The Principle of Maximal Aging - Capturing the Essence of Relativity

Take a number. Take a second number. Add both together to produce a third. Again, add the last two numbers to produce the next. Repeat ad infinitum.

What can be more boring?

Call it irreversibility, call it time's arrow, call it the second law of thermodynamics. Fact is that everything evolves in such a way that things get more messy. Disorder rises. Entropy increases. We do not observe the opposite happening. Heat flows from from hot to cold, not the other way around. Fluids mix but don't unmix. Shattered pieces of crystal don't reassemble into a vase.

An article in the latest (August 2009) edition of Scientific American describes an astronaut floating motionless with respect to his distant spaceship. He is not tethered to the spaceship and has no objects available that can be hurled away or can in some other way create a thrust.

How is he ever going to make it back to his spaceship?

When Albert Einstein constructed his general theory of relativity he decided to resort to some reverse engineering and introduced a 'pressure' term in his equations. The value of this pressure was chosen such that it kept the general relativistic description of the universe stable against the gravitational attraction of the matter filling the universe.