Arthur C. Clarke warns us about bold confident predictions

Summary: Arthur C. Clarke warns about the “Hazards of Prophecy.” Don’t take those predictions about 2018 & beyond too seriously. Especially the gloomy ones about technological stagnation, with so many signs that a new industrial revolution has begun.

We’re sailing into an unknown future.

Sailing into the Future


“Hazards of Prophecy: The Failure of Nerve”

By Arthur C. Clarke, inventor and writer about science and science fiction.

From Profiles of the Future: An Inquiry into the Limits of the Possible (1962).

Before one attempts to set up in business as a prophet, it is instructive to see what success others have made of this dangerous occupation — and it is even more instructive to see where they have failed.

With monotonous regularity, apparently competent men have laid down the law about what is technically possible or impossible — and have been proved utterly wrong, sometimes while the ink was scarcely dry from their pens. On careful analysis, it appears that these debacles fall into two classes, which I will call “failures of nerve” and “failures of imagination.

The failure of nerve seems to be the more common; it occurs when even given all the relevant facts the would-be prophet cannot see that they point to an inescapable conclusion. Some of these failures are so ludicrous as to be almost unbelievable, and would form an interesting subject for psychological analysis, “They said it couldn’t be done” is a phrase that occurs throughout the history of invention; I do not know if anyone has ever looked into the reasons why “they” said so, often with quite unnecessary vehemence.

Profiles of the Future: An Inquiry into the Limits of the Possible
Available at Amazon.

It is now impossible for us to recall the mental climate which existed when the first locomotives were being built, and critics gravely asserted that suffocation lay in wait for anyone who reached the awful speed of thirty miles an hour. It is equally difficult to believe that, only 80 years ago, the idea of the domestic electric light was pooh-poohed by all the “experts” — with the exception of a thirty-one-year-old American inventor named Thomas Alva Edison.

When gas securities nose-dived in 1878 because Edison (already a formidable figure, with the phonograph and the carbon microphone to his credit), announced that he was working on the incandescent lamp, the British Parliament set up a committee to look into the matter. (Westminster can beat Washington hands down at this game.)

The distinguished witnesses reported, to the relief of the gas companies, that Edison’s ideas were “good enough for our transatlantic friends. but unworthy of the attention of practical or scientific men.” And Sir William Preece, engineer-in-chief of the British Post Office, roundly declared that “Subdivision of the electric light is an absolute ignis fatuus.” {fire + foolish, a will-o’-the-wisp.} One feels that the fatuousness was not in the ignis {fire}.

The scientific absurdity being pilloried, be it noted, is not some wild-and-woolly dream like perpetual motion, but the humble little electric light bulb, which three generations of men have taken for granted, except when it burns out and leaves them in the dark. Yet although in this matter Edison saw far beyond his contemporaries, he too in later life was guilty of the same shortsightedness that afflicted Preece, for he opposed the introduction of alternating current.

The impossibility of commercial aircraft.

The most famous, and perhaps the most instructive, failures of nerve have occurred in the fields of aero- and astronautics. At the beginning of the twentieth century, scientists were almost unanimous in declaring that heavier-than-air flight was impossible, and that anyone who attempted to build airplanes was a fool. The great American astronomer, Simon Newcomb, wrote a celebrated essay which concluded…

“The demonstration that no possible combination of known substances, known forms of machinery and known forms of force, can be united in a practical machine by which man shall fly long distances through the air, seems to the writer as complete as it is possible for the demonstration of any physical fact to be.”

Oddly enough, Newcomb was sufficiently broad minded to admit that some wholly new discovery — he mentioned the neutralization of gravity — might make flight practical. One cannot, therefore, accuse him of lacking imagination; his error was in attempting to marshal the facts of aerodynamics when he did not understand that science. His failure of nerve lay in not realizing that the means of flight were already at hand.

For Newcomb’s article received wide publicity at just about the time that the Wright brothers, not having a suitable antigravity device in their bicycle shop, were mounting a gasoline engine on wings. When news of their success reached the astronomer, he was only momentarily taken aback. Flying machines might be a marginal possibility, he conceded — but they were certainly of no practical importance, for it was quite out of the question that they could carry the extra weight of a passenger as well as that of a pilot.

Such refusal to face facts which now seem obvious has continued throughout the history of aviation. Let me quote another astronomer, William H. Pickering, straightening out the uninformed public a few years after the first airplanes had started to fly.

“The popular mind often pictures gigantic flying machines speeding across the Atlantic and carrying in numerable passengers in a way analogous to our modern steamships. It seems safe to say that such ideas must be wholly visionary, and even if a machine could get across with one or two passengers the expense would be prohibitive to any but the capitalist who could own his own yacht.

“Another popular fallacy is to expect enormous speed to be obtained. It must be remembered that the resistance of the air increases as the square of the speed and the work as the cube. If with 30 h.p. we can now attain a speed of 40 m.p.h., then in order to reach a speed of 100 m.p.h. we must use a motor capable of 470 h.p. it is clear that with our present devices there is no hope of competing for racing speed with either our locomotives or our automobiles.”

It so happens that most of his fellow astronomers considered Pickering far too imaginative; he was prone to see vegetation — and even evidence for insect life — on the Moon. I am glad to say that by the time he died in 1938 at the ripe age of 80, Professor Pickering had seen air planes traveling at 400 m.p.h., and carrying considerably more than “one or two” passengers.

V-2 rocket launching

The impossibility of space flight.

Closer to the present, the opening of the space age has produced a mass vindication (and refutation) of prophecies on a scale and at a speed never before witnessed.

Having taken some part in this myself, and being no more immune than the next man to the pleasures of saying, “I told you so,” I would like to recall a few of the statements about space flight that have been made by prominent scientists in the past. It is necessary for someone to do this, and to jog the remarkably selective memories of the pessimists. The speed with which those who once declaimed, “It’s impossible” can switch to, “I said it could be done all the time” is really astounding.

As far as the general public is concerned, the idea of space flight as a serious possibility first appeared on the horizon in the 1920’s, largely as a result of newspaper reports of the work of the American Robert Goddard and the Rumanian Hermann Oberth. (The much earlier studies of Konstantin Tsiolkovsky in Russia then being almost unknown outside his own country.) When the ideas of Goddard and Oberth, usually distorted by the press, filtered through to the scientific world, they were received with hoots of derision.

For a sample of the kind of criticism the pioneers of astronautics had to face, I present this masterpiece from a paper published by one Professor A. W. Bickerton, in 1926. It should be read carefully, for as an example of the cocksure thinking of the time it would be very hard to beat.

The cannon from Jules Verne's "From the Earth to the Moon"
The cannon from Jules Verne’s From the Earth to the Moon.

“This foolish idea of shooting at the moon is an example of the absurd length to which vicious specialisation will carry scientists working in thought-tight compartments. Let us critically examine the proposal. For a projectile entirely to escape the gravitation of the earth, it needs a velocity of 7 miles a second.

“The thermal energy of a gramme at this speed is 15,180 calories. The energy of our most violent explosive — nitroglycerin — is less than 1,500 calories per gramme. Consequently, even had the explosive nothing to carry, it has only one-tenth of the energy necessary to escape the earth. Hence the proposition appears to be basically impossible.” {Bickerton is discussing proposals to use a cannon as a launch vehicle, a spacegun.}

Indignant readers in the Colombo public library pointed angrily to the SILENCE notices when I discovered this little gem. It is worth examining it in some detail to see just where “vicious specialisation,” if one may coin a phrase, led the professor so badly astray.

His first error is in the sentence: “The energy of our most violent explosive — nitroglycerine….” One would have thought it obvious that energy, not violence, is what we want from a rocket fuel; and as a matter of fact nitroglycerine and similar explosives contain much less energy, weight for weight, than such mixtures as kerosene and liquid oxygen. This had been carefully pointed out by Tsiolkovsky and Goddard years before.

Bickerton’s second error is much more culpable. What of it, if nitroglycerine has only a tenth of the energy necessary to escape from the Earth? That merely means that you have to use at least ten pounds of nitroglycerine to launch a single pound of payload. The dead weight of the rocket (propellent tanks, motors, etc.) would actually make the ratio very much higher, but that does not affect the argument.)

For the fuel itself has not got to escape from Earth; it can all be burned quite close to our planet, and as long as it imparts its energy to the payload, this is all that matters. When Lunik Il lifted thirty-three years after Professor Bickerton said it was impossible, most of its several hundred tons of kerosene and liquid oxygen never got very far from Russia — but the half-ton payload reached the Mare Imbrium.

As a comment on the above, I might add that Professor Bickerton, who was an active popularizer of science, numbered among his published books one with the title Perils of a Pioneer. Of the perils that all pioneers must face, few are more disheartening than the Bickertons.

Right through the 1930’s and 1940’s, eminent scientists continued to deride the rocket pioneers — when they bothered to notice them at all. Anyone who has access to a good college library can find, preserved for posterity in the dignified pages of the January 1941 Philosophical Magazine, an example that makes a worthy mate to the one I have just quoted.

It is a paper by the distinguished Canadian astronomer Professor J. W. Campbell, of the University of Alberta, entitled “Rocket Flight to the Moon.” Opening with a quotation from a 1938 Edmonton paper to the effect that “rocket flight to the Moon now seems less remote than television appeared a hundred years ago,” the professor then looks into the subject mathematically. After several pages of analysis, he arrives at the conclusion that it would require a million tons of take-off weight to carry one pound of payload on the round trip.

The correct figure, for today’s primitive fuels and technologies, is very roughly one ton per pound — a depressing ratio, but hardly as bad as that calculated by the professor. Yet his mathematics was impeccable; so what went wrong?

Merely his initial assumptions, which were hopelessly unrealistic. He chose a path for the rocket which was fantastically extravagant in energy, and he assumed the use of an acceleration so low that most of the fuel would be, wasted at low altitudes, fighting the Earth’s gravitational field. It was as if he had calculated the performance of an automobile — when the brakes were on. No wonder that he concluded: “While it is always dangerous to make a negative prediction, it would appear that the statement that rocket flight to the moon does not seem so remote as television did less than one hundred years ago is over-optimistic.”

I am sure that when the Philosophical Magazine subscribers read those words, back in 1941, many of them thought, “Well, that should put those crazy rocket men in their place!”

Yet the correct results had been published by Tsiolkovsky, Oberth and Goddard years before; though the work of the first two would have been very hard to consult at the time, Goddard’s paper “A Method of Reaching Extreme Altitudes” {large PDF} was already a classic and had been issued by that scarcely obscure body, the Smithsonian Institution. If Professor Campbell had only consulted it (or indeed any competent writer on the subject — there were some, even in 1941) he would not have misled his readers and himself.

The lesson to be learned from these examples is one that can never be repeated too often, and is one that is seldom understood by laymen — who have an almost superstitious awe of mathematics. But mathematics is only a tool, though an immensely powerful one. No equations, however impressive and complex, can arrive at the truth if the initial assumptions are incorrect. It is really quite amazing by what margins competent but conservative scientists and engineers can miss the mark, when they start with the preconceived idea that what they are investigating is impossible.

When this happens, the most well-informed men become blinded by their prejudices and are unable to see what lies directly ahead of them. What is even more incredible, they refuse to learn from experience and will continue to make the same mistake over and over again.

Some of my best friends are astronomers, and I am sorry to keep throwing stones at them — but they do seem to have an appalling record as prophets. If you still doubt this, let me tell a story so ironic that you might well accuse me of making it up. But I am not that much of a cynic, the facts are on file for anyone to check.

Back in the dark ages of 1935, the founder of the British Interplanetary Society, P. E. Cleator, was rash enough to write the first book on astronautics published in England. His Rockets through space : the dawn of interplanetary travel, gave an (incidentally highly entertaining) account of the experiments that had been carried out by the German and American rocket pioneers, and their plans for such commonplaces of today as giant multi-stage boosters and satellites.

Rather surprisingly, the staid scientific journal Nature reviewed the book in its issue for March 14, 1936, and summed up as follows:

“It must be said at once that the whole procedure sketched in the present volume presents difficulties of so fundamental a nature that we are forced to dismiss the notion as essentially impracticable, in spite of the author’s insistent appeal to put aside prejudice and to recollect the supposed impossibility of heavier-than-air fight before it was actually accomplished. An analogy such as this may be misleading, and we believe it to be so in this case.”

Well, the whole world now knows just how misleading this analogy was, though the reviewer, identified only by the unusual initials R.v.d.R.W. was of course fully entitled to his opinion.

Just twenty years later — after President Eisenhower had announced the United States satellite program — a new Astronomer Royal arrived in England to take up his appointment. The press asked him to give his views on space fight, and after two decades Dr. Richard van der Riet Woolley had seen no reason to change his mind. “Space travel,” he snorted, “is utter bilge.”

The newspapers did not allow him to forget this, when Sputnik I went up the very next year. Later — irony piled upon irony — Dr. Woolley became, by virtue of his position as Astronomer Royal, a leading member of the committee advising the British government on space research. The feelings of those who have been trying, for a generation, to get the United Kingdom interested in space can well be imagined.

About ballistic missiles.

Even those who suggested that rockets might be used for more modest, though much more reprehensible, purposes were overruled by the scientific authorities — except in Germany and Russia.

When the existence of the 200-mile-range V-2 was disclosed to an astonished world, there was considerable speculation about intercontinental missiles. This was firmly squashed by Dr. Vannevar Bush, the civilian general of the United States scientific war effort, in evidence, before a Senate committee on December 3, 1945. Listen…

“There has been a great deal said about a 3,000 miles high-angle rocket. In my opinion such a thing is impossible for many years. The people who have been writing these things that annoy me, have been talking about a 3,000 mile high-angle rocket shot from one continent to another, carrying an atomic bomb and so directed as to be a precise weapon which would land exactly on a certain target, such as a city.

“I say, technically, I don’t think anyone in the world knows how to do such a thing, and I feel confident that it will not be done for a very long period of time to come. I think we can leave that out of our thinking.”

A few months earlier (in May 1945) Prime Minister Churchill’s scientific advisor Lord Cherwell had expressed similar views in a House of Lords debate. This was only to be expected, for Cherwell was an extremely conservative and opinionated scientist who had advised the government that the V-2 itself was only a propaganda rumor.

In the May 1945 debate on defense, Lord Cherwell impressed his peers by a dazzling display of mental arithmetic from which he correctly concluded that a very long-range rocket must consist of more than 90 per cent fuel, and thus would have a negligible payload. The conclusion he let his listeners draw from this was that such a device would be wholly impracticable. That was true enough in the spring of 1945, but it was no longer true in the summer. …

When Dr. Vannevar Bush spoke to the Senate committee in December of the same year, the only important secret about the atomic bomb was that it weighed five tons. Anyone could then work out in his head, as Lord Cherwell had done, that a rocket to deliver it across intercontinental ranges would have to weigh about 200 tons — as against the mere 14 tons of the then awe-inspiring V-2.

The outcome was the greatest failure of nerve in history, which changed the future of the world — indeed, of many worlds. Faced with the same facts and the same calculations, American and Russian technology took two separate roads. The Pentagon — accountable to the tax-payer — virtually abandoned long-range rockets for almost half a decade, until the development of thermonuclear bombs made it possible to build warheads five times lighter yet several hundred times more powerful than the low-powered and now obsolete device that was dropped on Hiroshima.

The Russians had no such inhibitions. Faced with the need for a 200-ton rocket, they went right ahead and built it. By the time it was perfected, it was no longer required for military purposes, for Soviet physicists had bypassed the United States’ billion-dollar tritium bomb cul-de-sac and gone straight to the far cheaper lithium bomb. Having backed the wrong horse in rocketry, the Russians then entered it for a much more important event — and won the race into space.


Of the many lessons to be drawn from this slice of recent history, the one that I wish to emphasize is this. Anything that is theoretically possible will be achieved in practice, no matter what the technical difficulties, if it is desired greatly enough. It is no argument against any project to say: “Ile idea’s fantastic!” Most of the things that have happened in the last fifty years have been fantastic, and it is only by assuming that they will continue to be so that we have any hope of anticipating the future.

To do this — to avoid that failure of nerve for which history exacts so merciless a penalty — we must have the courage to follow all technical extrapolations to their logical conclusion. Yet even this is not enough, as I shall now demonstrate. To predict the future we need logic; but we also need faith and imagination which can sometimes defy logic itself.


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"Childhood's End" by Arthur C. Clarke
Available at Amazon.

One of the greatest science fiction novels, ever.

I strongly recommend reading Childhood’s End by Arthur C. Clarke. It tells the tale of humanity in a new way, from its beginning to its end. It does what few — very few — science fiction novels: describe a purpose and end for humanity’s long journey.

From the publisher …

“Without warning, giant silver ships from deep space appear in the skies above every major city on Earth. Manned by the Overlords, in fifty years, they eliminate ignorance, disease, and poverty. Then this golden age ends — and then the age of Mankind begins. …”

2 thoughts on “Arthur C. Clarke warns us about bold confident predictions”

  1. As far as predictions go, for our new information revolution era, the book I check in with from time to time is Kurtzweil’s “Age of Spiritual Machines.” So far, we are not where he thought we would be.

    I got “The Closing of the American Mind” from my Dad for Christmas. The chapter on Weimar Germany is still horrifying. Dad was semi-horrifed that an anti-militarist website like this one was also a fan of the book. Oh irony!

    As payback, may I recommend “First and Last Men” and “Star Maker” by Stapleton? A future history of Mankind, and the universe, respectively. “Childhood’s End” and about half of s-f “borrows” heavily from these two books, both from the 30s. “Star Maker” gave a detailed account of virtual reality, genetic engineering, manipulation of society by media control…..I think it was Clarke who called it the “great gray holy book of science fiction.” Or something like that. CS Lewis called it “a work of such strength I feel no shame to borrow”–and he despised Stapleton’s theology/philosophy.

    One of the earliest chapters of “First and Last Men” is “The American World.” It would provide rich material for an FM post or two.

    1. Larry Kummer, Editor


      “is Kurtzweil’s “Age of Spiritual Machines.” So far, we are not where he thought we would be.”

      Kurtzwell is a smart guy and fun to read. His track record of predictions is poor. His core theory is wrong. Most research shows that the rate of tech innovation has been slowing for decades (other than computing and communications). There are signs that this might soon change, however.

      “The chapter on Weimar Germany is still horrifying”

      You mean the nine pages 147-155? What did you find horrifying about it (i.e., amidst so much that is horrifying about the book)? People’s view of Weimar vary in interesting ways, as do their reactions to it.

      “Dad was semi-horrifed that an anti-militarist website like this one was also a fan of the book.”

      Why? I attended after Bloom left Cornell, but knew many people that read him. And I’ve read the book many times. Why would an “anti-militarist website” not like Closing? Also, the articles here oppose our mad war on terror. The authors support our military (many are officers, active duty or retired) — and some of our past wars.

      Thanks for the pointer to Stapleton’s work. I’ve heard of it, and the praises you mention!

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