The ultimate topic when it comes to the philosophy of physics is the idea of time. In the most basic sense time is the measure of decay as everything succumbs to the entropy crawl forced upon us by the second law of thermodynamics. Arguably time will only stop when there is nothing left to decay and so no real meaning behind the word. Since the end is uncertain we can look at the origin. Time began at the big bang, to ask what there was before the big bang is the equivalent of getting to the north pole and trying to take another step north. To take a step north from the north pole you must be going south and in a similar way a time before the big bang is equally impossible. The use of time as the “fourth dimension” is also often misunderstood. Really anything can be put in as the dimensions, in common experience x and y are the common two dimensions. In real life we experience three dimensions of motion. In order to solve advanced equations theoretical physicists imagine time as a dimension to assist in topological evaluation.
The real question on everyone’s minds is of course the concept of time travel. An unfortunate fact is that although it can be imagined as a dimension travelling through it is likely impossible and is unlikely to ever occur. But so long as their confusing science fiction films about the subject it should at least be understood on a conceptual level. Mostly it just irks me when people criticise a piece of media my confusing the type of time travel present. I like to think of these two types as the Back To The Future time travel and the Harry Potter time travel. In Back To The Future, time can be seen as a straight line with any alterations in the past causing a diverging line to be broken off as the new timeline. This matches the idea of free will and that every choice we make alters our future. In Harry Potter the time line can never be altered. From the perspective of the present everything in the past already happened the first time, including the arrival of our heroes. This creates a nice solid loop in the timeline with no changes occurring thus fitting the idea of pre-determinism and a destiny we all have to fulfil. Both of these should not be confused with time unravelling such as in Groundhog Day where all of time moves backwards to a certain point and then progresses from there.
I think the human fascination with the past is rooted in the concept of hindsight. How we would all love to have a second go at practically anything in our lives even to improve just a little. But I think it is an equally reassuring thought that what has happened is fastened and there is no way to change it. Until tomorrow, goodnight.