Here is an interesting observation about time and how we measure time, that came to me the other day. If you look at the flow of time, time spontaneously moves toward the future. We cannot go back into time, except in science fiction. I can't go back into time and become a teenager again. I can only look forward to the future. The flow of time is unidirectional to the future and does not spontaneously reverse itself.

Based on this observation, what are clocks actually simulating, since clocks work in cycles. Each day my clock allows me to return to midnight which is not how time flows. Although we measure time we do so in a way that is not based on the flow of time.

One type of clock with a more accurate representation of the flow of time, would be an entropy clock. Entropy, like time, is also unidirectional and according to the second law will increase over time. Entropy moves to the future, like time and does not spontaneously return to the past. As an example of an entropy clock, consider the **fish clock**. With this entropy clock we take a fresh fish, of a certain weight, and place it on the counter top, at 70F. When we can smell the dead fish at 25 feet, this is a unit of time. We cannot un-stink the fish and therefore this clock not only measures time, but is consistent with the flow of time.

With the fish clock if we lower the temperature of the room, we can slow the flow of time. With the fish clock temperature works similar to relativity. If we freeze the fish, it will not stink for months; time dilation. The fish still moves to the future and does not cycle back, while slowing down.

So the question becomes, what are we actually measuring with clocks, since time does not move in cycles like clocks, but rather time is more consistent with the unidirectional nature of entropy and the fish clock?

One way to answer this question is to look at the sand dial. A sand dial measures time based on the flow of sand from an upper to lower chamber; hour glass. The sand dial is a type of entropy clock, since each time we flip the sand dial, all the thousands of grains of sand will never be in the exact place, again; time via entropy.

The sand dial has the practical disadvantage of needing to be flipped, each hour, to measure extended periods of time. Therefore to get a continuous measurement of time, with a sand dial, we need to add energy; flipping, for each cycle. Based on this, all clocks are time plus energy with the energy used to add the cycling of time, which is not how time flows.

If we had a science fiction time machine, we would need to add energy to the machine; flux capacitor, to go back into time. To alter the flow of of time away from unidirectional into a cycle we need to add energy. So when GR and SR slow time, according to clocks, it is not just slowing time but it is also doing something to the energy we added to time to make time cycle. GR and SR contain potential energy; mass and kinetic energy, with this energy impacting the energy added to make time cycle.