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That’s the exact opposite of the grabby alien’s hypothesis tho. The grabby aliens hypothesis says that we’re very much average but that life as a whole is still

That’s the exact opposite of the grabby alien’s hypothesis tho. The grabby aliens hypothesis says that we’re very much average but that life as a whole is still quite young in the universe.

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delichon 3y ago
The galaxy is around 100k light years across and 13 billion years old. For us to be among the first generation born within 10^5 years of each other after a gestation of 10^10 years, would make us special. Being among the first civilizations in the galaxy is less special than being the first civilization, but more special than being just another in an ongoing ecosystem.
- tshaddox 3y ago
  Why is being first, or being among the first, “special”? To me “special” is different than just “specific.” If some civilization knew it was the 50th advanced civilization in the universe, 50 might seem like a very special number, but is it really more special than 1?
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- Veserv 3y ago
  The hypothesis goes: I want humans to be casually interstellar and expand across the galaxy. I want this to occur in less than N years, N << 10^10. If humans are casually interstellar and expansionist, then we would colonize the galaxy in M years, M << 10^10. Humans are not special, therefore if another alien species existed in the past at current human tech levels, then they would do the same as humans would and colonize the galaxy within N + M << 10^10 years after achieving current human tech level. We believe we can detect such a civilization. Therefore, if we are more than N + M years after a another civilization with current human tech level, then we would see them. We do not detect any such civilizations. Therefore one of the assumptions must be wrong. 1. We can not detect a galactic civilization. 2. No alien civilization has reached current human tech level within N + M years of now. 3. Humans are special. Only humans would colonize the galaxy if they had casual interstellar travel. 4. Humans are not special, but we will never invent casual interstellar travel/spread to the stars. So, if you think humans are not special (3 is false) and you hope humans will spread to the stars in the future (hope 4 is false), then you hope the answer is 1 (humans are bad at detection) or 2 (humans are early). If you rule out 1 and 2, then 4 can only be true if 3 is true. If you rule out 3 as well, then you must conclude humanity will never spread to the stars for unknown reasons.
  - sevensevennine 3y ago
    I don't follow the last point in your argument. Isn't 4 equivalent to, 'no civilization will invent casual interstellar travel/spread to the stars'? And isn't that hypothesis extremely likely, given what we now know about the costs of _interplanetary_ travel and its relative ease compared to interstellar travel? That's another assumption, that it's _possible_ to colonize a galaxy from a planetary base. We don't even know that it's possible to colonize a nearby planet. If we were confident that we could, we'd be filling up Siberia, Ellesmere Island, and Greenland first. There's also another assumption missing from your list- that technological civilizations can last long enough to colonize the galaxy. I'm also surprised that there isn't any discussion on the site or here of Great Filters. If the average technological civilization wipes itself out within a few hundred years of developing technologies that enable space travel or even radio, then all discussion of "filling the galaxy" is castles in the air.
    - eschaton 3y ago
      It also could be that interstellar travel is possible but never inexpensive enough to be casual or useful for ever-expanding colonization. Or it could be that civilizations stabilize before the point where ever-expanding colonization becomes attractive. As an example of the latter, look at birth rates in different societies on Earth: Almost universally, they decline to replacement level once they hit a certain level of per-capita wealth. It’s very likely that a society that achieves interstellar travel will do so after it achieves the ability to provide the highest standard of living for all of its members indefinitely using just the resources of its local system. This already describes Earth; the reasons we don’t do this are ideological, not based on any inherent constraints, while interstellar travel isn’t in our grasp yet and is likely to be extraordinarily costly. Such a society wouldn’t face any pressure to grow, so any colonization would itself likely be ideological—“We don’t want to do things Surak’s way, let’s pull up stakes and find a world where we can live the way we want!”—or as a contingency/hedge against large-scale existential risk. Neither demand colonizing even a small fraction of a galaxy, assuming habitable worlds are even remotely plentiful near and reachable from the origin world.
    - Veserv 3y ago

That’s the exact opposite of the grabby alien’s hypothesis tho. The grabby aliens hypothesis says that we’re very much average but that life as a whole is still quite young in the universe.

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delichon 3y ago

The galaxy is around 100k light years across and 13 billion years old. For us to be among the first generation born within 10^5 years of each other after a gestation of 10^10 years, would make us special. Being among the first civilizations in the galaxy is less special than being the first civilization, but more special than being just another in an ongoing ecosystem.

tshaddox 3y ago
Why is being first, or being among the first, “special”? To me “special” is different than just “specific.” If some civilization knew it was the 50th advanced civilization in the universe, 50 might seem like a very special number, but is it really more special than 1?
- deleted 3y ago
  [deleted]
Veserv 3y ago
The hypothesis goes: I want humans to be casually interstellar and expand across the galaxy. I want this to occur in less than N years, N << 10^10. If humans are casually interstellar and expansionist, then we would colonize the galaxy in M years, M << 10^10. Humans are not special, therefore if another alien species existed in the past at current human tech levels, then they would do the same as humans would and colonize the galaxy within N + M << 10^10 years after achieving current human tech level. We believe we can detect such a civilization. Therefore, if we are more than N + M years after a another civilization with current human tech level, then we would see them. We do not detect any such civilizations. Therefore one of the assumptions must be wrong. 1. We can not detect a galactic civilization. 2. No alien civilization has reached current human tech level within N + M years of now. 3. Humans are special. Only humans would colonize the galaxy if they had casual interstellar travel. 4. Humans are not special, but we will never invent casual interstellar travel/spread to the stars. So, if you think humans are not special (3 is false) and you hope humans will spread to the stars in the future (hope 4 is false), then you hope the answer is 1 (humans are bad at detection) or 2 (humans are early). If you rule out 1 and 2, then 4 can only be true if 3 is true. If you rule out 3 as well, then you must conclude humanity will never spread to the stars for unknown reasons.
- sevensevennine 3y ago
  I don't follow the last point in your argument. Isn't 4 equivalent to, 'no civilization will invent casual interstellar travel/spread to the stars'? And isn't that hypothesis extremely likely, given what we now know about the costs of _interplanetary_ travel and its relative ease compared to interstellar travel? That's another assumption, that it's _possible_ to colonize a galaxy from a planetary base. We don't even know that it's possible to colonize a nearby planet. If we were confident that we could, we'd be filling up Siberia, Ellesmere Island, and Greenland first. There's also another assumption missing from your list- that technological civilizations can last long enough to colonize the galaxy. I'm also surprised that there isn't any discussion on the site or here of Great Filters. If the average technological civilization wipes itself out within a few hundred years of developing technologies that enable space travel or even radio, then all discussion of "filling the galaxy" is castles in the air.
  - eschaton 3y ago
    It also could be that interstellar travel is possible but never inexpensive enough to be casual or useful for ever-expanding colonization. Or it could be that civilizations stabilize before the point where ever-expanding colonization becomes attractive. As an example of the latter, look at birth rates in different societies on Earth: Almost universally, they decline to replacement level once they hit a certain level of per-capita wealth. It’s very likely that a society that achieves interstellar travel will do so after it achieves the ability to provide the highest standard of living for all of its members indefinitely using just the resources of its local system. This already describes Earth; the reasons we don’t do this are ideological, not based on any inherent constraints, while interstellar travel isn’t in our grasp yet and is likely to be extraordinarily costly. Such a society wouldn’t face any pressure to grow, so any colonization would itself likely be ideological—“We don’t want to do things Surak’s way, let’s pull up stakes and find a world where we can live the way we want!”—or as a contingency/hedge against large-scale existential risk. Neither demand colonizing even a small fraction of a galaxy, assuming habitable worlds are even remotely plentiful near and reachable from the origin world.
  - Veserv 3y ago