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course will demand a bigger area on the ground.
The possibility of getting the solar energy directly in
this way is impressive, but the technical difficulties
would be very formidable indeed. Apart from all the
ordinary difficulties of big engineering projects, the chief
would probably be that it would be necessary to con-
centrate the heat from a good many square yards on to a
rather small focus, for it is only so that the heat losses
could be avoided which would destroy the engine's
efficiency; and this must somehow be done in spite of
the sun's motion all through the day, and its different
height at different times of year. Deserts, where the
sun always shines and there is no rainy season, would
be the best places for solar engines. The power would
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only come in daytime, and this would be less incon-
venient than tidal power, but still it would be nearly
essential to be able to store it. Altogether it would
be a tremendous undertaking. There may of course
be discovered other ways of getting energy out of
sunlight; for example, there may be chemical processes,
which would imitate those of the vegetables, but more
efficiently. There is also the possibility of getting the
energy photo-electrically, that is to say by causing the
light directly to make electric currents. At present
this is a hopelessly inefficient method, but it cannot be
excluded that some new idea might make it feasible,
and then it would probably be the best of all. Of all
the possible ways of collecting energy, the direct use of
sunlight is the most promising.
Finally, it may well prove that the various devices
discussed above are all of them too complicated and
troublesome to be really practical, and that it is best to
exploit the method used by nature, the vegetable. There
would have to be vast plantations, producing potatoes
or some such plants in enormous quantities, which could
be made into industrial alcohol for power. Or perhaps it
might be possible to exploit the ocean, by collecting the
microscopic vegetables floating on its surface. The quan-
tity of this plankton must be vast, but it is spread very
thin, and the collection would be a very difficult prob-
lem. However that may be, and wherever the vege-
tables grew, there would be all the trouble over bad
seasons and pestilences that we know too well already,
and it is possible that enormous greenhouses, in which
the plants grew under accurately controlled conditions
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MATERIAL CONDITIONS
might pay better; but whatever was found best would
have to be on a vast scale, because of the comparative
inefficiency of the vegetable in converting sunlight into
energy.
I think this completes the list of all reasonably possible
sources of energy, and apart from ordinary water-power
the results are not encouraging. This is hardly surprising,
for it certainly involves a great deal more work to live
on income than on the accumulated capital of geological
ages. Our present civilization is largely based on the
provision of mechanical power, and if it is to continue,
it would seem likely that a good fraction of humanity
will have to be engaged in collecting energy, either by
minding vast numbers of machines, or by tending
vegetables in plantations; it will have to be a far greater
number than those now engaged in mines and power-
stations. It is rather likely that the natural inefficiency of
mankind will prevent him from realizing to the full the
possibilities of winning energy out of nature, and that
he will often find that he has to get on with much less of it.
Turning now to other questions of the future condi-
tions of the world, it is of course likely that many tech-
nical inventions, both of utility and of luxury, will be
made, which may profoundly alter the detail of human
life. As I have already explained in an earlier chapter,
however, and as will be developed more fully later,
these are only to be regarded as details superposed on the
immensely more important questions of population and
of human nature. It is therefore not worth entering on
wild speculations about them, for such speculations
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THE NEXT MILLION YEARS
would surely be as wrong as the speculations of a natural
philosopher of two centuries ago would have been about
our present conditions. It may be noticed, however, that
the biological sciences, which in the nineteenth century
rather lagged behind the physical, are beginning to show
promise of quite astonishing new advances.
The proper consideration of these biological advances
must for the most part be deferred to later chapters, but
I may list some of them here without discussion. There
is first the possibility of new sources of food; for example
if grass or wood could be rendered edible, it is safe to say
that there would be immediately a great increase in the
population of the world. Then there is the probability
that medical science will continue still further the great
triumphs it can already claim in the conquest of disease.
It is also not impossible that medical science might suc-
ceed in materially lengthening life without senility,
though in a world of overcrowded population it is not
very clear what would be gained. Looking a little deeper
there is the possibility of substantially altering the intel-
lectual and moral natures of individuals by some sort of [ Pobierz całość w formacie PDF ]