Tuesday, September 20, 2016

TIME 1 - Time under definition

Welcome!  This post is going to be a little philosophical, and challenge you a bit in reading.  The whole intent is to get you to just think a little bigger, and about something you know all about, but maybe it's too under your nose that you've never really thought about.

Half of critical thinking is thinking about something for which we ordinarily have an automatic response for ...

On Twitter I've been having discussions with a lot of other testers about how do you define things.  In many ways how we define things essentially shapes how we think about them.  An example of a bad kind of definition is one where you use the word you're trying to define within the defintion, an example came from an ISTQB slide "security testing: testing the security of a system".

GOOD NEWS - I'm not going to ask you to define testing.  Phew.

Instead -  take some time to think about how you would explain time to me.  Surely much simpler huh?  You constantly use it.  So describe it to me ... you can use the comment below if you'd like.







Okay?  How did we go?  It's actually pretty hard isn't it.

If your answer was something like "time is - hours, minutes, days, months, years?" or "as seen on a clock" - it's the start of a good answer, but a bit shallow.  Time is something we use a lot, we have a vague idea of it's rules, but describing it is really difficult.

Here's some definitions I came across ...

Wikipedia

Time is the indefinite continued progression of existence and events that occur in apparently irreversible succession from the past through the present to the future. Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as the fourth dimension, along with the three spatial dimensions.

Google tells me

the indefinite continued progress of existence and events in the past, present, and future regarded as a whole.

Webbsters dictionary has
(simple)
the thing that is measured as seconds, minutes, hours, days, years, etc.

(complex)
the measured or measurable period during which an action, process, or condition exists or continues


Some of those definitions help, some are probably right if you think about them.  As a physicist, I of course have a fascination with time, and so I've spent a few years thinking about it and how we use it.

My definition is fairly simple, elegant but it has consequences ...

Mike Talks' Definition Of Time

Time - a phenomenon which allows change to occur.

That is to say, without time, a system will remain in stasis.

It's pretty neat, and in many ways close to Webster's complex answer.  But as I said, there's consequences.

One of which for certain is that time is not directly measurable.  The other is that time may not actually exist ... certainly not as we think of it.

Okay - that's a big ask - so do check the date on this post, and confirm it's not April 1st.  I do have past form in trickery ... it isn't, and I'm serious.

By now, I'm hoping you're thinking about scrolling down to the bottom of the page, and typing something angrily into the comments.  Maybe something like "but I can measure time on my watch ...".



Thanks for bringing that up ... if you have a digital watch, then it's powered by a quartz crystal.  When this crystal is put under an electric charge - many would say that it vibrates 32,768 times a second.

And I'd have a problem with that.  Because we're not measuring and counting time - we're measuring and counting change.  In actual fact, when you measure 32,768 oscillations in a quartz crystal, you're at that point making a mark to say "I think one second has passed".

Let's revisit that shallow answer again ...

Remember we said a shallow answer to the question would be that "time is - hours, minutes, days, months, years?".

What is a day?  It's the length of time between consecutive midday (when the Sun casts the smallest shadow).  Or how long it takes for the Earth to rotate once.

What is a month?  Well, a lunar month is the time it takes between the Moon's relative phases.  Or how long it takes to orbit the Earth once.

What is a year?  The time it takes the Earth to orbit the Sun once.

Are you noticing that each of these is measuring a change, and giving the period a value which for you is a measure of the time that's?  Or in other words "this unit of time is when this much change has occurred".  Notice a pattern here?


Let's look at another consequence ...

If nothing is changing - time cannot be said to be occurring

If a system is in complete stasis, then you're not able to say that time is occurring.  This of course probably seems absurd to you.  You probably would say "I know it's passing", and apply logic by looking at something outside of the system to prove it - that "thing" outside of our system under observation is of course undergoing change (hands on the clock mayhap?).

Let's consider a hypothetical universe ... it's approximately the year one googolplex, and the Universe has ground to a halt.  It stopped expanding an untold time ago - the last star burned out billions of years before that.

The Universe is in a constant temperature of absolute zero, no planets orbit stars anymore, no galaxy moves.  There is no chemical reaction remaining, and even electrons inside atoms are stationary.  The Universe is exhausted of all energy, and remains unmoving.

How would you be able to tell that any time at all way passing?

You couldn't.  You'd have to introduce something to this universe/system like a watch, where change occurs.  But by itself, there seems to be no time passing, as there seems to be no change happening.

It's impossible to tell here if time exists or not.  Certainly without something to change, time becomes completely irrelevant.

[You might notice a certain familiarity here with the idea of the heat death of the Universe ... also it was used in the Doctor Who story Utopia]


That's quite enough today - next time we're going to play a bit more with this definition, and think about how we can test even more.




Now playing:  "The Logical Song", Supertramp



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