I’ve written before about physicists’ ideas for gigantic particle accelerators, proposals for machines far bigger than the Large Hadron Collider or even plans for a Future Circular Collider. The ideas ranged from wacky but not obviously impossible (a particle collider under the ocean) to pure science fiction (a beam of neutrinos that can blow up nukes across the globe).

But what if you don’t want to accelerate particles? What if, instead, you want to detect particles from the depths of space? Can you still propose ridiculously huge things?

Neutrinos are extremely hard to detect. Immune to the strongest forces of nature, they only interact via the weak nuclear force and gravity. The weakness of these forces means they can pass through huge amounts of material without disturbing a single atom. The Sudbury Neutrino Observatory used a tank of 1000 tonnes of water in order to stop enough neutrinos to study them. The IceCube experiment is bigger yet, and getting even bigger: their planned expansion will fill eight cubic kilometers of Antarctic ice with neutrino detectors, letting them measure around a million neutrinos every year.

But if you want to detect the highest-energy neutrinos, you may have to get even bigger than that. With so few of them to study, you need to cover a huge area with antennas to spot a decent number of them.

Or, maybe you can just use trees.

That’s the proposal of Steven Prohira, a MacArthur Genius Grant winner who works as a professor at the University of Kansas. He suggests that, instead of setting up a giant array of antennas to detect high-energy neutrinos, trees could be used, with a coil of wire around the tree to measure electrical signals. Prohira even suggests that “A forest detector could also motivate the large-scale reforesting of land, to grow a neutrino detector for future generations”.

Despite sounding wacky, tree antennas have actually been used before. Militaries have looked into them as a way to set up antennas in remote locations, and later studies indicate they work surprisingly well. So the idea is not completely impossible, much like the “collider-under-the-sea”.

Like the “collider-under-the-sea”, though, some wackiness still remains. Prohira admits he hasn’t yet done all the work needed to test the idea’s feasibility, and comparing to mature experiments like IceCube makes it clear there is a lot more work to be done. Chatting with neutrino experts, one problem a few of them pointed out is that unlike devices sunk into Antarctic ice, trees are not uniformly spaced, and that might pose a problem if you want to measure neutrinos carefully.

What stands out to me, though, is that those questions are answerable. If the idea sounds promising, physicists can follow up. They can make more careful estimates, or do smaller-scale experiments. They won’t be stuck arguing over interpretations, or just building the full experiment and seeing if it works.

That’s the great benefit of a quantitative picture of the world. We can estimate some things very accurately, with theories that give very precise numbers for how neutrinos behave. Other things we can estimate less accurately, but still can work on: how tall trees are, how widely they are spaced, how much they vary. We have statistical tools and biological data. We can find numbers, and even better, we can know how uncertain we should be about those numbers. Because of that picture, we don’t need to argue fruitlessly about ideas like this. We can work out numbers, and check!