A Brief History of Science
For those who have a background in science and engineering, this is mostly a simple review. I hope it is also comprehensible and helpful to those with other backgrounds. Those who must expend a little more effort to comprehend will benefit more than those for whom it is easier. In this modern age, everyone needs to understand a little about science, especially those who have the privilege of a college education. Also, educated Christians at least need to have some basic ideas about how science relates to Christianity. But if you find yourself getting stuck here, skip on for now to chapter 2.
This history has an admitted bias toward physics and astronomy. There are two reasons. One is that I am biased; my educational background is physics and my hobby since childhood has been astronomy. The other reason is that any book on the history of science emphasizes these fields; they are in fact the root from which other branches of modern science grew. This chapter is the foundation of all that follows. Consideration of the principles and applications of science will be based on reference to examples from the history of science.
Even if you forget most of the details in this chapter, there are two main concepts which I hope are made clear by this brief summary of the history of science. These two concepts are applied repeatedly throughout the rest of the book, which is why this is the first chapter. The first concept is the importance of assumptions, or world view. No matter how correct the logic is, wrong assumptions usually lead to wrong conclusions, though there are interesting instances where someone was right for the wrong reasons, and others who were wrong for (some of) the right reasons. But the most serious consequence of wrong assumptions is that they may prevent awareness and discovery of important truths. The second concept is the pursuit of wide generality. Perhaps the briefest possible summary of the progress of science is to call it the pursuit of broader theories. A theory may be made broader by combining areas previously covered by several separate narrower theories, and most new theories also extend into new areas never known before. Watch for examples in the following account.
I Ancient times
The ancient Babylonians, Egyptians, and Chinese had basic astronomy and mathematics by 3000 BC. This included a quite accurate understanding of the motions of celestial objects, and the ability to predict them, as seen in their calendars and other records. The ancient Hebrews were also astute observers of nature, as hinted in some of Solomon’s proverbs. It is a mistaken stereotype to consider the ancients as mostly ignorant, for instance thinking that the earth is flat. Most of them knew the earth is a sphere.
The classical Greeks are represented by outstanding thinkers such as Aristotle around 350 BC, Archimedes around 250 BC, etc. The Chinese also developed to a similar level at about the same time. They both had the basic concepts of biology, physics, chemistry, mathematics, and geometry.
Aristotle’s physics was the Greeks’ highest scientific achievement, and was the greatest influence on the following two millennia in Europe. We will discuss this briefly, noticing especially the important influence of assumptions in determining conclusions. But this was not the only aspect of Aristotle’s work. He also assembled a prodigious amount of information on animals.
The first basic assumption of Aristotle’s physics is “Force produces motion.” This is based on common experience. If you see something moving, you look for something pushing it. If you stop pushing something, it stops moving. There are a few phenomena that seem to be exceptions, for example projectiles that move through the air with nothing visibly pushing them. We now recognize this as a fatal exception to this assumption, but Aristotle plugged this loophole by saying that the air in front of a projectile moves out of its way and around behind it, thus pushing it. Thus “small problems” with a theory can appear to be resolved. In ch. 2 we will consider such problems and their role in the acceptance or rejection of theories.
The second assumption is “Earth is the center of the universe.” This is called the geocentric theory. This too is based on the appearance of all that we see. The sky seems to be a spherical surface with the Earth at its center, and with everything revolving around the Earth. Objects all seem naturally to move either toward or away from the Earth.
The third assumption is about the composition of matter. Aristotle’s theory of chemistry was simple. He said earthly things consist of 4 elements: earth, air, fire, and water. This theory could explain all the properties and transformations of matter that they observed at that time.
Aristotle said heavenly bodies (Sun, Moon, planets, stars) consist of a fifth element, called ether. Unlike earthly matter, ether is eternally unchanging and perfect. Therefore objects in the sky which change, such as meteors, comets, and novae, must be below the heavens, in the Earth’s atmosphere, not among the planets and stars. The natural motion of Aristotle’s ether is not in a straight line toward the Earth, but in uniform circular motion around the Earth, and celestial objects must naturally be perfectly smooth and spherical. This is because a circle or sphere is the most perfect shape.
Aristotle’s theory was not the only product on the market. Others pointed out that the appearance of the sky could also be explained by saying the Earth rotates daily and travels around the Sun annually, and one logical argument in favor of this view is that the sky and the Sun are obviously far larger than the Earth, therefore more likely to be stationary. But Aristotle overwhelmingly overcame this one small detail, with numerous proofs of his own.
Aristotle gave five proofs for this theoretical system. First, we have no feeling of motion. When we walk, run, or ride a horse, cart, or boat, we can feel our motion, but on the Earth we feel nothing. Second, what force could move the Earth?! If we say it moves, we must explain why it moves, and that requires a force. Who can imagine a force large enough to move the Earth? Third, we feel no wind. When we walk or run, we feel a wind, so if the Earth were moving there should be a wind, but there is not. Fourth, there is no visible parallax, no change in the appearance of the sky caused by the Earth moving to a different location. If, for example, it is the Earth that goes around the Sun once a year instead of the Sun that goes around the Earth, then surely the stars would look different at different times of the year (see diagram). But they do not. Fifth, people are at the center of the universe. Whether this constitutes a high or low position is a good question. Obviously, this “proof” is in a different category from the more objective first four.
We now know that Aristotle’s entire system is wrong, and therefore his proofs are all mistaken. But we cannot laugh at him. If we lived then, would we come to any different conclusion? Based on what he knew, and his conceptual assumptions, it is all very reasonable, and anything else seems quite unreasonable. It was almost two thousand years before anyone was able to propose a different theory that convincingly answered Aristotle’s proofs. Doing so was a heroic achievement, a turning point in world history, and is now called the scientific revolution, a story briefly told in sec. III.
The further extension of Aristotle’s system was made by Ptolemy, in Alexandria, Egypt, AD 150. He developed the concept of epicycles for predicting the complex motions of the planets, Sun, and Moon. These objects do not appear to move in uniform circular motion, but move faster and slower and even sometimes backwards, and vary in brightness. Epicycles are circles on top of circles, a sort of machine to move these objects along the sky. Ptolemy himself probably did not really think there was a vast machine in the sky, but only analyzed the motions into several circles for purposes of computing predictions. But later generations considered these circles to be real, made of invisible material.
Also in the second century, Galen in Rome did some outstanding research on the structure of tissues and organs of animals and plants.
II Middle Ages
For more than one thousand years, no significant progress was made in astronomy, or science in general, in Europe. Alchemy was the nearest thing to scientific research, but it was a misguided and superstitious search for a way to transform cheap metals into gold, or a medicine that could heal all diseases and keep us young forever, or a universal solvent that could dissolve anything (but no one seems to have wondered what kind of container they would keep it in!). Alchemy did have one benefit, which was the accumulation of much experience and information on chemical reactions and characteristics of many materials.
The most progress occurred in the Arab world. Arabic numbers and algebra were developed, which were a great improvement over the inconvenient Roman numerals used before. The Arabs also invented zero. All of this provided the mathematical concepts and procedures which later were essential for scientific computation.
In Europe, Thomas Aquinas (1225-74) combined Aristotle’s philosophy with Catholic Church teachings, to produce a new system of thought, all of which became the official doctrine of the Catholic Church for many centuries. The Catholic Church insisted that all Christians accept all church doctrines, not only those that came from the Bible but also those from tradition and from Aristotle. If anyone expressed disagreement about anything, he could be severely punished, tortured, or even killed.
III Revolution in astronomy
By 1500, Ptolemy’s epicycle system had been extensively modified in order to agree with the observed positions of the planets, so that there were over eighty epicycles in the total system. One king is said to have commented that if he had been present at the time of creation he would have recommended that the heavens be created much more simply!
In Poland, Nicholas Copernicus (1473-1543) studied astronomy and saw that heliocentric (Sun-centered) epicycles would be much simpler and more accurate. He thus made the Sun the center instead of the Earth, with all the planets including the Earth revolving around the Sun, and he calculated the apparent positions of the other planets as seen from a moving Earth. This was a major difference from Aristotle’s teachings, which were also the church’s teachings. Copernicus only dared say that this was a more efficient calculation method, and even then he did not publish his book until he knew he was on his deathbed. But is it really true that the Earth moves? Some of his indirect comments hint that he actually thought so, that a theory so simple and accurate must be close to the truth. His friends stated after his death that he did believe this. But he had no answers to Aristotle’s “proofs.”
During the next several decades Copernicus’ theory became known in the intellectual community of Europe. There were many different opinions about it. Tycho Brahe (1546-1601) became interested in astronomy in 1572 because there was a bright supernova that year. By comparing observations from different places, he proved that the supernova was farther away than the atmosphere or even the Moon, therefore it was among the planets and stars. He realized that this contradicted the theory of Aristotle and Ptolemy. He produced a geocentric copernican theory, attempting to combine the best of the old and the new. He kept the Earth at the center, because that seemed reasonable and was the official church viewpoint. He had the planet orbits all centered on the Sun as Copernicus did, but he had the Sun and this entire system move around the Earth. In order to prove his theory correct, he obtained permission and money from the king of Denmark to build an observatory, and spent 20 years, 1576-97, making accurate observations of the planets, especially Mars because its motion was the most complex. His equipment was much more accurate than that of anyone before him; he was the last and best of the pre-telescope astronomers. In 1577, he also observed that a comet moved among the planets on a non-circular path, again contradicting Aristotle.
Before his death Brahe hired an assistant, Johannes Kepler (1571-1630). After Brahe’s death, Kepler kept Brahe’s data, and spent much of his time from 1600 to 1618 analyzing it. He accomplished this despite poor health, financial and family difficulties, and court cases by Brahe’s family trying to regain his data from Kepler. He was already convinced that the Copernican system was correct, and attempted to analyze the data according to that viewpoint. He slowly formed his famous 3 laws of planetary motion:
heliocentric elliptical orbitsThe first law contained several revolutionary concepts, and was his key breakthrough. One of course was his acceptance of the Copernican system, making the Sun the center with the Earth a planet like the other planets, moving around the Sun. Another was the shape of the orbits. Copernicus still used epicycles, and at first Kepler followed this principle. But no matter how Kepler adjusted the epicycles they could not quite fit Brahe’s data. Kepler had great faith in Brahe’s accuracy, and in the orderliness of the universe, so he refused to accept even a small error. Abandoning many years of calculations based on circles, he tried using the second-simplest shape, an ellipse, and was excited to find that it worked!
equal-area speed variation
With this accomplished, the second law described the variation of a planet’s speed as it moves along its orbit, moving faster when it is nearer the Sun. The third law described the relationship between the distances and periods of the different planets.
Kepler’s laws were only empirical, or descriptive. They very successfully explained the observed motions of the planets in the sky by describing their motion around the Sun, but he had no theory to explain why the planets should move around the Sun as they do. He had no answer to Aristotle’s first four proofs. That remained a mystery.
Galileo (1564-1642), a contemporary of Kepler, began to solve the mystery. He developed the concept of inertia. This means that any object’s natural state of motion is not necessarily stationary, but is motion in a straight line with constant speed. The reason that things we see usually stop moving when nothing pushes them is because there is a friction force resisting its motion. If the friction force is reduced, the object takes longer to slow down and stop. He observed the motion of projectiles, for which friction is very small, and balls rolling on smooth surfaces. Galileo reasoned that if friction could be totally avoided, an object would never stop.
Thus when we see an object moving, we do not need to ask what force is making it move. It is only when we see its motion changing that we must ask why. Contrary to Aristotle, Galileo said that force does not produce velocity, but force produces acceleration. This answered Aristotle’s question about what force could possibly be large enough to make the Earth move; this is the wrong question. There is no force that makes the Earth move, there is simply no force that makes it stop, and therefore it continues moving. This also answered Aristotle’s proof from the fact that we feel no wind caused by the Earth’s motion. The atmosphere and the Earth are moving along together.
Galileo’s second great contribution was that he used a telescope to view the heavens beginning in 1609, soon after the telescope was invented. Using it, he saw mountains, craters, and “seas” on the Moon, and changing spots on the Sun - imperfections! Aristotle said it is impossible for heavenly bodies, made of ether, to be anything but perfectly smooth unchanging spheres, but Galileo saw they were not smooth, and were changing. Galileo saw Jupiter’s 4 satellites - another center! Aristotle said everything must move around the Earth. Galileo observed Venus’ phases and apparent size change - it moves around the Sun! Aristotle was wrong again. Finally, looking anywhere in the sky, but particularly at the hazy band of light called the Milky Way, he saw that the sky is full of countless stars and star clusters - incredibly numerous, vast, and distant! There are not merely a few thousand stars attached to the inside surface of a sphere, but countless stars spread through space to great distances. This answered Aristotle’s proof from parallax. The reason the Earth’s motion does not produce any visible change in the appearance of the stars is that their distance is so great that the parallax is impossible to detect.
This provided answers to Aristotle’s first four proofs. But Galileo still did not have a theory to explain why Kepler’s three laws are true. Why are the orbits elliptical, and so on? And he could not prove the Earth actually moves. He wrongly considered the tides to be proof of the Earth’s motion. He is a classic example of being right for some wrong reasons.
As is well-known, Galileo was the center of one of the greatest debates in the history of the West. The church remained adamant in defending the Aristotle-Aquinas system. Outside the regions of the (Roman) church’s supervision, the Copernican system rapidly won general acceptance by the mid-1600s, and within decades even the church was shamed into quietly dropping the subject.
Notice that this victory was won with many questions still unanswered. Also, the invention of the telescope provided new information that played an important role, but that was not the only crucial factor. We will never know what the outcome would have been if the telescope had not happened to be invented at that moment. Copernicus, Brahe, and Kepler based their work on observation of the planets visible to the naked eye from ancient times onward. Galileo was not the first to observe pendulums, projectiles, and rolling balls. The other crucial factor was the presentation of a simple, accurate alternative concept with many logical and esthetic advantages, which is all very subjective. It was not a simple case of truth versus error. As the classic instance of the pitfalls along the path to knowledge, and particularly of the role of religion in this process, it will be discussed several more times in this book.
Isaac Newton (1642-1727) provided the needed theory, with the law of gravitation, 3 laws of motion (the first of which is Galileo’s inertia), and calculus. He developed his theory when he was 23, during a year in 1665-66 when the university was closed because of a plague. He finally published his theory in 1687 with the urging and financial assistance of his friend Edmond Halley.
Newton’s gravitation is an attraction force between any two objects. The Earth’s motion curves toward the Sun, forming an elliptical orbit around the Sun, because the Sun exerts a force on the Earth. The other planets orbit the Sun for the same reason. The Earth attracts the Moon, making it orbit the Earth. Jupiter attracts its satellites. The theory was so successful that it completed the overthrow of Aristotle’s system. But we must notice that in answering one question it produced a new question: why is there a gravitational force? Kepler described elliptical orbits, and left them unexplained. Newton explained elliptical orbits by describing the force of gravity, and left it unexplained. There was in fact considerable resistance to this concept for a time. A widely held principle was that force is transmitted only through contact, not at a distance through empty space. Newton himself related this “action-at-a-distance” to some theological concepts. Politics also was involved, as Newton’s theories were much more quickly accepted by his British compatriots than by European scientists. He also spent many years in a bitter battle with Leibnitz over which of them had priority in developing calculus. The progress of science is not the calm impersonal search for truth that it is sometimes idealized to be.
Galileo and Newton produced not only some new theories but a whole new method of explaining the natural world. Previous explanations were logical, philosophical, and geometrical. Aristotle attributed phenomena to essences and natures that implicitly personified the components of our world. Newton’s laws gave us a mathematical time-space theory, and an impersonal, mechanical universe, in which it seems that all events are predetermined. It encompassed both the heavens and the Earth, unlike Aristotle’s system. It seemed to encompass the entire universe.
One other important development in the 17th century was the first estimate of the speed of light. Galileo attempted to measure it, and found it simply too fast for his methods to give meaningful results. In 1676 Olaf Roemer studied the records of the motions of Jupiter’s moons, and concluded that it takes 22 minutes for light to travel across the diameter of the Earth’s orbit. This was not an accurate value (the correct value is just over 16 minutes), but at least it was approximately correct.
There were also developments in biology. Galileo was one of the first to use a microscope, and discovered the compound eyes of insects. In 1665 the English scientist Robert Hooke published his book titled Micrographie, which described the use of the microscope and some observations. The publication of this book stimulated European research on tiny things, including micro-organisms. In 1676 Anton van Leeuwenhoek in Holland used a microscope to observe living things and bacteria. He used a microscope made of glass, a very effective magnifier. The invention of the microscope opened the field of microbiology.
William Harvey in England discovered the circulation of blood. Previously the function of the heart was a mystery, and blood was considered to be just a body fluid.
IV 18th Century
The theories of Newton became widely known and understood, and many new applications and calculation methods were developed.
There were no new scientific revolutions in the 18th century. But there was a philosophical revolution that claimed a basis in Newton’s science. Although Newton himself was a committed Christian, within only a few decades philosophers were using his physical theories as a basis for increasingly materialistic and mechanistic worldviews. Newton attributed the order of nature to God’s governance, but others felt it could be attributed to nature itself with no need for God. The mechanical universe was viewed as self-sufficient. They felt that Newton had explained so much that there was almost nothing left for God to do, and many of them moved toward deism or even atheism. This began during Newton’s lifetime, and he opposed it, with little success.
In 1725 astronomers in England were attempting to observe the expected parallax of some of the stars, and instead observed stellar aberration in all the stars, an apparent annual oscillation in position amounting to an angle of 20.75 arcsec (an arcsec is 1/3600 degree). In 1729 this was explained as the result of the Earth’s constantly changing direction of orbital motion around the Sun, causing a shift in the direction from which incoming starlight arrives. This was the first actual observational evidence that the Earth is moving, more than a century after that fact began gaining general acceptance.
There were some important discoveries late in the century. Electrostatic charge was discovered by Benjamin Franklin in the United States and others in Europe. William Herschel in England discovered Uranus in 1781, adding a new planet to the solar system beyond Saturn.
Also, the invention of smallpox vaccine was a great accomplishment in medicine. At that time one-third of the children in Europe were dying of smallpox, and many others became blind because of it. A physician named Edward Jenner observed that farmers and milkmaids who contracted a milder disease from cows, called cowpox, were resistant to subsequent smallpox infection. This caused Jenner to think that perhaps he could plant cowpox in people, in order to prevent smallpox, and in 1796 this was confirmed. In 1798 he published his theory, which produced great excitement in England and all Europe. By 1801, in England 100,000 people had received the cowpox injection which gave immunity against smallpox.
The 18th century was also the period of Europe’s greatest exploration of many other parts of the world. It brought Europeans into contact with many types of people, animals, and plants of which they had never before been aware.
V 19th Century
Astronomers had long wondered why there was such a large gap between the orbits of Mars and Jupiter; it looked like there was a planet missing there, and they spent much time looking for one. They never found a large one, but finally they began finding many small ones, and called them asteroids. The first one was found on the first evening of the century, Jan. 1, 1801, by an Italian, Giuseppe Piazzi. It was named Ceres. Within a few years several more were discovered.
Astronomers knew that the distance of the stars was at least many light years. This means the light we see has traveled many years to reach us from the stars. But there was no actual measurement of the distance to any star. The distance to the nearest stars was measured by parallax in 1838, when instruments finally became accurate enough to observe such a tiny angle, less than one second of arc, 1/3600 of a degree. The distances were several light years. The nearest turned out to be a Centauri; its precise distance is now measured as 4.3 light years away. Sirius is 8 light years away, etc. This also finally confirmed the answer to Aristotle’s claim that there is no parallax, and thus, two centuries after Kepler and Galileo, it finally provided the first direct evidence that the Earth does move around the Sun. But of course, there was no one who still needed to be convinced.
Observation of Uranus’ motion showed a slight departure from the predictions of Newton’s laws. Two famous mathematicians in Europe used this departure to predict that there is another planet beyond Uranus, and to estimate its location. Neptune was found as predicted, in 1846. This was a great confirmation of Newton’s laws, showing that they really are universal.
Foucault in France demonstrated his pendulum in 1851. A very long heavy pendulum continues swinging for many hours, long enough for the Earth to rotate under it so that its direction of swing changes. This was the first direct evidence that the Earth is rotating, but again there was no longer anyone who needed proof.
Scientists continued to study electricity and magnetism,
and discovered that the two phenomena are interrelated. In 1865, James
Clerk Maxwell published the famous Maxwell’s
equations of electromagnetism. His theory showed that light is an electromagnetic
wave, and so optics became combined with electromagnetism.
Chemists were finding many rules of reaction between different substances, but there was no theoretical system to explain those rules. The periodic chart of the elements provided the concept of elements and compounds. The precise ratios of quantities observed in chemical reactions led to the concept of the atomic structure of matter.
Very near the end of the century, scientists began to realize that charged particles sometimes come out of some kinds of atoms (see below), and therefore atoms are made of positive and negative charges. This means that the name “atom,” which means in Greek “cannot be divided,” is a mistake. The atom is not the smallest, indivisible particle.
With all these discoveries, it was possible to explain why the sky is blue. This seemingly simple fact is really quite complex. The explanation requires knowing what the sky is: air is composed of atoms, which contain charged particles. It requires knowing what light and color are: light is an electromagnetic wave, and different colors have different wavelengths. And it requires knowing how light and atoms interact with each other, so that the blue component of white sunlight is scattered more than the red component.
The concepts and laws of thermodynamics were developed. The First Law - energy conservation - is one of the most basic concepts of physics; it applies to every known phenomenon. It means there is no free lunch, no creation of new energy, only transformation from one form to another, and we can use it in such processes. The Second Law - entropy increase - is equally broad. It says that not only can we not get anything free, we cannot even avoid waste, and the amount of usable energy in the universe is constantly decreasing. Every physical system changes toward decreasing orderliness. The implications of this are discussed further in ch. 6, I, A.
In the field of geology, study of the rock layers gradually led geologists to the conclusion that the age of Earth’s surface is at least tens of millions of years, not merely a few thousand years, as most people believed the Bible stated. This is currently a controversial issue in some Christian circles, which is the subject of ch. 7.
In biology, a revolutionary new concept rapidly gained general acceptance. In 1859, Charles Darwin published The Origin of Species, introducing the concepts of evolution and natural selection to explain the existence of living things. This of course was (and is) much different from the Biblical Christian viewpoint. In this book Darwin made no explicit reference to the human race, though his theory obviously had direct implications about human origins. In 1871 he published The Descent of Man, dealing with this subject. He also published various other books.
There were also two important breakthroughs in genetics. First, the Austrian monk Gregor Mendel (1822-1884) experimented with peas. He took different kinds of peas (for example, flowers with different color, pods with different shape) and cross-pollinated them. He then collected the resulting plants and made a statistical analysis. In 1865 he published the famous Mendel’s laws, also called the laws of genetics: peas display two kinds of characteristics, called dominant and recessive traits. These are controlled by hereditary units (which we now call genes). But Mendel’s laws were not widely known or accepted until the early 20th century, because it was far beyond the comprehension of scientists of his time.
The second great discovery in genetics, by others besides Mendel, was the phenomenon of mutations, sudden changes in the genetic makeup of an organism, which appear in succeeding generations.
In the field of medicine, the Frenchman Pasteur established the bacteria theory of disease, and methods of sterilization. People at the time felt that bacteria were the result of disease, but Pasteur happened to discover that bacteria were the cause of wine turning sour (because of their action on the sugar in wine). Because of this discovery, he developed the method of sterilizing food, killing the bacteria in the food by high temperature. This method is still used for milk, called pasteurization. The German physician Robert Koch isolated the bacteria which caused a certain disease in sheep, injected it in mice, which then contracted the same disease and produced the same bacteria. This method of testing came to be called Koch’s postulates in the medical world. Another medical accomplishment was by an English physician, Joseph Lister, who carried out a sterilization procedure before surgery.
The instruments and data of spectroscopy were developed. Any material can be burned or heated so as to emit light, and this light can be separated by a spectroscope into different wavelengths. The resulting spectrum is different for each chemical element and compound, and thus the composition of an unknown sample can be determined. With this data from laboratory measurements, the light from heavenly objects can be analyzed to determine the composition and conditions of planets and stars, even though we cannot travel to them.
At the end of the 19th century, scientists were very proud of the impressive progress they had made. Science seemed nearly complete, except for a few “small problems”, which no one could explain using the laws of physics that were known at that time. But they were sure these problems would soon be solved:
VI 20th Century
In 1905, Albert Einstein in Switzerland published 3 articles on the following subjects:
In 1915 Einstein published his theory of general relativity. Special relativity dealt with motion; general relativity dealt with acceleration, producing a new concept of the interrelation of space, time, and matter. This provided a new explanation of gravitation. Newton had said two objects attract one another, and left the attraction unexplained. Einstein said the attraction is produced by a curvature in space-time around a mass. What is a curvature in space-time? I don’t understand that either. But now the thing that is unexplained is why a mass curves the space-time near it. And what is mass? It is what curves space-time, whatever that means. Don’t ask me.
This illustrates a basic truth about science. There is always an unanswered “why?” left at the end of any scientific explanation. If the “why?” has an answer, then you aren’t to the end yet. The end is only the end of our understanding at present. Perhaps an answer will someday be found; perhaps not. As will be discussed later, science does have limits, and in some cases we bump into them.
In 1909 Ernest Rutherford discovered the atomic nucleus, a tiny object inside an atom in which nearly all its mass is concentrated, and all its positive charge, surrounded by a cloud of negative charge. Later research on the structure of the nucleus led to the discovery of two new forces, called the weak and strong forces.
Quantum physics was developed in the 1920s, and successfully explained the structure of atoms and the nature of the spectrum of light emitted from them. Basic concepts on which it was based included DeBroglie’s wave-particle duality and the Heisenberg uncertainty principle. Matter is not as simple, hard, and precise a system as it had been assumed to be from the time of Newton on. The formulas of quantum physics give accurate predictions of experimental measurements, but its philosophical implications about the nature of reality, and causality, are still widely debated. The uncertainty principle seems to overthrow the previous belief that all that happens in the universe is predetermined, but some physicists and philosophers argue that the uncertainty is only in our knowledge of the particles. Einstein made one of the founding contributions to quantum mechanics with his theory of the photoelectric effect, but he never accepted the later developments toward inherent probabilistic uncertainty in physical reality. His famous comment was “God does not play dice.”
The electroweak theory was developed in the 1960s, unifying the electromagnetic and weak forces into a single theory. This was another milestone on the road toward the goal of unifying all the separate laws of physics into a single theory. Now physicists are seeking a grand unified theory (GUT), hoping they can produce a theory which also includes the strong force and gravitation.
High-energy physics began with the study of radiation from radioactive elements and cosmic rays. Later on particle accelerators were built. Many new particles were discovered, which was confusing at first but led to the modern theory of quarks composing many of these particles. But according to the theory quarks are invisible, impossible to separate for observation outside of the particles containing them. This is a new type of theory, raising some interesting philosophical questions. Some theories also involve many dimensions, suggesting that in addition to the three dimensions we see (or four, including time) there may actually be many more, perhaps more than ten. What does this mean? Are these dimensions real? What do we mean by “real”? What is a theory?
The scanning tunneling microscope was invented in the early 1980s, and for the first time it became possible to see individual atoms directly, although almost everyone has believed in their existence for over a century, and Einstein removed the last doubts in 1905.
The late 20th century has seen the development of the theory of chaos, dealing with problems that are too complex to analyze with previous theoretical methods. This includes unpredictable systems and turbulence.
Pluto was discovered “as predicted,” in 1930, by an American, Clyde Tombaugh, after searching for it for several years. Its location had been predicted in the 1890s on the basis of apparent very small disturbances in the motion of Neptune, just as Neptune was predicted from its effect on the motion of Uranus. But Pluto is far too small to cause any observable disturbance, which is why Tombaugh had to search so long and hard before he finally found it. Astronomers reviewed the earlier calculations and found that the “disturbances” were in fact only small errors of observation!
Astronomers kept making progress in their understanding of the universe. The structure and size of the Milky Way slowly became apparent as larger telescopes and more sensitive instruments were built. The Milky Way is a galaxy, a flat, circular system about 100,000 light years in diameter, and the Sun is far from the center, at least 25,000 light years. A light year is the distance light travels in a year, about 10,000,000,000,000 kilometers.
Early in the 20th century astronomers believed that the Milky Way was all there was in the universe, but before long our understanding was greatly expanded. Spiral nebulae were observed in the 19th century, and their nature was a mystery. At first some astronomers thought they were other galaxies beyond our own, but that view gradually fell out of favor because most others could not imagine that the universe could be so vast. In the early 20th century most astronomers believed the spiral nebulae must be within our Milky Way. Using the 100-inch telescope Edwin Hubble was able to prove in 1925 that the Andromeda Nebula, M31, is composed of stars and is another galaxy far outside the Milky Way. This meant that the astronomers in the mid-19th century were right after all, and countless other more distant spiral nebulae are also all galaxies. Hubble and his contemporaries estimated that the most distant ones they could see were at least 100,000,000 light years away, and there was still no edge of the universe in sight. How big is the universe? Or is it infinite? We still do not know, though we have increased Hubble’s distance estimates considerably and can see many times farther with modern instruments.
Continuing observation of the galaxies discovered the red shift in their spectrum, in 1929. This means that the spectrum is similar to the spectrum of material in a laboratory, but the entire spectrum is shifted toward the red. The only reasonable explanation that has been proposed is that the galaxies are all moving away from us, and this lengthens the wavelength of their light and produces the redshift. The farther they are the faster they are moving. This is described as the expansion of the universe.
This means the universe is not stationary and unchanging forever, but it had a beginning or origin. In the 1940’s and 50’s this led to the development of the Big Bang theory, that the universe began from an explosion with a high temperature and density. This theory is able to explain many aspects of the origin of the lightest elements, and the formation and evolution of stars, though many details are the subject of continuing research.
But most astronomers still did not immediately accept
the theory in the 1950s, because one important prediction had not been
confirmed for lack of instruments with the required sensitivity. If the
Big Bang happened, there should be a low-temperature
cosmic background microwave background radiation coming from every direction in the sky, the “ashes” of the explosion. Finally in 1965 this radiation was observed by two engineers of the Bell Telephone Company, Arno Penzias and Robert Wilson. Its temperature was measured as about 3K, only 3 degrees above absolute zero. After this, all but a few astronomers regarded this as confirmation of the Big Bang theory.
The Cosmic Background Explorer satellite (COBE) in 1990 confirmed that the background radiation has a very precise blackbody spectrum, which could only arise from a very hot explosion. (There is a very small minority of astronomers who advocate a different explanation in terms of a plasma universe, but their theory and criticisms of the Big Bang theory have not gained wide acceptance in the astrophysical community.) One remaining problem was that the background radiation was so uniform that it was difficult to explain how the present non-uniform distribution of matter, in galaxies and galaxy clusters, developed from such a uniform state at the early stage when this radiation was emitted. In 1992 further analysis of COBE measurements showed very small nonuniformities, or ripples, in the radiation from different directions in the sky, solving this problem. Measurements since then with other equipment continues to confirm and refine the nature of these ripples.
With all this improved understanding of the origin of the universe and of stars, it is possible to estimate their ages. The age of the solar system is generally considered well-determined at 4.8 billion years, based on several types of evidence. The age of the universe is more difficult, and different types of evidence are inconsistent. The simplest approach is to estimate its age using the observed speed (measured by the spectral red-shift) and estimated distance of galaxies, up to over 10,000,000,000 light years. However, different methods of measurement of the distance give different results, which leads to different estimates of the age of the universe, ranging between 10 and 20 billion years and this problem has not yet been solved. An additional complicating factor is if and how the speed of expansion has changed with time. Other age estimates are based on the present state of stars, star clusters, and galaxies, and give results larger than the lower estimates based on speed and distance. But of course stars can’t be older than the universe! Actually, an uncertainty of a factor of 2 is tremendous progress in a single century, which began with the inability to even ask the question of the age of the universe. Work on this question is of course not finished, and newer results are narrowing the discrepancies in most cases, though bringing some surprises too. This story is far from finished.
Enough about physics and astronomy. The 20th century can be considered the golden age of biology and medicine. First T. H. Morgan, an embryologist, studied genetics in fruit flies, resulting in a great breakthrough in the concept and understanding of genes. But perhaps this must be attributed to the biologist Sutton, who first discovered the filamentary chromosomes in bacteria. In 1929 Alexander Fleming discovered the antibiotic penicillin, but it was not widely used at the time. During the Second World War, many injured soldiers died of infections, and penicillin finally was placed into wide use.
The following decades were the era of genetics and molecular biology. In 1931 the American scientist Barbara McClintock published her “theory of jumping genes” which shook the scientific world. She discovered that the genes in chromosomes were not completely fixed, but sometimes jumped to a different location. When she first published her theory, contemporary scientists considered it ridiculous and making something from nothing, and she received much cold sarcasm. But several decades later her theory was finally confirmed and accepted. In 1983 she received the Nobel Prize.
The field of molecular biology is a whole new world of complexity in living things, which was previously hardly even dreamed of. A single cell is an incredibly complex system of interacting proteins and other huge organic molecules. See ch. 6, II.
Another important discovery was that DNA (deoxyribonucleic acid) is the genetic material in cells. Avery, McLeod, and McCarty completed this research in 1944. Then the English scientists James Watson and Francis Crick (and the less-well-known Wilkins) received the Nobel Prize for discovering the three-dimensional structure of DNA. This discovery brought genetics into the DNA era, and many scientists are engaged in research on the wonders of chromosome DNA. This spiral molecule stores vast amounts of information in its sequences of units. For example, the DNA in every single cell of a human body contains several times as much information as a complete encyclopedia set.
In 1972 Paul Berg successfully completed the first DNA recombination experiment for which he received a Nobel Prize. This laid the foundation of modern genetic engineering. At present the production of type-B hepatitis vaccine, and insulin, is accomplished by the techniques of recombinant DNA. Even in the movie “Jurassic Park” the dinosaurs are produced by recombinant DNA technology.
An uncompleted project of the 20th century is Nobel Prize-winner Watson’s beginning work on human DNA, the Human Genome Project. The goal is to make a map of the mysteries of the entire 23 pairs of human chromosomes, in order to produce cures for genetic diseases and cancer. The map is already mostly complete, and its application to medical treatment in the twenty-first century is eagerly awaited, though also fraught with deep ethical and legal implications.
In the first half of the 20th century, biologists combined the theories of Darwin and Mendel to make a newer theory of the origin of living things, called the neo-Darwinian synthesis.
As scientists realized how amazing it is that the
universe is structured just exactly right to make it possible for living
things to exist, they began talking about the anthropic
principle, wondering what reason makes the universe like this. Some
have wondered if there are many other universes.
Because of their evolutionary assumptions, many scientists believe that life should exist in many other places in the universe, so they have begun the Search for Extra-Terrestrial Intelligence (SETI), with no success so far.
At the beginning of the 20th century, “science” meant the natural sciences. But during the 20th century we have seen the beginning of the social sciences: psychology, sociology, and anthropology. But that is mostly beyond the subject of this book, except as these fields relate to questions of religious faith.
Western civilization entered the 17th century with mankind considered to be at the center of a small, God-ordained universe. At the end of the 20th century, mankind is considered to be an insignificant accidental by-product of a measureless, meaningless, mechanical universe. Furthermore, it is generally believed that science has led us to this conclusion. Does science really lead to this?
Many people accept and advocate this conclusion, and invoke the authority of science to support it. Some of them consider this a rejection of all religion, some consider it unrelated to religion. But many other people do not agree that science leads to this conclusion, and also do not agree that it has therefore rejected all religion, nor that this whole question is independent of religion. I myself am one of them, and this book is written in order to point out the errors in this conclusion. I also present a very different conclusion, which encompasses progress in scientific research but not the opinions of all the people engaged in it, and also encompasses at least one certain form of religious faith, namely Biblical Christianity.