Introduction
Erwin Schrödinger, one of the giants of 20th-century physics, is best known for his contributions to quantum mechanics. However, his curiosity extended far beyond physics into other areas of science and philosophy. In 1943, Schrödinger delivered a series of lectures at Trinity College in Dublin, exploring the fundamental nature of biological life and how science can account for the complexity of living organisms. Later, in 1956, he returned with another series of lectures discussing the connection between mind, matter, and consciousness.
These lectures, later compiled into a book, would go on to inspire a whole generation of scientists and philosophers. "What is Life?" tackles some of the most profound questions about the nature of existence, blending physics, biology, and philosophy to offer unique insights into the mysteries of life and consciousness.
The Puzzle of Size: Why Are Atoms So Small?
Schrödinger begins by posing a seemingly simple question: Why are atoms so small? Or, from another perspective, why are living organisms so incredibly large compared to the atoms they're made of? To put this into perspective, atoms are so tiny that even with the most advanced microscopes of Schrödinger's time, the smallest visible object would still contain billions of atoms.
The answer to this question lies in the behavior of atoms and the laws that govern them. For any organism to function properly, it relies on its parts behaving in an orderly way and obeying strict physical laws. However, individual atoms behave in a rather disorderly manner, constantly vibrating and producing energy. In fact, the behavior of a single atom or a small group of atoms doesn't follow any recognizable physical laws.
It's only when you have a large enough number of atoms that they start to behave according to statistical laws. This phenomenon is evident in various physical processes, such as magnetism. For example, if you fill a tube with oxygen gas and place it in a magnetic field, the gas becomes magnetized, with the oxygen molecules orienting themselves parallel to the field. However, not every oxygen atom changes its orientation; rather, the atoms orient in the direction of the field on average, as a group.
Another example is the behavior of a light object suspended by a long thin fiber, often used in physics experiments to measure weak forces. As the object becomes lighter, it becomes more susceptible to weaker forces, eventually performing a constant and irregular dance around its neutral resting position.
These examples illustrate why living organisms need to be composed of a vast number of atoms. If the human body were small enough to be significantly affected by the behavior of individual atoms, it would be in constant, erratic motion, unable to function properly. For an organism to benefit from the statistical laws that govern large groups of atoms, its body must be large in comparison to its atoms.
The Paradox of Genetic Information: Small Groups with Enormous Influence
While living organisms must be composed of a huge number of atoms to function properly, we encounter a paradox when we consider genetic information. Tiny groups of atoms – much too small to display exact statistical laws – have an enormous influence over everything that occurs within a living organism.
These small groups of atoms, found in the genes, dictate all the features an organism acquires as it develops. They determine how the organism will function throughout its entire life, from its beginnings as a fertilized egg cell to its mature state when it begins to reproduce.
The entire pattern of an organism's development, or its ontogeny, is determined by the structure of just one cell: the fertilized egg. More specifically, it's determined by the nucleus of that cell. During cell division, when cells split in two and cause the organism to grow, the nucleus consists of rod-like particles called chromosomes. Inside these chromosomes are genes, which determine properties the organism will have, such as eye color.
A gene contains no more than a few million atoms at most – far too small a number to operate according to statistical physical laws. Yet these chromosomes contain all the code necessary to determine whether the egg should develop into a chicken, a fly, a corn plant, or a person. The code-script within the chromosomes contains the entire pattern of the individual's future development – how it will develop into its mature state.
But the role of chromosomes goes beyond just providing instructions. They also work to bring about that development, acting as both blueprint and architect. This dual role of genes – containing information and actively participating in the organism's development – is one of the most fascinating aspects of life.
Evolution and Quantum Theory: Unexpected Parallels
The stability of genes over time, combined with their small size and their crucial role in determining an organism's characteristics, presents a puzzle. How can these tiny structures, made up of atoms that tend to behave erratically, remain so stable and consistent in their function?
To answer this question, Schrödinger draws an unexpected parallel between the process of evolution and the principles of quantum theory. He begins by challenging a common misconception about evolution. Charles Darwin, the famous naturalist, theorized that natural selection occurs through small, continuous, accidental variations. However, Schrödinger argues that this view is incorrect.
Consider a crop of pure-strain barley. If you measure every ear in the crop and plot those measurements on a graph, you'll end up with a standard bell curve. If you then take a few outliers with extra-long ears from that crop and plant them in an empty field, you might expect the new crop to have a bell curve shifted towards longer ears. However, this is not the case. The new statistical curve would be exactly the same as the first one because small, continuous variations aren't inherited.
Instead, evolution occurs through discontinuous changes called mutations. These mutations are more like the sudden leaps described in quantum theory than the smooth, small changes Darwin envisioned. In quantum theory, very small systems can only possess specific amounts of energy. For such a system to increase its level of energy, it must make a "quantum" jump to the next possible level, without passing through any intermediary quantities of energy. Similarly, in evolution, there are no intermediate forms between the "unchanged" form of a species and the few "changed" offspring. Instead, changes happen in big leaps – and these leaps are extremely rare.
This quantum-like behavior of genes provides a potential answer to how they can remain relatively unchanged over time despite being made up of atoms that tend to be disorderly. Atoms can bond together to form molecules, and when this happens, the atoms are arranged in specific configurations that determine the molecule's stability. For the molecule to enter a different configuration, it must be brought to a different energy state, and even then, there's no guarantee of change. In fact, it could take thousands of years for any given molecule to make one of these jumps.
In this sense, a gene is like a huge molecule that can only change through large and infrequent jumps. This explanation aligns the behavior of genes with both the stability they exhibit over time and the quantum-like nature of evolutionary changes.
The Masterpiece of Life: Order at All Scales
The molecule we're describing here – the gene – is nothing short of a masterpiece of nature. It's incredibly small, yet remains highly ordered over long periods of time. The classical laws of physics don't seem to apply to it at all. However, this shouldn't surprise us, as this is often the case when it comes to discussions of life.
Consider the concept of entropy, the tendency of an isolated, inanimate system to decay into a state of thermodynamic equilibrium – essentially, into disorder. Normally, matter quickly decays into this state. Life, on the other hand, repeatedly feeds upon negative entropy – that is, order – inside of the food it eats. By doing so, it avoids death, the state of maximum entropy, and continuously generates order from order. The classical laws of physics would call that impossible.
In physics, there are two different methods by which order can be produced: the "statistical" and the "dynamic." The statistical method is when atoms behave in a disorderly way individually, but in an orderly, statistically predictable way in large groups. Through it, order is obtained from disorder. This statistical method is primarily found operating in nature.
Life, however, is governed by the dynamic principle, where order is obtained from order. A single group of atoms existing in one copy of the genetic code produces something marvelously orderly – a living organism, which continually violates the principle of entropy. That is, it somehow stays alive.
In a way, life is similar to the operation of a clock. The constituent parts of a clock operate according to dynamic laws, and so too does the overall mechanism. This is possible because clocks consist of solids bound to their shape by the forces of quantum mechanics. And these forces enable the clock to avoid the forces of entropy.
Similarly, living organisms are built from particular types of solids – which Schrödinger calls aperiodic crystals – that allow them to avoid entropy, too. These crystals are like the cogs in the organic machine. But these cogs are more than any ordinary human invention. Instead, they are, in Schrödinger's words, "the finest masterpiece ever achieved along the lines of the Lord's quantum mechanics."
It's worth noting that when Schrödinger delivered these lectures, the structure and role of DNA had not yet been fully worked out. However, his ideas played an important role in its discovery. Francis Crick, who together with James Watson won the Nobel Prize for working out the helical structure of DNA, was influenced by the ideas in these lectures.
Consciousness: The Teacher of Life
In his second series of lectures, Schrödinger delves into more philosophical territory, exploring the nature of consciousness. He begins with a classic philosophical conundrum: "If a tree falls in the forest and no one is around to hear it, does it still make a sound?" This leads to a broader question: Is it possible that the world only exists because human consciousness is there to make it manifest in our sensations, perceptions, and memories?
To answer this question, Schrödinger first defines consciousness from his perspective. He sees consciousness as an elegant and elaborate mechanism – in fact, the most ingenious of all survival mechanisms. It allows us to respond to a wide variety of different situations by altering our behavior.
However, Schrödinger argues that not every process in the brain is accompanied by consciousness. Some processes are like conscious experiences in that they're biologically significant and involve our minds and bodies reacting to the environment – for instance, things like blinking, breathing, or walking to work using your usual route. Although these reflexive processes are initiated by the brain, they aren't conscious. Our awareness is essentially separated from the sensations, perceptions, and even potentially the actions associated with them.
From this, Schrödinger concludes that a behavior only becomes conscious when something forces us to change that behavior. We might normally be able to walk to work practically in our sleep while thinking about something totally different. But if there's, say, some construction blocking the road and we have to take a different path, our behavior suddenly becomes conscious.
In this sense, consciousness is like a teacher. It educates us until we can do things without its assistance. From this definition, we can ultimately conclude that consciousness is what allows all life to become aware of itself – but only insofar as it continues to develop and create new forms. An infant only becomes conscious as its senses gradually begin to interact, adapt, and practice within an environment. And just like the tree falling in the forest, the world can only be aware of itself as long as human consciousness continues to learn from and interact with it.
Consciousness and Human Evolution
Schrödinger's discussion of consciousness leads to an intriguing question about human evolution. At first glance, it might seem that by becoming conscious beings, humans have effectively escaped the classic Darwinian survival of the fittest. After all, most people dislike seeing their fellow humans suffering and dying. Societies have developed ethical codes and laws that don't allow people to let others die – instead, they help them survive, whatever their physical or mental conditions might be. Moreover, Darwin's theory doesn't allow for the inheritance of learned traits. For instance, a person can't learn how to play the piano and then pass that skill on to their daughter purely through genetics.
These facts raise a crucial question: Given the apparent absence of evolutionary pressure, is humanity doomed not to advance any further biologically? Schrödinger's answer is a resounding no.
According to Darwinian theory, each mutation that leads to evolution is a single, fortuitous step that has nothing to do with the behavior of individuals throughout their lifetimes. But there's a caveat: certain mutations cause further behavior that continues to serve that mutation, effectively furthering evolution.
To illustrate this, consider a species of birds whose ability to fly high enables them to build nests high in the treetops, away from predators that could threaten their young. This gives these birds an advantage, and in addition, their nesting behavior also selects for the best fliers among their offspring – only young birds who can also fly high will make it back to the nest. In this way, the ability to fly produces a change of behavior related to the environment, leading to an accumulation of an ability.
This relates back to the question of humanity's evolution because it shows that behavior has a way of directing the mechanism of evolutionary selection. When organisms make appropriate use of adaptations – when birds which can fly higher use that ability – they aid the process of selection.
The ultimate conclusion is this: For humanity, evolution depends on people actively working toward it instead of resigning themselves to a fate determined by the laws of nature. In fact, our biological future is something we can determine by regulating our behavior.
However, Schrödinger also points out potential obstacles in humanity's way. In his era, factories were encouraging tedious and boring operations on the assembly line. If this continued, he believed selection would favor less intelligent people who'd find it easier to thrive in such an environment. His proposed solution? To replace humans with machines in unintelligent, tedious, mechanical work.
The Gap Between Scientific and Sensual Understanding
In the final part of his lectures, Schrödinger turns to another deeply mysterious aspect of consciousness – the question of sensual qualities. He asks, "What makes yellow yellow?"
If you ask a physicist how she conceives of yellow light, she might describe it in technical terms: Yellow light consists of transversal electromagnetic waves of wavelength around 590 millimicrons. While the physicist can describe the objective qualities of light waves in great detail, the sensation or experience of the color itself is totally absent from her description.
Similarly, a physiologist could tell you objectively which nerve fibers in the brain and eye are activated when a person sees yellow – without ever mentioning the specific sensation of color. At the same time, of course, your impression of the color yellow can't tell you the objective properties of light.
This illustrates a fundamental gap between our scientific understanding of the world and our sensual experience of it. Sensation isn't and can't be contained in scientific description. Instead, it exists only in the mind and the brain of the person doing the experiencing.
It's a baffling concept to contemplate, but everything only has meaning in relation to the consciously contemplating, perceiving, and feeling subject who observes it. Yet science still hasn't elaborated on a framework through which we can understand the mind and its role in producing our individual pictures of the world.
In fact, science tends to avoid any discussions of meaning at all – and the more attentively it observes and documents the world, the more meaningless everything appears to be. Science tells us that our minds have been produced by the very picture of the world we're constantly observing – and that it'll disappear when the sun cools down and the earth ceases to support human life.
This is a truly bewildering aspect of consciousness. It's the stage – in fact, the only stage – on which all the world's events take place. It contains the whole world, and without it, there's nothing. At the same time, consciousness is just an adaptation evolved to keep its owners alive – owners who grow and live within that same picture of the world. How can we reconcile these facts?
Schrödinger suggests that the answer is found primarily in Eastern, rather than Western, thought. The solution is to accept that our minds are identical with the world – in other words, mind and the world are one. Of course, there's a paradox there, because there appear to be many consciousnesses – individuals with conscious egos – all producing world pictures. The solution is to accept that consciousness is just one thing, consisting of a series of different aspects of that thing. So, when consciousness ceases to exist – when what you think of as you ceases to exist – there's no real death involved at all.
Conclusion: The Ongoing Mystery of Life
"What is Life?" by Erwin Schrödinger is a profound exploration of the fundamental nature of life and consciousness, blending insights from physics, biology, and philosophy. Through his lectures, Schrödinger tackles some of the most perplexing questions about existence and the nature of reality.
The book begins by addressing the puzzle of size in living organisms, explaining why living things must be composed of vast numbers of atoms to function properly. It then delves into the paradox of genetic information, where tiny groups of atoms have an enormous influence over an organism's development and characteristics.
Schrödinger draws fascinating parallels between the process of evolution and quantum theory, suggesting that evolutionary changes occur in quantum-like leaps rather than through gradual, continuous variations. This insight helps explain how genes can remain stable over time despite being composed of potentially erratic atoms.
The author portrays life as a masterpiece of nature, continuously generating order from order and defying the principle of entropy. He compares living organisms to intricate clockwork mechanisms, with genes acting as the cogs in this organic machine.
In the latter part of the book, Schrödinger explores the nature of consciousness, describing it as an ingenious survival mechanism that allows organisms to adapt to new situations. He argues that consciousness is what enables life to become aware of itself and continues to drive human evolution.
Finally, Schrödinger grapples with the gap between our scientific understanding of the world and our sensual experience of it. He points out that while science can describe the objective properties of things, it fails to capture the subjective experience of consciousness. This leads him to contemplate the relationship between mind and world, suggesting that they might be one and the same.
Throughout "What is Life?", Schrödinger demonstrates the power of interdisciplinary thinking, using concepts from physics to shed light on biological processes and philosophical questions. His ideas, though speculative at times, have had a lasting impact on various fields of study, including molecular biology and consciousness research.
The book serves as a reminder of the profound mysteries that still surround the nature of life and consciousness. It encourages readers to think beyond the boundaries of individual scientific disciplines and consider the bigger picture of existence. While many of Schrödinger's specific hypotheses have been superseded by subsequent discoveries, his approach to asking big questions and seeking connections between different areas of knowledge remains invaluable.
In the end, "What is Life?" doesn't provide definitive answers to all the questions it raises. Instead, it opens up new avenues of inquiry and encourages us to marvel at the complexity and wonder of life itself. It reminds us that despite all our scientific advancements, there is still much to learn about the fundamental nature of our existence and our place in the universe.
As we continue to unravel the mysteries of life and consciousness in the 21st century, Schrödinger's work serves as an inspiration to approach these questions with curiosity, creativity, and an openness to unexpected connections. The book stands as a testament to the power of asking profound questions and the ongoing quest to understand the nature of life itself.