When discussing the repugnanat conclusion, Eliezer commented:

I have advocated that "lives barely worth living" always be replaced with "lives barely worth celebrating" in every discussion of the 'Repugnant' Conclusion, to avoid equilibrating between "lives almost but not quite horrible enough to imply that a pre-existing person should commit suicide despite their intrinsic desire to live" versus "lives which we celebrate as good news upon learning about them, and hope to hear more such news in the future, but only to a very slight degree".

In a Big World, it's impossible to create anyone; all you can decide is where to allocate measure among experiences. My utilons for novelty are saturated by the size of reality, and that makes me an average utilitarian. As an average utilitarian, I do indeed accept that "mere addition", i.e., allocation of measure to experiences below-average for the global universe, is bad. If it were, unimaginably, to be demonstrated to me that Earth and its descendants were the only sentient beings in all of Tegmark levels I through IV, then I would embrace the actual creation of new experiences, and accept the Repugnant Conclusion without a qualm.

As I understand, a "Big World" is a world where every possible person exists in infinite copies. But how does this defeat total utilitarianism? These infinite copies of us exists too far away for us to interact with. If my actions cannot affect these people, why should I consider them when I face an ethical dilemma?