A story attributed to the wily Sufi philosopher Nasrudin tells of a man who offended the king and was condemned to die. "Give me but a year, lord, and I will teach your horse to talk," the man begged. After the king agreed to postpone the sentence for a year, a fellow prisoner asked the man why he'd made the crazy promise. "A lot can happen in a year," he said. "The king may die. I may die. The horse may die. And the horse may learn to talk."
Anyone claiming to predict the future faces the "horse may learn to talk" problem. Something totally unplanned and unexpected may change everything overnight. Such was the case in cosmology in 1998, when two independent research teams reported that not only was the universe expanding (known since the 1920s), but the expansion is accelerating. Shouldn't the mutual gravitational attraction between galaxies slow everything down? The usual explanation for the acceleration goes by the name "dark energy," a mysterious repulsive force permeating everything everywhere. (By "dark" cosmologists mean, "We haven't a clue what it is.")
That was in 1998, two years after John Horgan published The End of Science, a provocative and cantankerous bestseller in which he claimed, "The era of truly profound scientific revelations about the universe and our place in it is over." After interviewing a passel of luminaries that included Stephen Hawking, Francis Crick and Richard Dawkins, Horgan asserted science was coming up against fundamental limits. He was wrong: The discovery of dark energy was as much a "truly profound scientific revelation" as any before. But — big but — that's about it. Putting aside dark energy, we're left with a decades-long barren landscape devoid of any discoveries one could charitably call "profound."
Horgan's many critics have complained that since the initial publication of The End of Science (it was re-issued four years ago), we've made huge advances in science. But most of his detractors seemed to be confusing "pure science" (the effort to understand nature) with "applied science" (the effort to manipulate nature, usually under the umbrella term "technology").
To illustrate what I mean by pure science, here's my selective, idiosyncratic and incomplete list of what I consider to be revolutions in our fundamental understanding of nature (listed in chronological order of their discovery):
Vaccines (1796: Jenner); anesthesia (1798: Davy); germ theory of disease (1844: Bassi); evolution (1858: Darwin, Wallace); genetics (1865: Mendel); periodic table (1869: Mendeleev), quantum mechanics (1900: Planck); plate tectonics (1912: Wegener); general relativity (1915: Einstein); neurotransmitters (1921: Loewi); antibiotics (1928: Fleming); antimatter (1928: Dirac); expanding universe/big bang (1929: Lemaître, Friedman, Hubble); incompleteness theory (1931: Godel); nuclear fission (1938: Hahn, Meitner, Strassmann); double helix (1953: Crick, Watson, Franklin); dark energy (1998: Riess, Perlmutter). All these qualify for "talking horse" status as they were unexpected and paradigm changing. And each of them possesses that singular quality of great theories: They explain much while assuming little.
In a different category altogether are the wildly speculative ideas that barely qualify as "scientific." We're being asked to consider such increasingly weird (and — not incidentally — untestable) ideas as: string theory and supersymmetry, many and parallel worlds, multiverses, panpsychism, a timeless block universe, the Gaia hypothesis, an anthropic universe (ancient Greek solipsism brought up to date!), a conscious universe, the Kurzwell singularity. All we need now are talking horses.
Next time I'll consider whether applied science has achieved any revolutionary breakthroughs since 1996.
Barry Evans (firstname.lastname@example.org) prefers he/him pronouns and believes a science writer should both educate and provoke.