Some curves that start exponential are actual unimodal, in the long run. Some are oscillatory. Some are chaotic, some have undefined behaviour because the thing being plotted ceases to make sense.

Why do you think all of them are eventually S curves in particular?

There are ancient texts on this matter, such as

https://www.lesswrong.com/posts/34XxbRFe54FycoCDw/the-bottom-line

Short answer: once you know that you are listening to someone who wrote the bottom line first, then anything they wrote (or said) above the bottom line is worthless toward determining whether the bottom line is true.

It is still possible that they present information that is of some use in other respects, but only to the extent that it is not correlated with the truth or falsity of the bottom line.

Now, in some world it may be that if the bottom line were false, then fewer people would argue for it and such arguments would be less likely to appear on daytime television. That does not appear to be the world we live in.

But, I do think that we should prepare to have initiating the catpocalypse as a contingency.

I prefer the term "cataclysm". Though perhaps tiling the lightcone with some fraction of cats should be called a "catastrophe" given both the textual similarity and its intended meaning being related to some form of "cat-astrophysics".

My post is almost entirely about the enormous hidden assumptions in the word "finding" within your description "finding suitable trading partner in multiverse". The search space isn't just so large that you need galaxies full of computronium, because that's not even remotely close to enough. It's almost certainly not even within an order of magnitude of the number of orders of magnitude that it takes. It's not enough to just find one, because you need to average expected value over all of them to get any value at all.

The expected gains from every such trade are correspondingly small, even if you find some.

Just as a minor note (to other readers, mostly) decoherence doesn't really have "number of branches" in any physically real sense. It is an artifact of a person doing the modelling choosing to approximate a system that way. You do address this further down, though. On the whole, great post.

Acausal trades almost certainly don't work.

There are more possible agents than atom-femtoseconds in the universe (to put it mildly), so if you devote even one femtosecond of one atom to modelling the desires of any given acausal agent then you are massively over-representing that agent.

The best that is possible is some sort of averaged distribution, and even then it's only worth modelling agents capable of conducting acausal trade with you - but not you in particular. Just you in the sense of an enormously broad reference class in which you might be placed by agents like them.

Given even an extremely weak form of orthogonality thesis, the net contribution of your entire reference class will be as close to zero as makes no difference - not even enough to affect one atom (or some other insignificantly small equivalent in other physics). If orthogonality doesn't hold even slightly, then you already know that your desires are reflected in the other reference classes and acausal trade is irrelevant.

So the only case that is left is one in which you know that orthogonality almost completely fails, and there are only (say) 10^1 to 10^30 or so reasonably plausible sets of preferences for sufficiently intelligent agents instead of the more intuitively expected 10^10000000000000000000 or more. This is an extraordinarily specific set of circumstances! Then you need that ridiculously specific set to include a reasonably broad but not too broad set of preferences for acausal trade in particular, along with an almost certain expectation that they actually exist in any meaningful sense that matters for your own preferences and likewise that they consider your preference class to meaningfully exist for theirs.

Then, to the extent that you believe that all of these hold and that all of the agents that you consider to meaningfully exist outside your causal influence also hold these beliefs, you can start to consider what you would like to expect in their universes more than anything you could have done with those resources in your own. The answer will almost certainly be "nothing".

Then there's a HUGE hole in the scenario right where all the load-bearing assumptions are.

What sort of evidence convinced the person in the scenario that Christianity is actually with probability greater than 0.99 correct, and definitely less than 1% chance of every other scenario combined? How do you distinguish this from the whims of a powerful being who can read minds and do lots of other stuff, forcing people to accept that it is correct on pain of eternal death or torture? The only difference here from literal Christianity seems to be the idea that the powerful being is good and just in doing that, so what evidence made the person accept that?

I'm assuming that the powerful being can't (or won't) write minds as well, since being mind-probed into belief is not really that interesting.

Why do you believe that I believe that this is a scenario in which you are definitely not in a simulation? I do not.

I am saying that in general, FDT does not require that the agent must reason about whether they are in a simulation. In the published Bomb scenario in particular it is not stated whether the agent may be in a simulation, and it is also not stated whether the agent knows or believes that they may be in a simulation. In principle, all these combinations of cases must be considered separately.

Since the scenario does not make any statement in this respect, I do believe that it was not intended by the scenario author that the agent should reason as if they may be in a simulation. That would be just one of infinitely many unstated possibilities that might affect the analysis if they were considered, all of which would complicate and detract from the issue they intended to discuss.

So I do believe that the analysis described in the original scenario was carried out for an agent that does not consider whether or not they may be in a simulation, as distinct from them actually being definitely not in a simulation.

After all, the fact of the matter is that they are in a simulation. We are simulating what such an agent should do, and there is no "real" agent in this case.

Partly for the reasons outlined in my comment here. Mainly the following section:

Even under the most hardcore determinism and assuming immutable agents, they can be classified into those that would and those that wouldn't have performed that act and so there is definitely some sort of distinction to be made. 

In another comment (that I'm not finding after some minutes of search) I outline why this distinction is one that should be (and is) called moral culpability for all practical and most philosophical purposes. The few exceptions aren't relevant here, since even one counterexample renders the argument invalid.

It's a separate issue entirely. Scenarios in which you could be in a temporary simulation (especially in which the simulation outcome may be used to determine something for another instance of your decision process) are different and should be analysed differently from those in which you are definitely not.