Time – What is time? Time is, strictly speaking, not a dimension; so much as it is the rational ordering of events; It is an effect, an effect produced by the process of change.
Time is a mysterious amorphous entity whose presence is everywhere, yet its definition has eluded man ever since he started to question his understanding of the world.
So what is time? To determine that, we could start with defining what we know the Fundamentals of time. And yet, how can we determine the fundamentals of time, without defining what time is?
“Absolute, true and mathematical time, of itself, and from its own nature flows equably without regard to anything external, and by another name is called duration: relative, apparent and common time, is some sensible and external (whether accurate or inequable) measure of duration by the means of motion, which is commonly used instead of true time …”
Which seems to be a very sensible and concrete definition. It is something that agrees well with our own perception. That time flows equably, without regard to anything external, all we can do is to choose the background, or coordinate scale, against which to measure time. We can change the units we measure by, we can change their dimension but time moves inexorably on.
It is said, in a somewhat light-hearted way, that: “Time is what stops everything happening at once”; yet I would venture to declare that it is, in fact, the very opposite, that Time is created because changes don’t happen ‘in an instant’. Time is an effect of change.
Time Happens. It accumulates.
A Time Interval, is the temporal separation of two Events, that may, or may not, be at the same location.
A System is a set of interacting or interdependent components forming an integrated whole.
Any System has an Absolute time. That is the time measured from the start of that system. It stops at the end of that system. The Universe is one such system, where time began at the Big Bang.
Then time is being created by many systems at the same time, I hear you say, so what happens to it all?
The time created by each system is independent and created in parallel and can only be measured by comparison to other generated times.
And how is it absolute?
Because it can only be measured against another time. All times are measured against whatever timescale we choose.
And one time scale, the life of the Universe, encompasses all others. Every event occurs at one individual specific point on that scale.
So again What is time? A good question. For it is not easy to determine the fundamentals of time without defining what time is. Let us begin by examining what we do know about a strange entity that has a presence, with no physical form, yet is described as the fourth dimension.
How do we detect time? How does it interact with the physical world as we know it and with the other three dimensions?
Anything but an instantaneous change (if such a thing is even possible) has a duration. A period of time that lasts from the start of the process of change until the end of that change. Time is the label that we give to the interval between the start and the end of a change, or to the interval between Events.
(Remember; an Event is a specific point in space at a particular instant in time).
Whenever and however we measure time, we are measuring change. How long it takes to change from a ‘Before’ state to an ‘After’ state. Time is the Duration of that change.
If there existed a volume of Spacetime, of even a Spacetime, in which there were no change: a completely empty vacuum, not affected by any kind of radiation, for example; no time could pass within that volume.
(Think about it; if that space were visited at 1,000 year intervals, as measured by an outside observer, within that space nothing could have changed so, within that space, no time could be measured to have passed).
I believe it is valid therefore, to aver that time is generated by change. Intervals between Events are measured within a global or absolute time that has existed from the Big Bang since which there has been a single ongoing change – the expansion of the Universe.
If we keep two identical clocks, in identical systems, or in the same system, they would keep identical time. Viz. Einsteins First Postulate.
If we imagined them as the finest Swiss mechanical watches, or indeed as atomic clocks, it would mean that when synchronized, they would always read the same time but if one were to be set running slow then the time created by that clock would be less; e.g. it might read 59 secs when the other watch read a full minute. Or it could be stated just as correctly that one watch was running fast, reaching 60 seconds while the other read only 59 seconds. Each would be creating its own local time and standard or absolute time could be whichever time, whichever clock, we selected for our standard.
Time: that constitutes the intervals between events.
Event: a location in Spacetime; i.e. a point in space at an instant in time.
As Processes progress, so time accumulates.
The past cannot be changed, as it has already happened.
The present is where we are and it always will be, just where we are.
Future time does not exist, it has yet to be created.
Can time’s rate of progression vary?
Time is measured by comparison of the duration of a process against a standard. That standard may be one ongoing process of change, such as the expansion of the Universe, or it may be a count of a regular repeated change, such as an atomic clock. But all it is is a line along which events may be placed. All events then will have a specific place in that timeframe; time cannot run faster nor slower, for it defined by scale against which it is measured.
However time can be measured, to run faster or slower, for that is exactly what happens when a clock runs faster or slower, when a process is measured to run faster or slower due to the conditions under which those measurements are made.
The time created/measured by one clock would be a four dimensional Spacetime Sphere centred on the Origin of that clock’s Frame of Reference. And identically so, for any other clock.
Each clock would create Time according to its own dial, over the same period and, depending upon their accuracy, at the same rate!
So yes, time IS what is measured by a clock
Any time that we measure, however we measure it, is, in essence, only a comparison to a scale of measurement, in this case another measure of time, to another measure of ongoing or repetitive change; whether that be the slow background movement of the stars, constellations and Galaxies on the grand scale of our Universe, or the tiniest changes in a subatomic clock. Time is but a concept generated by change. Processes have duration. The speed of a process can change, subject to the conditions under which it happens, and we may measure different times depending on how, that is under what conditions, we measure it, but Time, as an individual entity, cannot vary because it is only a standard that we define to measure against.
Time is an effect created by change; It is no more than a measurement, against a scale.
Time does not pass at a rate, time cannot pass slowly or quickly. Time is merely something that is observed.
Processes may be fast or slow and this may affect the duration of an event; that is the time that has passed between the start and the end of a process, measured against some scale, but that does not mean that more or less time has passed, only how it is measured.
Only how many units of time have been counted, but the total amount of time measured is also dependent on the magnitude of those units of time.
Time is absolute. It may be considered to have started with the Big Bang and can, logically, be measured against the expansion of the Universe. Every event has happened at some point in that expansion of the Universe. At some point on a simple, single, straight-line scale. And each point marks how long after the Big-Bang that event occurred. If two events have the same separation from the Big-Bang then they must be simultaneous measured against the life of the Universe! It is as simple as that.
Different observers may perceive Time differently, but that is only because of the conditions under which they measure Time.
If we say that time passes more slowly when observed by a speeding observer, all we are identifying, is the interval in which a certain amount of change has accrued; i.e. How we measure that quantity of time. It is the processes of change rather than time that pass more slowly. And as we measure the passage of time by events (e.g. the ticking of a clock), then the clock will ‘tick’ more quickly (a shorter duration for each ‘tick’), that is more ‘ticks’ will be counted, when measured by a moving observer, giving the impression that more time has passed. The movement of the observer is affecting the measurement of time passing rather than the passage of time. It cannot be the passage of time, for that, when measured in the clock’s own Frame of Reference, is unchanged; and again, when measured against a wider scope, such as the expanding Universe, the same time will have passed.
This may seem like ‘nit picking’ the terminology; but it is much more than that, for it is bringing us into line with Minkowski’s Spacetime, where there is one time axis, one time dimension which is drawn as the vertical axis, the ordinate, in Minkowski diagrams with respect to the observer’s Frame of Reference in which the Observer is stationary. It is every other Frame that is moving and whose time axis is angled with respect to the drawn Frame; which reflects the changes to the scales against which the other Frame’s times are measured.