Impossible?
Already we could assemble a space-ship piece by piece while in orbit round a planet. Yet even this assembly work will become unnecessary in less than two decades, because it will be possible to prepare the giant space-ship for launching on the moon. Besides, the basic research for the rocket propulsion of tomorrow is in full swing. Future rocket motors will mainly be powered by nuclear fusion and travel at nearly the speed of light. A bold new method, the feasibility of which has already been shown by physical experiments on individual elementary particles, will be the photon rocket. The fuel carried on board the photon rocket enables the rocket's velocity to approach so close to the speed of light that the effects of relativity, especially the time dilation between launching site and space-ship, can operate to the full. The fuel supplies will be transformed into electro-magnetic radiation and ejected as a clustered propulsive jet with the speed of light. Theoretically a spaceship equipped with photon propulsion can reach 99 per cent of the speed of light. At this speed the boundaries of our solar system would be blasted open!
An idea that really makes the mind reel. But we who are on the threshold of a new age should remember that the giant strides in technology which our grandfathers experienced were just as staggering in their day: the railways, electricity, telegraphy, the first car, the first aeroplane. We ourselves heard music in the air for the first time; we see colour TV; we saw the first launching of space-ships and we get news and pictures from satellites that revolve around the earth. Our children's children will go on interstellar journeys and carry out cosmic research at technical faculties in the universities.
Let us follow the journey of our imaginary space-ship, whose goal is a distant fixed star. It would certainly be amusing to try to imagine what the crew of the space-ship did to kill time on their journey. Because however vast the distances they covered and however slowly time might crawl along for those left behind on earth, Einstein's theory of relativity still holds good. It may sound incredible, but time on board the space-ship travelling barely below the speed of light actually passes more slowly than on the earth.
If the space-ship travels at 99 per cent of the speed of light, only 14-1 years pass for our crew on their flight in the universe, whereas 100 years go by for those who stay at home. The difference in time between the space travellers and the people on earth can be calculated by the following formula, given by the Lorentz transformations:
----
[Insert pic p023]
(t = spacet-travellers' time, T=time on earth, v= speed of flight, c= speed of light).
The speed of the space-ship's flight can be calculated by the bask rocket equation worked out by Professor Ackeret:
[Insert pic p023a]
(v — velocity, w = speed of jet, c = speed of light, t = fuel load at launching).
----
At the moment when our space-ship is approaching the star which is its target, the crew will undoubtedly examine planets, fix their position, undertake spectral analyses, measure forces of gravity and calculate orbits. Lastly they will choose as landing-place the planet whose conditions come closest to those of our earth. If our space-ship consists solely of its pay load after a journey of shall we say eighty light years, because all the energy supplies have been used up, the crew will have to replenish the tanks of their space-craft with fissionable material at their goal.
Let us assume, then, that the planet chosen to land on is similar to the earth. I have already said that this assumption is by no means impossible. Let us also venture the supposition that the civilisation of the planet visited is in about the same state of development as the earth was 8,000 years ago. Of course, this would all have been confirmed by the instruments on board the space-ship long before the landing.
Naturally our space travellers have also picked on a landing site that lies close to a supply of fissionable matter. Their instruments show quickly and reliably in which mountain ranges uranium can be found.
The landing is carried out according to plan.
Our space travellers see beings making stone tools; they see them hunting and killing game with throwing spears; flocks of sheep and goats are grazing on the steppe; primitive potters are making simple household utensils. A strange sight to greet our astronauts!
But what do the primitive beings on this planet think about the monstrosity that has just landed there and the figures that climbed out of it? Let us not forget that we too were semi-savages 8,000 years ago. So it is not surprising when the semi-savages who experience this event bury their faces in the ground and dare not raise their eyes. Until this day they have worshipped the sun and the moon. And now something earthshaking has happened: the gods have come down from heaven!
From a safe hiding-place the inhabitants of the planet watch our space travellers, who wear strange hats with rods on their heads (helmets with antennae); they are amazed when the night is made bright as day (searchlights); they are terrified when the strangers rise effortlessly into the air (rocket-belts); they bury their heads in the ground again when weird unknown 'animals' soar in the air, droning, buzzing and snorting (helicopters, all-purpose vehicles), and lastly they take flight to the safe refuge of their caves when a frightening boom and rumble resounds from the mountains (a trial explosion). Undoubtedly our astronauts must seem like almighty gods to these primitive people 1
Day by day the space travellers continue their laborious work and after some time a delegation of priests or medicine men will probably approach the astronaut whom their primitive instincts tell them is the chief in order to make contact with the gods. They bring gifts to pay homage to their guests. It is conceivable that our spacemen will rapidly learn the language of the inhabitants with the help of a computer and can thank them for the courtesy shown. Yet although they can explain to the savages in their own language that no gods have landed, that no higher beings worthy of adoration have paid a visit, it has no effect. Our primitive friends simply do not believe it. The space travellers came from other stars, they obviously have tremendous power and the ability to perform miracles. They must be gods! There is also no point in the spacemen trying to explain any help they may offer. It is all far beyond the comprehension of these people who have been so terrifyingly invaded.
Although it is impossible to imagine all the things that might take place from the day of landing onwards, the following points might well figure on a preconceived plan:
Part of the population would be won over and trained to help search a crater formed by an explosion for fissionable matter needed for the return to earth.
The most intelligent of the inhabitants would be elected 'king'. As a visible sign of his power, he would be given a radio set through which he could contact and address the 'gods' at any time.
Our astronauts would try to teach the natives the simplest forms of civilisation and some moral concepts, in order to make the development of social order possible. A few specially selected women would be fertilised by the astronauts. Thus a new race would arise that skipped a stage in natural evolution.
We know from our own development how long it would take before this new race became space experts. Consequently, before the astronauts began their return flight to earth, they would leave behind clear and visible signs which only a highly technical, mathematically based society would be able to understand much much later.
An attempt to warn our proteges of dangers in store would have little chance of success. Even if we showed them the most horrifying films of terrestrial wars and atomic explosions, it would not prevent the beings living on this planet from committing the same follies any more than it now stops (almost) the whole of sentient humanity from constantly playing with the burning flame of war.