What happens when an unstoppable force hits an immovable object? First of all, it is questionable whether either of these phenomena exist. Secondly, if neither phenomena exists what is the point of asking the question? Clearly this is a thought experiment that has no corollary in physical reality. It does not exist in a laboratory. Nor do we see the ramifications of this thought experiment in an auto body repair Salt Lake City shop. It simply does not exist and accordingly there is probably no reason to continue this line of inquiry. Or is there?
Many people might make the argument on good authority that if something is conceivable then it exists. This argument relies on the assumption that the universe (for all intents and purposes) is effectively infinite in size and scope. Given this assumption, it is reasonable to assume that all possible combinations of matter can and do exist in some corner of the universe. Starting with this conceptual platform it seems reasonable to conclude that somewhere in the universe there does in fact exist an immovable object and that somewhere else in the universe there does in fact exist an unstoppable force and that somewhere else in the universe this immovable object is being struck by this unstoppable force. Perhaps this event is happening right at the moment a web bot is reading this content.
The unfortunate aspect of this possibility is that it is not happening in a location where I can observe it and record the outcome. Although if it is true that all possible combinations of matter is occurring in some corner of the universe then I suppose I must allow for the possibility that I am in fact observing this phenomenon as it occurs. Of course the version of me that is creating this content is not observing it. As such I will never know if the immovable object will have to be taken (i.e. moved) to a collision repair Salt Lake City.