Time- Human Invention, or Part of Reality?

I was listening to another perspective on KQED today. A rather artsy hippy type talking about time, and specifically how it is a human construct built upon an agreement of the concept of time. This lead me to wondering, is time a purely human construct?

This wouldn't be too suprising, as so many things are human constructs (in my humble opinion). For example, color distinction (there's really a spectrum, discrete colors are human), God and religion, money and economy (sorta- interesting work has been done on primates, but hey they are like our retarded cousins), and fashion. Some of these things extend into the animal world, but typically they don't go very far (like I've never seen a croc with a hat, or banana slug accounting). Even our political system is a hierarchy that extends from the same alpha/beta/gamma/delta system you see in social species like the great apes troops, prides of lions, etc- but clearly the political construct is a reflection of our humanity.

So, why not time?

In some ways I agree with the lady. Take the international date line. Is it really a different day on one side of the line vs the other? No. Obviously you can't have half of your body in one time/space point, and the other half one day later but same time/space point...it just doesn't make sense. That line is a human construct that helps to mesh the human perspective (living on a rotating sphere with a big bright sun in the center of our solar system) with the very non-human ticking of the atoms that make us up. Hell, I'd go so far as to say that the second is a purely human construct. Think about it, a second is 1/3600th of an hour, and an hour is 1/24 of a day, and a day is 1/365th of a revolution around our sun...OUR SUN. That's the human bit. A space invader from alpha-centuri isn't going to know what the hell a second is, they'll know what a falkinboo is- that's 1/4598th of a bookinva, which is 1/45 of a revolution around alpha-centuri. Or it's how many times their baby farts in an hour, whatever. The point is that clearly there are some things wrt time that really are human.

But that about time?

Personally, as a scientist, I think that time is one of the few things that is not simply human. We have a time t=0 - um the Big Bang; and we have an absolute metronome- the cesium atom. There was a gun that started the race 13.7 billion years ago, and every time an electron zips around a cesium atom, there is a steady ticking to count off the time between the bang of the gun and where we are now. This is pretty much all that you need to account for time.

It all gets screwed when you throw in the beautiful wrench that is Relativity. Basically time is not constant and depends on the frame of reference. If the frame of reference is moving or is in a gravitational field (eg Earth/Sun), then atomic clocks will tick differently. This has been proven with GPS satellites. They cruise around in an orbit around the Earth, in a smaller gravitational field than we do down here on Earth's surface, and their on board clocks slowly go out of sync with the ones on Earth. Now consider the Big Bang itself. Imagine the crazy gravity fields and energies and velocities and crazy shit that must have happened in those first few thousand ticks. Who knows what time was doing in those quantum moments.

Perhaps 13.7 billion years isn't so black and white. Perhaps that atomic clock isn't so tick-tock.