The Curvature Of Space-Time Reconstrued Through Systemic Functional Linguistics

Davies & Gribbin (1992: 84):

Einstein realised that tidal forces cannot be transformed away by changing the reference frame — they represent a genuine effect of the gravitational field at work. He reasoned that if the effect of these forces is to stretch or distort the distances between freely falling objects, then the most satisfactory description of tidal gravitation is as a distortion or stretching of spacetime itself. That is, rather than regard gravity as a force, Einstein proposed that we regard it as a curvature or warping of spacetime.

Blogger Comments:

To be clear, gravity is the relative contraction (not stretching) of space intervals due to the presence of matter. The tidal bulges on the Earth and the Moon are manifestations of the fact that the space intervals between the two bodies are relatively contracted. On the other hand, gravity is the relative expansion of time intervals — the time interval between each tick of a clock is expanded — such that processes unfold relatively more slowly.

So while it is true that gravity is, in this sense, a warping of spacetime, it is neither the stretching of space, nor the curvature of spacetime. What gravity curves is the geodesic trajectory of a body through space, not the three spatial dimensions through which it moves, nor the dimension of time along which the process unfolds.

The Gravitational Curvature Of Light Reconstrued Through Systemic Functional Linguistics

Davies & Gribbin (1992: 81):

If the acceleration of a falling elevator, plunging downwards at an ever increasing speed,  can precisely cancel the force of gravity, thereby producing weightlessness, then the gravitational force and the inertial force produced by the acceleration are equivalent to one another. …

Imagine being in that falling elevator and watching the path of a light pulse crossing the elevator. In the reference frame of the falling observer the light travels in a straight line; but this means that from the point of view of an observer standing on the ground the light path must curve downwards [i.e. falling with the elevator]. The latter observer would attribute the curvature of the light beam to the effect of gravity, so Einstein made the prediction that gravity bends light.

Blogger Comments:

To be clear, it is the geodesic that gravity curves: the shortest trajectory that light takes through space. Physicists routinely confuse this curvature with a curvature of space-time. The reason why the geodesic is curved is that spatial intervals are contracted in the direction of the centre of mass, relative to other directions, so the shortest distance between two points is towards that centre of mass.

Special Relativity On Past, Present And Future — Through Systemic Functional Linguistics [3]

Davies & Gribbin (1992: 77):

In one reference frame events B and A are simultaneous: event B occurs at 'the same moment' as event A. In another frame, it is [a later] event B' that is simultaneous with A.

If A is somebody's 'now', which event, B or B' can uniquely be described as happening 'now'? The answer is neither. There is a whole range of 'present moments' including B and B', and any definition of 'now' is entirely relative.

By changing one's state of motion, the choice of simultaneous events can be altered, perhaps by hundreds of years! Any attempt to argue that only 'present moments' are real therefore seem doomed: time must be stretched out, like space, so that past, present and future exist with equal status. 

Blogger Comments:

From the perspective of Systemic Functional Linguistic Theory, 'now' is the time of construing experience as meaning. If event A is somebody's 'now', and if event B' is later than event B, then event B happened in the observer's past, and event B' happened later in the observer's past (or in the observer's present). In this view, therefore, it is an error to claim that there is a whole range of 'present moments' including B and B'. Moreover, it is not the definition of 'now' that is relative, but the 'now' itself.

By changing one's state of motion, what is altered is the time interval between the time of observing and the time of the observed event. 'Present moments' are thus "real", but in the sense that they are the times of construing experience as meaning, as in the act of observing. Time is 'stretched out", but in the sense that it extends as a dimension: the dimension along which processes unfold. 

By the same token, past, present and future do not "exist" with equal status, since events in the past have happened (past in present), events in the present are happening (present in present), and events in the future are going to happen (future in present).

Special Relativity On Past, Present And Future — Through Systemic Functional Linguistics [2]

Davies & Gribbin (1992: 76-8):

To understand why this is so, you must first appreciate that your now and my now are not necessarily the same. This is because, as we have seen, the simultaneity of two spatially separated events is entirely relative. What one observer regards as happening at 'the same moment' but at another place, a second observer, located elsewhere, may regard as happening before, or after, that moment. … An event on a distant galaxy which we judge to be simultaneous with noon today in a laboratory on Earth can be shifted by centuries, from your point of view, if you happen to change your reference frame by boarding a train.

These ideas have a profound implication. If the 'present moment' elsewhere in the Universe depends on how you are moving, a whole span of 'presents' must exist, some of which will lie on what you regard as your past, some in your future, as seen by different observers. In other words, moments of time cannot be things which 'happen' everywhere at once, in which only the unique present is 'real'. Rather, time is extended in some way, like space; which particular event any given observer regards as happening in the mysterious moment of 'now' is purely relative.

So does the future, in some sense, already exist 'out there'? Might we be able to foresee events in our own future by changing our state of motion? … But it turns out that you cannot travel fast enough to see into your own future.

Blogger Comments:

From the perspective of Systemic Functional Linguistic Theory, the 'present moment' is the time of construing experience as meaning. Because light takes time to travel, observers who see an event in a distant galaxy see, in their present, events that happened in their past — congruently expressed as 'past in present' tense ('has happened'). What varies for different observers moving at different velocities is the duration between the observation and the event in the distant galaxy.

To be clear, moments of time are not things that 'happen'. Time is the dimension along which processes unfold, and it is in this sense that time is 'extended'. Processes are not observable until they unfold.

Special Relativity On Past, Present And Future — Through Systemic Functional Linguistics [1]

Davies & Gribbin (1992: 76):

This unified four-dimensional spacetime description has proved highly successful in explaining many physical phenomena, and is now the accepted view of the physical world. Powerful though it is, it has removed from the picture any vestige of a personal 'now', or the division of time into past, present and future. 

Einstein once expressed this point in a letter to a friend regarding the subject of death. 'To us who are committed physicists,' he wrote, 'the past, present and future are only illusions, however persistent.'

The reason for this is that, according to relativity theory, time does not 'happen' bit by bit, moment by moment: it is stretched out, like space, in its entirety. Time is simply there.

Blogger Comments:

From the perspective of Systemic Functional Linguistic Theory, four-dimensional space-time does not conflict with the division of time into past, present and future, because the latter is concerned with construed temporal locations and extents relative to the 'now' of meaning-making: saying or sensing.

From the perspective of Systemic Functional Linguistic Theory, time does not 'happen bit by bit, moment by moment', processes 'happen bit by bit, moment by moment', and time is 'stretched out' and 'simply there' in the sense that it is the dimension along which processes unfold. The confusion of time with process pervades the discourse of physics.