Empiricism, Forensics, and Science

What really is science? There are two types of science. Empirical science is the knowledge of an event or a thing witnessed through our senses. You know that the moon exists. You can see it! You know that the chair exists because you can see it or feel its support.

The other type of science is forensic science. Forensic science is not direct knowledge but indirect knowledge of something. You didn't witness the person's death and you didn't see how he died, but through careful collection and analysis of evidence you are able to determine how the death occurred.

--- Essay by Babu G. Ranganathan

Far too often in essays about science, the author completely misunderstands science. There are not two kinds of science. To explain why, I will describe a chair from the perspective of a scientist.

The fact that a chair exists is not, strictly speaking, an interesting piece of scientific information. It is a triviality. To a scientist, the interesting questions are, What is the chair made of? How do we know it is there? To answer these questions, a scientist requires models (theories) about all aspects of the chair and our perception of it. At the same time, a scientist must know, What is the process by which we can understand a chair? Experiments must be used to evaluate the theory.

For the case of a chair, I have written a separate post describing how a scientist might answer these questions.

In brief, to a scientist, a metal chair is the product of the metallurgy that formed it, the chemistry that extracted the metal from ore mined from the Earth, and the protons and electrons that interact quantum mechanically. A plastic chair is described similarly, but now the scientist needs to understand the molecular chemistry that results in a flexible plastic polymer. A wood chair is even more complicated, bringing in the biochemistry of the cells in the wood; the botany of why each tree produces wood with different density, durability and finish; and the evolutionary questions about how the tree and environment interact to determine its properties.

Science does not deal in simple facts, which are mistakenly labeled as "empirical science" by the author above. It deals in models, which must be evaluated by (often-complex) experiments. The facts are inferred, and understanding is sought, from testable models for how the universe works. The fact that the models can be tested makes science empirical.

Likewise, "forensic science" is not a category that over-arches the scientific enterprise. Forensics is a narrower field that applies scientific principles to reconstruct individual events. The scientific enterprise relies on multiple, repeatable experiments that test models from every possible angle. In the cases of the origin of the universe or of life, the event being modeled may turn out to be singular (in both cases, it is an open question). However the models are nonetheless based on scientific (with no qualifiers) experiments testing their sub-parts.

A Chair, To a Scientist

When a scientists really thinks about a chair, he or she might think of several questions. What is the chair made of? How do we know it is there? To answer these questions, a scientist requires models (theories) about all aspects of the chair and our perception of it. At the same time a scientist must know, What is the process by which we can understand a chair?

First, a scientist wants to know what it is made of. Is it metal, plastic, or wood?

If it is metal, a scientist would ask, what is a metal? At the highest level, the metal was refined from ore, mined from the Earth's crust. A chemical process was used to separate the metallic elements from compounds in the ore that was mined. This implies that there is a model in which elements are distinct, and can be separated because they behave both predictably and differently than other elements. In this case, that model is encapsulated at a high level by the periodic table of elements.

Then a scientist must ask, What is the basis of the "metalness", or more generally, of the periodic table? As it turns out, elements are composed of atoms, which are in turn composed of electrons, protons, and neutrons. Each element has a different number of protons and electrons (the number of a neutrons is not so important). How do we know this? Chemists can tell something like this is going on by measuring the mass of the atoms for various elements, and by examining how elements form crystals and how they combine with each other.

That is a good start, but more importantly, physicists have bombarded atoms with other atoms, with electrons and neutrons, and with X-ray light. They then identify how particles scattered off various materials, and have explained the results with a model in which there are point-like pieces within materials (Bragg scattering), and within atoms (Compton scattering). Compton scattering, in particular, reveals that atoms contain most of their mass in their nucleus, which has a positive charge from the protons. The electrons surround the nucleus in a diffuse cloud, and can be relatively easily separated form the atom to produce an ion.

At this point, a scientist would want to know how the structure of an atom determines its properties. For instance, what makes an element a metal, rather than a gas? For this, physicists use a model for the atom based on quantum mechanics. It turns out that the properties of an element are determined primarily by the number of electrons that it has. The electrons arrange themselves into structures around the nucleus, which are referred to as "energy levels." The structures were named this way because they are identified by measuring the energy of light absorbed (or released) as electrons are removed (or added) from each atom. This technique is called spectroscopy. The outermost structures, those with the lowest energies, determine how electrons interact. This in turn determines how atoms interact with each other. The structure of electrons in gases is such that atoms don't interact with each other. In metals, the electrons interact relatively strongly, and individual electrons can be shared among multiple atoms. This makes metals good conductors of electricity, and malleable enough to be formed into chairs.

By explaining the structure of the atom, quantum mechanics suggests even more ideas about the nature of matter. The structures formed by the electrons can be described mathematically using only the energy, angular momentum, and "spin" of each electron. In the model, each of the properties is "quantized". That is, the values of each property can only be integer multiple of a fixed fundamental value representing how a single electron and proton interact. In working out the theory mathematically, a range of startling hypotheses had to be put forward. For instance that light, electrons, protons, and neutrons could all be thought of as either particles and waves. More weirdly, all fundamental pieces of nature might have to be described not as having fixed properties, but as having a range of possible properties (quantized, of course) that would appear slightly different each time you tried to measure the "same" object.

This goes on yet further, because scientists used similar techniques to determine that protons and neutrons are made up of quarks. Rather than get into particle physics and three of the four fundamental forces (electromagnetic, weak nuclear, and strong nuclear; gravity is irrelevant here), I'll just stop at quantum mechanics.

A scientist also might want to understand how he or she knows that the chair exists. The answer requires similar tools as those explained above.

If a scientist sees the chair, it is because the chair reflects light that is received by the scientist's eyes. How the light reflects is determined by the structure of electrons within the molecules of the chair, and this in turn determines its color, luster, and opacity. The eye takes in this information thanks to the rods and cones of the retina. The retina produces an electrical signal that is distributed to the brain. The brain processes the signal and matches the information that it contains to memories of other objects that it remembers are chairs. The scientist concludes that the image of chair is present, and takes a guess as to what it is made of.

The existence of the chair is then confirmed by feeling it. It might be a hologram, after all. In touching the chair, the atoms of the chair interact with those in the scientist's hand, producing a pressure. Nerves in the hand generate electrical signals, which are again sent to the brain, which confirms the physical presence of the chair, as well as what the chair is made of --- metal, plastic, or wood, and all that implies.

The process can become meta, both in the sense of metaphysical, but also in the sense that a scientist understands perception by developing a model for how a brain models a chair.

A Short List of Medical Innovations since the 18th Century

The preamble to the Constitution gives Congress the power to "provide for the common Defence and general Welfare of the United States." The "general welfare" clause is generally cited to justify the wide variety of things that Congress has legislated in the more than two hundred years since the Constitution was written. What would the Founders think of all these new programs that the Federal government have started?

Take government's involvement in health care: Medicare, Medicaid, and now the Affordable Care Act (aka Obamacare). In 1776, medical practice was limited to herbal remedies (some effective, like willow bark), bed rest, vacations to better climates, bleeding, removing teeth, gall stone removal, cauterization, and amputation. However, for the most part, if you got really sick with an infection, or cancer, or heart disease, you died. It didn't matter how good a doctor you could afford.

Things were beginning to change, though. Scientific progress had been made in the previous years, including the identification of blood circulation, the invention of the microscope, and the realization that catching smallpox inoculated you to further infections. Digitalis was first mentioned as a treatment for heart conditions in English medical literature. The smallpox vaccine was discovered in 1796. Modern medicine began to really save lives.

The following two centuries brought a wave of new medical techniques that really started saving lives. In no particular order, here is a short list:

• Vaccines to smallpox, rabies, whooping cough, measles, mumps, diphtheria, polio, hepatitis, influenza
• Antibiotics such as penicillins, sulfonamides, cephalosporins, and tetracyclines
• Pain killers such as acetaminophen, ibuprophen, and morphine
• Drugs to lower cholesterol, control depression, treat menopause, and prevent pregnancies
• Treatments for chronic diseases like diabetes, thyroid disease, and AIDS
• Anesthesia
• Hygiene
• X-rays, ultrasounds, CAT scans, MRIs
• Open-heart surgeries, laproscopic appendectomies, hip replacements, kidney transplants
• Medical devices like IVs, stents, pacemakers, artificial hearts, dialysis machines
• Implants to let the deaf hear, speech synthesizers for those who can't talk, scooters for those having trouble walking
• Scientists discovered the role of bacteria and viruses in genes, understood the chemical nature of life, and have begun decoding human DNA

What would the Founders think of the government paying for all this? It's a dumb question. They were just people, much like the political leaders we have today, but dead so they're easier to idealize. The fact is, we know about these things now, and so are in a much better position to debate whether they should be available to everyone, or only those who can afford them.