Extraterrestrial Civilizations - Isaac Asimov [121]
But then we can, perhaps, short-circuit some of the difficulties of immortality by changing it to a temporary death followed by a resurrection, In other words, suppose we freeze the astronauts and place them into suspended animation, bringing them back to life only when the destination is in view.
Under such circumstances, the ship can proceed by coasting at low speeds, avoiding the disadvantages of speed-of-light travel, while the astronauts remain as unaware of the passage of time as they would in the case of time dilatation. To them, a voyage of thousands of years would pass in an eyeblink, and when brought back (it is to be presumed), they would not have aged perceptibly. In that way there would be no need for an inordinately reliable life-support system of the usual form; nor would there be the problem of keeping the astronauts occupied and unbored during the long flight.
There are obvious catches, though. The problem of freezing a human being without killing the person and then bringing about a successful revival is not a problem we seem (so far) to have much hope of solving.
Even if we could solve it, there might well be limits as to how long the frozen body could be kept with its spark of life intact. It might not be possible to maintain it throughout the long voyage between the stars. And if we could do that, then we would have to supply the ship with some foolproof system for maintaining the frozen state (a new form of life-support system) and for acting automatically to revive the astronauts at some appropriate moment. A device that can spring to life after some centuries of remaining dormant is not an easy thing to imagine.
The difficulties are enormous, and while we cannot insist that they will never be overcome given enough time, neither can we be certain that the problem will be solved inevitably.
Then, too, while the frozen astronauts are in suspended animation and, as a result, do not age, and are not aware of the passage of time, this is not true for the people back home who sent them off (unless the entire population of the planet undergoes freezing, which we may dismiss as ridiculous). This means that, exactly as in the case of time dilatation, the astronauts will return generations later and will experience a profound “future shock.”
In fact, even in the case of immortality, there would be difficulties. We might assume that if the astronauts are immortal, then the general population of the planet is immortal as well and that after the long trip the astronauts will return to report to the very people who sent them off long ages ago. But life is sure to have followed very different directions on the ship and on the planet, and the two groups of people are certain to be strangers to one another.
It seems quite likely that, under any circumstances so far mentioned, there will be no point to the astronauts’ returning home. Exploration of the stars would have to be undertaken on the understanding that the astronauts and the ships will never be seen again. Messages may be sent and received as the centuries and millennia pass, but that would be all.
The question, though, is whether, in that case, human beings would be willing to go into permanent exile. Or whether the home planet would be willing to undergo the expense of sending intelligent beings if all that will come of it are occasional messages received far in the future.
Might it not in that case be more economical, less difficult, and actually more productive, if automatic probes are sent to the stars? The astronomer Ronald N. Bracewell (1921–) suggested as early as 1960 that other civilizations might well have used this strategy.
We ourselves have taken this tack in connection with the planets. While astronauts have only been able to go as far as the Moon, automatic probes have landed on Mars and Venus and gone past Mercury and Jupiter. We have gained considerable knowledge as a result of these probes, and even if we were of the opinion that human exploration would be preferable,