# On travelling through a void, constantly [closed]

I posted a question some time ago on how SR conceptualised space in the 'frame' of a photon - which appears as a kind of void - even though admittedly standardly its a move not allowed; but it was a picture I found intriguing.

Even more intriguingly, in Physics IV.8 where Aristotle turns over the notion of the void in different senses, he writes:

It is a fact of experience that the greater the impulse of weight or lightness things have, the faster (other things being equal) they complete a journey

So, he concludes

the same should be true for magnitudes travelling through the void; but this is impossible

for

why should one move faster than another? In a plenum one is bound to move faster than another, because the greater the object the faster it cuts through the medium with its strength, since the moving or projected object cuts through either with its shape or it's impulse.

And

it follows, that in a void everything will travel at the same speed, which is impossible.

Noticibly, and famously light and any other massless particle) travels at a constant speed - always.

This, at least for me, is intriguing - given the observation above; but also, a little further he writes:

Also, if the more a thing is rare and void, the faster it will move upwards, it is clear that nothing would move faster than something which is entirely void

One could say, a massless particle is void of mass ...

Though he notes

And yet how can void move or have a place? The place to where it moves would have to become void of void

(This might be an error of translation or ambiguity for one expects where void moves to becomes 'full of void' and where it's moved from 'void of void')

Has anything been made of these parallels about motion theorised two Millenia ago, and that observed of the constancy of the speed of light in the early 20C?

## closed as unclear what you're asking by Joseph Weissman♦Jan 3 '16 at 18:16

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• This is definitely interesting but I was trying to write the headline as a question and sort of got stuck -- any thoughts on how to frame it a bit more interrogatively? – Joseph Weissman Jan 3 '16 at 18:17
• @weissman: not sure - A was theorising motion, void, and plenum when all these notions were in flux; so it's not surprising that an argument was discovered which postulated a maximal speed with some account why this might be true; now that we have found that this is true, we can see that there was a line of argument that wasn't developed in the main tradition. – Mozibur Ullah Feb 2 '16 at 20:36
• It might be usefully seen as an analogue to Copernicus, who is generally given the credit for Heliocentrism; when we know it was also suggested in Antiquity. – Mozibur Ullah Feb 2 '16 at 20:38