The popular view that physics has shown everyday reality to be an illusion is deeply flawed. Understanding how macroscopic phenomena emerge helps dispel this myth, writes Alexander Franklin.
Popular science often tells us that we are radically deceived by the commonplace appearance of everyday objects and that colour and solidity are illusions. For instance, the physicist Sir Arthur Eddington distinguished in 1928 between two tables: the familiar table and the scientific table, while the former is solid and coloured, the scientific table “is nearly all empty space”. Eddington then makes the striking claim that “modern physics has by delicate test and remorseless logic assured me that my second scientific table is the only one which is really there”.1
The idea that everyday objects are not really there is, of course, nonsense! There are few claims of which I am more certain than that the chair on which I’m currently seated is solid and brown.
The contradiction between these two sets of views prompts two questions, which we’ll explore in this article: why do some thinkers claim that we are radically deceived about everyday reality? And, given that they are mistaken, how is it that the nature of the objects that we can see and touch emerges from the very unfamiliar particles that make them up?
Eddington then makes the striking claim that “modern physics has by delicate test and remorseless logic assured me that my second scientific table is the only one which is really there”
The implication of claims like Eddington’s is that familiar objects are in some significant sense illusory, but how could that be? The philosopher Susan Stebbing critiques Eddington by noting that whenever we make the claim that some object is real, we do so in contrast to some illusory object, like an artificial apple: “It is quite sensible to contrast this ingenious fake with a ‘real’ apple, for a ‘real’ apple just is an object that really is an apple and not only seems to be one”.2 Unlike with artificial apples, it is misleading to claim that familiar tables are illusions. One could, sensibly, claim that some specific table has illusory properties – say it was coated in the highly light-absorbing material Vantablack and so its contours were obscured – but it is meaningless to claim that all tables and, worse, that all familiar objects aren’t real.
1 – Illusory properties: wrinkled aluminium foil with a portion – equally wrinkled – coated in Vantablack3
[It is, therefore, an error to claim that we are radically mistaken about the properties of everyday objects. When I claim that my chair is solid, I am surely right, as long as it continues to support my weight and prevent my falling through it. Likewise, in the absence of hallucinations or optical illusions I can be very confident in correctly discerning the colour of the objects around me.
I am opposing the view that the world deceives us as to the true properties of familiar objects and that much of what we think we observe are illusions, that my chair is really neither solid nor brown. Let’s call advocates of this view ‘Illusionists’.
The mistake that the Illusionists make is the assumption that everyday objects have just the same features as their fundamental constituents – so, if their constituents are colourless they infer that the object itself must also be colourless; any apparent colour is then written off as an illusion. This can be called the ‘Lego principle’. The idea is that physical objects, like objects made of Lego bricks, are such that if you take them apart they are just like their constituents. So, the pieces that make up a Lego dinosaur will be hard and colourful with various different small circular knobs on horizontal surfaces and smooth vertical surfaces. And, while the dinosaur will have a different shape from its components, it will inherit their colour and hardness.
I am opposing the view that the world deceives us as to the true properties of familiar objects and that much of what we think we observe are illusions
Illusionists assume the Lego principle applies to more than just Lego: they think that everyday objects should have similar properties to their parts. Eddington should be considered an Illusionist in this sense. The atomic theory of matter tells us that atoms are nearly all empty space – the nucleus is as tiny relative to the atom as a fly is to a cathedral. On that basis, Eddington supposed that his table is also “nearly all empty space”. Likewise, he would suggest that, since my chair is made up of lots of parts that lack solidity and colour, the chair itself cannot possibly be solid and brown.
The best response to the Illusionists is to deny the Lego principle and accept that the relation between the properties and features of fundamental particles and those of everyday objects is far more subtle and complex. The brownness and solidity of my chair are not illusory, they are real. To say otherwise is an abuse of language: to give another example in support of Stebbing’s point – if I were to claim that my chair is nearly all empty space, this would suggest that it is hollow, or has the structure of Swiss cheese. However, my chair is solid, and the fact that its atoms are, in some sense, rather empty, does not undermine its solidity! The right question is: how do these features of the chair emerge out of the underlying non-brownness and non-solidity of the particles that make up the chair? That question is addressed by the Emergentists.
In contrast to the Illusionists, Emergentists accept that my chair really is brown and solid. They then have a much more difficult challenge: how do everyday objects gain such features while these are lacked by their constituent parts?
Let’s think about how my chair holds me up and consider a small part of the complex array of processes, features, and mechanisms responsible for that. Like many scientific inquiries, there are many ways to proceed. One way to go is to think about how the chair is held together – so, if my chair is made of wood, we would need to think about the screws that connect the pieces and the fibres that underlie the structural integrity of each piece. A wonderful aspect of this kind of investigation is that it prompts a long chain of further questions concerning how each sub-part of each part of my chair is held together. What this demonstrates is that the subject matter of all the sciences is beautifully interconnected. A question as seemingly straightforward as one about how my chair holds me up can, with the right degree of perseverance, take us from an inquiry into the organic processes that make wood so robust, down to the strong nuclear force which holds the quarks together in the atomic nucleus!