Challenge accepted.

https://i.imgsafe.org/914f428.png

suppose that we (or Omega, since we're going to assume nigh omniscience) asked the person whether JFK was murdered by Lee Harvey Oswald or not, and if they get it wrong, then they are killed/tortured/dust-specked into oblivion/whatever.

Okay, but what is the utility function Omega is trying to optimize?

Let's say you walk up to Omega, tell it "was JFK murdered by Lee Harvey Oswald or not? And by the way, if you get this wrong, I am going to kill you/torture you/dust-spec you."

Unless we've figured out how to build safe oracles, with very high probability, Omega is not a safe oracle. Via https://arbital.com/p/instrumental_convergence/, even though Omega may or may not care if it gets tortured/dust-speced, we can assume it doesn't want to get killed. So what is it going to do?

Do you think it's going to tell you what it thinks is the true answer? Or do you think it's going to tell you the answer that will minimize the risk of it getting killed?

I can think of many situations where a zero prior gives rise to tangibly different behavior, and even severe consequences. To take your example, suppose that we (or Omega, since we're going to assume nigh omniscience) asked the person whether JFK was murdered by Lee Harvey Oswald or not, and if they get it wrong, then they are killed/tortured/dust-specked into oblivion/whatever. (let's also assume that the question is clearly defined enough that the person can't play with definitions and just say that God is in everyone and God killed JFK)

However, let me steelman this a bit by somewhat moving the goalposts: if we allow a single random belief to have P=0, then it seems very unlikely that it will have a serious effect. I guess that the above scenario would require that we know that the person has P=0 about something (or have Omega exist), which, if we agree that such a belief will not have much empirical effect, is almost impossible to know. So that's also unlikely.

Oh, yes, good old potential UFAI #261: let the AI learn proper human values from the internet.

The point here being, it seems obvious to me that the vast majority of possible intelligent agents are unfriendly, and that it doesn't really matter what we might learn from specific error cases. In order words, we need to deliberately look into what makes an AI friendly, not what makes it unfriendly.

In Soviet Union a woman survived mid-air frontal planes collision - her chair rotated together with part of the wing and failed into a forrest.

But the main idea here is that the same "me" may exist in different worlds - in one I am in a plane in the other I am in plane simulator. I will survive in the second one.