Time

It is the most used noun in the English language, and the least understood.

What is time?

Time is not a physical quantity, it is a philisophical model that we apply to measure relationships between objects. It is a mistake to think that time exists, since it is a product of cultural understanding.

The Language of Time
Different languages and cultures have different sets of tenses and ideas of how time works, although most now adopt the Western notion of cause-effect time. For example the African Ewe language has no past tense. Very few Eastern languages have a strongly developed future tense; the concept of future was not part of the philosophy of Eastern thinking. Pacific peoples have stronger ideas on past - present - future.

Time is essentially a relative measurement between two positions.
For example the position of a clock arm relative to the position of an athlete. Digital clocks simulate the clock position by comparing the position of electrons relative to the substrate on which they act.

The Speed Time Myth / Twins Paradox
There is a common myth in time formulae that makes it appear as if time travels more slowly the faster you travel. The results of this myth come from measuring clocks at various positions from earth. However it is gravity that causes friction on the clocks ( at the molecular level) that causes them to run more slowly as they approach a large body like Earth. This phenomenon is incorrectly extrapolated to say that a person traveling in space will age more slowly than their twin on Earth, or that time runs faster on the top of a mountain than at the base. A clock may run faster, but a clock is not time.

Mathematical Myths
Another reason we think time exists is because we are taught things like
Distance = Speed * Time. And so mathematically Time = Distance/Speed. So time appears to be something real.
However mathematics does not dictate reality, for example
4s - 6s = -2s,
is a completely nonsensical but mathematically correct statement. Mathematics can only interpret reality, it cannot define it. If a mathematical formula passes through a region of 'nonsense' at any stage it should invalidate the result, even if it appears to compute. In some experiments the calculations show that time travels backwards, but only mathematically. In real life time is still passing at the agreed upon rate.

Why do we perceive time?
Increasingly it appears that our conscious minds observe our actions, rather than cause them. This time disparity means our brains are constantly reacting to changes in phenomenon, rather than cause-effect. Our brains are constantly collecting information, and comparing to previous information. The phrase "Time flies when you're having fun" has some relevance, because when you are doing something that is relatively new and exciting, ie fun, there is no comparison and time appears to speed past. But, when we perform repetitive actions time seems to slow down, because there is more and finer comparison.

Eternal now
We exist in an eternal now. I am writing this now, you are reading this now. You are not doing this in the past. You can never read or observe something in the past. Matter moves around, and we measure the matter and compare it to the data we have stored about the matter. By comparing different data sets we create this illusion of time. We gather these changes and use the change of one to measure the change of another.

The Time Machine
Were time to exist it should be possible to build a machine that detects the absence or presence of time. Some machines are built to detect fluctuations in gravity; time is often part of gravitational calculations so we may think time itself being detected.

Time Travel
Given that time is a product of our society and philosophy, traveling through time becomes an unusual notion.

Time is an important abstract shortcut to understanding the world, but it does not exist!