Newton on the laws of nature and interstellar space

Since Space is Divisible in infinitum, and Matter is not necessarily in all places, it may also be allowed that God is able to create Particles of Matter of several Sizes and Figures, and in several Proportions to Space, and perhaps of different Densities and Forces, and thereby to vary the Laws of Nature, and make Worlds of several sorts in several Parts of the Universe.--Isaac Newton Opticks Query 31 

The quoted passages dates from the 1706 Latin edition of the Opticks and ended up in Query 31 of the later English edition. As regular readers know (recall here), I am rather fond of it, and I have explored the significance and implications of it also in my scholarly work (including writing with Zvi Biener here; and here solo). Because of a visit to Duke, and my conversations with Katherine Brading and Caleb Hazelwood while there, I had occasion to revisit the passage. 

Before I get to that let me offer some clarification on Newton's terminology for those of you who have never seen this passage before: the universe can (but need not) be composed of different worlds. Ordinarily, when Newton uses 'world,' he means thereby to refer to a solar system. Newton recognizes that the universe could be composed of different worlds that coexist (in the General scholium he remarks [recall] on the beauty of the night sky to aliens in other worlds)! A 'system of worlds' is a collection of solar systems (we would say, a 'galaxy') that, presumably, share in a uniform motion or frame of reference.

But Newton also uses 'world' in a metaphysically richer sense. A world in this richer sense is constituted and characterized by the kinds of “particles of Matter” and forces that are to be found in it. The matter and forces of a world can be described by laws of nature. Newton's attitude toward matter and forces is realist in that they are part of his basic ontology; matter and forces ground the laws of nature, which are derivative from them: note Newton's "thereby."

In fact, as an aside, at the start of the Principia, Newton notes that the "basic problem of philosophy seems to be to discover the forces of nature from the phenomena of motions and then to demonstrate the other phenomena from these forces." So, the ontological priority of forces (and matter) is reflected in his epistemic aims. 

The passage quoted at the top of this post suggests that Newton's laws are not primitive or productive in the sense that, say, Maudlin's treatment of laws implies (recall). In my work with Biener, especially, I have tried to explain how we should think of the metaphysics of laws according to Newton (short version: it's complicated). But in what follows I want to make a further suggestion about what we might call the extension or locality of the laws of nature.

For Newton, at every point of space, there is time and God, and places that might be filled by matter. (Conversely, there are space and God at every moment of time.) But there are also enormous number of otherwise empty spaces, some enormous. Now, we can discern in Newton treatment of four kinds of empty spaces: first, there are (interstitial) empty spaces within bodies. Second, there are empty spaces among (planetary) bodies within worlds. Third, there are vast empty spaces between solar systems. Fourth, there are enormous empty spaces between galaxies. (I think this is the doctrine of the Principia, but Newton did not always think this because he sometimes experimented with aether theories.)

Now, according to the doctrine that I ascribe to Newton based on the passage quote at the top of the post, the properties of bodies, and their forces of interaction generate the laws that govern them. How to think about the grounding relation between laws and the bodies they describe, I leave to others. (In fact, Caleb Hazelwood is circulating a fascinating paper about this.) On my view (see here), and also (say) David Miller Marshall (here), the Newtonian laws really are about interactions of bodies or systems of bodies (in which they are grounded).

So, here comes the pay-off of this discussion. It follows from these features of bodies, forces and laws, that on Newton's views the laws can be said to be present in interstitial spaces. They are also present in the spatial voids within and between solar systems. You may wonder, given the view I am sketching here, why I am so confident this is so between solar systems for Newton. However, on his view light easily and rapidly moves between solar systems, and we know that for Newton light rays themselves are composed of particles (with mass). Moreover, on his view solar systems tend to be part of a galaxy  which follows a uniform motion or has a general frame of reference.

I do not mean to suggest that all the laws of nature that exist in a galaxy are also always present in the vast voids that occupy the spaces of a galaxy. It's possible, after all, some kinds of bodies that can be found in parts of a galaxy are, in principle, unable to move among different solar systems. Notice, that lurking here is genuine lack of knowledge how many kinds of bodies there are in the universe and so how many kinds of laws will be discovered. Newton knew that he was making all kinds of homogeneity assumptions (this was explicit in hypothesis 3 of the first edition), and he also knew that the evidential basis of his claims was limited to a small speck of vast space.

So, on the view that I am sketching here, there need to be no laws of nature present in the vast empty spaces or darkness among galaxies (that is, the fourth kind of spaces). So, for Newton it's possible the total universe is rather dappled (in Nancy Cartwright's sense). Of course, in so far as light also may move among galaxies there may be considerable possibility for uncovering unified laws. (Brading teased me that on my view, as bodies move into empty spaces the laws of nature are simultaneously extended--which I find a lovely implication..) But that's an open question. (Zvi Biener and I argue that methodologically, within physics research, Newton assumes universal laws until there is evidence otherwise. But that's a different register.)

One final thought. Often discussions of Newton assimilate his views of laws of nature to Descartes. In Descartes, the laws are kind of second causes and are universal in scope. The issue I have sketched here does not arise there because, in principle, all bits of matter of the universe are indirectly in contact with each other (and are either part of a universal vortex, or mediate among large solar vortices). Spinoza grasps the significance of this picture with a beautiful treatment in a justly famous letter to Oldenburg (that I suspect shaped Leibniz's metaphysics non-trivially):

all bodies are surrounded by others, and are mutually determined to exist and operate in a fixed and definite proportion, while the relations between motion and rest in the sum total of them, that is, in the whole universe, remain unchanged. Hence it follows that each body, in so far as it exists as modified in a particular manner, must be considered as a part of the whole universe, as agreeing with the whole, and associated with the remaining parts. As the nature of the universe is not limited, like the nature of blood, but is absolutely infinite, its parts are by this nature of infinite power infinitely modified, and compelled to undergo infinite variations. 

While in my writings I tend to bring Newton rather close to Spinoza, it should be clear that on the view sketched here, Newton cannot endorse this lovely picture.

 

 

 

Comments

[Marco van Heugten]

From a more Spinozian point of view it's impossible to agree with 'there need to be no laws of nature present in the vast empty spaces or darkness among galaxies (that is, the fourth kind of spaces).'

Nature includes all. Universe(s), galaxies, 11 string-dimensions, they're temporarily, modi. All moves within God. Because there can not be a perfect vacuüm of Substance no 'empty spaces' are excluded from God and all the laws of Nature, that would be absurd. There is no grounding in negation. Spinoza has more eternalism. What begins and/or ends isn't God or Nature, or Being, or Will, or Self-Cause. No preference for the theological big bang universe(s) as metaphysical ground with dead in it's eye. Just for Natura Naturans no entropy. Only modi are and always will be too insufficient and dependable to be eternal. As Descartes, Newton is in conflict with his personal god (who for Spinoza is political). The only laws of nature that can be 'extended' are the ones we know of and they can not be the deepest, a priori unmeasarable Laws: self-causality is absolute and permanent, no 'second law' there.

I agree that Newton is likeable in his fantasia, as is Pascal, a very readable existentialist. Have you read the young Kant? Silly cosmology maybe leads to silly grounded ethics. Spinoza didn't read the Spinozism of Leibniz but would disagree: the attributes are not dual but points of view on the same; this can not be parallel. God is the undivisible causa immenens and not transiens, I confirm, 'maybe with all the old philosophers too'.