Isso soa como "By His Bootstraps" de Robert Heinlein , embora o homem original não exatamente "fique sozinho" no final.
Aqui está o início do resumo da trama da Wikipedia (acrescentei ênfase às partes que correspondem à sua descrição):
Bob Wilson locks himself in his room to finish his graduate thesis on a mathematical aspect of metaphysics, using the concept of time travel as a case in point. Someone says, "Don't bother with it. It's a lot of utter hogwash anyhow." The interloper, who looks strangely familiar, calls himself "Joe" and explains that he has come from the future through a Time Gate, a circle about 6 ft (1.8 m) in diameter in the air behind Joe. Joe tells Bob that great opportunities await him through the Gate and thousands of years in his future. By way of demonstration, Joe tosses Bob's hat into the Gate. It disappears.
Bob is reluctant. Joe plies him with drink, which Joe (a stranger, from Bob's point of view) inexplicably retrieves from its hiding place in the apartment, and Bob becomes intoxicated. Finally, Joe is about to manhandle Bob through the Gate when another man appears, one who looks very much like Joe. The newcomer does not want Bob to go. During the ensuing fight, Bob gets punched, sending him through the Gate.
Mais tarde, é revelado na história que os três homens são parecidos porque são o mesmo homem.
A história pode ser lida on-line no link .