Time is an illusion -- it doesn't exist!

Can you describe what "time" is? 

Time is merely a concept -- devised by certain races of somewhat intelligent. It is a concept that was invented to measure and compare synchronicity to some Known reference point. Without this known reference point, time does not mean anything -- It doesn't exist!

Time Vs Simple Universe

Let's make things simple. You were entering into a simple universe. In a simple universe, there would be -- nothing -- nothing at all, just you. The only way for you to tell "time" was by counting your breath. In and out, you counted one. In and out, you counted two: then three, four, five, and so on. The counting would go on such that you would be able to tell people outside how long you were in there. "I was in there for 1,478 breaths", you would say. Now, what happened if you fell asleep? How long were you in there? How long were you asleep? So, you, entering into that universe, you defined "time". Removing "you" from that simple universe, what was left, there would be "nothing" -- no "time".

Twins clock-makers 

Two identical clock-makers, twins, one of them accepted an invitation from an extraterrestrial to travel to a distant planet, decided to make 2 identical clocks. These clocks were highly accurate as they were built using atomic-variation technology -- their clocks were beating at exactly the same frequency -- on Earth. The departing twin promised to return when his clock produced 5,000,000 beats. He, then, left. How does anybody know if their clocks would remain synchronised? 

Sadly, the twins did not know about Einstein's Special Relativity theory -- timeframes of two moving bodies are always different -- one beat of the clock on Earth is not necessary equal to one beat of the clock outside the Earth.

Apocalypse Earth

Humankind had been flourishing for many ten thousands of years on Earth. With the detection of on coming killer asteroids, they must leave to seek a new home. However, some chose to stay -- hoping to rebuild Earth if humankind survived. There would be a long process of rise-and-fall of many civilisations before humankind was restored. They both agreed to build several monuments around the world to send a message to future generations that: that once there was an advanced civilisation of humankind. They need to note the date, a reference point in time. How? Sadly, they realised there was no way to tell the distant future of humankind -- how long ago they were once here. Then they realised something else more important. So they inscribed the message. It reads:

"Time is not important. What is important is Now."

Have you got anything important to do? When are you going to do it?