[epistemic status: this is mostly vague impressions I’ve accumulated]

I’m an undergraduate physicist interested in effective altruism, and have noticed in several places (here, here) that physics is offhandedly mentioned as a promising research area and/or skill to possess. However, so far, I haven’t seen any specifics; no indexing of research topics in physics with DALY numbers and instructions, or organisations that hire physicists, or anything like that.

I can’t write that article either, though to get something in this space (hey, it's highly neglected!) I’m going to describe some uses of physics and EA areas where I’ve seen physics be done.

Not Doing Physics

The EA recommendation I tend to see for physicists is to not do physics. I mean, nobody's said that explicitly, but physics has been passed over in recommendations for other fields for potentially good reasons.

Physics is, instead, useful because it gives you good quantitative skills, and a physics qualification is useful because it gives you a reliable signal of quantitative skills. Instead, consider a more useful field to employ the power of mathematics, like AI safety (via computer science) or global priorities research (via economics).

This is somewhat uninspiring to those excited by physics, though not as much as at first glance: AI safety is still about discovering universal truths, and global priorities research is still about using mathematics to predict experimental outcomes.

Still, there are some things that can be done even within the purview of the physics department, which is what the rest of this post is about.

Studying the Large-Scale Structure of the Universe

Most of the value that a civilisation will produce lies in the far future, and that means that the shape of the far future dictates how civilisation will behave and how much value it will capture. The long-term evolution of the universe is dictated by cosmology. Whatever conclusions are drawn have big implications in what behaviour we should expect to see from other civilisations, if any, and potentially in what our civilisation should do.

Some work I’ve seen in this area is Bostrom’s Astronomical waste paper which follows from knowledge about the size of the universe and the rate of loss of usable mass-energy. Knowing more about this would give better bounds on the tradeoff between existential risk and hastening technological development (also relevant here: the scale of s-risks).

The behaviour of other civilisations helps put bounds on the Fermi paradox, which might give us some insight into existential risk for our civilisation via determining the existence, size and location of the Great Filter(s). In this area we have Sandberg’s Spamming the Universe paper (summary: it is relatively easy to colonise the entire universe), and the Aestivation hypothesis paper (summary: the best use of mass-energy might be to wait until the universe is very cold before doing anything).

Also in this field is the idea of Boltzmann brains. If these will exist, they would make up most experience in the cosmos, which means that research to find out what the deal with them is might be valuable.

Philosophy and Foundational Research

Physics, as the science about how the world works at its most fundamental level, has a thing or two to say about how the world works at its most fundamental level. Counterintuitive discoveries from physics might lead to ethical insights that we wouldn’t have developed otherwise.

Using special relativity, Beckstead argues in On the Overwhelming Importance of Shaping the Long Term Future that there should not be an ethical asymmetry between space and time: if two civilisations exist simultaneously and outside each other’s light cones, then there is a reference frame where one civilisation lives entirely before the other. There's no classical analogue to this.

The many-worlds interpretation of quantum mechanics suggests that there exists a multiverse, which might have some implications for what one should do: there are decision-theoretic arguments for why certain actions we take might affect other universes, for example. Other potential sources of multiverses in physics include the possibility of eternal inflation, or the mathematical multiverse hypothesis. More physics research could give insight into the distribution of worlds, and avoid confusion among non-physicist foundational researchers about what a multiverse actually entails.

There’s also Brian Tomasik’s post on suffering in fundamental physics that you've read. Knowing what fundamental physics says about the world seems like it would be essential for this question; even with a complete understanding of consciousness it wold be important to know what processes are implemented by physics to say anything at all about any experiences, if any, that might be had.

Climate Science

Tail-end risks from climate change do have a chance of reducing the value of the long-term future (through, say, wiping out human civilisation), and like everything that affects the long-term future that makes them very important. Research into modelling the Earth’s climate would give us a better idea of where these risks lie and how best to mitigate them. This could be both directly (via geoengineering) and to better inform policy decisions (such as by predicting which populated areas will face the most heating to forecast geopolitical problems).

This is also, as of the time of writing, the topic of the only physics-related thesis on Effective Thesis.

Molecular Nanotechnology

Molecular nanotechnology seems in principle possible, and also seems like it would lead to massive economic growth if done properly. Many of the problems in molecular nanotechnology are physics problems, since it involves handling objects like individual atoms on small scales.

A crucial consideration in nanotechnology is its effect on x-risk: in the worst case, there’s a grey goo scenario (do some physics to evaluate the risk of this happening!), but even in ordinary cases nanotechnology might lead to weapons becoming much cheaper and computers becoming much cheaper (making the hardware overhang much worse if AI safety isn’t solved yet). Nanotechnology x-risks seem to be very neglected; better knowledge of the feasibility of molecular nanotechnology might help with this.

General Economic Growth Acceleration via Science

The standard use of physics is to make discoveries, which are eventually converted into actual applications that do something to improve someone’s life later down the line. This doesn't seem like it would be very neglected, because physicists have a direct incentive to do this (an easier time applying for funding), though historically it does seem to be the source of most of the good from physics. Since everything is a power-law, exceptional physicists might still be best placed here; I think Einstein doing physics was one of the best things that he could have done, simply for being so damn good at physics.

Other Things

And now I turn to you, Most Esteemed Reader. There are, undoubtedly, things that I've missed, and probably other material on this topic that's been published elsewhere. What else could potentially be done with physics in order to do the most good? Is there anything in physics that seems much more promising than other areas?

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A few more: energy (nuclear fusion, green tech, energy storage), medical physics, quantum computing (and its medical applications), risks from space and preparedness for worst case scenarios (like ALLFED).

Some other options and sources from the future:

  • A 2019 report on Quantum Computing by Jaime Sevilla: link
  • Switching to electrical engineering, there has been a call for more people in EA to be experts in computational hardware to better understand questions relevant to AI-Risk.

A possible note of caution for applied physics research or technology development in industry: you might want to take into account differential technological progress: develop safety first, before developing more powerful technologies (such as creating faster hardware). I assume that it depends much on your research field whether you should be concerned about differential technological progress. Does anyone have more thoughts about this?

The EA recommendation I tend to see for physicists is to not do physics.

I've been understanding this to mean that under the current institutional paradigm, more physics research on the margin probably isn't very helpful.

Achieving a fundamental breakthrough seems obviously great (though hard to do in the current paradigm), and meaningfully reforming the current paradigm would probably be very high-value as well (though tricky to do).

Robin Hanson has more to say on this (a):

Previously, physics foundations theorists were disciplined by a strong norm of respecting the theories that best fit the data. But with less data, theorists have turned to mainly judging proposed theories via various standards of “beauty” which advocates claim to have inferred from past patterns of success with data. Except that these standards (and their inferences) are mostly informal, change over time, differ greatly between individuals and schools of thought, and tend to label as “ugly” our actual best theories so far.

See also "What does any of this have to do with physics?" (a).

You mention nanotechnology; in a similar vein, understanding molecular biology could help deal with biotech x-risks. Knowing more about plausible levels of manufacture/detection could help us understand the strategic balance better, and there’s obviously also concrete work to be done in building eg better sensors.

On the more biochemical end, there’s of mechanical and biological engineering for cultured meat.

Also, wrt non-physics careers, a major one is quantitative trading (eg at Jane Street), which seems to benefit from a physics-y mindset and use some similar tools. I think there’s even a finance firm that mostly hires physics PhDs.

I worry that this could be somewhat motivated reasoning. It reads as though you started with the conclusion you wanted to reach, namely that physics can be a promising EA field, and worked backwards to find arguments that support that conclusion. [See also https://www.gocomics.com/nonsequitur/2010/04/22/.]

Thank you for writing this. I think it serves an important purpose, because like you I think the most likely impression for a physicist to form from the highest-profile EA career advice is that they should take their highly valuable transferable skills and get out of physics (even if it's not explicitly stated). This may be the correct advice, but it's worth explicitly considering whether that is true.

I did (computational quantum) physics to PhD level before exiting to policy, initially in climate change, so I effectively followed this advice (although before the EA movement existed in its current form). From my sample of one, I did find the skills/experience highly transferable.

However, I tend to believe that staying in physics can also offer high impact - and you have highlighted lots of reasons why. To be fair, the general potential of research is well profiled by e.g. 80k, it's just that physics doesn't get highlighted as a top choice.

Some people make the argument that generally boosting economic growth is so assured of positive results that it offers good impact to focus one's efforts generically in this direction. I wonder if a similar argument could apply to increasing humanity's understanding of the fundamental nature of the universe?

(A minor question: You refer to the many worlds interpretation as a possible reason to believe in a multiverse, and to consider the potential ethical implications of that. I am rusty, but my understanding was that all interpretations of quantum mechanics are essentially hypothetical ideas rather than rooted in any empirical evidence? I.e. unlike a "proper" theory, the different interpretations do not result in any changes to the underlying mathematics and are not testable? If I've got that right, then for me the interpretations would provide little to no motivation for taking their model of reality into account in decision-making.)

Thanks again.

Not an expert on the foundations of QM, but a few points on your question:

  • For some interpretations the mathematics does change somewhat (e.g. Bohmian Mechanics, Collapse Theories)
  • Some interpretations actually do make testable predictions (like the Many Wolds Interpretation), but they tend to be quite hard to test in practice
  • Some people have argued that some interpretations follow more naturally from the mathematics. It's pretty clear in my opinion that Bohmian Mechanics is postulating additional structure on top of the mathematics we have now, while many-worlds is not really doing that.

Your comment, and the links, were very helpful and thought-provoking - thanks.

I've definitely reached the limit of my expertise - so take this with a pinch of salt - but I think the key thing for me is whether any of the interpretations lead to observable real-world differences.

I didn't fully understand the link you provided to the many worlds interpretation making testable predictions, but it appeared to be talking only of thought experiments that would require non-existent technology to carry out in practice.

I agree with you that some interpretations would, if "true"*, require additional mathematics to describe the new underlying mechanism they postulate. But, from my limited understanding, that new mathematics would itself not be testable - because it would only result in the same real-world observable behaviour as all the other interpretations.

Thanks again.

*I'm not really sure what this word even means in this context (spot the non-philosopher), when there is no means of using experimental results to distinguish between interpretations.

Thanks for putting this all together! I just wanted to expand on Michael's suggestion of quantum computing. There is increasing interest in industry to provide quantum computing tools. A few standouts that I see publishing/talking at conferences are

These companies are advertising their product as a tool for machine learning (among other things). Further, these companies are all just cloud service providers. Their goal is to get their product online as fast as possible for use by whoever can afford it. I would need to do more research to figure out how quantum machine learning impacts x-risk (it could be small assuming machine learning on classical computers develops quickly but scaling quantum hardware is slow), but playing the right role in these companies could be very high impact.

I also wanted to add a possibly off-topic note of caution about physics research. I am currently a grad student in experimental physics, so this is possibly overly-pessimistic about university research (grass is always greener on the other side). However, I would be cautious optimizing your resume completely to do research as a professor, which is what I think many physicists do. Academic positions are extremely competitive and best suited to people who are interested in the research for its own sake rather than for the impact it has. So I think it is important to either be very sure how excited you are about physics for its own sake (does it match the level of your young professors?) or to build a resume that could also veer towards your favorite non-physics direction, if needed (e.g. taking a few classes in writing good code, doing an internship in industry).

[epistemic status: anecdotical] on not doing physics

If you want to build a resume in a non-physics direction, as Christopher suggests, and you are early in your career, don't wait too long to explore alternatives. I personally made a mistake by not exploring alternative options enough before I finished my master's degree (in Europe).

Great post, thanks for collecting all these in one place.

Very good post, thank you for collecting everything.

I'd be interested in a closer look into the field of energy (especially nuclear fussion, modern nuclear energy technology), i don't really know if there are neglected areas or positions.