There are no necessary conditions in the physical world. If you hadn't turned on the light, perhaps someone else would have. Or perhaps a bird or a meteorite could have flown through the window and struck the switch in just such a way as to turn it on. Or perhaps a wire could have come loose inside the switch and fallen in just such a way as to close the circuit.
Sure there are necessary conditions in the real world. It is a necessary condition for the apple to hang on the tree, for it to fall from the tree onto Newton's head.
By arguing there are no necessary conditions you are essentially saying we can't use mathematics to describe nature and there are no laws of physics.
For the apple to fall on Newton's head? It could have been dropped by a passing swallow (or possibly two, held on a line between the dorsal guiding feathers).
For it to fall from the tree? Well, that's a linguistic trick; for it to fall from the tree it must have been hanging on the tree, so that necessary condition is actually a tautology.
Physics describes a world with statistical regularities, not absolute laws. Even a clockwork Newtonian universe is not time-reversible; it has multiple pasts that can lead to the observed present.
It's not a tautology to say for an apple to fall of a tree it has to be on a tree, it's not a tautology for a plane to crash to be flying first or for a car to stop it needs to be in motion first. They are all necessary conditions, in fact this is the definition of a necessary condition.
Something to be a necessary condition has nothing to do with time-reversibility, it simply states a logical relationship
Let me give you another example: To accelerate a body with mass m it is necessary to exert a force onto it. All mathematical descriptions In fact equivalency, requires conditions to be necessary and sufficient.
Your argument that physics describes a world with statistical regularities is a maybe a nice philosophy, however most physicists (and regular people) do not believe we live in a simulation, but physical laws describe the real world.
Yes; a simple example is Norton's dome. It is possible to construct a frictionless curve such that a particle that is pushed up the curve with correct initial velocity will reach the top and halt in finite time. Observing a particle sitting at the top of the dome, there is no way to tell when it reached that point or from which direction.
I think it is hard to answer this without reducing the real world into something it may not be. What constitutes an event in the real world? Is the universe discrete or continuous? Do we really use mathematics to describe nature, or do we use it to model and approximate some properties of it?
