In 1997 a website where scientists, journalists and other eggheads—or Edgeheads—chitchat about science-related stuff called Edge.org asked me to participate in a debate about my book The End of Science. I summarized my argument that science, especially pure science, the quest to understand nature, is bumping up against fundamental limits; science will probably never again yield insights into nature as profound as quantum mechanics and relativity, the Big Bang, natural selection and genetics.
As evidence that scientists were hitting the wall, I noted the proliferation of what I called “ironic science,” highly speculative ideas that can never be empirically confirmed. As an example, I cited string theory, which holds that all of nature’s particles and forces stem from the wriggling of infinitesimal strings in a ten (or more) -dimensional hyperspace. Some enthusiasts called string theory a “theory of everything.”
A bunch of Edgeheads politely swatted away my meme. The response of physicist Lee Smolin was typical. “I believe [Horgan] is wrong,” he wrote, because science’s picture of reality is “full of holes, unanswered fundamental questions and, in some cases, basic inconsistencies” that will surely be resolved. Smolin insisted that string theory, contrary to my disparagement of it as science fiction with equations, offers “a growing list of experimental predictions.”
The manager of Edge.org, who’s a funny guy, titled the debate “The End of Horgan.” Recently, however, some Edgeheads have tentatively come to accept certain aspects of my argument. Every year since 1998, shortly after New Year’s Day Edge.org has posted Edgeheads’ reactions to a Big Question. Edge just posted more than 170 answers to this year’s question: What scientific idea is ready for retirement?
Physicist Martin Rees, former head of Britain’s Royal Society, suggests jettisoning the idea that “We’ll Never Hit Barriers To Scientific Understanding.” Although he loads his little essay with caveats, Rees writes: “We humans haven’t changed much since our remote ancestors roamed the African savannah. Our brains evolved to cope with the human-scale environment. So it is surely remarkable that we can make sense of phenomena that confound everyday intuition: in particular, the minuscule atoms we’re made of, and the vast cosmos that surrounds us. Nonetheless—and here I’m sticking my neck out—maybe some aspects of reality are intrinsically beyond us, in that their comprehension would require some post-human intellect—just as Euclidean geometry is beyond non-human primates.”
Yeah, like I said in 1997, we face cognitive limits, because “we are animals, designed by natural selection not for discovering deep truths of nature but for breeding.”
Citing Rees, physicist Peter Woit says on his blog “Not Even Wrong” that some Edgeheads “sound like John Horgan, announcing we’re reaching the limits of science.” Indeed, on Edge.org Woit and several other physicists, including Marcelo Gleiser, Frank Tipler and Paul Steinhardt, express some of the same frustration with particle physics and cosmology that I did back 17 years ago. Steinhardt’s essay is especially noteworthy, because he is one of the inventors of inflation, a popular theory of cosmic creation.
Steinhardt complains that string theory and inflation have devolved into a “theory of anything,” because they “predict” not only what we observe in our universe but also every other kind of conceivable universe. Unlike too many other modern physicists (see for example the Edge essay by Sean Carroll, who wants to retire “falsifiability”), Steinhardt realizes that a theory that predicts everything does not really predict anything.
“Science is useful insofar as it explains and predicts why things are the way they are and not some other way,” he writes. “The worth of a scientific theory is gauged by the number of do-or-die experimental tests it passes. A Theory of Anything is useless because it does not rule out any possibility and worthless because it submits to no do-or-die tests.”
Yeah! Like I said!
Back in 1997, Lee Smolin chastised me for my pessimism. But facing the limits of science represents not pessimism but realism.
John Horgan directs the Center for Science Writings, which is part of the College of Arts & Letters. This column is adapted from one originally published on his Scientific American blog, “Cross-check.”
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