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Developing propulsion technology to reach 0.1c velocity will move the needle on interstellar propulsion from impossible to just barely feasible. Although that i

Developing propulsion technology to reach 0.1c velocity will move the needle on interstellar propulsion from impossible to just barely feasible. Although that is at least 100-200 years away, we can absolutely start expanding into our Solar System, starting with nearby bodies, like Moon and Mars.

JumpCrisscross 1y ago
> Developing propulsion technology to reach 0.1c velocity will move the needle on interstellar propulsion from impossible to just barely feasible More than barely. "A 40-year one-way interstellar flyby mission to the nearest stars will require a relativistic spacecraft speed in excess of 6000 AU/yr (i.e., > 0.1c)" [1]. That means, practically speaking, nuclear-fusion, antimatter-annihilation and directed-energy propulsion. All of which are TRL ≤ 2. My bet would be on fusion propulsion. It's inherently easier than fusion power since you don't need to bother converting the energy to electricity. That said, solar sails [2] and directed-energy anti-drone weapons [3] are seeing quiet progress. [1] https://ntrs.nasa.gov/api/citations/20200000759/downloads/20200000759.pdf https://ntrs.nasa.gov/api/citations/20200000759/downloads/20... [2] https://www.nasa.gov/mission/acs3/ https://www.nasa.gov/mission/acs3/ [3] https://en.wikipedia.org/wiki/Silent_Hunter_(laser_weapon) https://en.wikipedia.org/wiki/Silent_Hunter_(laser_weapon)
- carpdiem 1y ago
  1 AU is about 8.3 light minutes. So 6k AU is about 50k light minutes. with ~525k minutes in a year, that means that 6k AU/yr is almost exactly 0.1c.
  - JumpCrisscross 1y ago
    > that means that 6k AU/yr is almost exactly 0.1c Nobody debates this. The point is that 0.1c propulsion is not necessarily 100+ years away. And its 40-year transit time is not "barely feasible," it's comparable to present deep-space mission timelines [1]. [1] https://science.nasa.gov/mission/voyager/ https://science.nasa.gov/mission/voyager/
pfdietz 1y ago
However, travel at 0.1c is not needed for the Fermi Argument to bite. Much slower speeds would allow a colonization wave to sweep a galaxy in time << the age of the universe.
- thechao 1y ago
  Even at .0006c (our current tech), the galaxy would be filled with (weakly self propagating) robotic probes after just 750 million years. Unless extremely long lived self-propagating probes just ... die out ... that implies no aliens older than 750 million years from our galaxy. It implies no aliens from the nearby galactic neighborhood within 3 billion years. That kind of implies we're all alone. I have three wild-eyed theories: (1) eukaryotism is an unbelievably exotic step; (2) and/or the moon is required and ultrarare; or, (3) advanced civilizations eschew yellow stars for being inconveniently short-lived: maybe they prefer brown dwarfs, white dwarfs, or black holes for their energy gradient.
  - qiine 1y ago
    you want a funny one I am starting to like more and more ? We are simply the first.
  - nradov 1y ago
    Long-lived self-propagating probes are probably impossible. Even out in deep space, mechanisms eventually decay. Building in redundant systems or automated repairs doesn't allow you to cheat the inevitable increase of entropy in that closed system.

JumpCrisscross 1y ago

> Developing propulsion technology to reach 0.1c velocity will move the needle on interstellar propulsion from impossible to just barely feasible More than barely. "A 40-year one-way interstellar flyby mission to the nearest stars will require a relativistic spacecraft speed in excess of 6000 AU/yr (i.e., > 0.1c)" [1]. That means, practically speaking, nuclear-fusion, antimatter-annihilation and directed-energy propulsion. All of which are TRL ≤ 2. My bet would be on fusion propulsion. It's inherently easier than fusion power since you don't need to bother converting the energy to electricity. That said, solar sails [2] and directed-energy anti-drone weapons [3] are seeing quiet progress. [1] https://ntrs.nasa.gov/api/citations/20200000759/downloads/20200000759.pdf https://ntrs.nasa.gov/api/citations/20200000759/downloads/20... [2] https://www.nasa.gov/mission/acs3/ https://www.nasa.gov/mission/acs3/ [3] https://en.wikipedia.org/wiki/Silent_Hunter_(laser_weapon) https://en.wikipedia.org/wiki/Silent_Hunter_(laser_weapon)

carpdiem 1y ago
1 AU is about 8.3 light minutes. So 6k AU is about 50k light minutes. with ~525k minutes in a year, that means that 6k AU/yr is almost exactly 0.1c.
- JumpCrisscross 1y ago
  > that means that 6k AU/yr is almost exactly 0.1c Nobody debates this. The point is that 0.1c propulsion is not necessarily 100+ years away. And its 40-year transit time is not "barely feasible," it's comparable to present deep-space mission timelines [1]. [1] https://science.nasa.gov/mission/voyager/ https://science.nasa.gov/mission/voyager/

pfdietz 1y ago

However, travel at 0.1c is not needed for the Fermi Argument to bite. Much slower speeds would allow a colonization wave to sweep a galaxy in time << the age of the universe.

thechao 1y ago
Even at .0006c (our current tech), the galaxy would be filled with (weakly self propagating) robotic probes after just 750 million years. Unless extremely long lived self-propagating probes just ... die out ... that implies no aliens older than 750 million years from our galaxy. It implies no aliens from the nearby galactic neighborhood within 3 billion years. That kind of implies we're all alone. I have three wild-eyed theories: (1) eukaryotism is an unbelievably exotic step; (2) and/or the moon is required and ultrarare; or, (3) advanced civilizations eschew yellow stars for being inconveniently short-lived: maybe they prefer brown dwarfs, white dwarfs, or black holes for their energy gradient.
- qiine 1y ago
  you want a funny one I am starting to like more and more ? We are simply the first.
- nradov 1y ago
  Long-lived self-propagating probes are probably impossible. Even out in deep space, mechanisms eventually decay. Building in redundant systems or automated repairs doesn't allow you to cheat the inevitable increase of entropy in that closed system.