The Biological Relativity Of Time

This is not about Einstein's Relativity. There is another kind of relativity of time that does not get much attention. It could be described as the perception of how quickly, or how slowly, time passes. We tend to consider time as somewhat fixed but it is actually entirely relative.

Since the rate of falling by gravity is constant near the earth's surface, 32 feet or 9.8 meters per second squared, we can use this as an example of Biological Time Relativity. We perceive objects as falling at a certain rate, but this is very relative and dependent on our biological processes. 

There could be a creature whose internal biological processes move much faster than ours. The creature might live only a few weeks, by our perspective, but might see it's own lifespan as lasting what we perceive of as a hundred years. We would see the creature as moving extremely fast, while it would see us as moving extremely slow. 

The creature would see raindrops as suspended in the air like stars, and moving toward the earth's surface only very, very slowly. It would see the water in rivers as moving at a glacial pace, like we see slowly-moving ice floes. Though we would see it's lifespan as very short, it would see itself as living for a long time. The laws of physics wouldn't be different but everything would move much more slowly, because the biological perception of time is relative.

On the other hand there could be a creature whose biological processes moved much more slowly than ours. We might not even be aware of it as a living thing. The creature would only catch fleeting glimpses of us as we sped by. Night and day would seem like a flashing light show. Winter and summer would seem like the warmer and cooler parts of a day. But the very fast-moving universe all around would seem just as normal to it as our view does to us.

What it comes down to is the rate at which the creature's internal biological processes operate. What about what we consider as a "moment"? A moment has no exact definition but is the shortest fragment of time during ordinary thinking.

How about a "second"? A second is our shortest named interval of time. A second is roughly the same thing as a "moment", although a second is officially defined while a moment isn't. What is interesting about a second is that it isn't based on any natural process. Despite it's importance a second is an apparently arbitrary unit of time.

But what about our heartbeat? The heartbeat of the average fit younger person is about a second. It makes sense that our heartbeat ultimately defines time for us because it is the pace of our heartbeat that drives our biological processes, and thus our perception of time. Notice how our pace of breathing, whether during exertion or at rest, roughly corresponds to our heartbeat.

The rate that our heart has to beat to sustain life ultimately depends on the laws of physics, relative to our scale. But this means that other creatures might have completely different perceptions of the biological relativity of time than we do. If our heartbeat was faster we would see the world around us as moving slower, and if our heartbeat was slower we would see it as moving faster, although the laws of physics would be the same.

The same concept, of course, applies to distance as well as to time. We consider atoms as being extremely tiny and electrons as nearly infinitesimal. But that is just as much a matter of perspective, because we are made of atoms, as time. From another point of view atoms are on the scale of the entire Solar System, as we see it now, and electrons are as big as we perceive the moon.