8 ms·

It's interesting that, under the given assumptions, you can put such tight bounds on the frequency of origination of grabby aliens. The assumption that seems m

by tlb 6y ago

It's interesting that, under the given assumptions, you can put such tight bounds on the frequency of origination of grabby aliens. The assumption that seems most unlikely is that civilizations will simply stop expanding when they encounter another one. Even if most civilizations would stop, a single aggressive one would quickly dominate. Especially under the assumption that they can expand at a large fraction of the speed of light, a defender would have little ability to organize a defense before being overrun.

philip142au 6y ago
There's going to be a lot of space wars
- DaiPlusPlus 6y ago
  Indeed, a very inefficient use of limited resources and energy in the known universe. How irrational.
  - nvet4 6y ago
    Calling war irrational is irrational.
    - Geezus_42 6y ago
      War is irrational...
      - pc86 6y ago
        If you have limited resourced (no money), but you do have military power, you can invade a neighbor with resources. If a neighbor invades you, you defend yourself. Neither of those positions is irrational, except maybe the first (maybe), but there's certainly scenarios where it would be your only choice.
        throwaway316943 6y ago
        It becomes irrational when you develop the capacity for mutually assured destruction.
        omginternets 6y ago
        MAD is grounded in game theory. It is designed to make the only winning move “don’t play”. It’s hyper-rational.
        DaiPlusPlus 6y ago
        MAD happened because of a (real, or perceived, I’m unsure myself...) risk of the Soviet Union invading Western Europe - and NATO ended up calculating that maintaining a nuclear deterrence was more affordable and more feasible than resisting a Warsaw Pact invasion using conventional forces. This assumes any kind of Soviet expansionism must be an absolute evil because the position is logically equivalent to “death is a preferable alternative to communism” (to steal a phrase from a video game...) which is patently absurd: it’s rational to prefer reduced standards of living over death, but credible deterrence requires drawing and maintaining a hard-line, even if that line is arbitrarily placed. ...given all of that is due to the risk of aggression from the Soviets, and I believe NATO may have disarmed themselves unilaterally if they didn’t see the SU/WP as a military threat (regardless of ideological threats) - what was making the SU so concerned about NATO military threats? Did the SU still have expansionist designs... or did they actually believe NATO still wanted to liberate/claim Poland long after the 1960s?
        omginternets 6y ago
        I respectfully insist: you are mistaken. MAD is a formal (i.e. mathematical) model. It is 100%, unequivocally rational. The problem is that this rational process leads to outcomes you and I dislike. These "bad outcomes" are value judgements. That is, MAD's outocmes don't align with our values. Therefore, the problem with mad (on which we agree!) is based in something extra-rational: values. Again: you and I agree there is a problem with MAD. Where you are wrong is that the problem is not "MAD is irrational". The problem is "MAD's logical conclusions run afoul of our values".
      - dukeofdoom 6y ago
        I read somewhere there's been something like 3000 wars in recorded human history. Seems like a pretty frequent thing. Thru out human history, raiding weaker neighbouring villages for resources, or access to females would be pretty rational behaviour for your villages growth and continuing success of your close genetic relatives. So much so that parts of Human Male's anatomy seems to be purposely driven for combat and survival. Things like larger muscles, thickness of skull, thickness of neck. Also, societies seem to come together and cooperate, hunker down, in war and conflict. Also seems to me to have some genetic component to that social behaviour. Only about 50% of men have reproduced through out human history. Raiding a neighbouring village, killing the man, and taking the best women for wives would be a rational though unethical behaviour. Its exactly what the Vikings did. In fact, there's a growing concern that large and growing percentage of men, currently unattractive to females (internet incels) will lead to radicalization and possibly conflict in the west. As those man try to better their odds of reproduction. Currently they are genetic rejects.
smoyer 6y ago
Your assumption sounds like it favors Star Wars over Star Trek (TOS).
ta202102 6y ago
The wording 'stop expanding' is confusing. Figure 1 makes it more clear: When two civilizations meet, expansion stops in this direction. In the free directions the civilizations still expand.
protoman3000 6y ago
I disagree. Countries and states exist.
throwaway316943 6y ago
What does a war between two interstellar civilizations look like? If they can accelerate mass to a high fraction of the speed of light doesn’t that mean their first strike weapons are all planet killers? If we assume they still primarily use planets as the sites of their industrial and population centres then doesn’t that mean any systems within striking distance are immediately obliterated by large, dark, unstoppable projectiles travelling at 0.7c? Any point defence you can think of fails when you can easily throw millions of these at a planet. There’s no way to win that game for either side. If we change our assumptions about whether they live on or even care about planets it becomes a very different story. Who knows if they even need the free energy that stars emit. Most of the interstellar medium is ionized so it may be that it’s much easier to just scoop up gas and dust with magnetic fields than it is to attempt to extract large quantities of matter from planets that are few and far between not to mention gravitationally bound.
- smichel17 6y ago
  Perhaps the winning move, like with today's nuclear weaponry, simply not to play.
  - goatlover 6y ago
    Or to hide in the Dark Forest instead of announcing yourself to the cosmos.
    - generalizations 6y ago
      This does seem to be the logical conclusion of a game theory analysis. Since planet killers can show up without any warning, the only solution is make it impossible to aim your unstoppable weapons, which means you have to be impossible to detect or locate. So as you said, maybe the solution to the Fermi Paradox is that every surviving civilization is hiding in cloaked habitats within the vastness of intergalactic space.
      - jerf 6y ago
zamfi 6y ago
> Even if most civilizations would stop, a single aggressive one would quickly dominate. Would this affect their model, though? If either of the two civilizations dominates, rather than both being obliterated through mutual destruction, you would expect to see the same thing: that volume of space time is now occupied by a civilization. I’m not sure it matters which one (to their model, of course it would presumably matter to the inhabitants) — and either would be visible and have the effect described in the paper.
- codeflo 6y ago
  That was my read as well, it doesn’t make a difference in terms of the total volume occupied by these “grabby” civs. Also, one civilization dominating wouldn’t mean that the other one would magically disappear. As a simple assumption, I can imagine the stronger civ expanding into the territory of the weaker one relatively unhindered (in terms of expansion speed). But the weaker civ would still expand outwards as well. If it’s expansion speed isn’t slower, it would continue to grow in absolute size.
- MattRix 6y ago
  Yep, this was my understanding too. It doesn’t change the fact that the area in space and time is now occupied by grabby aliens. The model and diagrams could easily be modified to use some heuristic like allowing older civilizations to take over younger ones when they collide, but it wouldn’t really matter for the purposes of the argument.
PaulHoule 6y ago
How could they stop? If a civilization is spread out in a 10000 light year area and encounters another in one place it seems impossible they could make a collective decision given the amount of communication that it would take.
- bryanrasmussen 6y ago
  If that's the case they wouldn't be able to collectively decide to keep expanding either, the decision would have to be made by the parts of the civilization that came in contact with the other civilization. This implies a lot of things though - let us say we expand to Mars and manage to terraform it somehow - after a few hundred years though Mars has enough of a population that they end up needing new resources (obviously we need some story as to how they expand this quickly, I blame genetic engineering and Hoxar Matos the dictator-general of Mars who commands a billion test tube babies be born and raised by robots in the underground Martian nursery creches). The model for grabby aliens is that Mars must find somewhere else to expand as they are part of the human civilization - but given human civilization it seems more like splitting the civilization and infighting to get more resources would be the most likely outcome.
sandworm101 6y ago
As likely is that two grabby expanding civilizations make be so different that thier volumes intercept without conflict. If one only likes warm rocky planets, and the other doesnt bother with solar systems, they might not even see each other as they pass. The "grabbed" volumes would then overlap, mooting this model. Contact would then not be a function or time and speed rather a matter of curiosity and willingness to explore non-desireable parts of one's grabbed space.
- barry-cotter 6y ago
  > As likely is that two grabby expanding civilizations make be so different that thier volumes intercept without conflict. Every volume contains only a certain amount of potential free energy that can be used before the end. That’s what you fight over. Dyson Spheres, fusion, antimatter, these are all details. Everybody wants negentropy and it’s a zero sum game.
throwanem 6y ago
> It's interesting that, under the given assumptions, you can put such tight bounds on... Is it, though? Grant me whatever assumptions I like and I can put tight bounds on anything - as long as it's unfalsifiable, at least.

by tlb 6y ago

philip142au 6y ago

There's going to be a lot of space wars

DaiPlusPlus 6y ago
Indeed, a very inefficient use of limited resources and energy in the known universe. How irrational.
- nvet4 6y ago
  Calling war irrational is irrational.
  - Geezus_42 6y ago
    War is irrational...
    - pc86 6y ago
      If you have limited resourced (no money), but you do have military power, you can invade a neighbor with resources. If a neighbor invades you, you defend yourself. Neither of those positions is irrational, except maybe the first (maybe), but there's certainly scenarios where it would be your only choice.
      - throwaway316943 6y ago
        It becomes irrational when you develop the capacity for mutually assured destruction.
        omginternets 6y ago
        MAD is grounded in game theory. It is designed to make the only winning move “don’t play”. It’s hyper-rational.
        DaiPlusPlus 6y ago
        MAD happened because of a (real, or perceived, I’m unsure myself...) risk of the Soviet Union invading Western Europe - and NATO ended up calculating that maintaining a nuclear deterrence was more affordable and more feasible than resisting a Warsaw Pact invasion using conventional forces. This assumes any kind of Soviet expansionism must be an absolute evil because the position is logically equivalent to “death is a preferable alternative to communism” (to steal a phrase from a video game...) which is patently absurd: it’s rational to prefer reduced standards of living over death, but credible deterrence requires drawing and maintaining a hard-line, even if that line is arbitrarily placed. ...given all of that is due to the risk of aggression from the Soviets, and I believe NATO may have disarmed themselves unilaterally if they didn’t see the SU/WP as a military threat (regardless of ideological threats) - what was making the SU so concerned about NATO military threats? Did the SU still have expansionist designs... or did they actually believe NATO still wanted to liberate/claim Poland long after the 1960s?
        omginternets 6y ago
        I respectfully insist: you are mistaken. MAD is a formal (i.e. mathematical) model. It is 100%, unequivocally rational. The problem is that this rational process leads to outcomes you and I dislike. These "bad outcomes" are value judgements. That is, MAD's outocmes don't align with our values. Therefore, the problem with mad (on which we agree!) is based in something extra-rational: values. Again: you and I agree there is a problem with MAD. Where you are wrong is that the problem is not "MAD is irrational". The problem is "MAD's logical conclusions run afoul of our values".
    - dukeofdoom 6y ago
      I read somewhere there's been something like 3000 wars in recorded human history. Seems like a pretty frequent thing. Thru out human history, raiding weaker neighbouring villages for resources, or access to females would be pretty rational behaviour for your villages growth and continuing success of your close genetic relatives. So much so that parts of Human Male's anatomy seems to be purposely driven for combat and survival. Things like larger muscles, thickness of skull, thickness of neck. Also, societies seem to come together and cooperate, hunker down, in war and conflict. Also seems to me to have some genetic component to that social behaviour. Only about 50% of men have reproduced through out human history. Raiding a neighbouring village, killing the man, and taking the best women for wives would be a rational though unethical behaviour. Its exactly what the Vikings did. In fact, there's a growing concern that large and growing percentage of men, currently unattractive to females (internet incels) will lead to radicalization and possibly conflict in the west. As those man try to better their odds of reproduction. Currently they are genetic rejects.

smoyer 6y ago

Your assumption sounds like it favors Star Wars over Star Trek (TOS).

ta202102 6y ago

The wording 'stop expanding' is confusing. Figure 1 makes it more clear: When two civilizations meet, expansion stops in this direction. In the free directions the civilizations still expand.

protoman3000 6y ago

I disagree. Countries and states exist.

throwaway316943 6y ago

What does a war between two interstellar civilizations look like? If they can accelerate mass to a high fraction of the speed of light doesn’t that mean their first strike weapons are all planet killers? If we assume they still primarily use planets as the sites of their industrial and population centres then doesn’t that mean any systems within striking distance are immediately obliterated by large, dark, unstoppable projectiles travelling at 0.7c? Any point defence you can think of fails when you can easily throw millions of these at a planet. There’s no way to win that game for either side. If we change our assumptions about whether they live on or even care about planets it becomes a very different story. Who knows if they even need the free energy that stars emit. Most of the interstellar medium is ionized so it may be that it’s much easier to just scoop up gas and dust with magnetic fields than it is to attempt to extract large quantities of matter from planets that are few and far between not to mention gravitationally bound.

smichel17 6y ago
Perhaps the winning move, like with today's nuclear weaponry, simply not to play.
- goatlover 6y ago
  Or to hide in the Dark Forest instead of announcing yourself to the cosmos.
  - generalizations 6y ago
    This does seem to be the logical conclusion of a game theory analysis. Since planet killers can show up without any warning, the only solution is make it impossible to aim your unstoppable weapons, which means you have to be impossible to detect or locate. So as you said, maybe the solution to the Fermi Paradox is that every surviving civilization is hiding in cloaked habitats within the vastness of intergalactic space.
    - jerf 6y ago

zamfi 6y ago

> Even if most civilizations would stop, a single aggressive one would quickly dominate. Would this affect their model, though? If either of the two civilizations dominates, rather than both being obliterated through mutual destruction, you would expect to see the same thing: that volume of space time is now occupied by a civilization. I’m not sure it matters which one (to their model, of course it would presumably matter to the inhabitants) — and either would be visible and have the effect described in the paper.

codeflo 6y ago
That was my read as well, it doesn’t make a difference in terms of the total volume occupied by these “grabby” civs. Also, one civilization dominating wouldn’t mean that the other one would magically disappear. As a simple assumption, I can imagine the stronger civ expanding into the territory of the weaker one relatively unhindered (in terms of expansion speed). But the weaker civ would still expand outwards as well. If it’s expansion speed isn’t slower, it would continue to grow in absolute size.
MattRix 6y ago
Yep, this was my understanding too. It doesn’t change the fact that the area in space and time is now occupied by grabby aliens. The model and diagrams could easily be modified to use some heuristic like allowing older civilizations to take over younger ones when they collide, but it wouldn’t really matter for the purposes of the argument.

PaulHoule 6y ago

How could they stop? If a civilization is spread out in a 10000 light year area and encounters another in one place it seems impossible they could make a collective decision given the amount of communication that it would take.

bryanrasmussen 6y ago
If that's the case they wouldn't be able to collectively decide to keep expanding either, the decision would have to be made by the parts of the civilization that came in contact with the other civilization. This implies a lot of things though - let us say we expand to Mars and manage to terraform it somehow - after a few hundred years though Mars has enough of a population that they end up needing new resources (obviously we need some story as to how they expand this quickly, I blame genetic engineering and Hoxar Matos the dictator-general of Mars who commands a billion test tube babies be born and raised by robots in the underground Martian nursery creches). The model for grabby aliens is that Mars must find somewhere else to expand as they are part of the human civilization - but given human civilization it seems more like splitting the civilization and infighting to get more resources would be the most likely outcome.

sandworm101 6y ago

As likely is that two grabby expanding civilizations make be so different that thier volumes intercept without conflict. If one only likes warm rocky planets, and the other doesnt bother with solar systems, they might not even see each other as they pass. The "grabbed" volumes would then overlap, mooting this model. Contact would then not be a function or time and speed rather a matter of curiosity and willingness to explore non-desireable parts of one's grabbed space.

barry-cotter 6y ago
> As likely is that two grabby expanding civilizations make be so different that thier volumes intercept without conflict. Every volume contains only a certain amount of potential free energy that can be used before the end. That’s what you fight over. Dyson Spheres, fusion, antimatter, these are all details. Everybody wants negentropy and it’s a zero sum game.

throwanem 6y ago

> It's interesting that, under the given assumptions, you can put such tight bounds on... Is it, though? Grant me whatever assumptions I like and I can put tight bounds on anything - as long as it's unfalsifiable, at least.