Science in Christian Perspective
From: JASA 17 (December
1965): 104-108, 117.
The objective of this paper will be to survey the historical background and thinking behind the present opinions as to the origin of our Solar System. A correlation will be made between the various theories presented and the Bible. The most widely accepted theory at the present time, developed by Dr. Gerard P. Kuiper, will be presented in detail. It will be pointed out that by means of this theory, when one explains the origin of our Solar System, one likewise has explained the origin of the Galaxy, and the Universe.
In developing this thesis, some of the major theories of past years will be briefly surveyed. This will cross the lines of the sciences, illustrating clearly that sciences are now more closely related than ever before. This will involve the question of time, the stumbling block over which so many people fall when trying to separate science and the Bible. It will be shown in clear detail that there is no conflict here.
The Heavens declare the Glory of God, and the Firmament Sheweth His Handiwork. Surely the Universe is full of His Glory.
The problem of the Origin of the Solar System is one of the most complex problems in Nature. It has intrigued men and women for ages, and still offers some of the most profound opportunities for advancement of scientific endeavor present today. The understanding of this problem offers the opportunity for the investigator to delve into the field of Mathematics of the most advanced type, and to cover the spectrum of science-Biology, Chemistry, Geology, Physics, and Engineering, not to mention Astronomy and Astrophysics.
I shall endeavor to present to you the fundamentals of the most widely accepted theory, and all such proposals are theories. This is the theory advanced by Dr. Gerard Peter Kuiper. He was doing his basic research on this problem during 1951 to 1952, while I was fortunate in being at the Yerkes Observatory, where this work was being done. And through the intervening years, Dr. Kuiper has kept his concepts up with the times, revising and enlarging the theory on the basis of the later developments. Through the years I have checked with the leading astronomers of our country as to the beliefs held by those of this discipline, and almost without exception, they tell me that Dr. Kuiper's protoplanet theory of origin is the one which comes most nearly explaining those things which are necessary to explain.
In explaining the Origin of the Solar System, the protoplanet hypothesis explains the Origin of the Universe. Whether there originates a solar system, a double star system, a stellar cluster, or a galaxy, is only a matter of degree. This we shall see.
However, we must first understand what it is that we wish to explain. Let us therefore first define our problem, This may best be done by demonstrating the ORDER of the Solar System, and listing its properties.So therefore, our Theory when complete, must explain: 1. The 9 planets and their properties.
a. The planets move in almost the same plane. b. They move in direct revolution about the Sun.
c. They move in direct rotation about their individual axes.
d. They move in nearly circular paths, obeying Kepler's Laws.
e. They are endowed with similar masses and densities.
f. Now let us name the planets in order as they progress outward from the Sun, and give only briefly their properties:
* Jack T. Kent is Professor of Math & Astronomy, Texas A&M University, College Station, Texas. Paper prepared for the 19th Annual Convention of the American Scientific Affilia tion, August 1964, at John Brown University, Siloam Springs Arkansas.
1. First comes Mercury, only 0.4 of the way from the Sun to the earth, moving rapidly in an eccentric orbit around the Sun in 88 days, keeping its same face to the sun, as does our moon. It is devoid of atmosphere, and literally the hottest and coldest spot in the Solar System, with the exception of the Sun.
2. Next we have Venus, the controversial planet, a near
sister planet to the earth in size. It is 0.7 of the way
from the Sun to the Earth, and covered with clouds of
carbon dioxide, with an unknown period of rotation
and an unknown temperature on its surface, which we
cannot see, and revolves around the Sun in 116 days.
3. The Earth comes third in this order.
4. After the earth, we find Mars, most nearly like the Earth in its ability to support life, actually possessing an elementary form of lichen life. It has two moons. Read Jonathan Swift's Gulliver's Travels for an interesting true story concerning these moons. Mars revolves with a period of a little under 2 years.
5. Between Mars and Jupiter we find the 35,000 Asteroids, of which some 1800 are catalogued with orbits.
6. Jupiter, some 5 astronomical units from the sun, revolving in 12 years, is the largest and most massive of the planets, as massive as all the others together, about 0.001 part of the Sun itself. With its 12 moons, it is truly a solar system within the Solar System, as Galileo stated. In fact it almost forms a double star system with the Sun.
7. Saturn, at 10 AU from the Sun, had a period of 29 years, and yet a density of only 0.7. It would float, were there a large enough tub of water in which to throw it.
8. Uranus appears at 19 AU from the Sun, just about the average distance for binary systems. It has five moons, and revolves in 84 years.
9. Neptune, with its 2 moons, appears at 30 AU and revolves once in 165 years.
10. Pluto, at 39 AU, is so far away from the Sun, that the Sun appears only as a dim star in its sky. Plutonians, were they to exist, would need to live to be 248 years old to have their first birthday.
3. Our theory must explain the Asteroids, ranging in distance of 2.7 to 3.1 times the Earth's mean distance from the Sun. There are a few exceptions. Some of these objects come very near to the Earth.
4. We must explain the Comets and Meteors, and
5. We must explain the Sun's Angular Momentum.
This is only 0.3 of 1% of the system, whereas the Sun's mass is more than 99.9% of the System. The smallness of this ratio requires explanation.
Now let us take only a moment to trace historically the development of thought as illustrated by a few of the more renowned theories.
1. Kant, in 1755, assumed a clotting of gas into a cloud, in slow rotation.
2. Laplace, in 1796, assumed a cloud of gas in slow rotation, contracting, and throwing off gas on the equatorial bulge, which later collected to form the planets. Laplace published his Theory very inconspicuously in an appendix of one of his volumes of Celestial Mechanics. Yet this theory governed Philosophical, Scientific, and Religious thought for 100 years.
3. By 1900 people began to realize that Laplace's Theory left much to be desired. So Chamberlain and Moulton, at Chicago suggested the near approach of two stars. The probability of this occurring was its downfall.
4. Sir James Jeans and Sir Harold Jeffreys, in 1917, assumed a grazing approach of two stars. They should have known better.
5. Lyttleton in 1936 thought of the Sun as a binary system, with a third star coming by and capturing the Sun's companion, leaving debris for the planetary system.
6. In the meantime, Berlage in Holland in 1930 had assumed that electrically charged particles shot out from the Sun to take up orbits according to their mass. His work was inspired by that of Birkeland in 1912.
7. Alfven, in Sweden in 1942 thought of the Sun as passing through a gaseous nebula, charging the particles to form rings.
8. By 1945, C. F. Von Weizsficker had visualized the collapse of a gaseous cloud to form a flat disk. A system of vortices formed in this disk in geometric progression, with more rapid rotation at the center. Coagulation occurred along the circles where secondary eddies were created by the viscous shear between the successive rings of the vortices.
Each of these theories, among other weaknesses, has essentially two. In the first place, none of them properly explains the distribution of angular momentum in the system.
In the second place, Dr. Lyman Spitzer, Jr., at Princeton University, proved in 1939, that the materials hypothesized by the theories up to that time would dispurse to outer space, not coagulate.
Of course, Dr. Von WeizsRcker was aware of this, and his theory was coming closer to what is thought to be the true explanation than any before. His difficulty was in not being bold enough, and not going sufficiently far.
Before proceeding farther, let us digress briefly merely to mention a few facts which serve to indicate the many facets which must be considered here. In 1930, at the University of Arkansas, I was taking a course in Mathematical Physics from R. A. Houstoun's book. Suddenly the age of the earth jumped overnight from 2x109 to 3x109 years. This was when radio active dating of rocks was first reported. Certainly the age of the earth must be a prime consideration. It is noteworthy to observe that none of the crustal rocks seem to be primeaval but to be secondary. Best estimates now indicate an age of from 5x109 to 7x109 years.
Temperature is also both an interesting problem and of great importance. In 1952, 1 heard Dr. E~. C. Bullard state that he felt the core of the earth to be fluid. His. latest paper that I have seen, coming out last year, states more or less the same thing. Perhaps "Mohole" will tell us more. It has been confirmed, however, by various corings in deep wells, that the temperature rises 1*C for each 125 feet down. I saw this confirmed in a deep water well at College Station, Texas a few years ago.
Harrison Brown, and others, furnish us with chemical clues. This leads us into the equally fascinating problem of abundances of elements. Certainly "Cosmic Composition" is uniformly true throughout the universe. However, for the lighter planets, the lighter elements, hydrogen and helium, were allowed to escape, which does not therefore leave an 80-20-1 distribution for H-He-Heavy Stuff on the earth and its sister planets. The major planets come closer to this cosmic distribution, because their masses retained a greater part of this original material. Certainly, however, the earth's atmosphere is secondary, with the earth's original atmosphere having been lost.
Meteors appear to be startlingly close to the age of the earth, and represent some primeavel matter. Harrison Brown shows that they must have been under tremendous pressure at some time, and it is interesting to note that many evidences of trapped gases have been found in meteors.
So the evidence piles up, and it must all be sifted, and coordinated. Order must be made out of the whole. Dr. Gerard Peter Kuiper, now at the Lunar and Planetary Laboratory, Tucson, Arizona, has seemed to come closest to this order than any one else. Now let us proceed in the presentation of his Protoplanet Theory.
Let us trace briefly the story, to return to the details later in this talk. Kuiper assumes the existence of a cloud of gas, whose mass is 100 times the present mass of the solar system. This cloud is in slow rotation, in a direction which we call west to east. He proves mathematically that this rotating cloud will collapse in a direction perpendicular to the plane of rotation. This collapsing process will continue for 10,000 years to 100,000 years, until a time occurs where the Roche Density obtains. This density is that density where the internal attraction of the cloud is equal to the tidal forces of the Sun, simply, where push is equal to pull.
Now why was Kuiper successful in almost identical assumptions where others failed. He started with a larger, more massive cloud, and he allowed the collapse to progress to a greater degree. Actually, 99% of the mass of the cloud was lost during the process of formation. So you see, if the present solar system should be wiped out completely, and spread out uniformly into a slowly rotating cloud, then the solar system could not form again.
And besides, this process makes Solar System formation the rule instead of the exception. It is estimated by Kuiper that there must be 109 solar systems in our galaxy similar to our own. Surely somewhere there must be some people living who have more common sense than we do, and can live together more peaceably by the rule of Christ. You no doubt remember when Frank Drake at the National Radio Observatory in West Virginia attempted to communicate with one of these systems. It happens the two nearest stars suitable for such life are 11 light years away, requiring 22 years for the round trip.
We must therefore enquire, "Just what type of star is best suited for a Planetary System?" It is more probable than not that certain classes of stars will have planetary systems about them. Astronomers classify stars with capital letters, the class being determined by its temperature. It turns out that when we have classified stars by temperature, we likewise have separated them according to their brightness, their chemical content, their mass, their space velocities, their age, and also to some degree as to their region of location in space. One says the following apothegm: "Why, Oh Be A Fine Girl, Kiss Me, Nay, Romeo, Scram." The first letters of these words form the stellar classification known as the Spectrum Luminosity Diagram, or the Henry Draper Classification, or the Hertzsprung-Russell Diagram.
Now this classification, W through M, carries us from surface temperatures of 100,000*K to 3200'K. It turns out that a star of class G, like our Sun, is of surface temperature 6,000'K. And this seems to be a very happy state for a star to be in if we expect to find a planetary system associated with it. Now this is not to say that a star of higher spectral class, such as F at 8,000'K, or even A at 12.000'K, may not have planetary systems revolving about them. But if they do, the chances are very good indeed that the system was formed before the temperature got that high. This is to say, condensations of size I MM in diameter occurred before the temperature rose too high.
If and when Roche Density occurs, the formation of a planetary system is a necessity. It cannot help being formed.
This Roche Density, or Limit, is quite critical. It must be realized within a factor of 3. A miss by a factor of three is all that is needed to cause the formation not to occur.
If, after the evaporation loss, and the radiation loss, and after the rotational flattening his occurred, then the density is less than this Limit by a factor of 3, all materials are lost to outer space, except for the central star, or we may get a system similar to the rings around Saturn. If however, the density is larger than this Roche Density by a factor of 3, then we get a binary system formed. It should be pointed out here that more than half, about 2 out of 3 stars are multiple systems. In fact, it appears that less than 10% of stars formed as singles, even if such a star is now a single star.
Now if our cloud has several hundred or several thousand times the solar nebula, we will get a cluster of stars, open or globular, depending on the amount. The open clusters are called Galactic clusters, since we see them only close at hand because of their smaller brightness. They are a passing phase of the Universe and our Galaxy, because they continue to be broken up and to lose member stars by the field star effects. The globular clusters are supposed to have been formed as original members of our system.
Certainly you can see that if sufficient material is present in some region of space, this same Rotational flattening effect will form a galaxy. The only thing left to do is to ask why the material collected together and rotated in the first place. Suffice it to say that the rule of the universe is motion. We do not live in a static universe. Where there is matter there is energy, and electromagnetic radiation. The mere shadow of a proton on an electron is sufficient to establish a thermal inequality, and hence motion.
So, let us now return to our solar nebula and carry this process farther. The Roche density, though critical, is surprisingly small.
This density, occurring where gravitational attraction balances tidal forces, gives a minimum distance for a planet to have satellites of 2.44 diameters. The distance for Saturn's rings is smaller. The distance of the moon is larger.
For comets, this gives a minimum distance of 90 million miles from the sun. Some creep closer, with more or less disastrous results. For example, Comet 1882 went through the Solar Corona at 1 million miles per hour, and came out on the other side as four comets. They will return to the sun around 2800 AD, spaced 200 years apart. This also serves to confirm that solar accretion cannot alone explain the heat of the sun, in fact is only an inconsequential part.
Now for a few startling figures. For Mercury's distance, this Roche Density is 10-5; for the earth's distance, it is 10-6; for Jupiter's distance, it is 10-10; and for Neptune's distance, it is 10-10 Naturally for Pluto's distance, it is negligible. Out past Pluto, all materials were pushed away from the sun.
Now condensation begins as loose snowflakes, ices, and silicate an dmetal grains. The flakes were composed of water, ammonia, methane, and other hydrocarbons, since 99% of matter is hydrogen and helium. And to him that hath shall be given, and to him that hath not shall be taken away, even that which he hath, one of the God Laws of Nature. The bigger flakes sweep up the smaller flakes and so it goes.
In the colder outer regions, objects of the order of 100 meters to 10 kilometers in diameter would form by the above process. These resemble comet heads. In the inner parts, where it was denser and warmer, objects of larger size were allowed to grow. These were largely composed of silicates and metals, with some H20 snow. These resemble Nereid, and Pluto, and smaller planets.
Out past Neptune, and out past Pluto, this process led to the formation of comets. Jupiter did not allow a large mass to form near it. Some think, and there seems to be evidence to substantiate it, that the asteroids were at one time about 10 to 100 protoplanets, but were caused by Jupiter to break into 35,000 odd pieces.
At maximum size, the protoplanets touched one another, thus sweeping the system relatively clean. Not completely though, for we, in the solar system are still bathed in the solar plasma, and subjected to the solar winds.
As a result, we find that Neptune is different from Mercury, not because of distance from the sun, but because proto-Mercury was smaller than proto-Neptune. Furthermore, no planet could form in a region of too low a density.
As the planets, or satellites grew, all particles spiraled inward. The smaller particles, less affected by friction, spiraled in more rapidly to form the nucleus, while the larger and lighter ones, come in more slowly to form the crust.
If it were not for the solar tides, the protoplanets would rotate three times as fast as they do. So if a body found itself revolving outside the envelope, then it may find itself shed to interstellar space. The contraction itself, perpendicular to the plane of rotation, occurs because of collisions and dissipation of energy. It is the transition from a Sun with weak, infrared emission to a central sun of its present ultra violet type of emission which allowed the planets to form, and then caused their near complete destruction by evaporation and the clearing out of interplanetary space by radiation pressure.
There were four methods of loss of material by the nebula: evaporation, radiation pressure, expulsion by solar corpuscular rays, and a quite hypothetical fourth method of hydromagnetic coupling between a rapidly rotating sun and the ionized cloud.
For efficiency, evaporation requires the root mean square velocity of the particles, usually here of atomic or less in size, to be no less than one-fourth the velocity of escape. The mean free path above the escape layer must be no less than the size of the solar nebula. Radiation pressure had little effect on the ionized HII regions. It was extremely important for low-latitude HI regions in the nebula. It was also extremely important in the mass losses for the protoplanets themselves. It seems therefore that radiation pressure was nearly the sole cause of the almost complete dissipation of these bodies. Furthermore the loss was entirely radial, and ejection for the most part began in low levels within the nebula. And we are talking about radiation pressure from the solar energy itself, and not of any local effects.
Bierman believes the high accelerations of the corpuscular rays was due to the action of the solar electrons on the cometary ions. The solar electrons are kept moving in turn by the solar protons. The rate of escape to space will be close to the maximum allowed by the total kinetic energy. The instreaming hydrogen atoms will be ionized by the solar UV radiation less than 910 A, and by corpuscular rays. Thus the second source of ionization, the corpuscular beam itself, probably dominated the dispersal of the solar nebula, by first ionizing the material and then sweeping it away.
Helium and the other high ionization potential gases were probably removed in the same manner as was hydrogen. Once these gases are ionized by corpuscular radiation, the ions are rejected much as happens in comet tails today.
Even at the present epoch, planetary evaporation and ejection is not entirely absent. However, interplanetary space is so low in density that only in the comets do we find the violent exposure to which formerly the entire solar nebula was subjected.
The planetary surface temperatures are not nearly so
important as the planetary exosphere temperatures for
the outer atmospheres. The latter determine the planetary mass losses. These temperatures became quite
high, of the order of 104 to 105 degrees Kelvin.
There were two different modes origin and evolu tion for satellites and comets, depending upon whether the planetary envelope in which they arose was gravitationally stable or unstable. The large ones formed as proto-satellites. The small ones formed as nebula type bodies where gravitational instability was permitted. Some satellites are 100,000 times as small as they should be to have formed as proto-satellites. For example, the outer satellites of Jupiter are no doubt nebula satellites, later captured. This will also explain retrograde motion which does occur in certain instances.
In the early stages, as evaporation occurred, the protoplanets shed their outer satellites of all sizes. They were either deposited into interplanetary space from which they could be recaptured, either by their own planet again, or by another planet; or they were pressed into forced orbits as are the Trojan Asteroids, which are probably spherical in shape; or they were scattered throughout the solar system by planetary perturbations. For example, some objects now near the Earth may have originated in Proto-Neptune.
It can be shown that in the absence of viscosity, the obliquity of the planetary axis will increase to, 90% and there remain fairly constant, unless acted on by other forces. However, where viscosity is present, obliquities may be shown to be about what they are today. The obliquity will oscillate due to perturbations.
So we may conclude this by returning to our original thesis, and state briefly how Kuiper's Protoplanet theory explains fairly satisfactorily those things which were required to be explained.
In the first place, the common direction of revolution of planets about the sun and their low inclination to the ecliptic are due to the extreme flatness of the solar nebula after collapse.
Second, the nearly circular orbits of the planets are due to the internal viscosity of the nebula. Mercury and Pluto are exceptions to this rule, because of the absence of a constraining force on the edges. All material within Mercury's orbit fell into the central Sun. All material outside Pluto's orbit was lost.
Third, the direct rotation from west to east of the planets is due to the solar tidal friction. The Roche Densities are nearly equal. Since this density is where solar tides and internal attraction nearly match, the protoplanets started with synchronized periods of rotation and revolution. Then the periods of rotation decreased with time. In these units, Neptune is no farther than Mercury from the central mass. However, the rotational periods are a complex problem in physics, chemistry, and dynamics. This is probably the most important source of potential information available today. This is associated with the, rotation of all stars by spectral classes, and leads us into the consideration of magnetic stars, which constitute a different story from what this lecture was designed to give.
Fourth, the largest obliquity can be go,. All of them are actually much less, as indicated above. However, the largeness of the obliquity for Uranus, having ittss equator nearly at right angles to the ecliptic, is no doubt due to the action of some extraneous body.
And finally Fifth, this theory gives 10,000 times the present angular momentum. So our problem here, instead of requiring the explanation of the absence of angular momentum, requires the explanation of its loss. This is an entirely different problem, and much simpler. Part is lost during the original evaporation period. Part is lost due to continued tidal friction. And it is still being lost.
So to use Kuiper's own words, truly this is a simple theory. The interdependence of the numerous subproblems makes the subject one of unusual fascination. One great surprise of course is that the planetary distances have changed so little during 3 billion years.
It is also most gratifying that this process of planetary formation is but a special case of the universal
process of binary-star formation, which seems to be
one of God's universal Laws. Also it is satisfying to
realize that there, are probably a billion systems like
our own in our galaxy alone, not to mention the myriads of other extra galactic systems. The probability
of the formation of such a system by this process is
100 million times, the probability of formation by an
approach or collision.
Truly God is in his Universe, and all will be right with the World.