The Wall Street Journal recently asked me to review Brief Answers to the Big Questions by Stephen Hawking and On the Future: Prospects for Humanity by Martin Rees. Below is a modified version of my review. See also Post-postscript for a response from Rees. —John Horgan

A high point of my career, and faith in science, was a cosmology workshop I bulled my way into in 1990, when I was a staff writer for Scientific American. Thirty leading physicists gathered in a rustic resort in northern Sweden to swap ideas about how our universe was born. If Stephen Hawking was the id of the meeting, a joker with cosmic swagger, Martin Rees, cool and elegant, was the superego, as befitting a future president of the Royal Society. Personalities aside, Hawking and Rees had much in common. Born in 1942, both became professors at the University of Cambridge, where Newton once taught, and both contributed to our modern understanding of the big bang, black holes, galaxies and other cosmic matters.

One afternoon the workshop participants traveled to a local church to hear a concert. As they marched down the center aisle of the packed church, led by Hawking in his wheelchair, the parishioners stood and applauded. The symbolism thrilled me. These churchgoers seemed to acknowledge that science was displacing religion as the source of answers to the deepest mysteries, like why we exist.

That scene came to mind as I read Brief Answers to the Big Questions by Hawking (the title recalls his mega-hit A Brief History of Time) and On the Future: Prospects for Humanity by Rees. The authors’ styles differ--Hawking is cocky, Rees sober--but both books evince a profound faith in science’s power to demystify nature and bend it to our ends.

Reading Brief Answers and On the Future was a bittersweet experience, and not only because Hawking died last March at the age of 76. (His book was completed by colleagues and family members.) The books resemble relics from a long-gone golden age of science. The high priests of science no longer enjoy the prestige and credibility that they did just a few decades ago.

Hawking personified the hubris of science in the late 20th century. In a 1980 lecture, “Is the End in Sight for Theoretical Physics?”, he expressed “cautious optimism” that within 20 years physicists would discover a “complete theory” that would solve the riddle of existence. It would tell us what reality is made of, where it came from and why it takes the form we observe. He expanded on these ideas in Brief History of Time, published in 1988. Hawking’s vision of the end of physics inspired me to write The End of Science. [See Postscript.]

In his new book Hawking pushes back his prediction for a final theory of physics to the end of this century, but otherwise his ideas haven’t changed much. String theory remains his favorite theory of everything. Also called M-theory, it conjectures that reality is made of infinitesimal strings, loops or membranes wriggling in a hyperspace of ten dimensions.

Noting that, according to quantum mechanics, empty space seethes with particles popping into and out of existence, Hawking suggests that the entire universe began as one of these virtual particles. The universe is “the ultimate free lunch,” he says, and our universe may also be just one of many. M-theory, quantum mechanics and inflation, a theory of cosmic creation, all suggest that our cosmos is just a minuscule bubble in an infinite, frothy ocean, or “multiverse.”

To explain why we live in this universe rather than one with radically different laws, Hawking invokes a bit of circular logic called the anthropic principle: If our universe were not as we observe it to be, we would not be here to observe it. Our scientific picture of the cosmos, Hawking proposes, is already so complete that it eliminates the need for God. “No one created the universe,” he declares, “and no one directs our fate.”

We don’t need God to save us either, Hawking suggests. If the Earth becomes unlivable, whether because of nuclear war, runaway global warming, pandemics or an asteroid collision, science gives us the means to establish colonies on Mars and elsewhere. Our future, Hawking states, “lies in going boldly where no one else has gone before.”

Rees’s worldview differs in a few respects from Hawking’s. Rees describes himself as a “practicing but non-believing Christian.” He respects believers, with whom he shares “a sense of wonder and mystery.” As for space-colonization, Rees asserts that it is “a dangerous delusion to think that space offers an escape from Earth’s problems.” He dwells more than Hawking on the threats posed by climate change, nuclear weapons, bioterrorism, asteroid collisions and economic inequality.

And yet he and Hawking agree on other major issues. That machines will inevitably become super-intelligent, capable of learning without human guidance and pursuing their own goals. That we can nonetheless harness these machines for our own ends, or even merge with them. That we need more science and technology to help us overcome challenges to our peace and prosperity. That science will eventually explain the origin of this universe and even confirm the existence of other universes.

“It’s highly speculative,” Rees says of multiverse theories. “But it’s exciting science. And it might be true.” Rees also shares Hawking’s sci-fi vision of “post-human” cyborgs fanning out through the universe colonizing other star systems. Our bionic descendants might be smart enough to invent warp-drive spaceships and time machines, Rees suggests. They might even solve what many scientists and philosophers consider the greatest mystery of all, the mind-body problem. This puzzle asks, as Rees puts it, “how atoms can assemble themselves into ‘grey matter’ that can become aware of itself and ponder its own origins.”

Hawking and Rees recognize science’s declining status. They deplore widespread doubts about global warming, nuclear power, vaccines, genetically-modified foods and evolution. They call for better science education to lure more young people into science and to counter public ignorance. “The low esteem in which science and scientists are held is having serious consequences,” Hawking complains.

They fail to mention that science’s wounds are at least partially self-inflicted. In 2005 statistician John Ioannidis presented evidence that “most published research findings are false.” That is, the findings cannot be replicated by follow-up research. Other scholars confirmed the work of Ioannidis, leading to the so-called replication crisis. The crisis is especially severe in fields with high financial stakes, such as oncology and psychopharmacology.

But physics, which should serve as the bedrock of science, is in some respects the most troubled field of all. Over the last few decades, physics in the grand mode practiced by Hawking and Rees has become increasingly disconnected from empirical evidence. Proponents of string and multiverse models tout their mathematical elegance, but strings are too small and multiverses too distant to be detected by any plausible experiment.

In her new book Lost in Math, German physicist Sabine Hossenfelder offers a far more candid and compelling assessment of modern physics than her English elders. She fears that physicists working on strings and multiverses are not really practicing physics. “I’m not sure anymore that what we do here, in the foundations of physics, is science,” she confesses.

As I finished Brief Answers and On the Future, a question came to mind. Will science ever regain its luster? Will it earn back the public’s trust in a new golden age, or will its credibility be permanently diminished? I’m not sure which scenario I prefer. I’m glad I witnessed science’s high priests at the height of their glory. But perhaps we are better off doubting all authorities, including scientific ones.

Postscript: In a recent essay in Los Angeles Review of Books, David Kordahl, a graduate student in physics, points out my indebtedness to Hawking. Kordahl writes: “It’s hard to imagine today’s popular writing about physics without the existence of two books in particular. The first is A Brief History of Time (1988), in which Stephen Hawking crystallized a way of pitching physics in grand terms — the “we will know the mind of God” stuff — that has proved irresistible for writers ever since… The second book is in some respects a response to Hawking. It is journalist John Horgan’s The End of Science: Facing the Limits of Knowledge in the Twilight of the Scientific Age (1996), which argues that scientists, having inherited answers to most of nature’s big questions, are now constrained either to study increasingly insignificant details or to play with abstractions increasingly unlikely to be tested.”

Post-postscript: Martin Rees sent me the following response to my review: “I think you give too gloomy a prospect of the current and future state of science. It's true that particle physics hasn't made much progress recently -- the ungathered fruit is still inaccessibly high-hanging. (Non-zero neutrino masses are the main discovery in last 30 years -- and not from accelerators!) But, unless you are ultra-reductionist, this is just one science and by no means the most important.

“The last five years have been tremendous for astronomy -- Gaia, Planck, LIGO, the field of exoplanets, and the insights following from computer  modeling. When I was young it wasn't clear whether there was a big bang at all. Now we can track it from a nanosecond onwards with 2-5 percent precision, and address seriously the ultra-early era when quantum effects generated the fluctuations. But, even more, the developments in genetics, neuroscience etc. are surely hugely important (for me, the most amazing discovery is the Moser/O’Keefe work on location-recognition).

“There are negative sociological implications-- commercial pressure, overpopulation (and increasingly geriatric character) of the research enterprise. I address these in my book, venturing the hope that there will be growing scope for 19th-century style independent scientists. I think you're a bit unfair in representing my attitude to 'fundamental' physics as unrealistic triumphalism. I felt I'd tried hard to emphasize just the opposite: downplaying the role of  armchair theory,' asserting that 'reductionism' is not true in any useful sense, that the main scientific challenges are in the bio and complex world, that there's nothing specially elevated about academic ability, nothing very special about the scientific method, etc.

“On string theory, etc., I've been wondering about the possibility that an AI may actually be able to 'learn' a particular model and calculate its consequences even of this was too hard for any human mathematician. If it came up with numbers for the physical constants that agreed (or that disagreed) with the real world, would we then be happy to accept its verdict on the theory? I think the answer is probably 'yes' -- but it's not as clear-cut as in the case of (say) the 4-colour theorem -- in that latter case the program used is transparent, whereas in the case of AI (even existing cases like Alpha Go Zero) tor programmer doesn't understand what the computer does.”

Further Reading:

Is Science Hitting a Wall?

How Physics Lost Its Way

Was I Wrong about The End of Science?

Beauty Does Not Equal Truth, in Physics or Elsewhere

Cosmic Thinker Worries about Ends of Science and Humanity

Is Science Infinite?

How Physics Lost Its Fizz

My Alarming, Inspiring Encounter with the Late Stephen Hawking

Stephen Hawking's "new" theory of everything is the same old CRAP

Is speculation in multiverses as immoral as speculation in subprime mortgages?

Is David Deutsch's Vision of Endless Understanding Delusional?

Meta-Post: Horgan Posts on Physics and Cosmology

See also my free, online book Mind-Body Problems: Science, Subjectivity & Who We Really Are.