beyond physics. You say this is impossible, but you don’t give an argument.

      I didn’t mention consciousness in this post, so I’m not sure what you raise it.

  4. bobby July 17, 2014 at 8:25 am #

    when you call me a human on what grounds do you make that judgement? I would hazard a guess it’s related to my appearance and to my actions. These could be easily describes as traits or properties. This is also how we distinguish other entities such as electrons, they have recognizable traits. Also on the point about mass, mass is a properties attributed to particles due to their interactions with the Higgs field. so we can explain mass much better than you seem to think.

    • conscienceandconsciousness July 17, 2014 at 9:13 am #

      Thanks Bobby. Interesting points, but I’m unclear what bearing they have on their argument. My claims are (i) physics tells us nothing about the nature of matter beyond what it does, (ii) there must be more to what matter is than what it does.
      Can you help me out with why what you say constitutes a counterexample or response to these two claims?

      • bobby July 17, 2014 at 9:28 am #

        basically My point is in a nutshell, I’m a human specfically because of the observable properties that make me a human, if you can’t tell whether or not I’m a human, then you don’t know what I am, i.e. I’m human simply because of observable properties I exhibit. This point applies more widely, the idea that every is defined based on it’s properties, including non-physics things like cars and bikes. there are certain properties that we look for and if those properties exist we call the thing the name attributed to the definition. That is how definitions work. What it is beyond that doesn’t have any meaning in any context, as yet defined. The question is can you define something that doesn’t depend on the properties of the object you’re defining.
        Matter is energy, simply defined as the ability to do work (there are probably better definitions of energy). very simply, we get this from e=mc^2 , the energy mass equivalence . We also have a definition for energy so we are for the purposes of this done.

  5. bobby July 17, 2014 at 9:32 am #

    sorry, I read matter and jump to mass, ignore the second paragraph

  6. earwicker August 1, 2014 at 9:43 pm #

    Whatever effort we put into “giving a complete description of the universe”, there will remain the possibility that there is something we are missing.

    Indeed, if you are the sort of person who enjoys mysteries, and perhaps (maybe without realising it) regard your own humanity as possessing an intrinsic mysteriousness, which most people do, then however much explanation you are given for the universe you inhabit, you will insist that something lies undiscovered beyond, inaccessible to *whatever* mode of explanation had been employed.

    Suppose some revolutionary thinker comes along and produces a description of “the intrinsic nature of reality” which you find satisfying. You’re cured of all curiosity. But an unsatisfiable skeptic would demand to know why you were so satisfied. How would you know that it was really a description of the intrinsic nature of reality, and not just *another* model? What tricked you into accepting it this time?

    By positing the distinction between the limited aims of science and a hypothetical replacement method of enquiry that would describe reality itself to your satisfaction, you pretend that it would be possible to satisfy you – just not by method X. Only when method Y comes along, whatever that may be. But truthfully, it would be wildly inconsistent of you to ever be satisfied: why now? Why abandon your supreme scepticism in the face of the description given by method Y, but not that given by method X? What could possibly indicate that a description is the *ultimate* right one, the one that describes the “intrinsic nature of reality” and not just some analogous model that happens to correspond with nature with perfect accuracy as far as we can presently determine?

    And this is before we even get into speculating on what method of enquiry could discover anything about the universe without relying on observation and model building, prediction and more observation, i.e. the tools of science. If you don’t test your guesswork, you just have untested guesswork… best of luck with that.

  7. forrestjsschreick February 17, 2016 at 4:41 am #

    Fantastic piece. You said that physics never has and never can tell us about the intrinsic nature of matter. In the post-Galilean epoch, are we able to only build up an elegant picture of the intrinsic nature of matter or would we be able to empirically investigate it as well?


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