Are there things that we’ll never know? Are there things that we’ll never even know that we’ll never know? Maybe some of the things that we’ll never know will bring us closer to the limits of what we can know.
These are the kinds of thoughts that occupy the minds of philosophers of science — and that were the subject of the cover story in a recent issue of New Scientist.
In “What we’ll never know,” Michael Brooks quotes British Astronomer Royal (and recent Templeton Prize winner) Martin Rees: “A chimpanzee can’t understand quantum mechanics.” More to the point, “It’s not that a chimpanzee is struggling to understand quantum mechanics. It’s not even aware of it.” And we’re not all that different. “There is no reason to believe that our brains are matched to understanding every level of reality.”
Brooks’s article goes on to outline the kinds of things that we can never know:
There are some things we can never know for sure because of the fundamental constraints of the physical world. Then there are the problems that we will probably never solve because of the way our brains work. And there may be equivalents to Rees’s observation about chimps and quantum mechanics — concepts that will forever lie beyond our ken.
Among the things that seem to be permanently beyond us:
Data from any celestial object more than 46 billion light years away —
according to the Hubble Law, the space carrying the data is expanding faster than the speed of light, so the data can never reach us;
The total characteristics at any one time of quantum objects —
according to Heisenberg’s uncertainty principle, observing the object alters its characteristics, so we can never “see all of it”;
Certain mathematical proofs —
according to Godel’s incompleteness theorem, we can’t use math to prove some of math’s basic axioms, so they will forever remain assumptions;
The specifics of the origin of life —
according to Jerry Coyne, “There are so many different scenarios for how life got going and they all involve molecules that don’t get fossilised.”
As Brooks writes, we can’t cross these barriers, but we can come close:
A combination of creative thinking and rigorous checks against what information we do have available has proved an astonishingly powerful tool. While we will never know for sure that the big bang theory is correct, we have lots of reasons to think it is. For example, the amounts of the elements hydrogen, helium and lithium present in the universe exactly match the predictions of our theories describing the beginning of everything.
It’s likely that the ultimate limits of what we can know reside in a realm as yet completely unknown to us. Brooks writes, “A little over 100 years ago, nobody had the slightest idea that the quantum world even existed. Now it lies at the heart of our understanding of the universe.”
While most scientists are not overly concerned about the incompleteness of human knowledge, others are not so sanguine.
There are some — postmodernists, post-structuralists, relativists of many subspecies — who for a variety of reasons reject the whole idea of “knowing” itself. Whether because we are conscious only in an internal perceptual bubble, or because there is no such thing as “fact” in the first place, or because “knowing” is an inherently oppressive way of privileging one intellectual paradigm over another — these thinkers reject the search for “knowledge” out of hand.
For them, it’s no surprise that there are limitations to science. Some of them believe that acknowledging these limitations deconstructs the false edifice of Enlightenment “truth.” That no thoughtful scientist ever disagrees with them that there are limits to what we know now and can know later has no effect on their “Gotcha!” moment. It seems that for some of these thinkers the obvious fact that knowledge is limited is all the justification one needs for denying the existence of any knowledge.
Then there are the theologians and their secular fellow travelers (Rees among them) who make the even more unjustified and illogical leap from incomplete knowledge to the existence of the unknowable. Their argument always relies or one or another version of “I don’t know. Therefore, God.”
The somewhat sensible among them amend the second sentence to “Therefore, maybe God”; and the most accurate of those change it to “Therefore, not (not God).” Whatever the form, the argument from ignorance to faith is little but wishful thinking. It seems that for some of these thinkers the obvious fact that knowledge is limited is all the justification one needs for asserting the existence of the even more unknowable supernatural.
I’ve yet to be convinced either that there is nothing we can really know or that there is a supraphysical realm of existence that interacts with our universe.
If nothing can be known with epistemological certainty, that limitation has little practical effect. We know enough, and we know it well enough, that in those parts of the universe where we hang out things like gravity and trajectory and unidirectional time are “true enough” that we stake our lives on them at every moment of every day.
If we can’t reject the remote possibility of the supernatural with ontological finality, that inability cannot logically go farther than the realization that if there is another “level of being” out there, it’s so different from objects in our world — and therefore so different from us — that we can’t interact with it in any even remotely reasonable way.
So let the anti-rational faction gloat over the impossibility of final knowledge. And let the pro-deity faction pitch its fervent mythologies.
While they’re doing that, I’ll be over here, content with a world where water wheels grind grain and electricity powers this netbook.