Thought Experiments

In a recent Scientific American, I came across an article with the title "Thought Experiments." I had read that Einstein had come up with his Theory of Relativity by using "thought experiments." Of course, his theory has been deemed correct by actual experiments. Until then, it was simply a theory.

What baffled me though about the article was the subheading which was "Some philosophers are doing more than thinking deeply. They are also conducting scientific experiments relating to the nature of free will and of good and evil." What!? This sounded like something I would read in magazine about philosophy or religion, not in a magazine devoted to science.

In the first place, a "thought experiment" is not science, but speculation perhaps bolstered by mathematics as in Einstein's case. This is the kind of thing philosophers, science fiction writers, futurists, prophets and other imaginative thinkers have been doing for thousands of years. One notable "thought experiment" is Rene Descartes' reasoning from "I think therefore I am" as the one irrefutable assumption to several other conclusions, all of which were refuted by later philosophers.

As to the "nature of free will," I believe psychologists have been doing actual experiments on this for some time without coming to any definite conclusions. Philosophers have debated "free will" to death. And then when the author throws in "good and evil" in the mix, these terms have no intrinsic meaning. Every person on this planet has a different idea of what is good and what is evil.

I read further in the article and find that persons the author calls "experimental philosophers" team up with psychologists and publish in journals. "They have spawned hundreds of papers and come up with surprising results and some strong opinions on every side." Note that he does not say that they have come up with any actual scientific facts.

The article blabs on this fashion for three pages, mixing "thought experiments" with some actual studies in psychology in this strange manner. He concludes with "... it can sometimes be helpful, and occasionally indispensable, to have a better understanding of the cognitive processes that give rise to these beliefs." Duh!

Shame on you Scientific American for printing such nonsense.     

What is Gravity?

One of the most familiar forces is also the most mysterious, and that is gravity. In general, gravity is the force that pulls together all matter (which is anything you can physically touch). The more matter, the more gravity, so things that have a lot of matter such as planets and moons and stars pull more strongly.

The amount of matter in something is called its mass. The more massive something is, the more of a gravitational pull it exerts. As we walk on the surface of the Earth, it pulls on us, and we pull back. But since the Earth is so much more massive than we are, the pull from us is not strong enough to move the Earth, while the pull from the Earth can make us fall flat on our faces.

In addition to depending on the amount of mass, gravity also depends on how far you are from something. This is why we are stuck to the surface of the Earth instead of being pulled off into the Sun, which has many more times the gravity of the Earth.

Most of us know the effects of the mysterious force called gravity. However, the question 'what is gravity' is not easy to answer, because we don't really understand what this force actually is (if it is a force at all).

What we do know about gravity is mostly due to the work of three men, Johannes Kepler, Sir Isaac Newton and Albert Einstein. Kepler worked out the details of how the orbits of the moon and planets can be described mathematically. This is known as the Kepler laws of planetary motion, but it does not answer the question 'what is gravity'.

Newton, reportedly while observing an apple falling from a tree, got an inspiration that allowed him to work out how the force of gravity can be described mathematically. It later became apparent that there are some scenarios where Newton's mathematical description does not quite hold, but it still the simplest way of describing gravity. It does however also not answer the 'what is' question. Newton was uncomfortable with his own theory of gravity. He said that his theory never "assigned the cause of this power." He was unable to experimentally identify what produces the force of gravity and he refused to even offer a hypothesis as to the cause of this force on grounds that to do so was not sound science.

Einstein later worked out how the force of gravity is not quite a force, but rather an artifact of the natural movement of objects through curved four-dimensional space-time. Einstein reportedly got the inspiration for this imaginative leap in understanding of gravity by contemplating a man falling off a building. Such a falling man would not experience any force while he is falling, at least not before hitting the ground and suffering severe forces.

In his monumental 1916 work 'The Foundation of the General Theory of Relativity', Albert Einstein unified his own Special Relativity, Newton's law of universal gravitation, and the crucial insight that the effects of gravity can be described by the curvature of space and time, usually called 'space-time' curvature. The radius of curvature is modified by relativistic factors, by a gravitational time dilation and by a velocity time dilation. This causes the acceleration of a falling object, as experienced by the free falling object to be larger than what Newton predicted.

So, what is gravity? The truth is that at the most fundamental level, no one really knows. This blog only summarizes the basics of Newton's and Einstein's gravity in terms of the gravitational acceleration caused by curved space-time and velocity.

We may have to wait for a theory of 'quantum gravity' to be completed for a better answer to 'what is gravity?' Quantum gravity (QG) is the field of theoretical physics attempting to unify quantum mechanics with general relativity in a self-consistent manner, or more precisely, to formulate a self-consistent theory which reduces to ordinary quantum mechanics in the limit of weak gravity (potentials much less than the speed of light squared) and which limits Einstein's general relativity to large actions (action much larger than Planck's constant). The theory must be able to predict the outcome of situations where both quantum effects and strong-field gravity are important (at the Planck scale, unless large extra dimension conjectures are correct). Although some quantum gravity theories such as string theory and other so-called theories of everything attempt to unify gravity with the other fundamental forces, others such as loop quantum gravity make no such attempt; they simply quantize the gravitational field while keeping it separate from the other forces.

So far, cosmologists, physicists and mathematicians have not arrived at a consistent theory of gravity that melds quantum mechanics with the theory of relativity.

Misconceptions About Science

I don't know whether it's the way that science is taught in our school system, but many people have misconceptions regarding what science is and what it does. I believe this may be because most of what is taught in the lower grades and high school concerns the history of science, the achievements of science and known facts that science has discovered. To me, this absolutely the wrong approach. What science really is, is a process for discovering the truth about ourselves, our environment and the universe in general.

Like any human endeavor, to succeed it requires a method and the proper tools. The method is really simple, it starts with observations about the real world, from these observations the scientist forms a hypothesis, next he or she must perform experiments to determine whether the hypothesis is valid and true. The experiment must be repeatable by anyone using the same equipment and the same methods.

The tool that a scientist uses depends upon the particular science one is pursuing and the experiment required to prove or disprove the hypothesis. This may vary from simple observation, such as Jane Goodall has done in her study of gorillas, to sophisticated and expensive equipment such microscopes, computers, particle accelerators and high powered telescopes. The one tool used by all sciences is mathematics. It is the cornerstone on which all science depends.

Now for the misconceptions. The first one is that any theory put forth by science is totally correct for all time or is false. Critics of science often cite the fact that scientific theory is constantly changing as new facts are learned and our equipment becomes more sophisticated. We often speak of "laws," such as The Law of Gravity. This is simply a misnomer. There is no such thing as an unmodifable scientific law. Nonetheless, this does not mean the findings of science are not valid. Most of the great theories are still correct for ninety-nine percent of the cases for which they apply. It is only a few exceptions that cause theories to be modified.

The second great misconception is that science is anti-religion or anti-God. This is not true. It may show that what has been written in the past in so-called holy books is incorrect, but it neither proves nor disproves the existence of a First Cause or Supreme Being.

People into the occult or believe in ghosts, UFOs, big foot, telepathy, etc. claim that there is a conspiracy by the scientific community to ignore the evidence for the existence of such things. They have it all backwards. It is not up to the scientific community to prove their claims, but the people who make them to do so. For example, let us say that I claim that a ghost is haunting my house. To prove this claim, I need to produce the ghost for credible skeptical witnesses. At one time, a Professor Rhine claimed that he had proof that mental telepathy existed in certain people. It turned out that he fudged the results of his experiments. When others tried to duplicate his experiments, they did not get the same results.

Another misconception is to blame science for the misuse of the technology that results from scientific discoveries. In the first place, scientists seldom know what will result from their discoveries. Most scientific discoveries have benefited mankind. Knowing more about the universe we live in cannot be a bad thing.