3 ms·

Sure, but are we sure these probes are instantaneous? What if it takes more than zero time to build a Dyson sphere? As I said earlier, you're only proving that

Sure, but are we sure these probes are instantaneous? What if it takes more than zero time to build a Dyson sphere? As I said earlier, you're only proving that they have been building spheres for less time than it takes to finish up the whole universe, which they say is big.

danieltillett 10y ago
The probe’s spread and and dyson sphere building does not need to be instantaneous, just that it had to have happened in the past. For example, if we were to create von Neumann probes and have them spread across the galaxy, it would take less than 100,000 years for the probes to reach every star. When you compare this to how long it took for our civilisation to evolve on Earth it is a blink of an eye. An interesting thought is if a new von Neumann spewing civilisation arose in the galaxy we would not have much warning before it reached us. The probes would be travelling just behind the light front and so would reach us only a little before the information that the stars between the probes origin and us went out. About the only way you could detect such an event is to look at very distant galaxies for examples that had spherical chunk taken out of them. I should get around to writing this all up in a blog post because it is such an interesting topic :)
- robbiep 10y ago
  There was a quote yesterday in HN (either here or through wiki) saying it would take 500,000 years for von Neumann probes to spread throughout the Galaxy. Not meaningfully different on cosmic timescales, but still. Also, your thought on the probes travelling behind the light front implies that they are going to be travelling at relativistic speeds. Is that realistic?
  - danieltillett 10y ago
    Yes they could be travelling just under the speed of light if the probes are very small and they are being accelerated by an energy source (say laser) at the origin.
    - robbiep 10y ago
      But then it needs to break away (and actually brake) at the next system, replicate at outrageous speeds, and fire a bunch more at a heap more stars
      - danieltillett 10y ago
        If they are sent as a swarm you could bounce the laser off one to slow a second. This way you would not need to transport fuel. Also since you are aiming at stars you could use a hub and spoke model which would speed up the takeover process since you could bypass the build stage for most stars.
        robbiep 10y ago
        Cool. Interesting. Thanks for your thoughts
- cgriswald 10y ago
  > About the only way you could detect such an event is to look at very distant galaxies for examples that had spherical chunk taken out of them. There have been actual studies searching for the waste heat of Dyson spheres[0]. You basically image an "empty" part of the sky in the visual spectrums and look for infrared waste. (The studies turned up nothing but were also limited in scope.) [0] - http://arxiv.org/abs/1408.1134 http://arxiv.org/abs/1408.1134
  - danieltillett 10y ago
    Yes I am aware of this study. From memory the temperature limit was 50K which no civilisation capable of building a Dyson Sphere would let leak out. Also the study was limited to our galaxy. The final issue is that if the von Neumann probes are moving at close to the speed of light we would not be able to detect these Dyson spheres anyway. It would be really interesting to do a survey of galaxies looking for these spherical chunks. It should be possible to just use existing data and some machine learning to scan for possible candidates. If anyone is interested in doing this with me my contact details are in my profile.

danieltillett 10y ago

The probe’s spread and and dyson sphere building does not need to be instantaneous, just that it had to have happened in the past. For example, if we were to create von Neumann probes and have them spread across the galaxy, it would take less than 100,000 years for the probes to reach every star. When you compare this to how long it took for our civilisation to evolve on Earth it is a blink of an eye. An interesting thought is if a new von Neumann spewing civilisation arose in the galaxy we would not have much warning before it reached us. The probes would be travelling just behind the light front and so would reach us only a little before the information that the stars between the probes origin and us went out. About the only way you could detect such an event is to look at very distant galaxies for examples that had spherical chunk taken out of them. I should get around to writing this all up in a blog post because it is such an interesting topic :)

robbiep 10y ago
There was a quote yesterday in HN (either here or through wiki) saying it would take 500,000 years for von Neumann probes to spread throughout the Galaxy. Not meaningfully different on cosmic timescales, but still. Also, your thought on the probes travelling behind the light front implies that they are going to be travelling at relativistic speeds. Is that realistic?
- danieltillett 10y ago
  Yes they could be travelling just under the speed of light if the probes are very small and they are being accelerated by an energy source (say laser) at the origin.
  - robbiep 10y ago
    But then it needs to break away (and actually brake) at the next system, replicate at outrageous speeds, and fire a bunch more at a heap more stars
    - danieltillett 10y ago
      If they are sent as a swarm you could bounce the laser off one to slow a second. This way you would not need to transport fuel. Also since you are aiming at stars you could use a hub and spoke model which would speed up the takeover process since you could bypass the build stage for most stars.
      - robbiep 10y ago
        Cool. Interesting. Thanks for your thoughts
cgriswald 10y ago
> About the only way you could detect such an event is to look at very distant galaxies for examples that had spherical chunk taken out of them. There have been actual studies searching for the waste heat of Dyson spheres[0]. You basically image an "empty" part of the sky in the visual spectrums and look for infrared waste. (The studies turned up nothing but were also limited in scope.) [0] - http://arxiv.org/abs/1408.1134 http://arxiv.org/abs/1408.1134
- danieltillett 10y ago
  Yes I am aware of this study. From memory the temperature limit was 50K which no civilisation capable of building a Dyson Sphere would let leak out. Also the study was limited to our galaxy. The final issue is that if the von Neumann probes are moving at close to the speed of light we would not be able to detect these Dyson spheres anyway. It would be really interesting to do a survey of galaxies looking for these spherical chunks. It should be possible to just use existing data and some machine learning to scan for possible candidates. If anyone is interested in doing this with me my contact details are in my profile.