1446 Introductory Astronomy II

1. 1446 Introductory Astronomy II Addendum X The Scientific Method R. S. Rubins Fall 2011

2. A Word from Albert Einstein The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand rapt in awe, is as good as dead: his eyes are closed. Albert Einstein (1879 – 1955)

3. The Scientific Method (simplified) • The scientific method is a continuous process of observation, hypothesis or theory, prediction and then further observation and experiment.

4. “Intelligent Design” Statement “Evolution is just a“theory”,not the“truth”. What is a scientific theory? Does the “truth” exist in science? • The word “theory”, as used above, actually means the scientific word “hypothesis”, which is just an educated guess, made to explain an observation or group of observations. • Scientists are engaged in refining the theories that best explain the observed phenomena. The “facts” may change in the light of improved observation, so that in science one can never claim that the “truth” is known.

5. ScientificTheories 1 The development of scientific theories is based on the belief that there is an underlying order to the Universe, the essence of which may be grasped by the human mind. A scientific theory is a comprehensive explanation of some aspect of the universe, based on a minimum of general rules and arbitrary assumptions, which is supported by a vast body of experimental evidence. Between competing theories, the one with the fewest arbitrary assumptions is usually preferred. This philosophical choice is known as Occam’s razor , named after William of Occam (1285-1349).

6. Scientific Theories 2 • A scientific theory must make testable predictions about the results of future observations. • All scientific theories are provisional, in the sense that they can never be proved to be absolutely “true”. • A theory is disproved if even a single observation disagrees with its predictions. However, any such observation must be confirmed independently. • Often, a new theory is just a modification of the older one, but on rare occasions, it has “revolutionized” our understanding of the universe.

7. Scientific Theories 3 • Its results must be both repeatable and verifiable. • It is based on models, often mathematical, which must be tested by new observations. • Science is understood to be an unfinished business, and scientists are aware that even well-established theories may turn out to be incomplete or limited in range of application. • Science is universal, and scientists come from all races and religions. ____ • Scientific progress is not a “democratic” procedure. It is not advanced by majority vote, even among leading scientists.

8. Science and Pseudoscience 1 • Unlike the doctrines of pseudoscience, scientific theories are not belief systems, so that trust or faith in an idea, regardless of its source, is not part of the scientific method. • While scientific theories must make testable predictions about the results of future observations, the ideas of pseudoscience, which are based on supernatural hypotheses, cannot be tested objectively. • A strength of science is its fluidity, which keeps it open to the adoption of new ideas as our knowledge grows. • Pseudoscience, usually based on a rigid doctrine, tends to resist change.

9. Science and Pseudoscience 2 • From astrophysical observations, the age of our universe has been found to be about 14 billion years old. • Geological and physical data show that the age of the solar system is about 4½ billion years. • A vast amount of geological and biological data indicate that the evolutionary history of primates on the Earth goes back about ten million years, while fossil skulls indicate identifiable humans have existed for about 100,000 years. • There are no observational data supporting a world that has existed for only 6000 years.

10. Human Weakness • There is a natural reluctance among people, scientists included, to accept new revolutionary theories that are in conflict with deep-rooted philosophical beliefs, even if the theories have been experimentally verified. • This prejudice is essentially the same as that for rejecting science for violating religious dogma. • Examples of the former were the rejection of the heliocentric universe by the later Greek philosophers, to Einstein’s theories of special relativity and the photoelectric effect, and by Einstein himself to the standard interpretation of quantum mechanics. • The heliocentric universe also provides an example of the latter, as does the current rejection of evolutionary biology by some Christian denominations.

11. The Scientific Method • The attraction of the scientific method goes beyond its enormous power and scope, however. There is also its uncompromising honesty. Every new discovery, every theory is required to pass rigorous tests of approval by the scientific community before it is accepted. Paul Davies, in “The Mind of God”, 1992

12. Nature of Physics 1 • It is the search for order in the Universe at all levels, from the smallest sub-atomic particles to the largest distributions of galaxies. • It is a study of matter, energy, motion, space and time, based on experimental observations. • Its aim is to explain the complexity of all measurable phenomena in terms of the smallest number of fundamental laws. • Mathematics is the language of physics.

13. Nature of Physics 2 • Physics is an experimental science, based on theories that are ultimately tested by quantitative observations. • All quantitative measurements are subject to experimental error, so that “facts” may change as the precision of a measurement is increased. • Physicists speak of the beauty and elegance of great theories, but only experiment and observation allows us to decide whether a theory should be retained, modified or discarded.

14. Major Physical Theories • Eighteenth century Newton’s Laws of Motion and Gravitation. • Nineteenth century Maxwell’s Equations of Electricity and Magnetism. Thermodynamics and Statistical Physics. • Twentieth century Special and General Relativity. Quantum Mechanics and Quantum Field Theory. • Twenty first century Quantum gravity ? String theory? Theory of Everything ?

15. The Twin Revolutions of The 20th Century • By the late nineteenth century, the Laws of Nature were thought to be understood. • What is now known as classical physics was destroyed by the twin revolutions of relativity and quantum mechanics (QM). • Special Relativity showed that universe is 4-dimensional, with space and time inextricably linked. General relativity, Einstein’s greatest achievement, describes gravity in terms of the curvature of space-time near matter. • The fundamental concept of causality is lost in QM, where many results can be given only as probabilities, defying our common sense. Most of the amazing technological developments of the present age are consequences of QM.

16. Some Cosmological Thoughts • The laws of physics are assumed to be the same everywhere in the universe, including the values of the universal constants, such as the speed of light c, the charge on the electron e, Planck’s constant h, and the gravitational constant G. • Our place in the universe is not special: our star (the Sun) is unexceptional, and nothing sets our galaxy (the Milky Way) apart from other galaxies. • We and our planet are made of “star-dust”, and together form a microscopic part of the visible universe. • The evolution of life on the Earth is just a tiny part of the evolution of the universe.

17. Overviewof the 20th Century While, according to Penrose, quantum theory has been shown to be accurate to one part in a hundred billion (1011) and general relativity has been tested on a binary pair of pulsars to one part in ten trillion (1013), problems of singlarities, infinities and measurement still cloud three of the four theories shown above. 17

18. Astronomers and Astrophysicists Astronomers and astrophysicists are at an enormous disadvantage, when compared with other scientists. A chemist can mix chemicals, heat them up or cool them down, and study how they react in a controlled environment. A physicist can use sophisticated equipment to test the mechanical and physical properties of a newly-created material. Astronomers ? They cannot drag the stars into their laboratories, or slice open galaxies in order to peer into their cores. Astronomers and astrophysicists can observe only what the universe offers, and speculate about what they cannot measure. Based very loosely on How Old is the Universe by David A. Weintraub (2010). 18

19. Science and Religion 1 • An area of study is not a science if it is based on a belief or philosophical system, which is held to be the absolute truth. • Conflict between science and religion need not exist, since both address different questions. • Science attempts to answer questions about how the Universe works, but not about the reasons for its existence, or the role of a “Creator”.

20. Science and Mysticism • Although many great physicists. Such as Kepler and Einstein, have believed in mysticism, it is a very personal matter, and so remains outside the realm of science. • On the other hand, great new ideas which have advanced physics, can come from any source. Indeed, numerous scientists have used mystical insights to formulate new insights. • One should not forget that every new idea, regardless of its source, must pass the standard tests of a physical theory: that it agrees with observation and can be used to make testable predictions.

21. Some Comments • In about 1600, Galileo argued that God would have not given humans intelligence if not to study nature. • In a compilation of the writings of Carl Sagan, published posthumously in 1985, he makes the point that the universe revealed to us currently by science is far grander than the simple world view of biblical times (and even that of just a century ago). • In 1992, Paul Davies wrote: “Through conscious beings the universe has developed self-awareness. This can be no trivial detail….We are truly meant to be here.”

22. Science and Religion 2 • “His (the scientist’s) religious feeling takes the form of a rapturous amazement at the harmony of natural law, which reveals an intelligence of such superiority that, compared with it, all the systematic thinking and acting of human beings is an utterly insignificant reflection.” • “This feeling is the guiding principle of his life and work… It is beyond question closely akin to that which has possessed the religious geniuses of all ages.” Albert Einstein, 1934 • “Those individuals to whom we owe the great achievements of science were all of them imbued with the truly religious conviction that this universe of ours is …. susceptible to the rational striving for knowledge.” Albert Einstein, 1948

23. Science and Religion 3 • “I belong to a group of scientists who do not subscribe to a conventional religion but nevertheless deny that the universe is a purposeless accident.” • “We, who are children of the universe – animated stardust – can nevertheless reflect on the nature of that same universe, even to the extent of glimpsing the rules on which it runs.” • “I cannot believe that our existence in this universe is a mere quirk of fate, an accident of history, an incidental blip in the great cosmic drama. Our involvement is too intimate.” • “Through conscious beings the universe has developed self-awareness. This can be no trivial detail….We are truly meant to be here.” Paul Davies, in “The Mind of God”, 1992

24. On Science 1 • “…The characteristics of nature…are determined always by the material with which we work, by nature herself.” • “We look and we see what we find, and we cannot say ahead of time successfully what it is going to look like. The most reasonable possibilities often turn out not to be the situation.” • “…. it is necessary for the very existence of science that minds exist which do not allow that nature must satisfy some preconceived conditions…” Richard Feynman, in the ’The Character of Physical Law’, 1965.

25. On Science 2 • If science is to progress, what we need is the ability to experiment, honesty in reporting results… and finally – an important thing – the intelligence to interpret the results.” • “An important point about this intelligence is that it should not be sure ahead of time (of) what must be. It can be prejudiced... Prejudice is different from absolute certainty. I do not mean absolute prejudice – just bias.” Richard Feynman, in the ’The Character of Physical Law’, 1965.

26. On Doubt • “Cherish your doubts, for doubt is the handmaiden of truth. Doubt is the key to the door of knowledge; it is the servant of discovery. A belief which may not be questioned binds us to error, for there is incompleteness and imperfection in every belief.” • “For truth, if it be truth, arises from each testing stronger, more secure. Those who would silence doubt are filled with fear; the house of their spirit is built on shifting sands.” • “Therefore, let us not fear doubt, but let us rejoice in its help. It is to the wise as a staff to the blind; doubt is the handmaiden of truth.” Robert T. Weston, Unitarian minister, 195x.