He was a physicist. A quantum pioneer with a Nobel Prize for a wave equation that basically defines how atoms behave. But in 1943, standing in front of a crowd at Trinity College, Dublin, Erwin Schrödinger decided to talk about something he wasn't technically qualified for: biology. He asked a question that seemed simple but was actually terrifyingly complex. What is life? Specifically, how can the random, chaotic movement of atoms produce a living organism that is so incredibly orderly?
It changed everything.
Most people know him for the cat. You know, the one that's both dead and alive in a box until you look at it. But honestly? His 1944 book What Is Life?—based on those Dublin lectures—might be his most important legacy. It acted as a bridge. It dragged physics into the messy world of cells and, in doing so, handed the keys of the kingdom to the people who would eventually discover DNA. If you’ve ever wondered why we view life as a "code" today, you can thank Schrödinger.
Why a physicist cared about a cell
Physics is obsessed with order. In the 1940s, scientists knew that life seemed to defy the second law of thermodynamics. That law says things move toward disorder, or entropy. Your coffee gets cold. Your room gets messy. The universe tends toward a lukewarm soup of nothingness. But life? Life builds. It stays organized. It grows.
Schrödinger realized that for a living thing to keep its "orderly" state, it had to constantly "feed" on something. He called this negative entropy.
It’s a weird way to put it, right? Basically, he argued that we eat, breathe, and photosynthesize to suck order out of the environment so we don't just crumble into dust. This was a massive shift in thinking. He wasn't looking at life as some magical "vital spark." He saw it as a thermodynamic miracle that obeyed the laws of physics, even if those laws looked different at a microscopic scale.
The hereditary code-script
This is where it gets wild. Remember, this was 1944. We didn't know what DNA did yet. People knew genes existed, but they thought they were probably made of proteins. Schrödinger used pure logic to predict what the "hereditary substance" must look like.
He called it an aperiodic crystal.
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Normal crystals, like salt or diamonds, are boring. They repeat the same pattern over and over. A-B-A-B-A-B. You can't store much information in a repeating pattern. But an aperiodic crystal? That’s different. It’s a structure that doesn't repeat perfectly but is still stable. He compared it to a Morse code. He argued that the entire blueprint for an organism must be packed into a tiny, permanent molecule that acts as a "code-script."
Think about that for a second.
Years before James Watson and Francis Crick mapped the double helix, Schrödinger was sitting in Ireland, telling the world that life was essentially a language written in atoms.
The people he inspired (and the ones he annoyed)
It’s hard to overstate how much this little book—barely a hundred pages—freaked out the scientific community. It was a beacon. Francis Crick, originally a physicist, said reading What is Life? Erwin Schrödinger's masterpiece was the reason he switched to biology. James Watson said the same thing. Even Maurice Wilkins, the third person in the DNA Nobel trio, was influenced by it.
They saw a path. They realized that if life was a physical "code-script," then they could use the tools of physics—like X-ray crystallography—to read it.
But not everyone was a fan. Linus Pauling, a legendary chemist, thought Schrödinger was being a bit of a tourist. Pauling felt that Schrödinger was oversimplifying chemistry and that his "negative entropy" was just a fancy way of saying "free energy," something chemists already understood.
He wasn't entirely wrong. Schrödinger’s biology wasn't perfect. He made some assumptions about how mutations work that we now know are more nuanced. But that’s missing the point. The book wasn't meant to be a textbook; it was a manifesto. It gave biologists permission to think like physicists and physicists a reason to care about the "sloppy" world of biology.
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Schrödinger’s most radical idea: Order from disorder
In the book, Schrödinger draws a distinction between two types of order.
- Order from disorder: This is how most things in the macro world work. A gas stays at a certain pressure because trillions of molecules are bouncing around randomly. The "order" is a statistical average.
- Order from order: This is life. A single gene, made of only a few thousand atoms, dictates the shape of a human being. This shouldn't work! According to the physics of the time, something that small should be constantly buffeted by heat movements (Brownian motion) until it falls apart.
Schrödinger’s genius was suggesting that the "code-script" was protected by quantum mechanics. He argued that the bonds between atoms in our genes are so strong (covalent bonds) that they can resist the chaotic jiggling of the environment. Life is a macroscopic system that somehow manages to behave with the precision of a quantum system.
It’s kind of beautiful. We are large-scale objects that run on atomic-scale clockwork.
Is the book still relevant?
Honestly, yeah. Maybe more than ever.
We are currently in the age of synthetic biology. We are literally rewriting the "code-script" Schrödinger talked about. When scientists use CRISPR to edit a genome, they are treating life exactly how Schrödinger envisioned it: as a physical information system.
But there’s a deeper, more philosophical side to the book that people often skip. In the final chapter, Schrödinger dives into the "Mind and Matter" problem. He starts talking about consciousness and the idea that our individual "I" might be part of a larger, singular consciousness. He was heavily influenced by the Upanishads (ancient Indian philosophy).
It’s a jarring shift. You go from talking about thermodynamics and aperiodic crystals to "What is the nature of the self?"
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But to him, it was all connected. If the universe is a physical system that can produce "order" and "information," and that information can observe itself, then the boundary between the observer and the observed starts to blur. It’s heady stuff. It’s also why many modern biologists find him a bit "woo-woo" toward the end. But you can't deny the man’s range.
What we get wrong about Schrödinger's biology
One common misconception is that Schrödinger "predicted" DNA. He didn't. He predicted the properties that the genetic material must have. He knew it had to be small, stable, and packed with information.
Another mistake is thinking he solved the mystery of life. He didn't. He actually ended the book by admitting that we might need "other laws of physics" to fully understand how life works. Some people think he was hinting at some "new" force, but he was likely just suggesting that we hadn't yet grasped how quantum effects scale up in living tissue.
We’re still working on that. The field of quantum biology—studying how things like bird navigation or photosynthesis might rely on quantum tunneling or entanglement—is the modern continuation of Schrödinger’s 1944 daydream.
Actionable insights from a 1940s physics book
If you’re a student, a creator, or just someone trying to understand the world, there are real lessons here. Schrödinger didn't stay in his lane. He was a physicist who dared to be "wrong" about biology to spark a revolution.
- Read across disciplines. If you only read within your field, you’ll only have the same ideas as everyone else. Schrödinger’s "aperiodic crystal" came from applying physics logic to biological problems.
- Focus on the "How." Instead of just asking what something is, ask how it maintains itself. Whether it’s a business, a relationship, or a cell, everything requires an input of "order" to fight off the natural drift toward chaos.
- Embrace the "Code" mindset. Understanding that life (and much of our modern world) is built on information systems allows you to see patterns that others miss. Everything is data.
Schrödinger’s little book reminds us that the world isn't neatly divided into "physics" and "biology" and "philosophy." Those are just labels we use. At the end of the day, it's all one giant, complex system trying its best not to fall apart.
If you want to truly understand the origins of the biotech revolution, you have to start with the man who looked at a cell and saw a crystal that could talk.
Next Steps for the Curious
- Read the original text: What Is Life? is surprisingly accessible. It’s short, lacks heavy math, and is written with a dry, Austrian wit.
- Look into "Quantum Biology": Search for the work of Jim Al-Khalili or Johnjoe McFadden. They are the modern torchbearers of Schrödinger’s biological questions.
- Study Entropy: To understand life, you have to understand what it's fighting against. Look into the Second Law of Thermodynamics and how "dissipative structures" (a term coined by Ilya Prigogine) explain how order emerges from chaos.