Uncategorized – Just Another Datapoint

Heavy Water Tastes Sweet

william — Tue, 13 Apr 2021 12:49:15 +0000

This is so cool. Apparently you can taste the difference between light and heavy water! So can rats!

https://www.nature.com/articles/s42003-021-01964-y

Today I learned a new word: Ultracrepidarianism

william — Fri, 06 Nov 2020 22:58:00 +0000

I was listening to No Stupid Questions and it was fascinating. In it, they introduce the word, “ultracrepidarianism”, which according to Wikipedia is “the giving of opinions and advice on matters outside of one’s knowledge”. Some of you may be familiar with Dunning and Kruger. Delving a bit more into research by Dunning, when we first start to learn something, we can realize that we are not experts—but as we begin to learn a little, we become deluded into believing that we are. This can be rather dangerous—especially for those of us who do cross-disciplinary work. This is basically a reminder for myself to be cautious. I will close with their reference to a poem:

“A little learning is a dang’rous thing;

Drink deep, or taste not the Pierian spring:

There shallow draughts intoxicate the brain,

And drinking largely sobers us again.

ALEXANDER POPE, 1711

Machine Learning

william — Mon, 19 Jun 2017 03:08:00 +0000

I have become interested in the intersection of machine learning with science. Two of my students will explore this intersection over the summer. One of our project involves classification, the other involves reinforcement learning. I’m excited!

Instabilities

william — Tue, 04 Nov 2014 02:45:43 +0000

I went for a jog today and thought back to an insight that I had in graduate school. During my phD, I studied frustrated magnetism. In frustrated magnets, you consider a material where the atoms are arranged in triangular motifs. If these atoms have unpaired spins on them and only nearest neighbor antiferromagnetic interactions, then the interactions will be unable to be simultaneously satisfied and the material will never order, despite having strong interactions. However, in practice, I found that Nature is tricky and that a number of these materials would order. In some cases, thermal or quantum fluctuations would result in ordering. In other cases, order in the system could be stabilized by a structural phase transition which would favor some interactions over others. However, one thing that gradually became clear was that there were interesting phases near such frustrated magnets and the interesting question is how a small perturbation might result in interesting physics.

I think this could be a general strategy for searching for switchable phenomena. Find a phase which is subject to an instability through some type of perturbation. For example, pressure, electric field, etc. If you can move the system towards the instability using one control parameter you’re half way there. The next challenge is whether you can use another perturbation to move it back across the boundary using another control parameter. If so, then you have a chance to build something interesting…

Uncontrolled!

william — Tue, 08 Jul 2014 01:46:51 +0000

I just finished reading Uncontrolled by Jim Manzi. He starts the book spending a surprising amount of time in the early chapters of the book trying to give the reader a crash course in the philosophy of science. The TL; DR is that I’m rather lucky to be a physicist. The longer answer is that in the hard sciences such as physics and chemistry, we often have basic models of how the world work which we constantly test against new observations. If we’re lucky, we find that our models don’t describe something in nature and that there is new science to discover. But, at a deep level, we have a few articles of faith. For example, we believe that the laws of physics don’t change from place to place. We also believe that the laws of nature don’t change with time (even if our understanding of them does). Other fields such as medicine are not so lucky. We still have a very rudimentary understanding of the human body. We don’t have strong enough models to say whether a given compound should cure a given disease. There are also many confounding factors. So, randomized trials are necessary to see whether the effects observed are intrinsic or accidental. Even if a randomized trial indicates that an effect is present, it can be difficult to generalize it to a different context or population. Sociology and economics are even more difficult. The author brings up a number of cases in economics where authors have overreached and made predictions that really should have been tested in randomized experiments—otherwise, they are far too overreaching with too little support from data.

After this introduction, Manzi delves into perhaps the strongest section of the book where he outlines how he used randomized experiments in business to determine strategy. When doing this, he looked into the literature of random trials in medicine, as well as random trials in social sciences (for example, leading up to welfare reform in the 90s, the federal government required a number of random trials for states which wanted to try different strategies.).

There is another section of political trials, which reminded me of Rick Perry and His Eggheads and the better Get Out the Vote, which deal with experimental tests in politics of what strategies work and which don’t in get out the vote efforts.

Perhaps the weakest section of the book is where the author attempts to make policy suggestions. But overall, I would recommend reading this book. If nothing else, it is helpful in increasing skepticism of predictions which lack experimental support.