“Do you see how our previous theories of time travel have been wrong? We expected to be able to step into a time machine in, say, 2004, set it for fifty years back, and then step out in the year 1954… but it does not work that way. The machine does not move in time. Only whatever is within the machine is affected, and then just with relation to itself and not to the rest of the Universe.
“I confirmed this with guinea pigs by sending one six weeks old five weeks back and it came out a baby.
“I need not outline all my experiments here. You will find a record of them in the desk and you can study it later.
“Do you understand now what has happened to you, Norman?”
You begin to understand. And you begin to sweat.
The I who wrote that letter you are now reading is you, yourself at the age of seventy-five, in the year of 2004. You are that seventy-five-year-old man, with your body returned to what it had been fifty years ago, with all the memories of fifty years of living wiped out.
You invented the time machine.
And before you used it on yourself, you made these arrangements to help you orient yourself. You wrote yourself the letter which you are now reading.
But if those fifty years are—to you—gone, what of all your friends, those you loved? What of your parents? What of the girl you are going—were going—to many?
You read on:
“Yes, you will want to know what has happened. Mom died in 1963, Dad in 1968. You married Barbara in 1956. I am sorry to tell you that she died only three years later, in a plane crash. You have one son. He is still living; his name is Walter; he is now forty-six years old and is an accountant in Kansas City.”
Tears come into your eyes and for a moment you can no longer read. Barbara dead—dead for forty-five years. And only minutes ago, in subjective time, you were sitting next to her, sitting in the bright sun in a Beverly Hills patio …
You force yourself to read again.
“But back to the discovery. You begin to see some of its implications. You will need time to think to see all of them.
“It does not permit time travel as we have thought of time travel, but it gives us immortality of a sort. Immortality of the kind I have temporarily given us.
“Is it good? Is it worthwhile to lose the memory of fifty years of one’s life in order to return one’s body to relative youth? The only way I can find out is to try, as soon as I have finished writing this and made my other preparations.
“You will know the answer.
“But before you decide, remember that there is another problem, more important than the psychological one. I mean overpopulation.
“If our discovery is given to the world, if all who are old or dying can make themselves young again, the population will almost double every generation. Nor would the world—not even our own relatively enlightened country—be willing to accept compulsory birth control as a solution.
“Give this to the world, as the world is today in 2004, and within a generation there will be famine, suffering, war. Perhaps a complete collapse of civilization.
“Yes, we have reached other planets, but they are not suitable for colonizing. The stars may be our answer, but we are a long way from reaching them. When we do, someday, the billions of habitable planets that must be out there will be our answer… our living room. But until then, what is the answer?
“Destroy the machine? But think of the countless lives it can save, the suffering it can prevent. Think of what it would mean to a man dying of cancer. Think…”
Think. You finish the letter and put it down.
You think of Barbara dead for forty-five years. And of the fact that you were married to her for three years and that those years are lost to you.
Fifty years lost. You damn the old man of seventy-five whom you became and who has done this to you… who has given you this decision to make.
Bitterly, you know what the decision must be. You think that he knew, too, and realize that he could safely leave it in your hands. Damn him, he should have known.
Too valuable to destroy, too dangerous to give.
The other answer is painfully obvious.
You must be custodian of this discovery and keep it secret until it is safe to give, until mankind has expanded to the stars and has new worlds to populate, or until, even without that, he has reached a state of civilization where he can avoid overpopulation by rationing births to the number of accidental—or voluntary—deaths.
If neither of those things has happened in another fifty years (and are they likely so soon?), then you, at seventy-five, will be writing another letter like this one. You will be undergoing another experience similar to the one you’re going through now. And making the same decision, of course.
Why not? You’ll be the same person again.
Time and again, to preserve this secret until Man is ready for it.
How often will you again sit at a desk like this one, thinking the thoughts you are thinking now, feeling the grief you now feel?
There is a click at the door and you know that the time lock has opened, that you are now free to leave this room, free to start a new life for yourself in place of the one you have already lived and lost.
But you are in no hurry now to walk directly through that door.
You sit there, staring straight ahead of you blindly, seeing in your mind’s eye the vista of a set of facing mirrors, like those in an old-fashioned barber shop, reflecting the same thing over and over again, diminishing into far distance.