Reconciling our subjective experience of the flow of time with the fact that there is no flow of time, or any distinction between the past, present, or future in the fundamental laws of physics is perhaps one of our biggest challenges. If time is static, as is suggested by our best physical theories, why does it seem to flow as if it's dynamic? And if time flows, why doesn't science confirm that? Why does the universe seem to conspire against us? Physicist Gene Tracy gives us some insight, from his article in Aeon, A Science Without Time. I've kept its original font because it came out looking so good on my site.
It’s possible that our experience of the flow of time is like our experience of colour. A physicist would say that colour does not exist as an inherent property of the world. Light has a variety of wavelengths, but they have no inherent property of ‘colour’. The things in the world absorb and emit and scatter photons, granules of light, of various wavelengths. It is only when our eyes intersect a tiny part of that sea of radiation, and our brain gets to work on it, that ‘colour’ emerges. It is an internal experience, a naming process, an activity of our brain trying to puzzle things out.
So the flow of time might be a story our brain creates, trying to make sense of chaos. In a 2013 paper, the physicists Leonard Mlodinow of Caltech and Todd Brun of the University of Southern California go even further and argue that any physical thing that has the characteristics of a memory will tend to align itself with the thermodynamic arrow of time, which in turn is defined by the behaviour of extremely large numbers of particles. According to this theory, it is no puzzle that we remember the past but not the future, even though the microscopic laws of nature are the same going forward or backward in time, and the past and future both exist. The nature of large systems is to progress toward increasing entropy – a measure of disorder, commonly experienced as the tendency of hot or cold objects to come into equilibrium with their surroundings. Increasing entropy means that a memory of the past is dynamically stable, whereas a memory of the future is unstable.
In this interpretation, we are unable to see the future not because it is impossible to do so, but because it is as unlikely as seeing a broken window heal itself, or as a tepid cup of tea taking energy from the atoms of the surrounding room and spontaneously beginning to boil. It is statistically extremely, extremely unlikely.