From: lexfridman
Entanglement is a fundamental concept in the field of [[quantum_mechanics_and_its_implications | quantum mechanics]] that describes a peculiar and non-intuitive connection between quantum systems. This interconnection allows for the properties of one particle to be dependent on, or correlated with, the properties of another, no matter the distance between them. Unlike anything present in [[quantum_mechanics_and_consciousness | classical mechanics]], entanglement suggests that particles can exhibit correlations that defy classical explanations regardless of the spatial separation <a class="yt-timestamp" data-t="00:33:01">[00:33:01]</a>.
## Definition of Entanglement
To understand entanglement, consider two quantum particles such as electrons. In classical terms, each electron can be independently described in terms of its own position or velocity. However, in the quantum realm, each pair of entangled electrons is described by a single, inseparable [[complementarity_in_quantum_mechanics | wave function]]. This wave function provides the probability of observing the state of both electrons at once. The distinctive feature of quantum entanglement is this kind of correlation: we might not know what state we will find one electron upon observation, but once measured, the state of its partner is instantaneously determined as well, highlighting a conditional dependency unique to quantum states <a class="yt-timestamp" data-t="00:33:10">[00:33:10]</a>.
## Entanglement and Distance
A fascinating aspect of entanglement is its apparent independence from classical notions of space and distance. Entangled particles maintain their quantum correlation irrespective of the physical space separating them. There is no intrinsic relationship between the distance of separation and the level of their entanglement in the quantum domain <a class="yt-timestamp" data-t="00:34:07">[00:34:07]</a>.
However, newer understanding through [[the_intersection_of_quantum_mechanics_and_general_relativity | quantum fields]] complicates this picture. Even in a vacuum — which is just empty space filled with quantum fields — these fields are seen to vibrate and are themselves entwined with one another. The level of entanglement of these quantum fields is often strongest between those that are close together. This indicates that while entanglement itself might not be limited by distance, the intrinsic properties and interactions modeled through quantum fields do show spatial variability <a class="yt-timestamp" data-t="00:34:36">[00:34:36]</a>.
## Implications of Entanglement
The concept challenges classical intuition and has profound implications for our understanding of [[the_concept_of_a_theory_of_everything | the fundamental nature of reality]]. Entanglement raises questions about the [[concept_of_time | concept of time]] and space and might hold keys to understanding how deeper connections in the universe function and how [[the_intersection_of_quantum_mechanics_and_general_relativity | general relativity]] and quantum mechanics might ultimately be reconciled.
Entanglement is not only a theoretical construct but has real-world applications, notably in fields like quantum computing, cryptography, and potentially in advancing theories related to the [[interconnection_of_technology_belief_and_alien_intelligence | interconnection of technology and intelligence]].
> [!info] The Many-Worlds Interpretation
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> The Many-Worlds Interpretation provides a fascinating lens through which to view entanglement. In this framework, what appears as an instantaneous collapse of entangled states when observed can instead be thought of as a branching of worlds, with each result constituting a distinct and non-communicative branch of reality. Sean Carroll expands on this interpretation to explain that measurement and observation in quantum mechanics do not introduce fundamental changes but lead to simultaneous existence across multiple possible states in different worlds <a class="yt-timestamp" data-t="00:46:15">[00:46:15]</a>.