Tuesday, December 02, 2008

Newton, Leibnitz and the (non?)existence of spectrum

My argument that spectrum doesn’t exist [see Note below for a recap] has deeper philosophical roots than I’d realized.

As I learned in a lecture on the Philosopher’s Zone podcast my contention parallels an argument between Leibnitz and Newton about whether space and time have an independent existence. Here’s Graham Priest, Professor of Philosophy at Melbourne:
“In the 17th century, there was a famous debate between Newton and Leibniz about the nature of space and time. And this was the question they focused on: Could you pick up the whole physical cosmos and move it five miles to the east and put it down? Or, could everything happen exactly the same way it does now, except all half an hour later? Newton said Yes to both those questions; Leibniz said No. Because Newton said space and time are kind of like buckets and it makes sense to suppose that the buckets have a certain kind of reality, and the contents just hang in there. So space is something, it will be there even if there were no events in space and time. And time likewise. So space and time have a certain kind of self existence, they don't depend on anything.

“Leibniz said this: No, it doesn't make any sense to suppose that you could lift everything up and move it five miles to the east, or that things could have started five minutes later. Because nothing would really have changed. Space and time aren't kind of big buckets that you put things in. Space and time are nothing more than the interned relationships between the events that happen in space and time. So if all the relationships, the befores and afters, the lefts and rights, if all those are the same, then nothing's changed. So if you moved everything supposing you could, five miles to the east, all the spatial relationships would have remained the same. So nothing would have changed. So if you have this view of the nature of space and time, then space and time do not have the same kind of self existence, ontological existence that they have for Newton.

“In the jargon of Buddhist philosophy, Newton thought that space and time had self existence. They were there independently of anything else. But for Leibniz they did not, they were just things in a system of relationships which kind of support each other by a system of relationships.”

Source: Why Asian philosophy? (podcast and transcript), The Philosopher’s Zone, 18 October 2008, a program of ABC Radio National.
Wikipedia’s article on the philosophy of space and time includes a paragraph on the Leibnitz/Newton debate. The question of whether or not time and space exist independently of the mind leads, in this case, to either the “absolutist” position that they are real objects themselves, or the “relationalist” position that they are merely orderings upon actual objects. Wkipedia summarizes the positions as follows:

Leibniz describes a space that exists only as a relation between objects, and which has no existence apart from the existence of those objects. Motion exists only as a relation between those objects. Newtonian space provided the absolute frame of reference within which objects can have motion. In Newton’s system the frame of reference exists independently of the objects which are contained in it. These objects can be described as moving in relation to space itself.

This notion of space and time as big buckets that you put things in reminds me of the dominant metaphor for spectrum: it’s like space, and often a container. (Blog post: De-situating Spectrum: Non-spatial metaphors for wireless communication. Papers: Imagining Radio: Mental Models of Wireless Communication; De-situating spectrum: Rethinking radio policy using non-spatial metaphors.)

When it comes to spectrum, I’m a relationalist. Frequency has no existence apart from the existence of electromagnetic radiation, and therefore there is no spectrum resource separable from the operation of radio systems.

Note: Why “spectrum doesn’t exist”

I contend that the term “spectrum” as commonly used doesn’t have any meaningful referent. It typically occurs as a synonym for frequency or a frequency band, as in “the service is in UHF spectrum”. However, frequency is simply a marker; spectrum aka frequency has no existence independent of the measured radiation. It therefore doesn’t make sense to talk of a “spectrum resource”.

Use of the term in the dictionary sense, to refer to a distribution of electromagnetic radiation (as in “the spectrum of that transmitter”) is rare. In this sense a spectrum exists when a radio transmitter is on, but not when it’s off. Again, “spectrum as a resource” isn’t meaningful.

The only arguably meaningful definition is that “spectrum” means “wireless operation”. This is the only way I can make sense of a term like “spectrum license”; it’s a license to operate a radio in a given way. However, few people use the word spectrum in a way that suggests they have “wireless operation” in mind as a synonym – though they may end up with this definition when pressed.

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