I was a bit surprised by this... if your possible models only include one light-cone (essentially just the observable universe) then they don't look too different from those of my stated hypothesis (at the start of the thread).
My disagreement is that the anthropic reasoning you use is not a good argument for non-existence of large civilizations.
How likely are these alternatives? ...
I am using a future light cone whereas your alternatives seem to be formulated in terms of a past light cone. Let me say that I think the probability to ever encounter another civilization is related to the ratio {asymptotic value of Hubble time} / {time since appearance of civilizations became possible}. I can't find the numbers this second, but my feeling is such an occurrence is far from certain.
Here's how it works...
Very good point! I think that if the "computronium universe" is not suppressed by some huge factor due to some sort of physical limit / great filter, then there is a significant probability such a universe arises from post-human civilization (e.g. due to FAI). All decisions with possible (even small) impact on the likelihood of and/or the properties of this future get a huge utility boost. Therefore I think decisions with long term impact should be made as if we are not in a simulation whereas decisions which involve purely short term optimizations should be made as if we are in a simulation (although I find it hard to imagine such a decision in which it is important whether we are in a simulation).
Another issue you might have concerns the time-discounting...
The effective time discount function is of rather slow decay because the sum over universes includes time translated versions of the same universe. As a result, the effective discount falls off as 2^{-Kolmogorov complexity of t} which is only slightly faster than 1/t. Nevertheless, for huge time differences your argument is correct. This is actually a good thing, since otherwise your decisions would be dominated by the Boltzmann brains appearing far after heat death.
As a result, the effective discount falls off as 2^{-Kolmogorov complexity of t} which is only slightly faster than 1/t.
It is about 1/t x 1/log t x 1/log log t etc. for most values of t (taking base 2 logarithms). There are exceptions for very regular values of t.
Incidentally, I've been thinking about a similar weighting approach towards anthropic reasoning, and it seems to avoid a strong form of the Doomsday Argument (one where we bet heavily against our civilisation expanding). Imagine listing all the observers (or observer moments) in order of appea...
The 'Irrationality Game' posts in discussion came before my time here, but I had a very good time reading the bits written in the comments section. I also had a number of thoughts I would've liked to post and get feedback on, but I knew that being buried in such old threads not much would come of it. So I asked around and feedback from people has suggested that they would be open to a reboot!
I hereby again quote the original rules:
I would suggest placing *related* propositions in the same comment, but wildly different ones might deserve separate comments for keeping threads separate.
Make sure you put "Irrationality Game" as the first two words of a post containing a proposition to be voted upon in the game's format.
Here we go!
EDIT: It was pointed out in the meta-thread below that this could be done with polls rather than karma so as to discourage playing-to-win and getting around the hiding of downvoted comments. If anyone resurrects this game in the future, please do so under that system If you wish to test a poll format in this thread feel free to do so, but continue voting as normal for those that are not in poll format.