Time

I question whether time can exist and therefore whether it would be possible to travel in time. I've had this conversation with my mate before now. In a maths lesson. We never really decided.
My main point is that we invented time. Ages and ages ago it was decided that we needed a way to keep track of things and tell when we needed to meet up. We went on to invent things like minutes, hours and days to fill this space.
So I am basically saying that minutes and hours are totally made up as a way of measuring EXISTENCE, the same way metres and centimetres measure Length. In dinosaur times, velociraptors didn't think, I've been hunting all day, but more likely thought, I've been hunting until the blue turned to black. A cow doesn't think, I've been milked for hours, it thinks I've been milked until I'm empty.
I have to say it would be hard to do things without the time. Try and say something without using either present, past or future tense.
Through the assumption that time is a measurement, it goes to show that there can be no time vortex or rips in time or however you believe we can travel through time. The past is gone, the future hasn't arrived yet. I say just don't bother trying.
Of course, this is one of those things that get more confusing as you think about it. But feel free to comment.