Title: GOD and the Multiverse: Humanity’s Expanding View of the Cosmos
Author: Victor J. Stenger
Publisher: Prometheus Books 2014
“I believe there is no source of deception in the investigation of
nature which can compare with a fixed belief that certain kinds of
phenomena are IMPOSSIBLE.” – William James
“Modern science should indeed arouse in all of us a humility before the
immensity of the unexplored and a tolerance for crazy hypotheses.”
– Martin Gardner
All the world says: yes we know what’s written in the books but now let’s see what our eyes tell us.”
― Bertolt Brecht, A Life of Galileo
Cosmos = Everything that was, is, and will be.
Imagine our pre-civilization ancestors trying to cope with the difficulties of survival. They would have had to discover that there is some sort of causal relationship between actions and events. They would have paid attention to their surroundings and would have begun early on to perceive a relationship between temporal events. They would have wondered about the life-giving sun, wondered why on certain days it was covered with thick clouds that on occasion provided life-giving rain to drop from the sky. Injuries, sickness, hunger, dangers of all sorts were about.
One can easily imagine the response was to try to assign some agency to the causal pattern observed, and then to try to influence that agent in one’s own interests. That seems to me to describe a rudimentary human approach to gathering information and for trying to predict and influence future events. Survival is the mother of science. Observation, hypothesis, prediction, verifiability and falsifiability become the best way we humans have of explaining our selves and our world. With limited knowledge and limited senses we would have been hard pressed to understand molecular processes let alone atomic and sub-atomic actions. What caused the death of my seemingly healthy children? Why did we get no rain this season? How did our enemies find us?
Hypothesis: some invisible agent is at work. And so forth … one can see how easily and naturally we developed a scientific method, at first quite rudimentary, but the beginnings of a way of knowing about the world that worked from time to time. We posited agents, named them, placed them as hypotheticals in an imaginary world that soon became populated with these gods. As we learned more and more about the way the natural world works we started to depopulate the other world. Many spirits became a regimented set of kings and princes. But still it seemed even they were subject to a higher power. Maybe there was only one all-powerful spirit who controlled the thousands of things that are: a hypothesis that seemed beyond testing.
From Aristotle on it was believed that an invisible, weightless stuff without any sensible properties MUST exist to fill all space. Why? Because the gods abhorred a vacuum. This stuff, called ether, was later believed to be the medium for light waves to travel through in a way similar to sound waves travelling through the air. The reasoning went something like this:
If light is a wave and not a particle it must travel through something and that something is ether. We cannot see ether or test for it with our senses but it must exist or we couldn’t, for example, see the sunlight. We do see the sunlight, so ether exists.
We think of sound waves as waves of compression in air. Actually, that is only one case-¬-sound will also travel through liquids, like water, and solids, like a steel bar. We have found experimentally that, other things being equal, sound travels faster through a medium that is harder to compress—the material just springs back faster and the wave moves through more rapidly. For media of equal springiness, the sound goes faster through the less heavy medium, essentially because the same amount of springiness can push things along faster in a lighter material. So when a sound wave passes, the material—air, water or solid—waves as it goes through. Taking this as a hint, it was natural to suppose that light must be just waves in some mysterious material, which was called the aether, surrounding and permeating everything. This aether must also fill all of space, out to the stars, because we can see them, so the medium must be there to carry the light. (We could never hear an explosion on the moon, however loud, because there is no air to carry the sound to us.) Let us think a bit about what properties this aether must have. Since light travels so fast, it must be very light, and very hard to compress. Yet, as mentioned above, it must allow solid bodies to pass through it freely, without aether resistance, or the planets would be slowing down. Thus we can picture it as a kind of ghostly wind blowing through the earth. But how can we prove any of this? Can we detect it?
While in Europe, Michelson began constructing an interferometer, a device designed to split a beam of light in two, send the parts along perpendicular paths, then bring them back together. If the light waves had, in the interim, fallen out of step, interference fringes of alternating light and dark bands would be obtained. From the width and number of those fringes, unprecedently delicate measurements could be made, comparing the velocity of light rays travelling at right angles to each other.
It was Michelson’s intention to use the interferometer to measure the Earth’s velocity against the “ether” that was then thought to make up the basic substratum of the universe. If the Earth were travelling through the light-conducting ether, then the speed of the light travelling in the same direction would be expected to be equal to the velocity of light plus the velocity of the Earth, whereas the speed of light travelling at right angles to the Earth’s path would be expected to travel only at the velocity of light.
At this point, Michelson had a very clever idea for detecting the aether wind. As he explained to his children (according to his daughter), it was based on the following puzzle:
Suppose we have a river of width w (say, 100 feet), and two swimmers who both swim at the same speed v feet per second (say, 5 feet per second). The river is flowing at a steady rate, say 3 feet per second. The swimmers race in the following way: they both start at the same point on one bank. One swims directly across the river to the closest point on the opposite bank, then turns around and swims back. The other stays on one side of the river, swimming upstream a distance (measured along the bank) exactly equal to the width of the river, then swims back to the start. Who wins?
Michelson’s great idea was to construct an exactly similar race for pulses of light, with the aether wind playing the part of the river. The scheme of the experiment is as follows: a pulse of light is directed at an angle of 45 degrees at a half-silvered, half transparent mirror, so that half the pulse goes on through the glass, half is reflected. These two half pulses are the two swimmers. They both go on to distant mirrors which reflect them back to the half-silvered mirror. At this point, they are again half reflected and half transmitted, but a telescope is placed behind the half-silvered mirror as shown in the figure so that half of each half-pulse will arrive in this telescope. Now, if there is an aether wind blowing, someone looking through the telescope should see the halves of the two half-pulses to arrive at slightly different times, since one would have gone more upstream and back, one more across stream in general. To maximize the effect, the whole apparatus, including the distant mirrors, was placed on a large turntable so it could be swung around. His earliest experiments in Berlin showed no interference fringes, however, which seemed to signify that there was no difference in the speed of the light rays, and, therefore, no Earth motion relative to the ether.
In Cleveland he concentrated his efforts on improving the delicacy of his interferometer experiment. By 1887, with the help of his colleague, American chemist Edward Williams Morley, he was ready to announce the results of what has since come to be called the Michelson-Morley experiment. Those results were still negative; there were no interference fringes and apparently no motion of the Earth relative to the ether. [Source; go here for an excellent animated flashlet of the experiment.]
They didn’t immediately conclude that the aether does not exist. In fact, they were so certain of its existence, its necessary existence, that they concluded there must be something wrong with their equipment!