This is my first post, so all criticism is welcome. I will assume that the reader already agrees with utilitarianism. I will argue that if existential threats are not able to have their risks minimized in any meaningful way(I do not believe there is a way to do so), that space accelerationism or "Spacism" as I will call it, is a viable candidate for the most effective way to be altruistic.
I will begin with a couple assumptions.
- Civilization will not end
- No currently physics-breaking science is discovered (faster than light space travel, infinite energy, or the like)
With there 2 conditions met, I would say it is safe to assume that humanity (or whatever takes our place) will colonize the galaxy and local group. Simply put, given enough time, Earth would have practically no reason to not launch a single von Neumann probe that would eventually settle the reachable universe for us.
I will now do some math to calculate a magnitude of souls that could exist on a cosmic scale. I will use very conservative estimates wherever applicable.
There are around 100 billion stars in the milky way alone, and over a trillion more stars will become within our reach after the Andromeda collides and the local group merges. I will round this down to a trillion.
We currently do not know how many planets the average star has, likely upwards of one, but I will use an estimate of 1 planet each. We also do not know the average size of a planet, so I will use our smallest planet (Mercury) for calculations. Most planets are not habitable, however that is largely irrelevant as a much more efficient use of the resources would be to convert them into habitats instead of living on the surface.
We currently do not have any real scientists calculating how many habitats an Mercury-sized planet could produce, so I used some volumetric calculations and obscenely inefficient resource usage. If we turned Mercury into O'Neil Cylinders 20km across with a 10km diameter interior (5km thick walls), we would have around 15x the surface area of earth to use.
Our final assumption is that Earth as it is now is our peak layout, and 15 earths worth of surface area can hold 15 times earth's current population.
Now let's multiply;
People per Earth Surface Area: 7500000000
Earth Surface Area Per Star: 15
Multiply this out, and you get 112,500,000,000,000,000,000,000 people who can live with our resources. If we can speed up the settling of every star by one second, we will have as many extra seconds of life as we have humans. Compacted into years, speeding up the start of galactic colonization by one second will reward us with 3,500,000,000,000,000 years of human life.
As I have mentioned, I have used very conservative estimates wherever I could, therefore the actual number is likely many orders of magnitude higher. Most planets we know of are much larger than Mercury. We will likely be able to create a habitat design that will require less than 7.5 km3 of material to build 1 km2 of living space. We will likely be able to layout living space more efficiently than Earth, which is mostly unusable water/desert/mountains. We may be able to modify humans to require less resources and have a higher moral weight. Not to mention that it may be possible to harvest matter from stars, and that future humans will use the extra time to prepare for the heat death of the universe(further increasing their time's utility). However adding a few more zeros is not likely to convince anyone else, it may as well be infinity.