Space and Time.
Both meanings of Time are abstract (the dimension and the flow); Space can mean something abstract (the dimension) and it can mean something tangible (the space that we inhabit?). This causes problems; problems of vagueness and ambiguity. So we are asking again, what then is space? The assumption is that it is mostly definitely ‘real’. We all live in it, so it must be real.
And we’ve mentioned the impact of the term ‘fourth dimension’; how it hence confers time with attributes of objective reality that there is no justification for implying. Space-time is articulated from the use of time as an abstract framework (not a mass noun – it’s about measurement, referencing and indexing). It is used to identify time (as an index) in a space-time co-ordinate.
Or is it that people struggle to differentiate between a referencing framework, and the underlying concrete reality being referenced? It seems to me that Space simply references position, and it certainly does when we use the word in the context of a dimension,
In the context of dimensions then, space references position, i.e. the right-angled vectors of length, breadth and height allow us to relatively position two points. That’s all very simple and straightforward. Space is the dimension of (relative) position.
By definition, the dimension of space excludes time i.e. change. Space, like all dimensions, is reference frame specific. Space is the dimension of static position.
And if you merge the dimension of position (space) with the dimension of change (time) you get the dimension of motion (i.e. changing position). Space-time is the dimension of motion.
As a dimension, space-time is also reference frame specific, even if one of its references is motion.
Revelatory though Einstein’s’ theory of relativity – and hence his articulation of space-time – might be, it is still only a set of mathematic/geometric relationships; it is merely a mental model, albeit a complex one. It does not provide anything tangible; it merely explains how the relationship between tangible objects operates and how they interact. It no more expresses a proof or explanation of time (or space) than Pythagoras theorem proves the existence of triangles. For sure, it remarkably predicted hitherto unknown jewels of tangible reality (e.g. blackholes)….but that doesn’t make it ‘real’ itself.
So, two fundamentals of reality, position and change, are referenced by two abstract frameworks – space and time. And space-time is the amalgam of the dimension of position and the dimension of change. Space-time is the (compound) dimension of motion; and not a simple linear dimension.
It is time dilation that many people (of a physics countenance) point to as ‘proving’ the existence of time (or more usually, space-time).
Dilation is “the act of enlarging, stretching or becoming wider…” It hence infers this action is on a physical thing.
But time isn’t a physical thing, the evidence shows this. How does a non-physical ‘thing’ dilate. “But we know it does…” I hear the cries. “GPS calculations prove it daily…”. A very common response.
Time is abstract, and is NOT a universal tangible unity. If it was, that would mean it had a physical manifestation. What evidence of a physical manifestation is there? [Yet leading Theoretical Physicists still claim that time is ‘real’…again the question, what evidence of this tangible manifestation is there?] As we have said, all there is, is change.
Time (the dimension) is also reference frame specific, like all dimensions. And linear; we construct it on simple linear units of years, days, hours etc.
However, introduce motion, and you then must determine what your single reference frame is; (i.e. is it the man in the rocket, the man on earth, or the light beam bouncing up and down between two mirrors etc.)
Relative motion causes the ‘dilation’. Introduce motion, and space-time takes over. Space-time is non-linear (and complex, as Einstein showed). Motion makes this a complex framework – the complexity of dynamic geometry and the consequence of the limitations of the speed of light.
And if the relative movement isn’t constant, there is a higher dimension ‘on top’ of simple space-time; acceleration (Space-time-time perhaps). And there could be another on top of that for increasing acceleration (space-time-time-time). So, it soon gets complex.
Explaining the geometric complexity of space-time is way off the agenda for this piece. But recognising that it is the dimension of motion, and it is an amalgam, a complex, compound dimension is a simple step from the main point of this, which is to understand the nature of Time.
Time doesn’t dilate – it’s just that you’re moving the refence frame, and space-time is complex, even ‘warped’.
The misleading ‘fourth dimension’.
As we’ve already discussed, a dimension is a measure, a calibration, of something. Space (in the context of dimensions) is the dimension of position. It is always spoken about as three dimensions. It is actually a compound dimension that is calibrated by three simpler dimensions (i.e. height, breadth and depth) which really are better described as vectors.
And then Einstein comes along and talks about time as the fourth dimension. So what does everyone do? They all assume he means a fourth vector. In doing this it heavily infers that time could have applied to it the same rules as the vectors of length, breadth and height.
A final thought on this; people talk about ‘moving’ or ‘travelling’ through time. ‘Move’ is a spatial concept. You don’t ‘move’ through time, you change through time. You wouldn’t say ‘you move through temperature’ you would say ‘you heat up’.