The quality of smartphone cameras has increased exponentially over the past decade. Today's smartphone cameras can not only capture photos that rival those of stand-alone camera systems but also offer practical applications, like heart-rate measurement, foreign-text translation, and augmented reality.
What's the next major functionality of smartphone cameras? It could be the ability to identify chemicals, drugs, and biological molecules, according to a new study published in the Review of Scientific Instruments.
The study describes how a team of scientists at Texas A&M turned a common smartphone into a "pocket-sized" Raman and emission spectral detector by modifying it with just $50 worth of extra equipment. With the added hardware, the smartphone was able to identify chemicals in the field within minutes.
The technology could have a wide range of applications, including diagnosing certain diseases, detecting the presence of pathogens and dangerous chemicals, identifying impurities in food, and verifying the authenticity of valuable artwork and minerals.
Raman and fluorescence spectroscopy
Raman and fluorescence spectroscopies are techniques for discerning the chemical composition of materials. Both strategies exploit the fact that light interacts with certain types of matter in unique ways. But there are some differences between the two techniques.
As the name suggests, fluorescence spectroscopy measures the fluorescence — that is, the light emitted by a substance when it absorbs light or other electromagnetic radiation — of a given material. It works by shining light on a material, which excites the electrons within the molecules of the material. The electrons then emit fluorescent light toward a filter that measures fluorescence.
The particular spectra of fluorescent light that's emitted can help scientists detect small concentrations of particular types of biological molecules within a material. But some biomolecules, such as RNA and DNA, don't emit fluorescent light, or they only do so at extremely low levels. That's where Raman spectroscopy comes into play.
Raman spectroscopy involves shooting a laser at a sample and observing how the light scatters. When light hits molecules, the atoms within the molecules vibrate and photons get scattered. Most of the scattered light is of the same wavelength and color as the original light, so it provides no information. But a tiny fraction of the light gets scattered differently; that is, the wavelength and color are different. Known as Raman scattering, this is extremely useful because it provides highly precise information about the chemical composition of the molecule. In other words, all molecules have a unique Raman "fingerprint."
Creating an affordable, pocket-sized spectrometer
To build the spectrometer, the researchers connected a smartphone to a laser and a series of plastic lenses. The smartphone camera was placed facing a transmission diffraction grating, which splits incoming light into its constituent wavelengths and colors. After a laser is fired into a sample, the scattered light is diffracted through this grating, and the smartphone camera analyzes the light on the other side.
Schematic diagram of the designed system.Credit: Dhankhar et al.
To test the spectrometer, the researchers analyzed a range of sample materials, including carrots and bacteria. The laser used in the spectrometer emits a wavelength that's readily absorbed by the pigments in carrots and bacteria, which is why these materials were chosen.
The results showed that the smartphone spectrometer was able to correctly identify the materials, but it wasn't quite as effective as the best commercially available Raman spectrometers. The researchers noted that their system might be improved by using specific High Dynamic Range (HDR) smartphone camera applications.
Ultimately, the study highlights how improving the fundamentals of a technology, like smartphone cameras, can lead to a surprisingly wide range of useful applications.
"This inexpensive yet accurate recording pocket Raman system has the potential of being an integral part of ubiquitous cell phones that will make it possible to identify chemical impurities and pathogens, in situ within minutes," the researchers concluded.
Here's a new version of an old argument for the existence of God. It's called the "nomological argument," after the Greek nomos or "law," because it's based on laws of nature.
Suppose that you receive five consecutive royal flushes in a game of poker. What explains this? You could have received them by chance, but that seems unlikely. A better explanation is that someone has arranged the decks in your favor.
Similarly, we can ask for an explanation of why nature is full of regularities, such as that planets have elliptical orbits and that oppositely charged particles attract. As with your sequence of hands, these regularities could be the result of chance, but that seems unlikely. A better explanation is that something is responsible for them. But what?
To clarify, we're not asking why we have the specific regularities that we do in fact have. Thus, we're not asking why the laws of nature appear to be fine-tuned to support life: for example, that gravity is the correct strength to permit the formation of stars. We think that's an interesting question but not our present topic. (See our "Further Reading" section below if you want to learn more.) Similarly, we're not talking about "intelligent design"; we're not asking why well-adapted species exist today. We think that can be adequately explained by citing regularities of natural selection and genetics. Our question is more general: Why are there any regularities at all, as opposed to irregularities?
Regularities: The nomological argument for the existence of God
Credit: NASA / JPL-Caltech / Space Science Institute
According to the nomological argument, the best explanation of regularities involves a supernatural personal being, God. It's not necessary for God to have all the attributes of a theistic or Biblical god — namely, omnipotence, omniscience, and moral perfection — but only that God is an intelligent being with the power to control whether nature exhibits regularities. In other words, this argument holds that regularities in nature are analogous to your winning poker hands.
To begin, why does the best explanation of your sequence of royal flushes involve a person? Well, we can think of pragmatic, aesthetic, and even moral reasons why a person might want to impose order on decks of cards. A pragmatic reason is about self-interest: someone might impose order on the deck of cards because they want you to win some money. An aesthetic reason is about elegance or beauty: royal flushes might just look nice. And maybe a moral reason could be that you deserve to win.
Similarly, we can think of pragmatic, aesthetic, and even moral reasons why God might want to impose regularities on nature: notably, most of the valuable things we know of (such as happiness, love, rationality, knowledge, or meaningfully free choices) cannot be realized in worlds without regularities. And since God is a person, we have reason to think that God might have moral and aesthetic preferences. Indeed, this would be so even if God were evil or had poor taste, since almost any moral and aesthetic states of affairs require some degree of regularity. As a result, if you knew that a personal being was about to create a world, you wouldn't be unreasonable in anticipating regularities, even if you knew nothing else about that being.
Objections and further development
At this point, someone might object as follows: Do we really need to invoke God? Doesn't Occam's Razor say we should prefer a simpler explanation or not posit this extra, unnecessary thing? Well, positing God doesn't really commit us to much more than other explanations of regularity would; they too would posit additional entities.
For example, suppose we try to posit laws of nature to explain regularities instead of God. We all have some idea of what a law of nature is supposed to be: Newton's laws of motion, the law that nothing can travel faster than the speed of light, or the ideal gas laws. Scientists posit laws such as these to explain things all the time. However, scientists typically assume that there are regularities, and they try to determine which ones are the most significant, important, or fundamental. When they've found one, they call it a "law of nature." In their role as scientists, they don't try to explain why there are fundamental laws of nature in the first place. So if we want to explain why there are regularities as opposed to irregularities — indeed, if we want to explain why science is possible at all — we have to do some philosophy. If we were going to explain regularities by positing laws, we'd first have to say what a law is.
This appeal to God has some important explanatory virtues and that, as a result, it deserves serious consideration as an explanation of why there are regularities.
There are philosophical accounts of laws that do not involve God, but those that attempt to explain regularities all do so by positing extra entities, too. These involve exotic things such as Platonic universals, Aristotelian natural kind essences, or other sorts of primitive necessities. As far as Occam's Razor is concerned, that's no better than positing God.
Moreover, these competing theories face a different problem. Positing mindless laws of nature with no ultimate explanation just seems to push the problem back. Now we have yet another interesting phenomenon to explain. Why did the laws that just randomly happened to exist generate regularities, which are only a relatively tiny portion of the possible set of events? To return to our analogy, it wouldn't be satisfying to say that you got five royal flushes in a row because some mindless law just happened to guarantee that result. (Why wasn't there a different law, one that generated any one of the octillions of other possible sequences instead? Just a huge coincidence?) In any case, we say a lot more in our journal article about why other explanations, such as alternative philosophical accounts of the nature of laws, don't do a great job of explaining regularities.
One might worry that positing God pushes the problem back in exactly the same way: What explains the existence of God? Well, everyone has to posit something, and we can always ask for an explanation of those things. Because positing God is relatively modest, we think it's more or less on the same footing as positing anything else — maybe no philosophical theory can really explain its fundamental entities. However, positing God answers a difficult question that other accounts don't: namely, why are there regularities as opposed to irregularities? To posit nothing, or pure, random chance, is modest but doesn't do a good job of explaining: random chance doesn't explain the five royal flushes. To posit some mindless explanation that just happened, coincidentally, to give us something as complex and consistent as a regularity does a good job of explaining but isn't really modest: your poker opponent would be very skeptical if you posited something as complex and coincidental as that as an explanation of your five royal flushes. (For those familiar with Bayesian reasoning, we're arguing that "God" strikes the best balance between prior probability of the explanation and likelihood of the phenomenon to be explained.) As a result, it doesn't merely push back the specific problem that concerns us.
Credit: ROBERT SULLIVAN via Getty Images
Another objection might be that we've just posited a "God of the gaps" — simply positing God ad hoc when there's some gap in our knowledge. However, we haven't argued, "We don't know why laws of nature exist, and therefore, God did it." Instead, we've argued as follows: We know why God would create regularities, but we don't know why random chance or some mindless law would. And recall, the version of God we've described — simply a person with the power to control whether there are regularities — is relatively modest. Therefore, God provides a pretty good explanation of these regularities.
We'll mention one last objection. Proponents of a multiverse might say that regularity isn't surprising, because the probability that at least one universe exhibits regularity is high. Some proponents of a multiverse are motivated by scientific considerations. However, since the relevant scientific theories (inflation, string theory, many-worlds interpretations of quantum mechanics) posit underlying regularities that generate and maintain the multiverse, we can simply ask what explains those regularities. Other proponents of a multiverse are motivated by philosophical considerations — for example, that we should posit a plurality of possible worlds to make sense of our concepts of possibility and necessity. This might be a good reason to posit possible worlds, but it doesn't really explain regularities in our world. After all, you wouldn't find your sequence of royal flushes any less surprising upon learning that poker is a very popular game.
Philosophy is hard
One last disclaimer: Philosophy can be really hard. We don't claim to provide a proof, or even an especially strong argument, for the existence of God. Instead, we merely claim that this appeal to God has some important explanatory virtues and that, as a result, it deserves serious consideration as an explanation of why there are regularities.
Though modest, this conclusion is noteworthy. As we alluded to above, scientific practice requires regularities. By providing a philosophical explanation of regularities, we are trying to explain why science is possible in the first place. Relatedly, many Early Modern philosophers thought that scientific investigation of the natural world allowed us insight into the mind of God. If God's relation to the laws of nature might be as we've suggested, theists should have a very positive attitude towards the sciences. Likewise, those who prefer naturalistic or atheistic accounts should at least be open-minded about the relationship between science and religion. This is not a new lesson, but it provides a further illustration of the fact that, while there may be no role for God or other supernatural entities in scientific explanations, this does not mean that science itself is necessarily at odds with religious belief.
Suggestions for further reading
The journal article on which this essay is based is:
Tyler Hildebrand and Thomas Metcalf, "The Nomological Argument for the Existence of God." Noûs. DOI 10.1111/nous.12364 (available on EarlyView)
For a book length defense of a divine explanation of regularities, see:
John Foster, The Divine Lawmaker. Oxford University Press, 2004
For an introduction to the metaphysics of laws of nature, see:
Tyler Hildebrand, "Non-Humean Theories of Natural Necessity." Philosophy Compass 15, 2020
For more on multiverse-style objections to design arguments, see:
Thomas Metcalf, "On Friederich's New Fine-Tuning Argument," Foundations of Physics 51, 2021
Thomas Metcalf, "Fine-Tuning the Multiverse," Faith and Philosophy 35, 2018
For readers interested in the role of God philosophical accounts of laws in the Early Modern period, see:
Ott & Patton's Laws of Nature (Oxford University Press, 2018)
Ott's Causation and Laws of Nature in Early Modern Philosophy (Oxford University Press, 2009)
For introductory essays aimed at relative beginners, see:
Thomas Metcalf, "Design Arguments for the Existence of God," in 1000-Word Philosophy: https://1000wordphilosophy.com/2018/02/28/design-a...
Thomas Metcalf, "Philosophy and its Contrast with Science," in 1000-Word Philosophy: https://1000wordphilosophy.com/2018/02/13/philosop...
Michael Zerella, "Laws of Nature," in 1000-Word Philosophy: https://1000wordphilosophy.com/2014/02/17/laws-of-...
Stop me if you have heard this one before. "Sociologists defer to Psychologists. Psychologists defer to Neurologists. Neurologists defer to Biologists. Biologists defer to Chemists. Chemists defer to Physicists. Physicists defer to mathematicians. Mathematicians defer to God."
While told as a joke among physicists (and mathematicians, I suppose), what this little list really describes is a hierarchy where the truth of some fields reduces to the truths of others. This "reductionist" view is so prevalent in our culture that it's really a default or implicit philosophy of science floating around in people's heads even if they never explicitly think about it.
Today, I want to begin a series of explorations of this idea of reduction — and its alternative — for two reasons. First, I am pretty sure reductionism is wrong, and that's not the way the world works at all. Second, this view of the world is more than just a matter of philosophy. It has manifested in ways that can be dangerous for our future. For instance, how do we use the living world if we see it as "nothing but" resources? (My colleague Marcelo Gleiser has an answer to that.) What do we expect from artificial intelligence if we see ourselves as "nothing but" neurons?
Thankfully, there is another way of looking at science, truth, and the world which might be more correct and less dangerous. It's called emergence, and it's going to be the focus of this series.
The problem with reductionism
A duck, reducedCredit: Public Domain / Wikipedia
Let's take the 10,000-foot view to get an understanding of the problem. Here is a nice description of the reductionism perspective from philosopher Paul Humphreys:
"The world is nothing but spatiotemporal arrangements of fundamental physical objects and properties. You and I, rocks and galaxies, toads and scrambled eggs are just processes, the successive states of which are spatial arrangements of elementary physical objects. These elementary physical objects, arranged in different configurations, account for all the astonishing variety that we encounter in our day-to-day lives."
Those "fundamental objects" in Humphreys description are the elementary particles of physics: electrons, quarks, etc. So, the idea is that once you have made a list of all those elementary particles and once you know how those particles can interact (i.e., what forces they respond to), you are, in principle, done. Everything that can ever happen, everything that ever will happen is, in principle, encoded in that list of particles and their interactions. That's why, again in principle, all the truths the sociologist uncovers must ultimately be explained by the truths that the physicist has uncovered.
The simple picture reductionism offers of a world made solely of atoms can no longer be seen as the only "sober" view of science.
Of course, and this is important, sophisticated supporters of this kind of reductionist view have a sophisticated philosophical understanding of how the chain of causes goes upward, letting you go from quarks to mollusks to governments. That's why I want to unpack the questions reductionism raises over a series of posts. But the little description I've penned above demonstrates one of reductionism's most important consequences. It describes a world without fundamental novelty or essential innovation.
This is really a question of "bottom-up" predictability. If you know the fundamental entities and their laws, you can, in principle, predict everything that will or can happen. All of future history, all of evolution, is just a rearrangement of those electrons and quarks. In the reductionist view, you, your dog, your love for you dog, and the doggie love it feels for you are all nothing but arrangements and rearrangements of atoms. End of story.
An emerging challenge
"Emergence" is the alternative to this view. As philosophers Brigitte Falkenburg and Margaret Morrison put it, "A phenomenon is emergent if it cannot be reduced to, explained or predicted from its constituent parts… emergent phenomena arise out of lower-level entities, but they cannot be reduced to, explained nor predicted from their micro-level base." From an emergentist view, over the course of the universe's history, new entities and even new laws governing those entities have appeared.
The key is evolution.
According to at least one kind of emergentist, the universe most definitely has the capacity to innovate and create novelty. The process it uses is evolution, and evolution is more than just physics. So, from this view, while you are obviously made of atoms, you are also more than just atoms. You, your dog, and the specifics of your person-dog affection could not be predicted, even in principle, even from perfect knowledge of all your elementary particles.
Water crystals demonstrating an emergent, fractal process.Credit: Rusfuture via Wikipedia and licensed under CC BY-SA 3.0
As a philosophy, emergence was first introduced by a group of British philosophers in the early 20th century. They argued that phenomena like life and consciousness were so different from the systems physics studied, that they must represent new entities. But as the biochemical basis for life (e.g., DNA) was uncovered in the 1950s and 60s, interest in emergence waned. As Paul Humphreys notes, there wasn't even an entry for emergence in the 1967 Encyclopedia of Philosophy. Since then, however, critical developments in a number of fields have brought emergence back into view for both scientists and philosophers.
Science needs emergence
One of the most important reasons emergence has reappeared is science needs it. At the frontiers of research, there is a remarkable new field called complex systems. Drawing insights from physics, biology, and the study of social systems, the theory of complex systems has given scientists a wide range of examples where new entities and new rules appear to emerge from the networked interaction of simpler parts. Colloquially, the whole is greater than the sum of its parts.
These studies have drawn a new generation of philosophers to re-engage with the ideas of emergence, using the advances in science as a spur to unpack how chains of causation can be closed or opened and run from the bottom-up or the top-down. In these examinations, there have come distinctions like "weak" vs "strong" emergence, as well as those who challenge the need for that split. These are the kinds of issues I want to unpack in this series over the next few months.
To sum it up for now, when it comes to reductionism and emergence, there are many thorny issues that require scrutiny. What is clear, though, is that the simple picture reductionism offers of a world made solely of atoms can no longer be seen as the only "sober" view of science and its perspective on life, the universe, and everything.
