The furthest away parts of the theoretically reachable universe is 16-18 billion years away, so a 100 years delay is worth it if you can just increase the speed by 1⁄100 millionth of c
Why is there a tradeoff? Why don’t you launch your early comparatively technologically-unsophisticated probes as soon as you can, and then, if you develop faster probes, also launch those if you calculate that they could catch up to the ones that you already launched?
It’s not like the resources spent on early probes trade off appreciably with technological development.
There are a lot of stars and even galaxies in the affectable universe, so if you want to reach all of them quickly, being relatively judicious with your resources, especially your earliest resources, is key. There’s just massive opportunity cost in sending out early probes as opposed to spending relevant resources on compute/research, saving them up for future probes, etc.
I’m skeptical. I guess that cost of probes turns out to be negligible compared to the resources available (and possibly the cost of research will also turn out to be negligible—it remains unclear how fast an intelligence explosion shoots all the way up to technological maturity).
Checking with a BOTEC:
Probes will be nanotechnological, and so probably pretty tiny. The lower the mass the less energy it takes to accelerate them to near lightspeed. Let’s say each probe is the mass of a coke can. (This is probably a significant overestimate.)
Claude tells me that it takes 7.1 e17 J to accelerate that mass to 99.9% the speed of light, assuming unrealistic perfect efficiency. There are an extra 3 or so orders of magnitude for thermodynamic inefficiency. So let’s go up to 7.1 e20 J.
There are ~7 billion galaxies in the reachable universe.
Sending one probe to every galaxy would take 4 e30 J.
Claude also tells me that, in one day, earth’s sun outputs about 3.3 e31 J.
So we could send a probe to every galaxy in the reachable universe using a tenth of the energy of one day, after building a Dyson swarm.
...which is I guess not actually negligible, such that resource allocation question isn’t literally overdetermined.
Hmm I haven’t thought carefully about the numbers but I think the big thing you’re forgetting is the importance of deceleration (or “decel” as the cool kids are calling it).
Anders’ paper is called Eternity in 6 hours, assuming technological maturity and even then it’s at 25% of a day efficiency, despite assuming “only” 30g probes and also substantially slower (like .5c iirc).
no because for a probe you don’t have a reverse launcher on the receiving end, which means that to decelerate:
you can’t use some of the “long-launcher” technologies Claude was referring to, like a particle accelerator or a E-M railgun.
If you’re planning to decelerate via fuel, you need to ~square the single-burn mass ratio, thanks to the rocket equation. iiuc it gets a bit worse with relativity.
You might be able to decel without carrying deceleration fuel (eg with magsails), but this also adds weight to your payload.
I thought that there were mechanisms for using the same particle beam to decelerate as to accelerate?
Something like “You put a mirror that can be deployed at the front of your probe. When you want to start slowing down, you aim the beam at the mirror, and it bounces off and hits the probe, now adding thrust away from the direction of motion.”
Why would there be? Is the disagreement with Eternity in 6 hours that technological maturity would take a long time to reach? My best guess is it would take a few weeks at most when you are actually at the point of having nanomachines autonomously self-replicating into compute.
The material costs of marginal self-replicating probes assuming you are at the point of disassembling Mercury are extremely negligible. You can send hundreds of them to each solar system without breaking a sweat.
“You can send hundreds of them to each solar system without breaking a sweat.” Can you demonstrate this with a BOTEC? I don’t think it’s correct. Mercury has a weight of 10^23 kg, and there are ~10^22 stars in the reachable universe, so sending say a few hundred probes to each star is already burning a significant fraction of your mass, not to mention energy costs.
The speed of reaching technological maturity is evidence in favor of my point, not against it. The faster you can reach technological maturity, the lower the EV of sending probes early is and the better it is to wait until maturity.
Why is there a tradeoff? Why don’t you launch your early comparatively technologically-unsophisticated probes as soon as you can, and then, if you develop faster probes, also launch those if you calculate that they could catch up to the ones that you already launched?
It’s not like the resources spent on early probes trade off appreciably with technological development.
There are a lot of stars and even galaxies in the affectable universe, so if you want to reach all of them quickly, being relatively judicious with your resources, especially your earliest resources, is key. There’s just massive opportunity cost in sending out early probes as opposed to spending relevant resources on compute/research, saving them up for future probes, etc.
I’m skeptical. I guess that cost of probes turns out to be negligible compared to the resources available (and possibly the cost of research will also turn out to be negligible—it remains unclear how fast an intelligence explosion shoots all the way up to technological maturity).
Checking with a BOTEC:
Probes will be nanotechnological, and so probably pretty tiny. The lower the mass the less energy it takes to accelerate them to near lightspeed. Let’s say each probe is the mass of a coke can. (This is probably a significant overestimate.)
Claude tells me that it takes 7.1 e17 J to accelerate that mass to 99.9% the speed of light, assuming unrealistic perfect efficiency. There are an extra 3 or so orders of magnitude for thermodynamic inefficiency. So let’s go up to 7.1 e20 J.
There are ~7 billion galaxies in the reachable universe.
Sending one probe to every galaxy would take 4 e30 J.
Claude also tells me that, in one day, earth’s sun outputs about 3.3 e31 J.
So we could send a probe to every galaxy in the reachable universe using a tenth of the energy of one day, after building a Dyson swarm.
...which is I guess not actually negligible, such that resource allocation question isn’t literally overdetermined.
Hmm I haven’t thought carefully about the numbers but I think the big thing you’re forgetting is the importance of deceleration (or “decel” as the cool kids are calling it).
Anders’ paper is called Eternity in 6 hours, assuming technological maturity and even then it’s at 25% of a day efficiency, despite assuming “only” 30g probes and also substantially slower (like .5c iirc).
Isn’t decel just a difference of a factor of 2?
no because for a probe you don’t have a reverse launcher on the receiving end, which means that to decelerate:
you can’t use some of the “long-launcher” technologies Claude was referring to, like a particle accelerator or a E-M railgun.
If you’re planning to decelerate via fuel, you need to ~square the single-burn mass ratio, thanks to the rocket equation. iiuc it gets a bit worse with relativity.
You might be able to decel without carrying deceleration fuel (eg with magsails), but this also adds weight to your payload.
I thought that there were mechanisms for using the same particle beam to decelerate as to accelerate?
Something like “You put a mirror that can be deployed at the front of your probe. When you want to start slowing down, you aim the beam at the mirror, and it bounces off and hits the probe, now adding thrust away from the direction of motion.”
Why would there be? Is the disagreement with Eternity in 6 hours that technological maturity would take a long time to reach? My best guess is it would take a few weeks at most when you are actually at the point of having nanomachines autonomously self-replicating into compute.
The material costs of marginal self-replicating probes assuming you are at the point of disassembling Mercury are extremely negligible. You can send hundreds of them to each solar system without breaking a sweat.
“You can send hundreds of them to each solar system without breaking a sweat.”
Can you demonstrate this with a BOTEC? I don’t think it’s correct. Mercury has a weight of 10^23 kg, and there are ~10^22 stars in the reachable universe, so sending say a few hundred probes to each star is already burning a significant fraction of your mass, not to mention energy costs.
The speed of reaching technological maturity is evidence in favor of my point, not against it. The faster you can reach technological maturity, the lower the EV of sending probes early is and the better it is to wait until maturity.