Urusan
@Azure While I haven't read Max Tegmark's book, I read the paper that led to it.
I don't think he was arguing that universes like ours are inherently more likely, just that they're more likely to be observed.
The basic premise of the Mathematical Universe Hypothesis is that all mathematical structures exist, so yeah, our specific type of universe make up an infinitesimal proportion of the total universes.
However, similar universes are much more likely to have observers.
Urusan
@Azure One last important note about this kind of reasoning: if there's evidence to the contrary then it has a strong effect against it.
I know that living in an affluent Western society is somewhat unusual because there's evidence to the contrary. A billionaire would know that most/all people aren't billionaires because there is ample evidence for this.
This kind of reasoning is most durable in situations where evidence to the contrary stubbornly refuses to show up.
Urusan
@Azure On top of that, a robust galactic civilization is unlikely to go extinct, so that makes early extinction or structurally low populations more likely than a late catastrophe.
Urusan
@Azure What is an issue is a galactic population of, say, 1e21 humans.
10 trillion humans is 1e13 humans, so it instantly breaks the bank and pushes the probabilities way into implausible (though, of course, not impossible) territory.
If these humans are living standard human lifespans, these already staggering numbers get even more staggering.
Urusan
@Azure When this is projected forward rather than backwards, it means that situations where, say, there are going to be 10 trillion humans are still reasonably likely.
Whether these 10 trillion humans live over 70,000-100,000 years with a consistent population of 10 billion or even vaster time periods with much smaller populations and/or longer lifespans doesn't really impact the analysis.
Urusan
@Azure Similarly, our chances of being alive now instead of during an earlier historical era are only around 5-10% (and being in an affluent Western society is on the order of 1%), but it's also true that the human population is surprisingly concentrated into the specific situation we find ourselves in.
Urusan
@Azure So, if red dwarf stars cannot give rise to life, then the probability that a random living observer on their species' homeworld will find themselves orbiting around a red dwarf is zero, even though they are by far the most common type of star.
Urusan
@Azure The erroneous "most people live in affluent Western societies" conclusion is related to the fact that all of this is a statistical argument rather than some sort of airtight deductive reasoning.
Sure, most people live outside of affluent Western societies, but a surprisingly high proportion do. It depends on how you measure it, but at least 1 billion people live in affluent Western societies, so at least 1-in-8 or 12.5%.
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