“Time is the fire in which we burn.”
–Delmore Schwartz
I was posting the other day about time, entropy, and clocks as a measure of mortality. Someone commented:
I was tempted to say something snarky and dismissive. But instead, I thought about the question, and realized that it has some profound implications. I’m not sure that the commenter was even aware of the complexity of what she was asking. So I’ll try to unpack it in this article.
What is human mortality?
We are made of stardust, yet we are mortal. To define mortality, we first have to define what makes us alive. If we’re going to answer the question of whether inanimate matter such as stardust has mortality, we first have to look at the mortality of living beings.
Life is defined as “a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy transformation, and reproduction.”
But there’s an equivocation trap in this definition. Can you spot it? The definition “distinguishes matter” that has biological processes “from that which does not.” As if matter itself changes between life and death.
It does not.
The chemical composition of the human body is 99% oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. It’s less than 1% potassium, sulfur, sodium, chlorine, and magnesium. And there are about 10 grams of trace elements in the body which represent most of the remainder of the periodic table. All the elements with an atomic mass greater than lithium were formed by fusion at the heart of stars, or during a supernova.
So it is entirely correct to say we are “made of stardust.”
When a person dies, the mass of their body does not change. The chemical elements present before and after clinical death remain the same. Many cells in the human body can continue to function for hours or days after brain activity ceases.
Decomposition of the body begins almost immediately upon cessation of metabolism, leading to chemical changes, and a fascinating cellular and microbial ecosystem that continues to teem with life.
Left unattended, a decomposing body also becomes a host for insects that feed on the corpse and help break the body down to its chemical components, which then return to nature.
As with any chemical reaction, mass must be conserved during bodily decomposition. The mass of the reactants will always equal the mass of the products. It cannot be otherwise, according to the laws of physics.
There’s a persistent rumor that the mass of the “soul” leaving the body upon death is 21 grams. It’s based on a poorly conducted 1907 experiment, which inspired the eponymous 2003 film. There’s no evidence for any such mass change, for any living organism at the time of death.
What makes up human identity?
If the mass of the body doesn’t change from life to death, then what happens to the “spirit” of the person who dies? The word spirit is related to the Greek pneuma, meaning breath, spirit, or soul. We can understand in the pre-modern era, how people might have thought that as a person exhaled their last breath, their “spirit” left their body. The dying person changed from a living, breathing, interacting being, into something else. Something that rotted and became morbid and scary and repulsive.
That corpus can’t be all there is to a human being, can it?
Without a general understanding of brain function, there’s a strong temptation to believe that the identity of a person is something immaterial, and that upon death it must “go somewhere.” That belief underlies philosophical dualism, a separation between body and mind, matter and spirit. It’s also part and parcel of the “hard problem of consciousness,” which is the struggle to understand how any organism composed entirely of matter is capable of phenomenal experience. I discussed the many theories of consciousness in this 2021 podcast episode A Matter of Consciousness.
But what if the immaterial nature of consciousness is an outmoded illusion? Modern neuroscience demonstrates that our experiences arise from the chemical interaction of neurons. If we see the color red, there is something unique to that experience (qualia). It is the sensation we get when our brain and visual system experiences light in wavelengths from 620 to 750 nanometers. It’s not that odd, that an external stimulus would trigger a unique internal experience. The gestalt helps us react, form memories, and classify our response. A noxious odor triggers disgust, a growl triggers fear, while a floral arrangement or a glass of Pinot Noir triggers positive feelings. These stimuli would be incomprehensible without conscious awareness. In light of what we know about neurology, the so-called “hard problem of consciousness” becomes a paper tiger.
Just as the eye has evolved many times in many different species, so have these essential methods of conscious perception. The ability to quickly respond to stimuli granted our evolutionary ancestors advantages over unconscious organisms. Improvements in cognition led to tool use, planning, agriculture and the formation of complex societies.
In the neurological model of consciousness, we see a pattern of computation performed by the underlying matter of the brain. There is no need for an animating spirit to explain behavior or experience. The conditions that give rise to each unique individual are determined by DNA that instructs cells to self-assemble in a configuration that makes up the human body and mind. When a baby is born, it already has 100 billion neurons. During some phases of gestation, neurons replicate at the rate of 12 to 15 million per hour. By the time a newborn opens its eyes, it’s well on the way to forming an identity. As a child grows, it learns by making memories and associations and deepening neural connections. Around the age of 3, and during the teenage years, there’s a pruning of neurons, leading to further specialization.
Over the course of a life, we enhance and deepen that pattern. We collect experiences, we reproduce, we try to find meaning as we can. We pass on our knowledge to our offspring and others we influence. And then–our patterns all go away, never to return. They are unique, and individual, so far as we know within the entire history of the universe, and will never be repeated.
Nor is there any conceivable way for that pattern of identity to go somewhere else. After death, the stardust that made up our bodies continues on to fill other roles in the ecosystem, and becomes raw material for new plants and animals and the substrate for the bodies and minds of new organisms. The pattern is lost, the stardust remains.
That’s the cycle of human life. By comparison to other natural processes in cosmic time, we’re an eyeblink, a single flash of a firefly.
And as Richard Dawkins said, we are the lucky ones.
“We are going to die, and that makes us the lucky ones. Most people are never going to die because they are never going to be born. The potential people who could have been here in my place but who will in fact never see the light of day outnumber the sand grains of Arabia. Certainly those unborn ghosts include greater poets than Keats, scientists greater than Newton. We know this because the set of possible people allowed by our DNA so massively exceeds the set of actual people. In the teeth of these stupefying odds it is you and I, in our ordinariness, that are here. We privileged few, who won the lottery of birth against all odds, how dare we whine at our inevitable return to that prior state from which the vast majority have never stirred?”
― Richard Dawkins, Unweaving the Rainbow: Science, Delusion and the Appetite for Wonder
Immortality is for particles, not living beings
You can’t be a self-aware human with any dignity, and pretend you’ll meet your loved ones or pets again someday in any version of “heaven.” People would like to hope that they can cheat death in this manner. This patent illusion even infects our language. Upon death, many people will say that someone has “passed,” which seems more polite than saying they “died.”
But it’s incorrect.
Metabolism is the only thing holding our pattern of identity together. When our cell metabolism ceases, our bodies and brains break down and our identity is lost forever in the stream of entropy. Which brings me full circle to the original question “Is stardust mortal?” And I have to answer it with another question. Would it make any difference to us?
All current evidence indicates that the fundamental particles that make up the universe are the same age. The protons, neutrons, quarks, leptons, bosons and others that compose everything in the universe do not age or die, since they were never alive in the first place. The universe does age, in a manner of speaking, through entropy, or increasing disorder. Over time, the universe becomes more random, uncertain, and chaotic. But unless directly altered by high-energy impacts, atoms and their component particles remain constant.
So the answer is, no. Stardust is not mortal.
I can only surmise that the person asking this question was trying to preserve some notion of human immortality by correctly stating that the elementary particles in our bodies are indestructible. They do not die. But that’s not the point. Because we are not our particles. We are the arrangement of our particles.
Mortal beings are the pattern–not the immortal stardust.