Science Corner: Anointing with Oil Again, and Again…

When I come across a science story with a video of the experiment or phenomenon in question, it is hard to pass up. Even if the topic is less familiar, or less obviously connected to my usual themes, the opportunity to show as well as tell is appealing. And so today I find myself writing about bouncing droplets of oil. First, go ahead and watch for yourself. (Video from this story on this paper)

Mesmerizing, no? Just me? Actually, I suppose there is a risk it looks too banal; who hasn’t seen a ball bounce? You might have to remind yourself (I did at first) that this is a droplet of liquid and they don’t normally bounce like this. It should spread out once it hits the surface. And indeed, under most circumstances it will. But it turns out with the right kind of surface, vibrated at just the right speed, you (or at least Lebo Molefe et al) can get it to bounce. And not just once or twice, but over and over and over.

That just right surface? Atomically smooth mica. That means it is so smooth that any bumps or divots are on the order of one or a few atoms high or deep. And it has to be very precisely level to keep the droplet from bouncing out of the shot. This is painstaking work; it took two years of experimentation to prove it could be done and capture the video above. At that pace of producing footage, the next year’s highly anticipated Avengers: Doomsday would be released in 2325. Making movies that way is inconceivable, but that kind of monastic devotion and pace of producing results is typical–maybe even quick–for science.

And what do we get for that effort? At the moment, the satisfaction of finding a way to do what had previously been impossible. And maybe that’s all it will ever be, or maybe there will be practical uses as well. The news story hints at possible applications, such as producing pharmaceuticals. In your daily life, precision droplet physics may only play a role in your inkjet printer (okay, maybe weekly or monthly), but in certain manufacturing sectors it is a big deal.

Personally, I’m most intrigued by the teases of using this droplets in quantum analog demonstrations. You may be aware that there are numerous ways to think about quantum physics (different ways to formulate the foundations), from the Copenhagen interpretation to Everettian many worlds. (This lengthy episode of the Mindscape podcast starts with a survey of the options before delving into a new one.) So far, they all give the same numerical results, but they imply different things about the underlying nature of the world. While I don’t have any particular reason for thinking it is more true, I do have a soft spot for the de Broglie-Bohm pilot wave formulation. One reason is that you can qualitatively reproduce some aspects of quantum behavior with fluid droplets and waves at a scale humans can see; this maps most closely to the de Broglie-Bohm picture.

It is an interesting time to be a scientist in America. Cynicism and hostility towards the results of the scientific process and those who produce them seem to be on the rise–if not in numbers of people than at least in influence on policy. I’d suggest this is partly due to the way that contemporary science so often operates at scales away from human experience. The frontiers of physics, at least the ones that make headlines, deal with either the furthest reaches of the cosmos or the equally inaccessible subatomic scale. Climate pretty much by definition is beyond direct experience, working with long-term averages rather than today’s weather. Biology, formally the domain of familiar plants and animals, increasingly focuses on molecules and ecosystems, neither of which you can touch or see. (You can smell some molecules, but that doesn’t tell you much about what they can do.) Medicines that restore an unwell person to health are generally welcome, but those which prevent illness are harder to experience the benefits of.

Thus I welcome anything which makes inaccessible phenomena accessible to the curious novice. I understand to some disagree the dissatisfaction that many physicists have with the de Broglie-Bohm model as the foundation for quantum physics; it adds elements in a way that is at odds with Occam’s razor. But if videos and demonstrations with tangible liquids and droplets can illustrate quantum behavior, I think that is a great benefit. It is making the otherwise invisible incarnate.

I can appreciate that what we are doing at that point isn’t really science, per se. It is almost more like a form of natural theology. Not in the more traditional sense of natural theology–studying the natural world to understand God. Rather it is more of a theology for nature, a way of teaching about things ineffable in a way that they can be grasped. Of course, there is the danger of suggesting then that nature itself is God or divine and perhaps leading towards some kind of pantheism or panentheism. None of that is my intention, and so theology is probably the wrong word. It is not that subject is God; rather, it is that the pedagogical challenge for contemporary science is akin to that traditionally faced by theology. And so maybe some version of the same tools or same approach is needed.

And this is not an entirely new idea. Popularizing science has long involved metaphors and toy models, which face many of the same pitfalls and criticisms as analogies for the Trinity, say. But explicitly recognizing the commonalities in the work may yet provide some advantages or insights.