The arrow of time

I have not written a single Steemit post in an entire month due to the fact that I had been busy with both my exam and my student's. We are still waiting on his results, but I have passed all mine and cam say that I am done with year two! This is where I became interested in the theory of time...

What is time?

()

The earliest time measurement were observations of cycles of the natural world, using patterns of changes from day and night and season to season to build calendars. More precise time keeping like sundials and mechanical wrist watches eventually came along to put time in more convenient boxes. But what exactly is it that we are measuring?

Is time something that physically exists? Or is it just in our heads?
At first the answer seems obvious, of course time exists it constantly unfolds all around us and it’s hard to imagine the universe without it.
But our understanding of time started getting complicated thanks to Einstein.

()

His theory of relativity tells us that time passes for everyone but doesn’t always pass at the same rate for people in different situations. Like those traveling close to the speed of light or orbiting a super massive black hole.

Einstein resolved the vulnerability of time by combining it with space to define space time which can bend but behaves in consistent predictable ways.

Einstein’s theory seemed to confirm that time is woven into the very fabric of the universe but there’s a big question that it didn’t fully resolve…

Why is it that we can move through space in any direction but through time in only one? No matter what we do the past is always stubbornly behind us.

This is called the arrow of time.

When a drop of food coloring is dropped into a glass of water, we instinctively know that the coloring will drift out from the drop eventually filling the glass.
Imagine watching the opposite happen.

Here we’d recognize time as unfolding backwards. We live in a universe where the coloring spreads out in the water not in a universe where it collects together.

In physics this is described as the second law in thermos dynamics:

Systems will gain disorder overtime.

Systems in our universe move from order to disorder and it is that property of the universe that defines the directions of times arrow.