What is life? Why cells and atoms haven’t answered the question.
75 years after Erwin Schrödinger's prescient description of something like DNA, we still don't know the "laws of life."
Adam Frank is a professor of astrophysics at the University of Rochester and a leading expert on the final stages of evolution for stars like the sun. Frank's computational research group at the University of Rochester has developed advanced supercomputer tools for studying how stars form and how they die. A self-described “evangelist of science," he is the author of four books and the co-founder of 13.8, where he explores the beauty and power of science in culture with physicist Marcelo Gleiser.
- Erwin Schrödinger's 1944 book "What Is Life?" revolutionized how physicists thought about the 'laws of life.' Schrödinger anticipated how DNA would hold life's blueprints.
- In recent years, however, a new path forward has appeared that holds a unique promise. Rather than reduce biology to physics, the new direction would transform them both.
- Scientists working across domains now think that understanding life requires putting a new actor on to the stage and letting it take the lead: the flow of information.
In 1944, Erwin Schrödinger was already considered one of the greatest physicists of his generation, having discovered quantum physics' most essential equation for describing atomic-level reality. But being intellectually restless, Schrödinger was ready to take on an even more difficult subject: the nature of organisms. What was it, he asked, that makes living systems different from non-living ones? The results of his thinking became one of the most essential books in the exciting and yet dangerous territory lying between physics and biology. That book's question was also its title, "What Is Life?". Its ideas are worth looking at now because more than 75 years after its publication, there are stunning new directions opening up toward an answer that both affirms and goes far beyond Schrödinger original vision.
Left: "What is Life" by Erwin Schrödinger, Second Reprint, 1946. Right: Nobel Prize-winning Austrian physicist Dr. Erwin Schrödinger addresses the 5th World Power Conference in Vienna, Austria, 1956.
"What Is Life?" focused on the need to find the underlying physical principles that make living systems behave so differently. The hope had always been to find "laws of life" similar to what has been found for the fundamental laws of nature in other areas of physics. Looking at life from a physicists' viewpoint, Schrödinger saw that one of its most compelling properties was the defeat of the omnipresent second law of thermodynamics. The second law states that the evolution of any physical system always tends toward states of maximum disorder (i.e., maximum entropy). But at the local level of an organism's body, life manages to create and maintain staggering degrees of order. It beats back chaos, for a while at least. Thus, somehow, life manifested what Schrödinger called "negentropy" or negative entropy.
Being one of the founders of quantum mechanics, which is the science of the microworld, Schrödinger also thought deeply about life's mechanics at the molecular level. Here, he was prescient, famously conjecturing that within cells there must reside an "aperiodic crystal" that held the information needed to transmit heritable traits from one generation to the next, allowing evolution to work. By aperiodic crystal, Schrödinger meant a molecule that had a stable, regular (i.e., repeatable) structure. If it was too regular and repeatable, however, you couldn't use it to code a living organism's structure. So 'aperiodic' meant 'kinda, sorta repeating.' A decade later, Francis Crick and James Watson credited this conjecture as their inspiration for using Rosalind Franklin's X-ray data to discover DNA as the blueprint for life.
So yeah, "What Is Life?" was a really, really important book.
But as powerful as the book was, 75 years after its publication no foundational physical laws for life have ever been found. There is no F=ma or E=mc2 or even a Schrödinger's equation for living systems. In spite of decades of searching, physicists have been unable to fully "reduce" the domains of the biologist (cells and organs and ecologies) into the domains of their own (atoms and energy and forces). In recent years, however, a new path forward has appeared that holds a unique promise. Rather than reduce biology to physics, the new direction would transform them both.
The focus on networks of information flows means its laws may be emergent. Life's laws would not, therefore, be encoded in the laws of quarks.
What has become clear to scientists like Paul Davies, Sara Walker, and Lee Cronin, who are working across domains, is that understanding life requires putting a new actor onto the stage and letting it take the lead. That actor is information. Rather than focusing on the mechanics of life—meaning how the laws of atoms can be built up into a living organism—researchers are beginning to see that what really matters is how atoms and molecules become conduits for complex flows of information. Rather than just thinking about forces or energy exchanges between molecular parts, the key becomes seeing the whole; seeing how these parts can be seen as something more, something that only emerges when information becomes important to a system.
Why is this new perspective so radical? What's most important is it's not reductive. That means it does not reduce life to "just" the laws governing quarks or whatever quarks are made of. Without doubt, life is a physical system, but by creating and then harnessing intricate ballets of information flows, life does something amazing: it creates. The focus on networks of information flows means its laws may be emergent. Life's laws would not, therefore, be encoded in the laws of quarks. Instead, they only emerge when enough matter is brought together in the right conditions for networks of information flows to become possible. That's when novelty enters the universe.
The other radical consequence of seeing life as a dance of information that rides matter is that this emergence continues upwards in scale. Just as new rules appear for cells, so to do they appear for collections of cells in animals or plants. And then even newer rules appear higher up on the level of ecosystems made of many animals and plants. At even higher levels still, new laws and structures must emerge in the creation of social organizations via ants, tribes of chimps, and even global technological cultures.
We'll be exploring this information flow perspective on life a lot more in the coming months, but for now it's enough to just recognize one of the key starting points. Schrödinger's "What Is Life?" was a remarkable first step because he saw information playing a central role in those aperiodic crystals. But what he could not have seen was how the focus on information flows would transform not just the answer but the very question that he posed. Because if you are going to focus on information, the next question you'll have to address is who or what knows that information. We'll leave that question for another time.
Why haven't we found aliens? Because we don't know what life is.
A new paper reveals that the Voyager 1 spacecraft detected a constant hum coming from outside our Solar System.
Voyager 1, humanity's most faraway spacecraft, has detected an unusual "hum" coming from outside our solar system. Fourteen billion miles away from Earth, the Voyager's instruments picked up a droning sound that may be caused by plasma (ionized gas) in the vast emptiness of interstellar space.
Launched in 1977, the Voyager 1 space probe — along with its twin Voyager 2 — has been traveling farther and farther into space for over 44 years. It has now breached the edge of our solar system, exiting the heliosphere, the bubble-like region of space influenced by the sun. Now, the spacecraft is moving through the "interstellar medium," where it recorded the peculiar sound.
Stella Koch Ocker, a doctoral student in astronomy at Cornell University, discovered the sound in the data from the Voyager's Plasma Wave System (PWS), which measures electron density. Ocker called the drone coming from plasma shock waves "very faint and monotone," likely due to the narrow bandwidth of its frequency.
While they think the persistent background hum may be coming from interstellar gas, the researchers don't yet know what exactly is causing it. It might be produced by "thermally excited plasma oscillations and quasi-thermal noise."
The new paper from Ocker and her colleagues at Cornell University and the University of Iowa, published in Nature Astronomy, also proposes that this is not the last we'll hear of the strange noise. The scientists write that "the emission's persistence suggests that Voyager 1 may be able to continue tracking the interstellar plasma density in the absence of shock-generated plasma oscillation events."
Voyager Captures Sounds of Interstellar Space www.youtube.com
The researchers think the droning sound may hold clues to how interstellar space and the heliopause, which can be thought of as the solar's system border, may be affecting each other. When it first entered interstellar space, the PWS instrument reported disturbances in the gas caused by the sun. But in between such eruptions is where the researchers spotted the steady signature made by the near-vacuum.
Senior author James Cordes, a professor of astronomy at Cornell, compared the interstellar medium to "a quiet or gentle rain," adding that "in the case of a solar outburst, it's like detecting a lightning burst in a thunderstorm and then it's back to a gentle rain."
More data from Voyager over the next few years may hold crucial information to the origins of the hum. The findings are already remarkable considering the space probe is functioning on technology from the mid-1970s. The craft has about 70 kilobytes of computer memory. It also carries a Golden Record created by a committee chaired by the late Carl Sagan, who taught at Cornell University. The 12-inch gold-plated copper disk record is essentially a time capsule, meant to tell the story of Earthlings to extraterrestrials. It contains sounds and images that showcase the diversity of Earth's life and culture.
A team of scientists managed to install onto a smartphone a spectrometer that's capable of identifying specific molecules — with cheap parts you can buy online.
- Spectroscopy provides a non-invasive way to study the chemical composition of matter.
- These techniques analyze the unique ways light interacts with certain materials.
- If spectrometers become a common feature of smartphones, it could someday potentially allow anyone to identify pathogens, detect impurities in food, and verify the authenticity of valuable minerals.
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.
- Lawrence Kohlberg's experiments gave children a series of moral dilemmas to test how they differed in their responses across various ages.
- He identified three separate stages of moral development from the egoist to the principled person.
- Some people do not progress through all the stages of moral development, which means they will remain "morally undeveloped."
Has your sense of right and wrong changed over the years? Are there things that you see as acceptable today that you'd never dream of doing when you were younger? If you spend time around children, do you notice how starkly different their sense of morality is? How black and white, or egocentric, or oddly rational it can be?
These were questions that Lawrence Kohlberg asked, and his "stages of moral development" dominates a lot of moral psychology today.
The Heinz Dilemma
Kohlberg was curious to see how and why children differed in their ethical judgements, and so he gave roughly 60 children, across a variety of ages, a series of moral dilemmas. They were all given open-ended questions to explain their answers in order to minimize the risk of leading them to a certain response.
For instance, one of the better-known dilemmas involved an old man called Heinz who needed an expensive drug for his dying wife. Heinz only managed to raise half the required money, which the pharmacists wouldn't accept. Unable to afford it, he has only three options. What should he do?
(a) Not steal it because it's breaking the law.
(b) Steal it, and go to jail for breaking the law.
(c) Steal it, but be let off a prison sentence.
What option would you choose?
Stages of Moral Development
From the answers he got, Kohlberg identified three definite levels or stages of our moral development.
Pre-conventional stage. This is characterized by an ego-centric attitude that seeks pleasure and to prevent pain. The primary motivation is to avoid punishment or claim a reward. In this stage of moral development, "good" is defined as whatever is beneficial to oneself. "Bad" is the opposite. For instance, a young child might share their food with a younger sibling not from kindness or some altruistic impulse but because they know that they'll be praised by their parents (or, perhaps, have their food taken away from them).
In the pre-conventional stage, there is no inherent sense of right and wrong, per se, but rather "good" is associated with reward and "bad" is associated with punishment. At this stage, children are sort of like puppies.
If you spend time around children, do you notice how starkly different their sense of morality is? How black and white, or egocentric, or oddly rational it can be?
Conventional stage. This stage reflects a growing sense of social belonging and hence a higher regard for others. Approval and praise are seen as rewards, and behavior is calibrated to please others, obey the law, and promote the good of the family/tribe/nation. In the conventional stage, a person comes to see themselves as part of a community and that their actions have consequences.
Consequently, this stage is much more rule-focused and comes along with a desire to be seen as good. Image, reputation, and prestige matter the most in motivating good behavior — we want to fit into our community.
Post-conventional stage. In this final stage, there is much more self-reflection and moral reasoning, which gives people the capacity to challenge authority. Committing to principles is considered more important than blindly obeying fixed laws. Importantly, a person comes to understand the difference between what is "legal" and what is "right." Ideas such as justice and fairness start to mature. Laws or rules are no longer equated to morality but might be seen as imperfect manifestations of larger principles.
A lot of moral philosophy is only possible in the post-conventional stage. Theories like utilitarianism or Immanuel Kant's duty-focused ethics ask us to consider what's right or wrong in itself, not just because we get a reward or look good to others. Aristotle perhaps sums it up best when he wrote, "I have gained this from philosophy: that I do without being commanded what others do only from fear of the law."
How morally developed are you?
Kohlberg identified these stages as a developmental progression from early infancy all the way to adulthood, and they map almost perfectly onto Jean Piaget's psychology of child development. For instance, the pre-conventional stage usually lasts from birth to roughly nine years old, the conventional occurs mainly during adolescence, and the post-conventional goes into adulthood.
What's important to note, though, is that this is not a fatalistic timetable to which all humans adhere. Kohlberg thought, for instance, that some people never progress or mature. It's quite possible, maybe, for someone to have no actual moral compass at all (which is sometimes associated with psychopathy).
More commonly, though, we all know people who are resolutely bound to the conventional stage, where they care only for their image or others' judgment. Those who do not develop beyond this stage are usually stubbornly, even aggressively, strict in following the rules or the law. Prepubescent children can be positively authoritarian when it comes to obeying the rules of a board game, for instance.
So, what's your answer to the Heinz dilemma? Where do you fall on Kohlberg's moral development scale? Is he right to view it is a progressive, hierarchical maturing, where we have "better" and "worse" stages? Or could it be that as we grow older, we grow more immoral?
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