Can Science Survive the Death of the Universe? – Scientific American

Faith isnt faith if its based on evidence, so its 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 were 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, lets say that within the next century or two we solve our biggest problems, including tyranny, injustice, poverty, pandemics, climate change and war. Lets 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 Im right, but I could be wrong. Below I describe the views of three physicistsFreeman Dyson, Roger Penrose and David Deutschwho 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, sciences most depressing insight into nature. It decrees that closed systems, which dont get infusions of energy from an outside source, tend over time to become more disordered. Thats 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 endin which time itself ceases, as physics writer George Musser points outin one googol years. A googol is 10 to the 100th power.

Yeah, thats 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 weve achieved seem pathetically insignificant and meaningless, an infinitesimal backward eddy in the universes 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 DYSONS 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 Weinbergs 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 Gdels 1931 proof that any system of mathematical axioms is incomplete, posing questions that cannot be answered with those axioms. Gdels 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 Dysons 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 speculate further about our fate in an accelerating cosmos until the observational evidence becomes clearer.

ROGER PENROSES ETERNAL CYCLIC COSMOS

Roger Penrose, who won a Nobel Prize last year, has carried on Dysons 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. Were not so insignificant after all!

Early in his career, moreover, Penrose made a mathematical discovery that lends support to Dysons 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 Gdel, 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 endeither in catastrophe or in some sort of completionor is it unbounded? Deutschs book is one long argument for unboundedness. (See my review of Deutschs book here and my conversations with him here and here.)

Deutsch asserts that all our progressmoral, political, technological, medical, artistic, scientificstems 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 electrons 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 its not. I guess I have faith in progress after all.

This is an opinion and analysis article.

Further Reading:

The End of Science (updated 2015 edition)

Was I Wrong about The End of Science?

Is Science Infinite?

A Pep Talk from Steven Pinker

Will the Universe Remember Us after Were Gone?

Is David Deutsch's Vision of Endless Understanding Delusional?

I admit to second thoughts about The End of Science in a recent chat on The Jolly Swagman podcast.

I also talk about the limits of knowledge in my online bookMind-Body Problems and my new bookPay Attention: Sex, Death, and Science.

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Can Science Survive the Death of the Universe? - Scientific American