&gt; The interpretation requires that the many worlds do not interact<p>...What? In MWI, interactions between &quot;worlds&quot; is the mechanism for all the quantum effects. If they never interacted, it&#x27;d give the wrong predictions.<p>Also, many proponents of MWI (e.g. Sean Carroll) don&#x27;t think of the theory in terms of worlds at all. It&#x27;s just a name that stuck. Really it&#x27;s just what you get when you infer the Born rule from the unitarity postulate instead of having the Born rule as an extra postulate.<p>An intuition pump for this idea is: you probably think photons passing the point of no return and escape our Hubble bubble continue to exist. But you&#x27;ll never ever see them again, even in principle! Wouldn&#x27;t a model that says they simply get deleted out of reality be <i>strictly simpler</i> in terms of number of entities and therefore be preferred? Assuming a rule that simply deletes parts of the wave function that decohere away from us (i.e. collapse) is pretty analogous to that ( See: <a href="http:&#x2F;&#x2F;lesswrong.com&#x2F;lw&#x2F;pb&#x2F;belief_in_the_implied_invisible&#x2F;" rel="nofollow">http:&#x2F;&#x2F;lesswrong.com&#x2F;lw&#x2F;pb&#x2F;belief_in_the_implied_invisible&#x2F;</a> ). Getting rid of the photon-deletion rule is analogous to accepting MWI (though I don&#x27;t mean to imply it&#x27;s the only game in town).