I can only recognize time as the rate at which energy can change in the corresponding gravitational potential energy field. If everything which exists is comprised of energy, than time is the elapsing change of energy which is limited by the constant of the speed of light. Yet the rate at which energy can change (the speed of light) is determined by the medium of gravitational potential energy which it moves through. This gravitational potential energy is relative to the proximity of that environment to a gravity well (massive body). So therefore, as gravitational potential increases (move away from massive body), the rate at which energy can change increases. This means that the rate time is elapsing isn't really changing, but more energy is changing in an equal interval as you move farther from the massive body. This variation is minute for great ranges as gravitational potential energy only degreases slightly for a great distance as you move away from a massive body but it is none the less relative and not constant. Proof of this: A clock buried deep beneath the earth will run slower than another at the earth's surface. Why? With less gravitational potential energy (deep underground) all which exists changes at a rate slower in an equal time interval in comparison to that which is changing at the surface level gravitational potential. So, if energy changes at a slower rate, the underground clock runs slower and the clock at the surface reads 24:00 hours elapsed and the clock underground reads 23:59 at the exact same moment. Why does energy slow down as is moves from a high gravitational potential to a low one like near to a massive body? I believe all energy which moves over great distances acts like massive waves moving through an ocean. Take a tsunami for example; when the waves move across the deep ocean they are very spaced out and move at a very high speed. As the waves reach the shore they bunch up and slow down because the medium through which they are moving has changed. If gravitational potential energy is the ocean and energy is the waves, the velocity of the waves (energy) decreases as the ocean (GPE) gets shallower or lower in the case of GPE. So in other words, the waves of energy move faster in outer space and therefore the rate at which energy can change is greater than here on earth. This would make time appear to elapse at a faster rate out there (get older faster) than here. I have read that deep space communication transmissions will arrive at their destination slightly later than expected if they pass nearby a gravity well (massive body). I suppose this would confirm the concept. So in conclusion, if time is relative to the rate at which energy can change, than time is just a word because it is not constant anywhere at all.