h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've been thinking recently and have come to a conclusion. Time can stop or end. Its all to do with how we define time. There are the three arrows of time, The cosmological, the thermodynamic and the Physiological. The cosmological arrow is the direction the universe is expanding and not contracting, the thermodynamic arrow is the way entropy (disorder if you like) is increasing and not decreasing, and the physiological arrow is the way in which we percieve time to pass (for instance we remember the past but not the future.
Now If the universe is at the critical mass it will eventually stabalise and stay at a constant volume. This will allow entropy to increase untill it can increase no more (this is asumming that the universe keeping a critical mass doesn't stop entropy from increasing). When this happens then both the Thermodynamic and cosmological arrows will have stopped. By this time there will be no complex molecules (because of there being no 'order') let alone intelligent life to remember the past, so you that arrow of time will have stopped also.
However this provokes the question "How can time stop?" There must either be another definition of time or we will have to accept that time can stop.
You will notice the I use the word 'can' rather than 'will'. This is because at the moment only about 10% of the critical mass has been accounted for, so at the moment the universe is expected to increase infinitly because there is not enough mass in the universe to stop the expansion