Time is an ever present concept in the human soul. All cultures throughout history have had a concept of time and a fascination with its linear nature. No matter what we do we can’t go backwards in time and we seem stuck stumbling forwards with no ability to see where we’re going and only able to know where we’ve been. For a physicist time is defined as the direction of increasing entropy (or if you want to be fancy the direction of increasing information). Entropy itself is a concept that is hard to understand often poorly described as a measure of disorder in a system; but then no adequate description of “disorder” is given or why molecules in a gas are more disordered when spread around a room then when they all huddle in a corner (an event that is extremely unlikely but possible). The best definition of disorder that I can give is as follows:
A measure of the number of ways a certain amount of energy can be distributed among a certain number of particles with the most disordered being the most likely combination of particles and energy packets.
This means that if you have 7 particles with 4 units of energy you could be left with 1 particle containing all 4 units and 6 with none (7 combinations); 1 particle with 3 energy units, 1 particle with 1 energy unit and 5 with none (42 combinations) and so on. In the end there are 105 ways that the combination 1 particle with 2 energies, 2 particles with 1 energy and 4 with none can be created and so this is the most likely event and contains the most disorder.
Hopefully this has made the topic of entropy, one of the most confusing in physics, a bit more understandable. Until tomorrow, goodnight.