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I'm proposing no such thing. GP said that if they had built large structures then it was obvious they could do interstellar travel. I said that implication was

I'm proposing no such thing. GP said that if they had built large structures then it was obvious they could do interstellar travel. I said that implication was false, it's clear how we might build large orbital structures but not clear how we might to interstellar travel. As a counter example.

pfdietz 3y ago
The implication is as clearly true as such things could be. The barrier to interstellar travel is largely economic(*). The resources needed to construct star-spanning structures are many orders of magnitude greater than needed to construct and launch a starship (or a laser with an aperture capable of projecting a beam to interstellar distances). (*) https://galileo.phys.virginia.edu/classes/109.jvn.spring00/nuc_rocket/Dyson.pdf https://galileo.phys.virginia.edu/classes/109.jvn.spring00/n...
- jcranmer 3y ago
  One of the problems with this stuff is most of the problems are analyzed by physicists, who tend to reduce the problem to "can we make the physics work" rather than looking at more practical problems like "do we know if any materials will stand up to getting front-row seats to nuclear explosions?" and the other kinds of engineering problems that have bedeviled rocket science in its entire existence. And that's before getting into more fundamental issues like "what is the effect of space life on human biology?" (to which the answer appears to be somewhere between "maybe unmitigatably harmful" to "catastrophic"). There's a lot of questions that need to be answered before we can truly answer the question "what does it take to make interstellar travel", and the fact that many boosters for space exploration are glibly ignoring those questions is perhaps the biggest barrier of all.
  - Nevermark 3y ago
    We are getting close to fusion with magnetic containment. So at some point, regular materials won’t be a limit But materials are improving at a rapid pace. So many orders of scale to co-optimize meta materials. Materials in the future will be magic compared to the limits we have now. Materials won’t be a barrier to interstellar travel We are only decades away from being able to do it, for very low mass ships/probes with AI. Long before we will be able to create mega structures
    - jvanderbot 3y ago
      And my point mostly is proven here: We could build a giant space station with spaceX + more iron into space. We could build an interstellar probe in "Some point - we're getting close" or "future" or "a few decades".
      - pfdietz 3y ago
        Since this whole discussion has been about putative aliens with billions of times our production, not about what we ourselves can do soon, I'm not sure why you're harping on this.

pfdietz 3y ago

The implication is as clearly true as such things could be. The barrier to interstellar travel is largely economic(*). The resources needed to construct star-spanning structures are many orders of magnitude greater than needed to construct and launch a starship (or a laser with an aperture capable of projecting a beam to interstellar distances). (*) https://galileo.phys.virginia.edu/classes/109.jvn.spring00/nuc_rocket/Dyson.pdf https://galileo.phys.virginia.edu/classes/109.jvn.spring00/n...

jcranmer 3y ago
One of the problems with this stuff is most of the problems are analyzed by physicists, who tend to reduce the problem to "can we make the physics work" rather than looking at more practical problems like "do we know if any materials will stand up to getting front-row seats to nuclear explosions?" and the other kinds of engineering problems that have bedeviled rocket science in its entire existence. And that's before getting into more fundamental issues like "what is the effect of space life on human biology?" (to which the answer appears to be somewhere between "maybe unmitigatably harmful" to "catastrophic"). There's a lot of questions that need to be answered before we can truly answer the question "what does it take to make interstellar travel", and the fact that many boosters for space exploration are glibly ignoring those questions is perhaps the biggest barrier of all.
- Nevermark 3y ago
  We are getting close to fusion with magnetic containment. So at some point, regular materials won’t be a limit But materials are improving at a rapid pace. So many orders of scale to co-optimize meta materials. Materials in the future will be magic compared to the limits we have now. Materials won’t be a barrier to interstellar travel We are only decades away from being able to do it, for very low mass ships/probes with AI. Long before we will be able to create mega structures
  - jvanderbot 3y ago
    And my point mostly is proven here: We could build a giant space station with spaceX + more iron into space. We could build an interstellar probe in "Some point - we're getting close" or "future" or "a few decades".
    - pfdietz 3y ago
      Since this whole discussion has been about putative aliens with billions of times our production, not about what we ourselves can do soon, I'm not sure why you're harping on this.