Susskind Is Wrong About Many Worlds

Leonard Susskind's objections to the Many-Worlds interpretation regarding branch recombination and probability amplitudes have established answers that redefine 'branches' as emergent, causally autonomous entities, explaining how they differentiate without true splitting or recombination.

• Susskind's objections to Many-Worlds have established answers, re-conceptualizing branches.

• Branches are emergent properties; 'universes' only form when causally autonomous post-measurement.

• Interference shows interconnectedness, not recombination, before full differentiation.

Leonard Susskind raised two technical objections to the Many-Worlds interpretation: the recombination of quantum branches and the handling of irrational probability amplitudes like one-third or two-thirds. These issues have long-standing answers that clarify the nature of branches as emergent properties rather than fundamental divisions. The key lies in understanding that universes are only considered distinct when they become causally autonomous, typically after a measurement process, while interference phenomena demonstrate their interconnectedness before such a separation.

Susskind's Objections

• 00:00:06 Leonard Susskind, a fundamental physicist, questioned the Many-Worlds interpretation, citing two primary technical issues. First, he argued that quantum branches can recombine, challenging the notion of completely separate branches. Second, he questioned how the universe would split according to irrational probability amplitudes, such as one-third versus two-thirds, suggesting that the concept of splitting into discrete 'thirds' is problematic.

Emergence of Branches

• 00:05:06 Branches are understood as emergent properties, not fundamental components of the theory. In this view, there isn't a single world that splits into many; rather, there is always a continuum of possibilities within a single pure state. A 'universe' is only considered a distinct entity when it becomes causally autonomous, meaning its evolution is independent of other branches, a state typically achieved after a measurement.

Branch Recombination

• 00:06:52 The apparent recombination of branches, as seen in interference experiments, occurs precisely because the different parts of the quantum system are still interacting and are not yet causally autonomous. During interference, various components of a single photon, for example, affect each other, meaning they have not yet differentiated into distinct, independent universes. Therefore, one cannot speak of separate universes during this phase.

Differentiation Process

• 00:08:20 The process of branches forming is not a sudden 'split' but a gradual differentiation where one branch affects another less and less over time. When a measurement is made and information is copied, the interaction between branches diminishes to an infinitesimally small level. At this point, they can be considered distinct universes, as they are effectively causally separated, allowing for the emergence of separate realities without a literal, instantaneous division.