# Effective Altruism for Ghosts

Halloween is approaching, and that leads to spooky thoughts.

It is known that the dead outnumber the living by a factor of about 13:1. Hence anything that affects the welfare of the dead can affect a large number of people, assuming that the dead are people and have welfare.

The traditional answer is to remember and honour ancestors, a near-universal practice. Assuming this improves ancestor well-being significantly this would seem to be a very effective thing to do. Bigger, better and more frequent All Hallows Eve and Dia Los Muertes celebrations as a new cause area for philanthropists?

Not so fast. First, it is not entirely clear how much well-being is improved (cost effectiveness may be low), but more importantly, most ancestor veneration only goes back a finite number of generations. While there is some general veneration of the dead in general, mostly the focus is on people who are remembered. Since cultural memory only lasts a few generations that means that only a fraction of the dead will benefit. Hence at the very least veneration of all dead seems to scale better and treat each soul neutrally. In a prioritarianism framework veneration of neglected dead is even more important.

However, a more serious issue is the general welfare state of the dead. If there are places of eternal punishment they are obviously major sources of disvalue (unless one thinks they are just punishments, in which case they might be positive) and should be removed. Even improving a fairly dreary afterlife like the Greek one would seem to provide a potential long-lasting benefit to a vast number. While clearly a neglected question, tractability appears low. Still, especially models ascribing near-pessimal suffering lasting eternally would run into the fanaticism problem that improving this would always be the top priority intervention, no matter how hard. One can consider this a form of Pascal’s mugging.

Taking a longtermist perspective on the dead produces other interesting issues. Over the span of the future many people will die, producing a potentially vast number of future dead. If the dead have unlives worth living this can become a dominant contribution to the overall good. If the dead have unlives not worth living on the other hand it becomes a strong argument for either early extinction, or radical life-extension ensuring that future generations do not die. If the afterlife can be improved in the future or future dead can be given unlives worth living this can also outweigh the current issue.

One issue is whether dead are resistant to proton decay and the heat death of the universe. If they are, and their state can be improved to be positive, then this might provide a massive existential hope.

Clearly these considerations are preliminary. We do not have a strong evidence base to even estimate QAUYs (Quality Adjusted Unlife Years) to an order or magnitude. It is very possible that dead have literally zero experience and well-being. But as the above considerations show, even a low credence of nonzero QAUYs provide in expectation a very strong reason to act in some way, if possible. Hence the value of information in regard to the state of the dead is extremely high. This suggests that paranormal investigations should be regarded as a potentially valuable near term cause area for effective altruism.

However, this might miss an even bigger opportunity: ghostly effective altruism. While dead people likely have a fairly weak ability to affect the physical world, if they have the abilities commonly ascribed to them (perceive descendant lives, precognition, nudge things in an eerie way) they could, if they coordinated better, likely improve the life of the living in many ways. Since there are many dead per living individual, that would give each living person a team that could enhance their life. Even if past dead may not have been too effective, we should expect an increasing number of effective altruists in the afterlife. They may of course primarily choose to focus on the biggest risks, haunting nuclear weapons control systems, biowarfare labs and sleep depriving AI researchers with a lacking commitment to safety.

So if you encounter something mysterious and frightening late at night, maybe it is just a nudge from the other side to increase the long-term flourishing of humanity.

Happy Halloween!

# Starkiller base versus the ideal gas law

My friend Stuart explains why the Death Stars and the Starkiller Base in the Star Wars universe are inefficient ways of taking over the galaxy. I generally agree: even a super-inefficient robot army will win if you simply bury enemy planets in robots.

But thinking about the physics of absurd superweapons is fun and warms the heart.

## The ideal gas law: how do you compress stars?

My biggest problem with the Starkiller Base is the ideal gas law. The weapon works by sucking up a star and then beaming its energy or plasma at remote targets. A sun-like star has a volume around 1.4*1018 cubic kilometres, while an Earthlike planet has a volume around 1012 cubic kilometres. So if you suck up a star it will get compressed by a factor of 1.4 million times. The ideal gas law states that pressure times volume equals temperature times the number of particles and some constant: $PV=nRT$

1.4 million times less volume needs to be balanced somehow: either the pressure P has to go down, the temperature T has to go up, or the number of particles n need to go down.

Pressure reduction seems to be a non-starter, unless the Starkiller base actually contains some kind of alternate dimension where there is no pressure (or an enormous volume).

The second case implies a temperature increase by a factor of a 1.4 million. Remember how hot a bike pump gets when compressing air: this is the same effect. This would heat the photosphere gas to 8.4 billion degrees and the core to 2.2*1013 K, 22 TeraKelvin; the average would be somewhere between, on the hotter side. We are talking about temperatures microseconds after the Big Bang, hotter than a supernova: protons and neutrons melt at 0.5–1.2 TK into a quark-gluon plasma. Excellent doomsday weapon material but now containment seems problematic. Even if we have antigravity forcefields to hold the star, the black-body radiation is beyond the supernova range. Keeping it inside a planet would be tough: the amount of neutrino radiation would likely blow up the surface like a supernova bounce does.

Maybe the extra energy is bled off somehow? That might be a way to merely get super-hot plasma rather than something evaporating the system. Maybe those pesky neutrinos can be shunted into hyperspace, taking most of the heat with them (neutrino cooling can be surprisingly fast for very hot objects; at these absurd temperatures it is likely subsecond down to mere supernova temperatures).

Another bizarre and fun approach is to reduce the number of gas particles: simply fuse them all into a single nucleus. A neutron star is in a sense a single atomic nucleus. As a bonus, the star would now be a tiny multikilometre sphere held together by its own gravity. If n is reduced by a factor of 1057 it could outweigh the compression temperature boost. There would be heating from all the fusion; my guesstimate is that it is about a percent of the mass energy, or 2.7*1045 J. This would heat the initial gas to around 96 billion degrees, still manageable by the dramatic particle number reduction. This approach still would involve handling massive neutrino emissions, since the neutronium would still be pretty hot.

In this case the star would remain gravitationally bound into a small blob: convenient as a bullet. Maybe the red “beam” is actually just an accelerated neutron star, leaking mass along its trajectory. The actual colour would of course be more like blinding white with a peak in the gamma ray spectrum. Given the intense magnetic fields locked into neutron stars, moving them electromagnetically looks pretty feasible… assuming you have something on the other end of the electromagnetic field that is heavier or more robust. If a planet shoots a star-mass bullet at a high velocity, then we should expect the recoil to send the planet moving at about a million times faster in the opposite direction.

## Other issues

We have also ignored gravity: putting a sun-mass inside an Earth-radius means we get 333,000 times higher gravity. We can try to hand-wave this by arguing that the antigravity used to control the star eating also compensates for the extra gravity. But even a minor glitch in the field would produce an instant, dramatic squishing. Messing up the system* containing the star would not produce conveniently dramatic earthquakes and rifts, but rather near-instant compression into degenerate matter.

(* System – singular. Wow. After two disasters due to single-point catastrophic failures one would imagine designers learning their lesson. Three times is enemy action: if I were the Supreme Leader I would seriously check if the lead designer happens to be named Skywalker.)

There is also the issue of the amount of energy needed to run the base. Sucking up a star from a distance requires supplying the material with the gravitational binding energy of the star, 6.87*1041 J for the sun. Doing this over an hour or so is a pretty impressive power, about 1.9*1038 W. This is about 486 billion times the solar luminosity. In fact, just beaming that power at a target using any part of the electromagnetic spectrum would fry just about anything.

Of course, a device that can suck up a star ought to be able to suck up planets a million times faster. So there is no real need to go for stars: just suck up the Republic. Since the base can suck up space fleets too, local defences are not much of a problem. Yes, you may have to go there with your base, but if the Death Star can move, the Starkiller can too. If nothing else, it could use its beam to propel itself.

If the First Order want me to consult on their next (undoubtedly even more ambitious) project I am open for offers. However, one iron-clad condition given recent history is that I get to work from home, as far away as possible from the superweapon. Ideally in a galaxy far, far away.