The First Scientific Concept of Rockets for Space Travel by Robert Godwin Part 8
From The Space Library
Light and Time
After touring the solar system Leitch proposed that the reader should then embark on a journey to the stars.
“We have still an expedition before us, which may be compared to the crossing of the Atlantic, or a voyage to China. We have not yet really left home, and now that we propose going abroad, what vehicle shall we take to aid us in our flight to other systems? The comet is all too slow for our purpose. We must have something still more subtle and swift. The only physical agency that can serve our purpose is a ray of light...Let us suppose, then, that, with the ethereal vehicle of light we are to start upon a journey far beyond the solar system, where shall be our first resting-place? Alpha Centauri is the nearest of the stars whose distance has been well determined; but with all the spiritual swiftness of light, we can reach it only in three years and a quarter.”
This “vehicle of the imagination” seems to have resonated down the decades and is highly reminiscent of the Cosmos television series created by Cornell astronomer Carl Sagan in the 1980s. It is certainly crystal clear that Leitch understood the barrier presented by stellar distances, but his comprehension of light-speed is almost as remarkable as his other insights.
“From the simple law, that light requires time to travel from one point to another, it follows, that we see everything in the past. In the case of very distant objects, this leads to startling results. For every event in the past history of the world, there is a corresponding point in space, and if we were situated on a star at that point, we would, on looking down upon the earth, see the corresponding event transacted.
“For example, if we took up our position in a star, to which light would take six thousand years to travel from this globe, we would witness the scenes of paradise, and the roll of the world’s history would unfold itself to our eyes. If the course of events appeared too slow, we could hasten it, in any degree, by gliding swiftly towards the earth, along the course of the rays. If we could accomplish the journey in an hour, the history of six thousand years would be condensed into that period.
“The schoolmen defined eternity as punctum stans, and the propagation of light gives a startling illustration of their meaning. We can arrest the flow of time by continued motion. Suppose our world is the illuminated dial of a clock, that the hand is at twelve o’clock, and that the machinery is faithfully doing its duty; we have only to take up our position in a star that moves from the earth as rapidly as the rays from the dial, in order to arrest the hand for ever at that hour. To one who is stationary, the hand makes its ordinary revolution; but one who moves away with the rapidity of light, sees it perfectly fixed. Nay, it is possible to turn back the hand, as in the case of the dial of Ahaz.
“In a star moving away from the earth more rapidly than the light, a person would see the hands gradually move in the reverse order, from twelve to eleven o’clock, and so on. By moving in the direction opposite to that of the light, centuries might be concentrated into hours, and hours into seconds. Had we unlimited powers of locomotion, we would not be under the necessity of reading unintelligible and prosaic accounts of campaigns and battles in the past history of our country; it would only be necessary to wing our way to some star where the light from the seat of war is just arriving, and leisurely watch the actual progress of events.”
It cannot be stated with any certainty that these are original thoughts by Leitch but they serve to illustrate his grasp of complex concepts. There was no Einstein or Relativity when this was written. Nor was there any concept of the speed of light being an absolute, thus preventing any possibility of outpacing it. Relative speed had been discussed quite coherently by Nicholas of Cusa in 1440, but this is more than that. It is a lucid description of the special relationship of light with time, and his idea of perceiving frozen time, due to a relative state, is only one step removed from Einstein’s “happy thought” of perceiving a frozen light wave.
The Size of the Universe and the Great Debate
In one other comment Leitch explained:
“But from our (observation) position we find that the Milky Way, with its millions of stars is not the only luminous disc. The whole heavens are studded over with similar patches of light or nebulae which, on closer inspection, are found to be firmaments, consisting, like the Galaxy, of innumerable stars. They may appear as single, hazy stars, but they are the combined light of countless hosts. These groups are separated by gulfs which it would require millions of years for a ray of light to traverse.”
Again we seem to see Leitch pushing himself out of his own time. The only method for detecting stellar distances at this time was Bessel’s parallax system. William Huggins would not use the Doppler Effect to detect relative motions in stars until four years after Leitch’s death. Henrietta Leavitt would not discover the special properties of the Cepheid variable until 1912. Both discoveries would help astronomers to get a grip on the size of the visible universe.
On April 26th 1920 an important debate took place at the US National Academy of Sciences. In fact this was such an important debate it became known as “The Great Debate”. The two contestants were astronomers Harlow Shapley and Heber Curtis and they had literally come to debate the scale of the universe. Their best estimates were derived from the latest technology and science.
Curtis had researched the frequency of novae in the Andromeda “nebula” and he concluded that there were far too many exploding stars for such a small area if it were inside our galaxy. In fact the numbers seemed comparable to those observed within the rest of the entire Milky Way. He had to conclude that this meant the Andromeda “nebula” was in fact another galaxy. If that were the case then the other spiral nebulae could be anything from 500,000 to 100,000,000 light years distant. This sort of debate had been ongoing for decades, long after Leitch (and Nichol) had already accepted that millions of light years separated the galaxies.
He concluded his extraordinary tour-de-force with this.
“When we step from planet to sun, from sun to system, and from system to firmament, we are ascending the rounds of the ladder that leads up to the Infinite; and this is the great end of the book of God in the heavens. But a hard-featured philosophy comes, and tells us that we cannot know the Infinite, that the notion we form is merely a synthesis of finites, that no number of finites can ever make an infinite; and that this arises from the very limits of thought. This is true, if it means merely that we cannot construe to our minds the image of an infinite ladder, by indefinitely increasing the rounds of it; but surely we can know a thing, though we cannot draw a definite picture of it to the eye or the imagination.”
Despite, or perhaps because, he was a devout and pious man Leitch was clearly not going to be intimidated by the Cosmos. He even dipped his toes into the highly controversial anthropic principle when he stated, “What is space? Is it an objective reality, or a subjective condition of thought? We cannot enter on this mare magnum of controversy…”
“A Journey Through Space” was first published by Strahan in “Good Words” in September of 1861. It was evidently presented to Macleod during Leitch’s trip to Scotland that summer. Click here for Part 9
