Until the End of Time: Mind, Matter, and Our Search for Meaning in an Evolving Universe

by Brian Greene

We are influenced by these predispositions but human activity emerges from a comingling of behavioral tendencies with our complex, deliberative, self-reflective minds.

The ability to manipulate the environment thoughtfully provides the capacity to shift our vantage point, to hover above the timeline and contemplate what was and imagine what will be.

Nabokov’s description of a human life as a “brief crack of light between two eternities of darkness”6 may apply to the phenomenon of life itself.

But in a universe that will ultimately be devoid of life and consciousness, even a symbolic legacy—a whisper intended for our distant descendants—will disappear into the void.

We see it in Emily Dickinson’s “Forever—is composed of Nows”8 and Thoreau’s “eternity in each moment.”9 It is a perspective, I’ve found, that becomes all the more palpable when we immerse ourselves in the full expanse of time—beginning to end—a cosmological backdrop that provides unmatched clarity on how singular and fleeting the here and now actually is.

We are ambitious explorers seeking to grasp a vast reality. Centuries of effort have illuminated dark terrains of matter, mind, and the cosmos.

As our trek across time will make clear, life is likely transient, and all understanding that arose with its emergence will almost certainly dissolve with its conclusion. Nothing is permanent. Nothing is absolute. And so, in the search for value and purpose, the only insights of relevance, the only answers of significance, are those of our own making. In the end, during our brief moment in the sun, we are tasked with the noble charge of finding our own meaning.

While entropy and the second law enjoy a great many cultural references, public nods to the first law of thermodynamics are less common. Yet to fully grasp the second law it’s good to grasp the first law first. As it turns out, the first law is widely known too, but under an alias. It’s the law of energy conservation. Whatever energy you have at the beginning of a process is the same energy you’ll have at the end of the process. You must be fastidious in your energy accounting, including all forms into which an initial cache of energy may have transformed, such as kinetic energy (energy of motion), or potential energy (stored energy, as in a stretched spring), or radiation (energy carried by fields, like the electromagnetic or gravitational fields), or heat (the random jittery motion of molecules and atoms). But if you keep track carefully, the first law of thermodynamics ensures that the energy balance sheet will balance.

But the conclusion is pithy: whereas the first law of thermodynamics declares that the quantity of energy is conserved over time, the second law declares that the quality of that energy deteriorates over time.

Grab hold of a sauté pan’s hot handle and it feels like heat is flowing to your hand. But does anything actually flow? There was a time long ago when scientists thought the answer was yes. They envisioned a fluidlike substance, called “caloric,” which would flow from hotter locations to cooler ones much like a river flows from upstream to downstream. In time, the more refined understanding of matter’s ingredients provided a different description. When you grasp the pan’s handle, its faster-moving molecules collide with the slower-moving molecules in your hand, on average causing the speed of those in your hand to go up and those in the handle to go down. You sense the increased speed of the molecules in your hand as warmth; the temperature of your hand has increased. Correspondingly, the slower speed of the molecules in the handle means its temperature has decreased. What flows, then, is not a substance. The molecules in the handle stay in the handle, and those in your hand stay in your hand. Instead, much as information flows from one person to the next in a game of telephone, molecular agitation flows from molecules in the handle to those in your hand when you grab it. And so, whereas matter itself does not flow from handle to hand, a quality of matter—average molecular speed—does. That is what we mean by the flow of heat.

As the description makes manifest, the flow of heat and the flow of entropy are intimately connected. To absorb heat is to absorb energy that is carried by random molecular motion. That energy, in turn, drives the receiving molecules to move more quickly or spread more widely, thus contributing to an increase in entropy. The conclusion, then, is that to shift entropy from here to there, heat needs to flow from here to there. And when heat flows from here to there, entropy shifts from here to there. In short, entropy rides the wave of flowing heat.

It is this entropic dance that will choreograph the rise of life and mind, as well as most everything that minds deem to matter.

Antonyms abound because experience is full of opposites. Physics, too, has its share: order and disorder, matter and antimatter, positive and negative.

Since we’re focused on the entire universe, something big, you might think the preoccupation of quantum physics with all things small would make it irrelevant. And if it weren’t for inflationary cosmology, your intuition would be on the mark. But much as stretching a piece of spandex reveals the intricate pattern of its stitches, stretching space through a burst of inflationary expansion reveals quantum features usually cordoned off in the microworld. In essence, inflationary expansion reaches into the microworld and stretches quantum features clear across the sky.

It is actually the classical perspective that provides an approximate and hence imprecise view of the true quantum reality.

Although I described the inflaton’s value as being uniform, taking on the same value at all locations within the inflating patch of space, quantum uncertainty fuzzes this out. Uncertainty overlays quantum jitters on the classical uniformity, resulting in the field’s value, and hence its energy, being a tiny bit higher here and a tiny bit lower there. When inflationary expansion rapidly stretches these minute quantum energy variations, they spread across space making the temperature a touch hotter over here and a touch cooler over there. Not by much. Mathematical analyses, first carried out by physicists in the 1980s, showed that the temperatures of hot and cold spots would differ by as little as one part in a hundred thousand. But the mathematical analyses also suggested that the tiny temperature variations would be visible if you knew how to look for them. The calculations revealed that the stretched-out quantum jitters result in a distinct pattern of temperature variations across space, a cosmological fingerprint available for astronomical forensics. Indeed, since the early 1990s, a sequence of telescopes deployed above the distortions caused by earth’s atmosphere have confirmed the predicted pattern of temperature variations with ever-greater precision.

It is a spectacular success, demonstrating once again the uncanny capacity of mathematics to encapsulate nature’s patterns.

Quantum uncertainty, magnified by inflationary stretching and concentrated by gravitational snowballing, results in the points of light dotting the night sky.

Once fusion begins, it can power a star for billions of years, relentlessly synthesizing complex atomic nuclei as it extracts an otherwise inaccessible trove of entropy that it sprays outward through heat and light.

More often than not, physicists are reductionists and so tend to look beneath complex phenomena for explanations that rely on properties and interactions of simpler constituents.

Schrödinger raised some eyebrows (and lost his first publisher) when he invoked the Hindu Upanishads to suggest that we are all part of an “omnipresent, all-comprehending eternal self,” and the freedom of will we each exert reflects our divine powers.

Deep mysteries call for clarity delivered through a collection of nested stories. Whether reductionist or emergent, whether mathematical or figurative, whether scientific or poetic, we piece together the richest understanding by approaching questions from a range of different perspectives.

There are many ways of understanding the world.

The sciences are not separate.

The mathematics allows us to work out their relative abundances: about 75 percent hydrogen (one proton), 25 percent helium (two protons, two neutrons), and trace amounts of deuterium (a heavy form of hydrogen, with one proton and one neutron), helium-3 (a light form of helium with two protons and one neutron), and lithium (three protons, four neutrons).11 Detailed astronomical observations of atomic abundances have confirmed that these ratios are spot-on, a triumph of mathematics and physics in illuminating the detailed processes that happened within minutes of the big bang.

In 2017, neutron-star collisions migrated from theoretical plaything to observational fact when scientists detected the gravitational waves such collisions generate (which followed on the heels of the very first gravitational waves detected, which were produced by the collision of two black holes). A flurry of analyses have determined that neutron-star collisions produce heavier elements more efficiently and abundantly than supernova explosions, and so it may be that the majority of the universe’s heavy elements were produced through these astrophysical smashups. Fused in stars and ejected in supernova explosions, or jettisoned by stellar collisions and amalgamated in particle plumes, an assortment of atomic species float through space, where they swirl together and coalesce into large clouds of gas, which over yet more time clump anew into stars and planets, and ultimately into us. Such is the origin of the ingredients constituting anything and everything you have ever encountered.

At just over four and a half billion years old, the sun is a cosmic newcomer. It was not among the universe’s first generation of stars.

Based on the composition of the sun—the quantities of various heavy elements it now contains, determined by spectroscopic measurements—solar physicists believe the sun is a grandchild of the universe’s first stars, a third-generation arrival.

It’s why Albert Szent-Györgyi, continuing his poetic reflections, mused, “Life is nothing but an electron looking for a place to rest.”

To give a feel for just how rare such changes are, copying errors creep in at the rate of roughly one per every one hundred million DNA base pairs. That’s like a medieval scribe getting a single letter wrong per every thirty copies of the Bible. And even that tiny rate is an overestimate, because 99 percent of the misprints are repaired by chemical proofreading mechanisms operating within each cell, reducing the net error rate to about one per every ten billion base pairs. Even such minimal genetic modification, when accumulated over a great many generations, can give rise to massive physical and physiological development.

Instead, evolution by natural selection is better described as innovation by trial and error.

Nature is not in a hurry and does not need to meet a bottom line.

All of this is physics. When atoms and molecules push or pull or snap together, it is the electromagnetic force in action. The point, then, is that information in a cell is not abstract. It is not a free-floating set of instructions that molecules need to study, memorize, and execute. Instead, the information is encoded in the molecular arrangements themselves, arrangements that coax other molecules to bump or join or interact in a manner that carries out cellular processes like growth, repair, or reproduction. Even though the molecules inhabiting a cell lack intent or purpose, and even though they are thoroughly oblivious, their physical structure allows them to accomplish highly specialized tasks. In this sense, the processes of life are molecular meanderings fully described by physical law that simultaneously tell a higher-level, information-based story.

When you reach for a cup of coffee, the motion of every atom constituting every molecule in your hand, arm, body, and brain is fully governed by the laws of physics. Again, with gusto: Life does not and cannot contravene physical law. Nothing can. But the fact that a huge number of your molecules can act in concert, coordinating their overall motion to cause your arm to reach out across a table and your hand to clutch a mug, reflects the wealth of biological information, embodied in atomic and molecular arrangements, directing a profusion of complex molecular processes. Life is physics orchestrated.

Belgian physical chemist Ilya Prigogine, who was awarded the 1977 Nobel Prize for his pioneering work in the field, developed the mathematics for analyzing configurations of matter that, when subject to a continual source of energy, can spontaneously become ordered—what Prigogine called “order out of chaos.”

“Everything begins with consciousness and nothing is worth anything except through it,”1 is how Albert Camus put it.

Not only is mind our tether to reality, perhaps it is our tether to eternity.

What’s changed in recent years is newfound access to observable and measurable features of brain activity that, at the very least, access processes that reliably accompany conscious experience. When researchers can use functional magnetic resonance imaging to meticulously track blood flow supporting neural activity, or insert deep brain probes to detect electrical impulses firing along individual neurons, or use electroencephalograms to monitor electromagnetic waves rippling across the brain, and when the data reveal clear patterns that mirror both observed behavior and reports of inner experience, the case for approaching consciousness as a physical phenomenon strengthens substantially.

Researchers have developed clever ways to peek over the mind’s shoulder and track brain activity lying beneath the level of conscious awareness. Some of the most striking studies involve patients who have lost some degree of neurological function. A well-known case, involving a subject known as P.S. who sustained right cerebral damage, was documented in the late 1980s by Peter Halligan and John Marshall.11 As anticipated with this type of impairment, P.S. would fail to report details on the far left side of any image she was shown. She claimed, for instance, that two dark green line drawings of a house were identical even though the left side of one of the houses was being consumed by a raging red fire. Yet, when asked which of the two houses she’d prefer to call home, P.S. consistently chose the house that was not burning. The researchers argued that although P.S. was unable to acquire conscious awareness of the blaze, the information had entered covertly and was influencing her decision from behind the scenes. Healthy brains, too, reveal their own dependence on hidden influences. Psychologists have established that even if you are paying close attention, an image flashed on-screen for less than about forty milliseconds (and sandwiched between somewhat longer flashes of other images known as masks) will fail to enter your conscious awareness. Nevertheless, such subliminal images can influence conscious decisions.

Although we still lack a complete understanding of life’s origin, there is nearly universal scientific consensus that no magical spark is required. Particles configured into a hierarchy of structures—atoms, molecules, organelles, cells, tissues, and so on—are all that’s necessary. The evidence strongly favors the existing framework of physics, chemistry, and biology as being fully sufficient for explaining life.

One possibility, simple and bold, is that individual particles themselves are endowed with an innate attribute of consciousness—call it proto-consciousness to avoid imagery of elated electrons or cranky quarks—that cannot be described in terms of anything more fundamental. That is, our description of reality must widen to include an intrinsic and irreducible subjective quality that is infused in nature’s elementary material ingredients.

Intuitively, we think of these as direct experiences of an external reality, but as we have known for centuries they are not. Modern science makes this explicit. Red light reflecting off the Ferrari’s surface is an electric field that oscillates at roughly four hundred trillion times each second at right angles to a similarly oscillating magnetic field, all traveling toward you at three hundred million meters per second. That is the physics of red light, and that is the stimulus your eyes encounter.30 Notice that there is no “red” in the physics description. Red happens when the electromagnetic field enters your eyes, tickles light-sensitive molecules in your retina, and generates an impulse carried to your brain’s visual cortex, which specializes in visual information processing and interprets the signal. Red is a human construct that happens deep inside your head.

That the mind can do all it does is extraordinary.

Take in the number I just quoted: quantum mechanical calculations, based on Schrödinger’s equation, agree with experimental measurements to better than nine digits after the decimal point.35 Trumpets should blare and the species should take a bow because that represents a triumph of human understanding. Nevertheless, there is a puzzle at the core of quantum theory.

Instead, quantum mechanics says the particle is hovering in a fuzzy mixture of being both here and there. And if the probabilities give the electron a nonzero chance to be at a variety of different locations, then according to quantum mechanics it would be hovering in a fuzzy mixture of being simultaneously situated at all of them. This is so fantastically strange, and so counter to experience, that you might be tempted to dismiss the theory out of hand. And if it weren’t for quantum mechanics’ unmatched capacity to explain experimental data, that reaction would be both widespread and justified. However, the data force us to treat quantum mechanics with utmost respect, and so we scientists have worked tirelessly to make sense of this counterintuitive feature.36 The problem is, the more we’ve worked, the weirder things have become.

A freely willed choice is not constrained, even in a statistical sense, by mathematical rules. But as the evidence demonstrates in this instance and all others too, the math does rule. So although the passage from quantum probabilities to experiential certainties remains puzzling, it is clear that free will is not part of the process.

Our freedom is not from physical laws that are beyond our ability to affect. Our freedom is to exhibit behaviors—leaping, thinking, imagining, observing, deliberating, explaining, and so on—that are not available to most other collections of particles.

I am free not because I can supersede physical law, but because my prodigious internal organization has emancipated my behavioral responses.

Neither our thoughts nor our behaviors can break free from the grip of physical law.

Is mathematics a language humankind developed to describe patterns we encounter? Or is mathematics the source of reality, rendering the world’s patterns the expression of mathematical truth? My romantic sensibilities lean toward the latter.