TLDR: scroll here for the pretty interactive picture.

Over two years ago I abandoned my post at the University of Washington as a assistant research professor studying quantum computing and started a new career as a software developer for Google. Back when I was a denizen of the ivory tower I used to daydream that when I left academia I would write a long “Jerry Maguire”-esque piece about the sordid state of the academic world, of my lot in that world, and how unfair and f**ked up it all is. But maybe with less Tom Cruise. You know the text, the standard rebellious view of all young rebels stuck in the machine (without any mirror.) The song “Mad World” has a lyric that I always thought summed up what I thought it would feel like to leave and write such a blog post: “The dreams in which I’m dying are the best I’ve ever had.”

But I never wrote that post. Partially this was because every time I thought about it, the content of that post seemed so run-of-the-mill boring that I feared my friends who read it would never ever come visit me again after they read it. The story of why I left really is not that exciting. Partially because writing a post about why “you left” is about as “you”-centric as you can get, and yes I realize I have a problem with ego-centric ramblings. Partially because I have been busy learning a new career and writing a lot (omg a lot) of code. Partially also because the notion of “why” is one I—as a card carrying ex-Physicist—cherish and I knew that I could not possibly do justice to giving a decent “why” explanation.

Indeed: what would a “why” explanation for a life decision such as the one I faced look like? For many years when I would think about this I would simply think “well it’s complicated and how can I ever?” There are, of course, the many different components that you think about when considering such decisions. But then what do you do with them? Does it make sense to think about them as probabilities? “I chose to go to Caltech, 50 percent because I liked physics, and 50 percent because it produced a lot Nobel prize winners.” That does not seem very satisfying.

Maybe the way to do it is to phrase the decisions in terms of probabilities that I was assigning before making the decision. “The probability that I’ll be able to contribute something to physics will be 20 percent if I go to Caltech versus 10 percent if I go to MIT.” But despite what some economists would like to believe there ain’t no way I ever made most decisions via explicit calculation of my subjective odds. Thinking about decisions in terms of what an actor feels each decision would do to increase his/her chances of success feels better than just blindly associating probabilities to components in a decision, but it also seems like a lie, attributing math where something else is at play.

So what would a good description of the model be? After pondering this for a while I realized I was an idiot (for about the eighth time that day. It was a good day.) The best way to describe how my brain was working is, of course, nothing short than my brain itself. So here, for your amusement, is my brain (sorry, only tested using Chrome). Yes, it is interactive.

## Cosmology meets Philanthropy — guest post by Jess Riedel

My colleague Jess Riedel recently attended a conference  exploring the connection between these seemingly disparate subjects, which led him to compose the following essay.–CHB

People sometimes ask me what how my research will help society.  This question is familiar to physicists, especially those of us whose research is connected to every-day life only… shall we say…tenuously.  And of course, this is a fair question from the layman; tax dollars support most of our work.

I generally take the attitude of former Fermilab director Robert R. Wilson.  During his testimony before the Joint Committee on Atomic Energy in the US Congress, he was asked how discoveries from the proposed accelerator would contribute to national security during a time of intense Cold War competition with the USSR.  He famously replied “this new knowledge has all to do with honor and country but it has nothing to do directly with defending our country except to help make it worth defending.”

Still, it turns out there are philosophers of practical ethics who think a few of the academic questions physicists study could have tremendous moral implications, and in fact might drive key decisions we all make each day. Oxford philosopher Nick Bostrom has in particular written about the idea of “astronomical waste“.  As is well known to physicists, the universe has a finite, ever-dwindling supply of negentropy, i.e. the difference between our current low-entropy state and the bleak maximal entropy state that lies in our far future.  And just about everything we might value is ultimately powered by it.  As we speak (or blog), the stupendously vast majority of negentropy usage is directed toward rather uninspiring ends, like illuminating distant planets no one will ever see.

These resources can probably be put to better use.  Bostrom points out that, assuming we don’t destroy ourselves, our descendants likely will one day spread through the universe.  Delaying our colonization of the Virgo Supercluster by one second forgoes about $10^{16}$ human life-years. Each year, on average, an entire galaxywith its billions of starsis slipping outside of our cosmological event horizon, forever separating it from Earth-originating life.  Maybe we should get on with it?

But the careful reader will note that not everyone believes the supply of negentropy is well understood or even necessarily fixed, especially given the open questions in general relativity, cosmology, quantum mechanics, and (recently) black holes.  Changes in our understanding of these and other issues could have deep implications for the future.  And, as we shall see, for what we do tomorrow.

On the other side of the pond, two young investment analysts at Bridgewater Associates got interested in giving some of their new disposable income to charity. Naturally, they wanted to get something for their investment, and so they went looking for information about what charity would get them the most bang for their buck.   But it turned out that not too many people in the philanthropic world seemed to have many good answer.  A casual observer would even be forgiven for thinking that nobody really cared about what was actually getting done with the quarter trillion donated annually to charity.  And this is no small matter; as measured by just about any metric you choose—lives saved, seals unclubbed, children dewormed—charities vary by many orders of magnitude in efficiency.

This prompted them to start GiveWell, now considered by many esteemed commentators to be the premier charity evaluator.  One such commentator is Princeton philosopher Peter Singer, who proposed the famous thought experiment of the drowning child.  Singer is also actively involved with a larger movement that these days goes by the name “Effective Altruism”.  It’s founding question: If one wants to accomplish the most good in the world, what, precisely, should one be doing?

You won’t be surprised that there is a fair amount of disagreement on the answer.  But what might surprise you is how disagreement about the fundamental normative questions involved (regardless of the empirical uncertainties) leads to dramatically different recommendations for action.

A first key topic is animals.  Should our concern about human suffering be traded off against animal suffering? Perhaps weighted by neural mass?  Are we responsible for just the animals we farm, or the untold number suffering in the wild?  Given Nature’s fearsome indifference, is the average animal life even worth living?  Counterintuitive results abound, like the argument that we should eat more meat because animal farming actually displaces much more wild animal suffering than it creates.

Putting animals aside, we will still need to balance “suffering averted”  with “flourishing created”.  How many malaria deaths will we allow to preserve a Rembrandt?  Very, very bad futures controlled by totalitarian regimes are conceivable; should we play it safe and blow up the sun?

But the accounting for future people leads to some of the most arresting ideas.  Should we care about people any less just because they will live in the far future?  If their existence is contingent on our action, is it bad for them to not exist?  Here, we stumble on deep issues in population ethics.  Legendary Oxford philosopher Derek Parfit formulated the argument of the ”repugnant conclusion”.  It casts doubt on the idea that a billion rich, wealthy people living sustainably for millennia on Earth would be as ideal as you might initially think.

(Incidentally, the aim of such arguments is not to convince you of some axiomatic position that you find implausible on its face, e.g. “We should maximize the number of people who are born”.  Rather, the idea is to show you that your own already-existing beliefs about the badness of letting people needlessly suffer will probably compel you to act differently, if only you reflect carefully on it.)

The most extreme end of this reasoning brings us back to Bostrom, who points out that we find ourselves at a pivotal time in history. Excepting the last century, humans have existed for a million years without the ability to cause our own extinction.  In probably a few hundred years—or undoubtedly in a few thousand—we will have the ability to create sustainable settlements on other worlds, greatly decreasing the chance that a calamity could wipe us out. In this cosmologically narrow time window we could conceivably extinguish our potentially intergalactic civilization through nuclear holocaust or other new technologies.  Even tiny, well-understood risks like asteroid and comet strikes (probability of extinction event: ~$10^{-7}$ per century) become seriously compelling when the value of the future is brought to bear. Indeed, between $10^{35}$ and $10^{58}$ future human lives hang in the balance, so it’s worth thinking hard about.

So why are you on Facebook when you could be working on Wall Street and donating all your salary to avert disaster? Convincingly dodging this argument is harder than you might guess.  And there are quite a number of smart people who bite the bullet.