Periods, Intervals and Events


A period is a slippery idea. It is defined in various, straight-forward ways:- as a quantity of time, or as a round of time, or an interval of time. This seems simple enough, surely.

But as we don’t know what time is, how meaningful are these simple definitions?

Well if we can’t define period in terms of time (because we don’t know what time is) how do we define it?

A period must have a beginning and an end. And these two events (the beginning and the end) are the determiner of the period. So the beginning event, the period and the ending event form a discrete set. And, for that set, there is no change between the first event and the last (there can’t be, there are only two events in this set). So time is irrelevant to this set, UNLESS and until you calibrate the period using an external calibration (e.g. the earth’s rotation). But this external calibration confers no intrinsic “Time” on the period. The set (event one, period, event two) is static and hence timeless until an external calibration is imposed around it.

In other words, for a discrete object set (the set to whom the beginning event and the end event belong), period is irrelevant – when this set is viewed in isolation (e.g. our static object above). There is nothing between the beginning of the period and the end, by definition. Time is therefore meaningless.

It’s only when you calibrate this gap between the two events by reference to an external event-series that it is given a “quantity” definition; and even then this quantity definition confers no impact or intrinsic quality on the discrete set itself. ‘Time’ only matters to the external event-series – it’s just a relative calibration exercise.

It’s accepting the idea that period does not have a universal application, that it refers only to a discrete set, and is hence isolated from external “time” until this is referenced which is the hard part to grasp here.


The same conundrum occurs for interval as for period. In fact interval can be defined as the period between two events. There is an implied assumption that two events must have an interval between them. But for a specific object in a closed environment, where the object hasn’t altered state (i.e. changed) between the two events (and it hasn’t else we would reference the intermediate event) then there is no interval (i.e. no time lapse) UNTIL an external calibrator references the interval. Time doesn’t ‘exist’ in the closed environment if there is no change, and change happens at events. Hence between two events, when nothing is happening, time doesn’t have anything to measure, so it doesn’t ‘exist’.

It’s only when the environment is opened up, and external changes are referenced, and hence calibration appears, that the non-event period of the initial closed object is then measured by reference to external change.  We could say that time is allowed to ‘infiltrate’ the closed environment.

This is a crucial notion in the understanding of time. Take the example, say, of a rock, formed millions of years ago. And it has sat, unchanged (assume no weathering) for millions of years. Has time passed for it? Well, no, it hasn’t. For the rock alone, time has not passed. Sure, the earth had spun on its axis several million times, so yes there has been many events that have happened in the world around the rock. So in relative terms we might say ‘time has passed’ or more accurately we mean external events have happened around the rock. But for the rock on its own there has been no ‘time passage’ – nothing has happened to it. It is indistinguishable from the rock a million years ago. Time is only relevant when the events of the world outside are used to measure against the rock itself.

This means there is no such thing as interval, when we talk about a single object (the rock) alone. Time is irrelevant to a single object between its own events.

The reason this is crucial is that this dismisses the need for a ‘universal time’. People suppose that although the rock has been unchanged for millions of year, the ‘passage of time’ is proven because the two events (the formation of the rock, and ‘now’) have an interval.

Well, they don’t – only external events create (i.e. calibrate) the ‘interval’. Universal time (as a concrete phenomenon) ceases to have any meaning – only events matter.


Period (or interval) is dependent on a discrete set composed of an event, a gap and another event. So we are seeing that time is merely an expression, one way or the other, of events happening; without events there is no time.

The word ‘event’ can only refer to a single object (the object to which the event happens, clearly). The event might have multiple consequences, but the object of the event is singular (e.g. if a bomb explodes; the consequences could be multiple, but the event, the explosion, only happened to the bomb).

And, as we’ve already said, an event happening means change happens. If no change happens, it’s not an event.

This would lead to the observation that ‘time passing’ actually refers to events happening. If events don’t happen, time doesn’t pass. (There is an issue discussed later about how can we make the assertion that time ‘passes’ if we don’t know what time is – ‘passing’ is a poor word to use, common though the phrase is).

Every time one single thing in the universe changes – one tiniest quantum event – this brings about ‘time passing’ (relatively) for every other object in the universe. Time passing for a single object is simply the relative calibration of other events happening elsewhere.

It is also worth considering that although an event can only be referenced to a single object, the object could be a composite object, i.e. an object made up of many smaller component objects. So, for example, the Earth spinning is a (continual) event happening to the Earth.  The Earth is obviously a composite object – it includes all the sea, the land, the billions of us, the trillions of molecules that make it up etc. But the event references the Earth only, the composite, singular object. So when we talk about a discrete set, it might be that the set includes composite objects – it doesn’t necessarily mean referring to a quantum set.

Events and change

Event and change are very related words. If change doesn’t occur (at an event) then did an event occur? Well, as mentioned earlier, it is possible to reference a notional event, such as ‘now’, but essentially, an event is the marking of change. From the section above on interval, if interval has no meaning in a closed environment, then event and change become synonymous.

It’s only when an event to event gap is measured or calibrated against the outside world that ‘event’ and ‘change’ then mean slightly different things. Change, or change-rate, includes the external measurement of the interval.