Have you ever asked yourself what makes you alive? What makes everything alive?

At the 2012 American Chemical Society meeting, Andrew Ellington put forward a radical theory in a session on the origin of life: “Life does not exist.” Andy is a chemistry professor at the University of Texas at Austin, and this was the first slide of his presentation on RNA chemistry and the origin of life. His idea confused me beyond belief.

I was baffled because I probably should have agreed with Andy. But I don’t. When I went to Andy’s talk, I was pretty sure I was alive, as I am now. You’re probably convinced you’re alive too. Haven’t you spent your whole life living? Being alive is important. It’s very different from not being alive.

Yet despite our natural confidence in our own existence, some scientists question this and argue that life may be just an illusion or an epiphenomenon that can be explained by known physical and chemical laws.

Physicist and intellectual Sean Carroll is one of those people. At a well-attended evening lecture on the campus of Arizona State University, where I work, I sat in horror as Sean explained that the equations of particle physics are sufficient to explain the existence of all matter—including you and me. Jack Szostak, a Nobel Prize winner, takes a similar view, arguing that focusing on the definition of life keeps us from understanding the origin of life. According to Jack, the closer you look at the “defining” properties of life, the more the line between life and nonlife becomes blurred.

I remember trying to take apart an insect as a child and then failing to put it back to its original state. I was too surprised at the time to even get upset. We all know that life is not reducible to its constituent parts, be they elementary particles, atoms or even molecules. Perhaps the easiest way to argue, as Andy, Jack and Sean do, is to take the view that life is not a property of its constituent parts and so we don’t need to worry about defining it. If that’s true, it follows that we only need to understand those constituent parts to understand what life does and how it comes into being.

During my training as a theoretical physicist, I was taught that life was not a conceptually deep scientific problem. Rather, the most fundamental concepts about the nature of reality were what other physicists had studied—things like space, time, light, energy, and matter. In fact, the achievements of physics have been nothing short of profound: in the short span of the last four hundred years, we have gained a deep understanding of how our universe works. We have even defined what we mean by the “universe.” At very small scales, we understand a great deal about the elemental constituents of all matter. At the very largest scales, we can take photographs of distant galaxies whose light took more than 13.5 billion years to reach our telescopes.

And yet the origin of life remains one of science’s greatest mysteries. Physics, as we understand it today, provides a basic description of a universe without life. It’s not the universe I live in, and I bet you don’t live there either.

But if there is life, what is it?

What are we?

If vitalism is dead, maybe you are too

In stark contrast to the views of modern physicists and chemists, scientists once believed that life existed as a separate category from matter.

It was believed that living matter was endowed with a “living” force, sometimes referred to as Joy of life. Aristotle called it entelechy; Gottfried Wilhelm Leibniz called it monads. Both, like many others, described a unique property found only in living things that governs the behaviors of living things, such as the development of an embryo, the regeneration of a lost body part, or any of the other goal-directed activities that seem unique to life. This concept of being alive is somewhat similar to the religious concept of a soul, and some have even called it that. Whatever you call it, we believe these characteristics are reserved for life, since we do not observe them in nonliving things. A rock will not return to its original shape if cut in half, but a planarian can and does. Vitalism, as the scientific movement was called, was based on the idea that what makes matter alive cannot be described mechanically and is therefore nonmaterial.

While modern materialists like Andy, Sean and Jack see the known properties of matter as sufficient to explain life, the vitalists took a very different view. They believed that life does indeed exist, but cannot be explained in terms of the properties of matter. The idea of ​​a life principle in the sense of a vital energy or spark of life that could animate even dead matter was often discussed. If this sounds a bit like Frankenstein, that’s because it is. Mary Shelley was just twenty-one when her famous novel Frankenstein was published in 1818. When she wrote the book, she was thinking about the leading sciences of her time, particularly theories about the soul, what makes us alive, and how we could revive the dead with electricity. Mary was influenced by the contemporary work of Luigi Galvani, later continued by his nephew Giovanni Aldini. These two attempted to animate body parts through electrical stimulation; they stimulated the legs of dead frogs with electric shocks to make them “dance.” Mary was also reportedly inspired by Erasmus Darwin, grandfather of the more famous Darwin Charles. The elder Darwin wrote on the subject of spontaneous generation, arguing how inanimate materials could spontaneously come to life in water heated by sunlight.

In Mary’s novel, the body parts of the recently deceased could be reanimated by electrocution if they were wired together properly. This is how her main character, Dr. Victor Frankenstein, created his “living” monster from dead bodies. If we were to try to write down physical laws that could explain Dr. Frankenstein’s unique insight in animating the monster, we might surmise that he had discovered a life force that slowly dissipated after death, and that the substance that made up this force was strongly coupled to electromagnetism. It’s a somewhat odd set of properties that Dr. Frankenstein discovered in his fictional universe, but matter in our real universe has many odd properties as well. Our universe is odd when you start to understand it (in fact, it gets stranger the more you think you understand it).

We might imagine that Dr. Frankenstein used consistent physics to explain life. It’s just that the physics he encountered is not the physics that describes our real universe. The real physics underlying life might be even stranger. While we don’t understand at the moment what principles govern life, one day they might be as obvious to future generations as the curvature of spacetime or the existence of light particles (photons) are to us today.

Many vitalists believed that life could not be produced by things that were not already alive themselves. Living matter was special because its parts were special and carried some of the necessary vital energy. Therefore, living things were necessary to create more living things; even Dr. Frankenstein had to create his monster from once-living parts that had only recently died.

Around the time of Frankenstein’s publication, the idea that life is necessary to produce the stuff of life was already beginning to lose popularity within the scientific community. In 1828, Friedrich Wöhler synthesized urea, an organic molecule found in urine, from two other simple molecules, cyanic acid and ammonium. Friedrich’s experiment demonstrated that biological molecules do not carry any life force within them. The constituents of living matter are no different from those of inanimate matter. In experiments like these, scientists have repeatedly shown that there is no difference between the properties of inanimate and living chemistry: the former can easily be converted into the latter under the right conditions. The sharp line between inanimate and living began to blur as humanity began to understand more about chemistry and the physics underlying it. Sean, Jack, Andy, and many others who hold similar views are right… to an extent.

In fact, no matter how hard we searched, we found that no known physical or chemical law precludes the transformation of an inanimate substance into an animate one. There is no law of life that says that life can neither be created nor destroyed. Of course, this is obvious, because we know that organisms are born and die – but sometimes the most obvious observations are the hardest to explain scientifically and even harder to translate into a mathematical law.

Modern science has taught us that life is not a property of matter.

Physicists and chemists recognize precisely what the rest of us who believe in the existence of life cannot: There is no magical transition point at which a molecule or collection of molecules suddenly becomes “alive.”

Life is the vaporware of chemistry: a property that is so obvious in our everyday experience – that we are alive – does not exist when you look at our parts.

If life is not a property of matter and material things exist, then life does not exist. This is probably the logic Andy had in mind.

And yet here we are.