I just applied to an ACX grant (asking between $ 20k and 50k) to carry out this project https://mariopasquato.substack.com/p/testing-universal-free-fall-with

Scott says that grantees will have "money in their hands" by March 1, 2024. If I do receive at least 10k by March 15, I will resolve YES. Otherwise I will resolve NO. This applies only to money actually wired to my account, not to formal acceptance of the grant. Any delays due to banking issues or other unexpected events do not matter as long as Manifund or suitable related entities actually sent the wire.

This is the text from my application:

The universality of free fall (all materials fall with the same acceleration) is a cornerstone of modern physics. If it were disproved, general relativity would be proven wrong. The history of empirical tests of the universality of free fall is as long as the history of physics, with Galileo already allegedly conducting experiments of this kind. Current experiments test the universality of free fall with great precision (one part in 10^15) on test bodies that typically are spheres of suitable metals (e.g. titanium and platinum in the MICROSCOPE experiment). This does not rule out violations occurring to different materials. Newton seems to have been the last to test a broad array of materials, albeit with a crude method. Modern experiments rely on atomic theory, assuming that at the core all matter is neutrons, protons and electrons. But what if some obscure compound experiences a configuration-dependent fifth force leading to a violation while its constituent atoms or subatomic particles would not? This is very unlikely (how unlikely? Maybe Manifold can tell) but setting probabilities to zero is a display of arrogance. In physics experience should always have the last word. Huge returns are possible if a groundbreaking discovery happens this way; otherwise we can just fell more confident that free fall is universal, which is still a result.

The goal of this project is to empirically test the universality of free fall with a citizen science setup. Essentially I will arrange to manufacture experimental kits resembling the original setup by Newton with two pendulums whose bobs are identical and can be filled with different compounds in the same amount (as measured in terms of gravitational mass by weighing) and to distribute those kits to citizen-scientists, probably high schools, libraries or groups of interested citizens. The goal is to provide them with an ikea-like experience, so they can easily assemble the kit and take the relevant measurements. This amounts to measuring the period difference between the two pendulums and should be precise to few parts in 1000.

The kits would be useful for demonstration purposes anyway in a physics lab, but unlike your ordinary demonstration they would let the participants contribute to actual science: I plan to publish an academic paper on the results once the data collection is completed, and the paper would acknowledge the participants by name. In fact the kits could even be sold or given in exchange of a small donation, allowing the project to recoup at least a fraction of the costs.

Edit, addendum: Would this grant have good scientific returns in expectation?

At present we are between 3% and ~0.5% probability that a violation is detected in my experiment (see linked markets) and at around 30% probability that I find a not completely trivial explanation for the violation. All told >0.1% probability of getting something cool (a shot at new physics) out of this grant. If you estimate the value of having a good chance of discovering new physics at about the price of a big science experiment (~10^7-10^9 $) then this is pretty good value for the grant money (in expectation). See https://open.substack.com/pub/mariopasquato/p/costs-probabilities-expectations and https://mariopasquato.substack.com/p/compounds-compounds for further discussion.