Faith isn’t faith if it’s based on evidence, so it’s wrong to say that I have faith in human progress. Unlike God, progress is objectively real, a demonstrable fact, as much so as evolution. Humanity has gotten wealthier, healthier, freer, more peaceful and smarter. We know more than our ancestors did, and we’re learning more all the time. These trends, any reasonable person must acknowledge, constitute progress. The question is, how long can this progress last?
Let me back up a moment. I recently concurred with megapundit Steven Pinker that over the last two centuries we have achieved material, moral and intellectual progress, which should give us hope that we can achieve still more. I expected, and have gotten, pushback. Pessimists argue that our progress will prove to be ephemeral; that we will inevitably succumb to our own nastiness and stupidity and destroy ourselves.
Maybe, maybe not. Just for the sake of argument, let’s say that within the next century or two we solve our biggest problems, including tyranny, injustice, poverty, pandemics, climate change and war. Let’s say we create a world in which we can do pretty much anything we choose. Many will pursue pleasure, finding ever more exciting ways to enjoy themselves. Others may seek spiritual enlightenment or devote themselves to artistic expression.
No matter what our descendants choose to do, some will surely keep investigating the universe and everything in it, including us. How long can the quest for knowledge continue? Not long, I argued 25 years ago this month in The End of Science, which contends that particle physics, cosmology, neuroscience and other fields are bumping into fundamental limits. I still think I’m right, but I could be wrong. Below I describe the views of three physicists—Freeman Dyson, Roger Penrose and David Deutsch—who hold that knowledge seeking can continue for a long, long time, and possibly forever, even in the face of the heat death of the universe.
If you are speculating about our long-term cosmic future, you must confront the second law of thermodynamics, science’s most depressing insight into nature. It decrees that closed systems, which don’t get infusions of energy from an outside source, tend over time to become more disordered. That’s a euphemism for boring. The second law implies that the universe will inevitably lapse into heat death, in which everything, everywhere, is exactly the same temperature, near absolute zero, and nothing ever happens.
The discovery in the late 1990s that the universe is expanding at an accelerating rate implies that we are approaching heat death, also known as the big chill, at an increasing rate. Not good. As the universe keeps ballooning, stars, including our own sun (after first becoming a red giant and incinerating the Earth), and even black holes will eventually radiate away all their energy, and the universe will go dark, forever. Cosmologists have calculated that we will reach this cosmic dead end—in which time itself ceases, as physics writer George Musser points out—in one googol years. A googol is 10 to the 100th power.
Yeah, that’s a long time. (In contrast, the sun is expected to become a red giant and incinerate our planet in a mere five billion years, or five times 10 to the ninth power.) But this dreary prophecy makes all the progress we’ve achieved seem pathetically insignificant and meaningless, an infinitesimal backward eddy in the universe’s tsunamilike slide toward eternal night. All our knowledge-seeking will be for naught, because everything we have learned will be forgotten as the universe lapses into utter, irreversible mindlessness.
FREEMAN DYSON’S SENTIENT GAS CLOUD
Disturbed by the prospect of cosmic oblivion, scientists have imagined ways in which we can avoid it. A pioneer in such speculation was Freeman Dyson, who died last year at the age of 96. Dyson was provoked into thinking about the long-term fate of the universe in the late 1970s by physicist Steven Weinberg’s infamous remark that “the more the universe seems comprehensible, the more it also seems pointless.”
In a 1979 paper, “Time without end: Physics and biology in an open universe,” Dyson asserts that the universe has a point, a purpose, as long as it harbors intelligence. Eons from now, he conjectures, our descendants may occupy other star systems and galaxies, perhaps after shedding their flesh-and-blood bodies and becoming clouds of sentient gas. Dyson presents mathematical arguments that these beings can, through shrewd conservation of energy, maintain the resources needed to survive, cogitate and communicate in an eternally expanding cosmos.
Our descendants will always have plenty to think about, Dyson insists. He takes heart from Kurt Gödel’s 1931 proof that any system of mathematical axioms is “incomplete,” posing questions that cannot be answered with those axioms. Gödel’s incompleteness theorem implies that both mathematics and physical reality will challenge us with “inexhaustible” problems. Dyson asserts that “no matter how far we go into the future, there will always be new things happening, new information coming in, new worlds to explore, a constantly expanding domain of life, consciousness, and memory.”
After I mentioned Dyson’s paper in a 2018 column, he e-mailed me to point out that his paper is “obsolete because it assumed a linearly expanding universe, which the cosmologists believed to be correct in 1979. We now have strong evidence that the universe is accelerating, and this makes a big difference to the future of life and intelligence.” Dyson declined to “
Roger Penrose, who won a Nobel Prize last year, has carried on Dyson’s project of imagining our cosmic future. In 2005, Penrose was “depressing himself” by “thinking of the wastes of time that stretch ahead of the universe according to the latest cosmological observations, which suggest an ever-accelerating expansion,” according to an article in Physics World. Penrose wondered, “Who will be around then to be bored by this apparent overpowering eventual tedium?”
Penrose overcame his funk by inventing a new model of the universe, conformal cyclic cosmology, which he spells out in his 2010 book Cycles of Time. The theory holds that our increasingly vacuous cosmos will eventually produce a singularity, a rupture in spacetime similar to the big bang. In this way, an expanding universe can spawn new universes, one after the other, ad infinitum.
Better yet, according to Penrose and a collaborator, each new universe can pass on its accumulated information to the next in the form of the cosmic microwave radiation left over from its big bang. That means the microwave radiation pervading our universe might contain messages from previous universes. In the same way, the knowledge we accumulate may be passed on to inhabitants of future universes. We’re not so insignificant after all!
Early in his career, moreover, Penrose made a mathematical discovery that lends support to Dyson’s claim that the universe will never cease to surprise us. Penrose showed that a class of polygons now called Penrose tiles can combine to form aperiodic patterns, which never repeat themselves. Like the incompleteness theorem of Gödel, and like the Game of Life, a cellular automaton invented by mathematician John Conway, Penrose tiles suggest that even a universe based on simple rules can generate infinite, unpredictable complexity. Nature will always present us with new riddles to solve, if we keep our eyes open.
DAVID DEUTSCH AND THE BEGINNING OF INFINITY
David Deutsch opens his 2011 book The Beginning of Infinity by asking: “Must progress come to an end—either in catastrophe or in some sort of completion—or is it unbounded?” Deutsch’s book is one long argument for unboundedness. (See my review of Deutsch’s book here and my conversations with him here and here.)
Deutsch asserts that all our progress—moral, political, technological, medical, artistic, scientific—stems from our attempts to find “good explanations.” There will always be more to explain, Deutsch says, because our knowledge of reality will always be incomplete. Deutsch thus dismisses my claim in The End of Science that science might not yield any more insights into nature as profound as evolution, quantum mechanics and the big bang. The discovery of the acceleration of the cosmos, Deutsch argues, contradicts my thesis.
He suggests, moreover that our descendants might harness the dark energy thought to be fueling this cosmic acceleration so that “knowledge-creation” can “continue forever.” Heat death? No problem. Deutsch dislikes all human futures that smack of finality. He thus rejects the possibility of a utopia so perfect that we no longer have problems to solve. He told me in 2018 that “the world will never be perfected, even when everything we think of as problematic today has been eliminated. We shall always be at the beginning of infinity. Never satisfied.”
Deutsch is an adamant advocate of the many-worlds hypothesis, which seeks to explain why, when we observe an electron, we see only one of the many possible trajectories represented by the electron’s wave function. The many-worlds hypothesis holds that all the possibilities embodied by the wave function are realized in other universes. When I interviewed him in 2018, Deutsch likened the evidence for alternate realities to the evidence for dinosaurs. Other universes are “real,” he said, “get over it.”
I recently asked Deutsch ask if he thought our descendants might be able to jump to other universes to continue knowledge-seeking. In his response, Deutsch showed that his optimism, like that of Dyson and Penrose, is tempered by hard-headed skepticism. Universe-jumping might be possible under certain “exotic and highly speculative scenarios,” Deutsch said.
“But future generations might think it a little comical,” he added, “for us to be speculating about events 100-plus billon years in the future when our theories of basic cosmology are still changing on a timescale of decades. A bit like someone in 1400 speculating about the future domestication of fire-breathing dragons for steelmaking because their maps speculatively said ‘here be dragons’ on unexplored regions.”
Yes, the prophesies of Dyson, Penrose and Deutsch contradict my claim that science is finite. But we share convictions, too, namely that we will never entirely solve the riddle of reality, and that knowledge-seeking, more than any other endeavor, makes our existence meaningful. Moreover, the older I get, the more my hope that science is infinite outweighs my fear that it’s not. I guess I have faith in progress after all.
This is an opinion and analysis article.
The End of Science (updated 2015 edition)
I admit to second thoughts about The End of Science in a recent chat on “The Jolly Swagman” podcast.