The well of inspiration

AP News recently ran a story on the interface of religious inspiration and the search for dark matter. I thought about commenting on it, then thought better of it, but now here I am again. I know some but not all of the people who are quoted, all good scientists. The article ends with a nice quote from Jennifer Wiseman:

“Studying the deep universe may make us feel insignificant,” Wiseman said. “But it also gives us a sense of unity that we’re all on the same planet. … The hope is we get a sense of joy, humility and love from these contemplations.”

I’ve known Dr. Wiseman since undergrad days, before either of us were Ph.Ds. We don’t agree on much that is specific to religion, but somehow manage to be friends anyway, and I completely agree with the sentiments she expresses here.

There is a tendency to portray religion as being at odds with science, and that can certainly happen. But they share more in common than this trope implies. Both arise from a deep wellspring in the human spirit, the same wellspring: the desire to know. How does the universe work? How did it come to be so? Why? and on and on. Where they differ is in approach: when encountering an unknown, especially things that are fundamentally unknowable (e.g., does God exist?), religion asserts an answer and asks that we accept it on faith. Faith is anathema to the scientific process; one is, in principle, to search for the truth through observation and experimentation.

Religion and science come into conflict when scientific knowledge encroaches on religion’s known unknowns. There was a time when the structure of the heavens must have seemed unknowable; the realm of the sacred, safe from access by mundane human knowledge. So it is easy to see how Galileo came into conflict with the Church despite being a faithful member:

Church: Scripture teaches us that the Earth is the unmoving center of mortal corruption; the heavens above us are perfect and unchanging.

Galileo: I can see spots on the sun and mountains on the moon.

Church: We are the center about which the heavens rotate every day, clearly the center of all rotation.

Galileo: I see satellites circling Jupiter.

Church: God is great; He could do one thing one day and an entirely different thing another day*.

Galileo: It appears that the Earth revolves around the Sun, never the other way around.

Church: Do you see these instruments of torture?

This is a tongue-in-cheek portrayal of a serious historical incident, but my point is that conflict arises when scientific knowledge encroaches onto turf that had formerly been the exclusive province of religion. Addressing our spiritual need to know can be inspirational, but it can also be a let down. Giving specific answers to formerly unknowable questions can be a bit of a mood killer. Is that all there is?

Another downside of scientific knowledge is that it can never be complete. There is always something left unknown, and we are not supposed to fill that void with something we take on faith. Yet we are profoundly uncomfortable with not knowing. A little extrapolation at and beyond the fringes of current knowledge is natural, and can sometimes provides a useful way forward in driving new discoveries. But it can get carried away, e.g., string theory. So extraordinary caution is also warranted: the temptation to fill in the blank is where empiricism transitions to theology.

Understanding that we know a lot – as we do at this juncture in the history of science – and yet still don’t know something important, like what most of the universe is made of, is hard to accept. It becomes even harder when admitting something we thought we understood is wrong, or is less complete than we thought. We know most of the mass in the universe is made of non-baryonic cold dark matter^&. Don’t we?

The dynamical evidence for acceleration discrepancies is abundant. That these must be caused by non-baryonic cold dark matter is less clear. This is where cosmology intrudes. Cosmology has always been the nexus where science and religion meet, with philosophical imperatives often obscuring essential observational facts. Before Kepler, orbits had to be circular. After Inflation, the density parameter had to be one. (We meant Ω_m = 1, not the modern weak-sauce version Ω_m + Ω_Λ = 1.) The mass density is larger than the baryon density from BBN (Ω_m > Ω_b), so there has to be non-baryonic dark matter. That such a substance is also required to fit the acoustic power spectrum of the CMB amplifies our faith in the existence of such stuff.

We think we’ve solved cosmology, and that solution requires non-baryonic cold dark matter. So to admit that maybe we were wrong about dark matter just because it persistently remains undetected and provides unsatisfactory explanations of many astronomical observations and is consistently outperformed in predictive capacity by an alternative theory is to admit that we don’t understand as much about the universe as we thought. That’s really, really hard. Our unwillingness to admit that maybe we have been wrong about such an important issue is where human nature kicks in to blur the line between scientific knowledge and religious faith. It’s much easier to ignore those nagging doubts^% and have faith that we were right all along.

Cosmology works so well that dark matter has to exist. I’ve head this sentiment expressed over and over by many different scientists, yet this is an assertion of faith. A more conservative statement is that cosmology as we currently conceive it works if, and only if, an appropriate form of non-baryonic dark matter exists with the required cosmic density. If not, then we need a new model – something that presumably^{^} stems from a more general underlying theory.

Since both religion and science arise from the same desire to know, it is easy to have faith that we know more than we actually do.

This is the sticking point we’ve hit in the dark matter debate. We’ve been calling the acceleration discrepancy the dark matter problem for so long that this linguistic mistake has morphed into an absolute certainty that invisible mass exists. It has become a matter of faith.

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*Of course an omnipotent deity could do that. Apparently He chooses not to do so, sparking the schism between theists, for whom God actively intervenes in miraculous ways in real world affairs, and deists, who view God more as the great watchmaker, setting creation in motion but not interfering with its operation. Deism is conducive to science, as the search to identify the rules by which the universe works is to gain insight – however remote – into the mind of God. I suspect this attitude informed Einstein’s complaint against quantum mechanics: “God does not play dice with the universe.”

^&I certainly thought so before I didn’t.

^%The social pressure to conform to the preferred cosmology is enormous. I know I’m only making it worse for myself. But an explanation that omits MOND is a lie of omission. Here science and religion certainly overlap in the sentiments expressed by the seventeenth century cleric Paul Gerhardt:

“When a man lies, he murders some part of the world.”

Assertions that somehow “feedback” explains MOND are simply a numerical form of magical thinking; an excuse to not have to explain the inexplicable. By eliding MOND, we murder a part of the world.

^{^}Here I am extrapolating at the fringes of knowledge.