It is also important to consider that when a person, an apple, or anything else goes back in time, as mentioned above, it ceases to persist into the future, following the time from which it left for the past. This represents something of a four-dimensional zero-sum game. In other words, if we enter a spinning disc and go back in time to meet an earlier version of ourselves—despite their now being two copies of us in the past—there are no longer any copies of us directly following when we left to visit ourselves in that past. So even though there are now two versions of the same person existing
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