You could spend forever trying to find the perfect wash cycle for a mix of cotton and woollen socks. If instead you note that the two are different, you can easily find a suitable wash cycle for cotton socks, and one for woollen socks by experimentation. Time is the same.
1. Consecutive Time.
This is the most fundamental type of time. Universal time, if you like. It is bluntly, the succession of events. One event follows another. This is a good general definition if anyone interrupts you during your cornflakes and asks you to define time.
Scientists would want to measure it, and find a universal time constant, the smallest amount of time, but that misses the point. To measure something it has to be digital. Analogue things have to be measured differently, in useful chunks, or defined (hertz). Consecutive Time is different. It is a definition that one event follows another, but not a measurement of it.
We cannot measure a 'smallest' amount of Consecutive Time because it doesn't exist (scientists hate that). You could only do that from outside of the universe, so for now lets call it impossible.
Consecutive Time is important as it makes other laws of time easier to deal with, and is an absolute guarantee that 'time travel' backwards cannot happen. Ever. [Actually time travel cannot happen in either way, but its easier to fake it forwards.]
What about the speed of light etc? Well, light travels as fast as it's design determines it should, as does sound, and anything else. We think light is the fastest thing out there because of how we measure the speed of things, and because of the limits of our perception. Other things may be faster, and we may be able to make things go faster. The speed of light is not a boundary to a law of time, just something measured by us, using our ways of measuring time.
2. Personal Time and the Perception of Time.
Personal Time is a lot easier. We carve up time using various criteria, seconds, hours etc. These are useful measurements, and objective (or rather objectivised) in their own way, but this isn't Personal Time. Personal Time is time relative to our perception. We have our own semi-objective time measurement, our bodyclock, which is used to regulate our biology, but can be fooled by non-biological stuff (air travel, not washing powder, unless you snort it).
As we grow up, we come to terms with Consecutive Time, and develop our perception of time. Our bodyclock is probably genetically programmed, and we develop an understanding of the year, the seasons, and time passing. This continues to develop as we age, and alters to accomodate biological issues like puberty and old age. There may be a direct link between growth spurts during puberty and a desire for fast perception (rock and roll, computer games, fast cars etc).
This is how our bodies and minds cope. Now to get scientific, lets start with something easy: time travel. We can't travel backwards due to the fundamental nature of Consecutive Time, and without seriously screwing with our mind (hypnosis) we cannot alter our perception of time, travelling backwards. Here, we have locally been taken back to a past occurence, say in therapy, and are cheating our perception.
Perception of time travel forwards is easier, our biology does it to us regularly: sleep. You go to sleep, you wake up, you have no perception of time passing, but it has. You have effectively travelled in time. Freeze your biology for 2 centuries and you can physcially transport yourself to another time. Take too many drugs and your body starts to lose its ability to regulate itself. You may lose your ability to perceive time in a way your mind can cope with, as you would on an acid trip.
What about objective, scientific issues related to time? Well, it is all still perceived time, but we set up an external bodyclock and call it GMT. We can measure things against this, but it still fails us. All that stuff about time slowing down and gravity warping it, sorry Einstein, but it doesn't wash. The only alternatives to Consecutive Time are time as we individually perceive it, and an externalised personal time using a clock.
When we see time apparently stand still near a black hole, it is just a temporal illusion. This is because we are only measuring our externalised perception of time, so it is little more than one step removed from an optical illusion. If we could go there, we could see, just as we can by walking a distance and seeing that the tree wasn't smaller than the lollipop, it was just a trick of perspective.
So time is very simple, if we accept our own temporal position, much as astronomy became simpler when we accepted that the earth went round the sun.
Copyright August 2000.