Testing the Multiverse: Beyond the Limits of Science? (Op-Ed)
Robert Lawrence Kuhn is the creator, writer and host of “Closer to Truth,” a public television series and online resource that features the world’s leading thinkers humanity’s deepest questions (produced and directed by Peter Getzels). This essay is the second in a series of three on the multiverse. The first is available at: “Confronting the Multiverse: What ‘Infinite Universes’ Would Mean.” Kuhn contributed this essay to Space.com’s Expert Voices: Op-Ed.
My night musings often drift to deep truths of existence: thoughts on cosmos, consciousness, meaning (if any). I can’t help it. That’s why I’m entranced by the idea of a multiverse, the theory that there are many universes, multiple universes, innumerable universes, perhaps an infinite number of universes. But the same set of facts, theories and inferences that imply a multiverse also severely limit, and perhaps proscribe completely, humans’ capacity to conduct high-grade scientific studies, experimental or observational, to detect a possible multiverse.
It depends on what the word “science” means
I studied science (my doctorate is in brain research) because science discerns how the world works. If there is any way to find agreement among disparate cultures and creeds, there’s no way better way than through science.
Some scientists say that the scientific method is the only way of knowing. If science cannot know something, these scientists say, then that something is either not knowable or not worth knowing.
But are there truths, real truths, beyond science? What are the limits of science? How far can it go? Are there philosophical boundaries beyond which science cannot travel?
“I don’t see them,” said Frank Wilczek, who won the Nobel Prize in Physics for deciphering the inner structure of protons and neutrons (they’re almost all empty space). “The application of science can give insight into any question that makes sense. It may not give an answer. It may advise that the question is ill-posed, or it may provide only partial insight — but I don’t think anything should be ruled out as inaccessible to science.”
A multiverse, as we shall see, is a test case.
The essence of science — what science is actually doing — may seem obvious to scientists, but not to philosophers of science.
Bas van Fraassen is just such a philosopher of science, at San Francisco State University, and a professor of philosophy emeritus at Princeton University in New
Jersey, and he is a strict empiricist, meaning that he believes knowledge qua knowledge must come directly from observation and data. “When I think about science,” he told me, “I think of it as a large human enterprise that has certain criteria of success, and, as an empiricist, I say that all such success relates to what’s observable. When science is successful, it gives the best possible descriptions and explanations of what we find in the observable realm.” (All quotes are from “Closer to Truth.”)
Van Fraassen said he is not a “scientific realist,” meaning that he does not accept that the scientific criterion of success is “truth in every respect” or “truth, period.” He said he rejects the prevailing notion that science can penetrate deeper than “just what’s observable” and “postulate all things needed in order to explain observable things.”
He has argued that we must decouple what we observe from whatever underlying reality may be generating those observations. In other words, there are (at least) two levels of reality: One consists of the rules and regularities of the physical world, which science can access and measure. But the other level, the ultimate source of those rules and regulations, science can never even access, much less come to know.
“To say you accept a scientific theory,” van Fraassen said, “[only] means that you believe that it is empirically adequate with respect to the observable phenomena, what we find via inspection and measurement. I do not see the scientist as Columbus discovering America, but rather as constructing models and theories in order to represent observable phenomena.”Strict empiricism offers a more modest mission for science. So does its philosophical cousin, anti-scientific realism, which rejects, for various reasons, the common-sense idea that what we perceive is what really exists (for example, doubting that reality is mind-independent). Both strict empiricism and anti-scientific realism see an unbridgeable gap between deep reality and human cognition, because, like in a relay race, the “baton of information” is passed from one medium to another: from the actual source in deep reality, to electromagnetic radiation, to man-made instruments of observation, to biological sense organs, to neural processing in brains.
At each stage of that “information relay,” argues the strict empiricist (and the anti-scientific realist), information is lost. There are several gaps, which combine to constitute an overall, unbridgeable gap.
As a strict empiricist, van Fraassen affirms only that which human beings can know for sure. He allows only observations and models into his realm of certitude, but not the underlying realities that generate them. “The scientific realist must have theories referring to real things,” he stressed, “but to an empiricist, that is not a scientific explanation — it’s a metaphysical explanation — and not the thing to do.”
Princeton physics professor J. Richard Gott described the boundaries of science in terms of what science can and cannot know. “We’ve learned a great deal about the universe — age, structure, initial conditions, how it started, how it’s developing. But a theologian might say, ‘Well, have you really answered the question of why is there a universe, as opposed to no universe at all?’ It’s easy to imagine no universe at all. Science is not prepared to answer this question, at least not at the present time,” he said.
