Quantum mechanics, not antimatter. That's the "many worlds" interpretation of quantum theory; it's probably not in itself actually a "theory", in the sense that it's not testable. Trying to think too hard about this stuff is the quick route from physics to epistemology; the latter is an interesting place to visit but I wouldn't want to live there.There are also anti matter theories that state that when you make a decision between various choices, that on another plane, you are making all the other choices as well.
Well, the thermodynamic kind of entropy sort of argues that time *isn't* "just" a human construct, it's a property of physical systems; at least the "arrow" nature of time is. Relativity says time isn't as synchronized as it looks at the human scale, quantum mechanics says the far end of the arrow isn't as predictable as it looks at the human scale, but the basic concept of time (best defined, I think, as "time is what keeps everything from happening all at once") seems to hold together as a "real" thing, at least inasmuch as we can call anything "real".For some reason I love this stuff.... time may just be a human construct to make us feel some comfort but really it's far more complicated than our limited senses can comprehend.
I submit that this discussion isn't even off-topic, in that photography is fundamentally about (the illusion of) defying time by turning temporary light into permanent light. As such, anything that can be said about time should lead to something that can be said about photography.
The many-worlds interpretation has obvious similarities to multiple exposures. Exercise for the reader: What tools does the photographic vocabulary have to address relativistic time dilation?