Time as an invention
Time is something we talk about everyday yet it is difficult to define. If you flick through a book, you’ll notice that the book doesn’t have infinite pages. It has a beginning, middle and end. Humans possess a thing called a narrative bias; we make sense of the world around us through stories. To process the great amount of information coming our way, our brain creates a narrative to link the different inputs together. The brain then drops the other facts that do not fit in the story. This helps us retain and make use of information more efficiently.
We didn’t all of a sudden realize that time is the phenomenon that arises from daytime and night, or the change of the seasons. Instead, humans saw these different phenomena taking place and tried to make sense out of it –– the result of their system of making “sense” out of their surrounds was time. It was not discovered but invented.
It’s just a method for measuring the ‘perpetual change’. Because of our need to measure this perpetual change we decided to divide the ‘cyclic changes’ such as seasons and day and night, into months, twenty-four hours, minutes etc. People get sidestepped into believing time exists as a physical entity because we’ve invented clocks. Measuring it doesn’t prove its physical existence. This is just a comparison of events.
It has always been inextricably linked with the Sun. The ancient Egyptians and Babylonians used sundials that roughly divided daylight into 12 equal segments. 60-minute hours and 60-second minutes are the product of the ancient Mesopotamian sexigesimal (base 60) numbering system. The French attempted to use the decimal system (base 10 rather than 12), but that never caught on. The Greeks improved the sundial by marking gradations on sundials to indicate the divisions of time during the day.
Relativity and the Space-time Continuum
Time is inextricably related to space, so to understand it you need to understand space-time.
In his Special Theory of Relativity, Einstein states two postulates:
- The speed of light (about 300,000,000 meters per second) is the same for all observers, whether or not they’re moving.
- Anyone moving at a constant speed should observe the same physical laws.
Putting these two ideas together, Einstein realized that space and time are relative — an object in motion actually experiences time at a slower rate than one at rest. Although this may seem absurd to us, we travel incredibly slow when compared to the speed of light, so we don’t notice the hands on our watches ticking slower when we’re running or traveling. The closer an object gets to the speed of light, that object actually experiences time at a significantly slower rate.
The phenomenon – called gravitational time dilation – has been demonstrated by putting atomic clocks on jumbo jets and flying them at high altitudes. It also means that your head ages more quickly than your feet, that people living on the top floor of a tower block age more quickly than those on the first floor – and that time passes more slowly for people living at sea level than it does for those on mountains.
Just an illusion
There’s no such thing as “now” as far as physics is concerned. Space and time are fluid, affected by gravity and your speed. Einstein put it like this: “For us physicists, the distinction between past, present and future is only an illusion, however persistent.”
We’ve spent a lifetime believing that time and space are external realities. To place ourselves as their creator goes against every bit of our common sense, life experience, and education. It takes a radical shift of perspective for us to intuit the idea because the implications are so startling!
A deep understanding of this concept is essential if we are to ever solve the problem of time travel.