Is there a crisis in theoretical physics?

Nicolaus Copernicus

Physics has been, for the last seven centuries, the queen of sciences: its object is the study of the lowest-level of reality; its most akin to mathematics; it has seen happen the highest number of new, spectacular and revolutionary theories and discoveries. Let's see a few of them:

• 13th century: Roger Bacon studies reflection, refraction, spherical aberration and the use of lenses to correct vision defects. He also suggests the possibility of building telescopes, microscopes, and flying vehicles.
• 14^th century: Jean Buridan, Nicolás Oresme, Albert of Saxony and the calculators of Merton College revolutionize Mechanics, separating it for the first time from the work of the Greek philosophers, and introducing new concepts such as impetus.
• 16th century: Copernicus proposes replacing Ptolemy's geocentric system by a much simpler heliocentric system. Kepler modifies the theory of Copernicus and discovers the three empirical laws that bear his name.
• 17th century: Galileo perfects the telescope and makes with it astronomical discoveries. He also recapitulates and organizes the mechanical discoveries of the 14th century. Newton revolutionizes physics with the theory of universal gravitation, which unifies terrestrial and celestial mechanics, and makes great advances in optics. Other important physicists of that century are Pascal, Huygens, Boyle, Mariotte, and many more.
• 18th century: Although it's possible to detect a certain slowdown in scientific research, we can mention the Bernoulli brothers, and near the 19th century, Galvani, Volta and Laplace.
• In the 19th century, discoveries in theoretical and experimental physics and the number of professional physicists increased dramatically. Let's mention just a few of the most important: Dalton, Faraday, Ampère, Gauss, Maxwell, Carnot, Lord Kelvin and Boltzmann.

Influence of aesthetic ideas in physics

The Birth of Venus by Botticelli

In a previous post I reviewed the new book in Spanish by Francisco José Soler Gil, entitled The enigma of the natural order. Its third chapter, whose title is Aesthetic ideas in physics, which reproduces a lecture given by the author at the Faculty of Chemistry of the University of Seville, has provided me with matter for this post in my blog.

The influence on physics of aesthetic ideas is very old, perhaps as old as physics. One of its oldest precursors is Pythagoras, who proposed the concept of the harmony of the celestial spheres, according to which the distances between the planets would reproduce harmonious musical intervals.

What does science say about miracles?

Victor Hugo

In his work Quatrevingt-Treize, a title usually translated as “Ninety-three” (it refers to 1793, the year of the Reign of Terror and the Vendée), Victor Hugo introduces a character named Cimourdain, a former priest who has lost his faith because of science:

Science had demolished his faith; the dogma had vanished in him... He knew everything about science and he knew nothing about life.

Apart from the fact that the second sentence is quite debatable (no one can know everything about science), the first raises the confrontation between science and faith, which began with the Enlightenment and reached its maximum philosophical effect in the nineteenth century, Victor Hugo‘s time. He is probably projecting his prejudices into a historical anachronism.

What really happened in the history of cosmology

To complete last week’s post, I will offer here a summary of the history of Cosmology, from the Greeks to the paradigm shift that took place in the sixteenth and seventeenth centuries.

The basic elements of Ptolemaic astronomy, showing a planet on an epicycle (smaller dashed circle), a deferent (larger dashed circle), the eccentric (×) and the equant (•).

• Greek cosmology (with the exception of Aristarchus of Samos) put the Earth at the center of the universe. Plato and, above all, Aristotle established the idea that, since the sky is perfect, the orbits of the planets must be exactly circular, because, for them, the circumference is the most perfect curve of all.
• The Greek model explained well the movements of the sun and moon, and therefore made it possible to predict eclipses, but had a problem with the retrograde movements of the planets then known (Mercury, Venus, Mars, Jupiter and Saturn). Three centuries before Christ, Apollonius of Pergamum proposed that the orbits of these planets are epicycles, circumferences centered on another circumference (the deferent), which in turn revolves around a point located near the Earth, but apart from its center (the eccentric).

Was physics wrong in Ptolemy's cosmology?

1919 solar eclipse

A recent article in the journal Science News has this title: Eclipses show wrong physics can give right results. It claims that Ptolemy’s physics was incorrect, because he assumed that the Earth was at the center of the universe, and yet Greek science was able to predict the dates of eclipses.

According to the article, Ptolemy’s physics was less correct than the physics of Copernicus, who fourteen centuries later proposed that it was not the Earth, but the Sun, at the center of the universe.

The analysis in this article in Science News is completely wrong. Ptolemy’s physics was exactly the same as the physics of Copernicus. Copernicus did not propose a change in the physical theories that had governed classical astronomy since Hipparchus (2nd century BC). Copernicus just showed that, with a change in the coordinate system, and applying the same physics, the calculations are easier to perform. Logically, the same results are obtained.