I think this is a very exciting time for the field of psychiatry and neuroscience in general. I believe that with the developments in such diverse disciplines as neuroimaging, graph theory, and systems neuroscience, we are closer to significantly improving the practice of psychiatry. The increasing attention paid to quantitative methods and ways of probing brain activity appears promising. However, despite the progress, we may simply just be at a place in history comparable to the period in physics right before the ultimate application of the tools of mathematics to the terrestrial and celestial physical worlds. One is reminded of the high middle ages (in which key physical concepts such as the notion of inertia, delineated by Jean Buriden, emerged) through to the beginning of the enlightenment when scholars gradually started applying the methods of mathematics experimentally to address questions pertaining to the natural world.

This culminated, in many ways, in the persons of Johannes Kepler, Galilei Galileo and Isaac Newton. Johannes Kepler believed that there was some deeply rational, if not simple, mathematical principle imbued into nature and that the laws that explained the movement of planets were elegant and needed not be complex. With this belief in beauty and elegance embed in nature, he confidently approached astronomical data with a view to find simple relationships. And succeed he did. He was able to delineate simple laws that seemed to accurately describe planetary motion – this became known as celestial mechanics.

Galilei Galileo who was influenced by the growing interests in inductive reasoning (controlled observation of phenomenon vs speculations concerning platonic ideals) would begin putting on a shower of impressive experiments and demonstrations, concerning the motions of bodies here on earth, ultimately shattering the remnants of Aristotelian physics. It is important to stress here that the works and insights of Johannes Kepler were done only after painstakingly poring over existing data collected by the renowned astronomer Tycho Brahe. It was from the data already amassed that Kepler gleamed his elegant insights. This seems to be an enduring pattern that under girths any discipline that tethers on the edge of being a science. The pattern is that there first emerges the accumulation of data, reliable data which raised interesting questions. Typically, there is some pattern to this data that might not be very obvious. And the data could be of such a nature that it raises questions that begs for an explanation. A curious individual looking at the data is able to unravel its hidden patterns and then come up with a quantitative theory that can be expressed in the language of mathematics. We see this very clearly with Kepler and we see the pattern repeat itself numerous times in the history of science.

Moreover, it is important to note that for the longest time particularly dating back to Aristotle, the dominant view of the Greeks was that certain kinds of laws applied to heavens. The principles that governed the motion of the stars were not the same principles that governed the movements of bodies here on earth. There was a tendency to think that heavenly laws were different from earthly laws.A conceptual shift was required to break this tendency. While the idea that the heavens and the earth obeyed the same laws seemed to have first taken hold in the scholastic age (the 12-15th century, the so-called dark ages which were not so dark after all), it took the extreme genius of Isaac Newton to look at the celestial mechanics of Kepler and the terrestrial mechanics of Galileo and to realize (and demonstrate with the language of mathematics) that these laws were describing the exact same thing. Bodies moving here on earth were playing by the same rules as the bodies moving up above in the skies. The laws that governed the fall of the moon was the same as that which governed the fall of the apple and pretty much everything here on this planet and the rest of the observable cosmos and universe. That was the insight of Isaac Newton.

These universe-upending insights of Newton where summarized and expressed in his beautiful equations pertaining to the universal laws of gravity and his laws of motion. His equations became models of the universe and ushered an age of unprecedented optimism in the ability of man to understand the phenomena of this world. And even till this day we can still feel the impact of this insight. It is due to his laws of motion and gravity that we were have satellites and aircraft. Entire industries (automotive industries for instance) constantly utilize the laws of Newton. Another interesting aspect of a proper science is that it ultimately phases into an engineering. This is made possible because a good science is able to be expressed in a quantitative form such as an equation. Knowing the equation, one is able to understand how certain variables result in certain outcomes, which gives us a measure of control over the various phenomena of this world.

Another great example of the incredible utility of equations would be found in the sublime works of the eighteenth century, Scottish mathematical, physicist, the indelible James Clark Maxwell. His contemporary, the incredible British experimentalist (perhaps the greatest of all time), Michael Faraday had done impressive experiments delineating the relationship between electricity and magnetism. Even though Faraday did not have a mathematical background and could not formulate his findings in quantitative laws, his intuition about the physical world was second to none. From his experiments, he intuited the indispensable notion of a “field” which has been a foundational concept in all of physics. In wake of Faraday’s fascinating experiments and insights, Maxwell was able to describe the findings of Faraday in very simple equations (Maxwell equations) that basically showed electricity and magnetism are two sides of the same basic phenomenon and he was able to show using his equations that light was an electromagnetic wave (solely predicted from his equations). Of course, this effort underpins the entirety of our electrical world.

At the turn of the 20^{th} century there were important problems in radiation that needed explanation. There was data pertaining to model of radiation (black bodies) that produces certain spectra that did not seem to fit the predictions of classical physics. This at first might have seemed an esoteric problem. But it was an esoteric problem whose solution changed the world. From the data acquired from black body radiation, it seemed that a new understanding of the fundamental nature of reality was needed. Max Planck, a theoretical physicist with an admirable respect for the universality of laws was interested in the problem. Looking at the available data, he endeavored to come up with equations to describe this black body radiation spectrum. His attempts ultimately led to perhaps the most successful scientific theory of all time – quantum mechanics.

Perhaps an individual who exemplified the power of a quantitative approach to nature unlike any other was Albert Einstein. To begin, he was able to demonstrate the existence of atoms mathematically. And this is perhaps the least of his achievements. Along with Max Planck, he is also considered one of the important founders of quatum mechanics, when he demonstrated convincingly the particulate nature of light. He unified mass and energy in perhaps the most famous equation of all time. And he single-handedly founded general and special theories of relativity which basically extended and greatly refined Isaac Newton’s universal laws. His field equations pertaining to the General theory of relativity made precise predictions about the nature of light that was ultimately experimentally verified. The general theory of relativity along with quantum mechanics are today, the two foundations of all of physics and they both have been experimentally verified countless times.

It must feel strange to read a post on psychiatry that starts by recounting a highly summarized history of physics (instead of a history psychiatry). But I think there are profound lessons to be learned from physics, especially since it is in many ways the most successful of all the sciences. And sometimes I think that we are today in a similar position in which physicists (natural philosophers) were prior to the fusion of mathematical principles and with the study of the natural world.

Now, to be clear I don’t know or think that we can ever fully reduce something so complex as human behavior, human subjective experience to simple equations. I think it is entirely plausible that there might be some, in principle, limitation to reduction the brain to physical laws – we simply do not know if the brain can in principle be fully understood deterministically. However, it is very likely that if not the entirety of the brain, at least aspects of its functioning may be understood quantitatively.

I think psychiatrists have a great role to play in this exciting adventure as we continue to understood the scientific principles of the brain. I believe psychiatry and psychology might constitute the field in which theories and findings from sister discipline (such as systems neuroscience) are validated. Many theories would ultimately be put to the test in their ability to correctly describe the human endeavor and in their ability to perhaps treat various mental illness.

## Leave a Reply