At the age of seven or eight, I recall experiencing a recurring feeling of vulnerability. Being the only child of immigrants, with all of my aunts, uncles, and grandparents overseas - most of them trapped behind the iron curtain of the powerful Soviet Union of the early 1960s - I could sense my precarious existence. The thought of being orphaned was often on my mind.
This angst lead me through various imagined scenarios. What if both my parents had died, but were surreptitiously replaced by artificial beings who were programed to react to all events exactly as would my real parents? If I hurt myself, they would hug me with facial expressions of sympathy; and, would provide the same level of emotional and material comforts as my real parents. I concluded that I would probably be just as happy. If there were no test that could betray their artificial nature, how would I know otherwise?
The scientific method works in much the same way. Controlled experiments are designed to observe the reactions of a system under various conditions to deduce its "essence." The observed behavior under the influence of an external stimulus is called a response function, and provides a window into the inner workings of everything. The characterization of my parents in terms of the sum total of all possible responses to all my possible actions defined their being. The old expression "we are what we do" is not far from saying that a full characterization of our response function defines us. We are all judged by our works - be it our compassion, diligence, intelligence, empathy, selflessness, greed, selfishness, etc.
Thermodynamics serves as an instructive example from physics. The heat capacity of a material is a response function that quantifies the change in temperature (response) per unit of heat supplied (input). Other examples are a material's compressibility; in optics, the nonlinear susceptibility; and in material structure determinations, the scattering cross-section. All of these quantities are measured by poking things and observing how they respond, from which we deduce the underlying properties.
Such simple experiments have lead to some of the deepest concepts developed by the human mind. For example, statistical mechanics seeks to explain all of thermodynamics in terms of the motions of a large number of tiny particles. Since materials responded to all experiments as predicted under the assumption of the existence of small and undetectable particles, early twentieth century scientists begrudgingly accepted the notion that for all practical purposes, materials were made of such stuff.
Whether the result of great intellect or luck, the particle picture turned out to be accurate. New experiments were designed that more directly confirmed the existence of molecules, atoms, and subatomic particles. For example, bubble chambers yield tracks of the paths of elementary particles -- from which their masses and charges can be determined. By the end of the twentieth century, the scanning tunneling microscope (STM) was developed, making it possible to not only directly image atoms and molecules, but atoms could be picked up and placed on a smooth surface at will. One early demonstration of this technique spelled out the letters IBM by intentionally arranging a group of atoms on a flat crystal surface.
This approach we call science, which views phenomena from new angles, leads to an ever more precise characterization of our world, leading us closer to what I would call the truth. The picture becomes more and more in focus as we become more clever in our prodding and poking.
Due to its complexity, studies of the human mind until modern times had been limited to measuring its response function in much the same way as I defined my parents. Breakthroughs in physics, biochemistry and new technologies now allow us to probe the brain directly with noninvasive methods. While an individual is responding to old-fashioned stimuli such as hunger, lust, satisfaction, and deep thought, the neural activity of the brain can be mapped. The STM brought us pictures of atoms while brain-scanning technology has brought us images of thought and emotion.
One can rightly argue that seeing an image of the brain while the subject is having an experience in response to stimuli does not imply that thoughts and experience reside in the complex firing of neurons. Rather, it could be merely a byproduct of thought. A definitive test would be the deliberate creation of thought, emotion, or sensation using a direct stimulus of the brain. Indeed, researchers have been able to reproduce not only simple sensations, but have been able to make subjects feel spirituality, unity with the universe, and a divine presence.
As experimental technology becomes more sophisticated, and researchers more clever, we are finding direct evidence that those qualities that define our humanness and spirituality are all the result of material processes. Ironically, my father is almost 95 years old, so I am yet to be orphaned. The fact that he is defined by his response function and I by mine does not detract from the meaning derived from human interactions. This knowledge enriches my life with the understanding of how the material world is interconnected and I value the incredible privilege of being a locus of material that has arranged itself in a way to give me consciousness and loved ones, friends and collegues with whom I can share my experiences.