Sunday, January 12, 2014

Embrace Uncertainty

There is a nice article in Scientific American titled "The Case against Copernicus".  Fundamentally, it suggests that when Copernicus published his theory that the earth and planets all revolved around the sun early in the 17th Century -- and for many years after that -- astronomers were skeptical.

In ancient days, nights were dark and people looked at the night sky. They saw the stars move across that night sky. They saw the planets, and were bemused by the fact that they alone (other than the moon) moved with respect to the stars. For a very long time, people sought to explain the behavior of the planets.

The video shows three models:

  • The Geocentric model, in which the earth is the center of the system, and there are complex processes leading to the path of the planets against the celestial sphere;
  • The Geoheliocentric model, in which the earth is the center, but the sun is in orbit around the earth, and the other planets are in orbit around the sun; and
  • The Heliocentric model, in which the earth and the other planets revolve around the sun.
People had a very good idea of the size of the earth, and the idea that it was making a revolution every day was hard to accept. Scientists thought that, were that true, they should be able to detect the motion in the flight of shot from a canon. If the shot were at a right angle to the direction of rotation, would the shot not appear to deviate from the point at which it was aimed? The did not realize that they did not have sufficiently accurate instruments to detect the effect.

People also knew that it was hard to move big, heavy things, and the earth was very big and very heavy. They found it very hard to believe that the earth could be moving around the sun. Of course they had no theory of gravity to explain the force which at such a distance could move the earth. They believed that celestial objects were of a different sort of matter, much lighter, and as a result could move easily in orbit.

Lest that seem  silly, note that astronomers now postulate that there is dark matter and dark energy that we can not see, but that is needed in their models to explain the motion of the stars and galaxies.

The point of the article is that the astronomers of the 17th century had good reason to be skeptical about the Galileo and Copernicus. I would say that their first concern was having the means to accurately predict the paths of the planets in the night sky. A model would not be useful unless it proved better at those predictions than other models.

Galileo was condemned by the Catholic Church, basically on the charge of heresy in that he did not accept the Church's belief in the geocentric model. As a scientist, I think he did not believe in any model, nor should he have believed in any model.  A scientist may believe a model is very probably true, and an alternative is very improbable, but skepticism about ultimate truth of theory is the hallmark of science.

Einstein's theory has proven to make predictions in some circumstances that are more accurate than Newton's theory. Still, scientists recognize that they don't have a means of understanding both Relativity Theory and Quantum Theory and are keeping their minds open. They look for experiments that might supply new observations to falsify one of the other theory, leading to the construction of still better theories.

Perhaps that acceptance of uncertainty should be much more widely used. Would our 21st century foreign policy have been better had U.S. government leaders been more willing to acknowledge the uncertainty in their understanding of Iraq and Afghanistan? Would the Congress work better now if Republicans and Democrats be more willing to acknowledge the uncertainty in their understanding of the economy and national development? I suspect so!

No comments: