Quantum Physics

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When physicists are asked about “parallel worlds” or ideas along those lines, they have to be careful to distinguish among different interpretations of that idea. There is the “multiverse” of inflationary cosmology, the “many worlds” or “branches of the wave function” of quantum mechanics, and “parallel branes” of string theory. Increasingly, however, people are wondering whether the first two concepts might actually represent the same underlying idea. Are Many Worlds and the Multiverse the Same Idea? | Cosmic Variance Are Many Worlds and the Multiverse the Same Idea? | Cosmic Variance
Experiment
Experiment - Multimedia
How Cosmic Inflation Creates an Infinity of Universes [Video]
arovas_Stern_2007
In physics, the world line of an object is the unique path of that object as it travels through 4-dimensional spacetime. The concept of "world line" is distinguished from the concept of "orbit" or "trajectory" (such as an orbit in space or a trajectory of a truck on a road map) by the time dimension, and typically encompasses a large area of spacetime wherein perceptually straight paths are recalculated to show their (relatively) more absolute position states — to reveal the nature of special relativity or gravitational interactions. The idea of world lines originates in physics and was pioneered by Hermann Minkowski. The term is now most often used in relativity theories (i.e., special relativity and general relativity). However, world lines are a general way of representing the course of events. The use of it is not bound to any specific theory. World line World line
Diffraction of water waves (opening)
<em>From Eternity to Here:</em> Book Club | Cosmic Variance
From Eternity to Book Club: Chapter Eleven | Cosmic Variance From Eternity to Book Club: Chapter Eleven | Cosmic Variance Welcome to this week’s installment of the From Eternity to Here book club. Part Three of the book concludes with Chapter Eleven, “Quantum Time.” Excerpt: This distinction between “incomplete knowledge” and “intrinsic quantum indeterminacy” is worth dwelling on.
with probability p1, or it may be found in state with probability p2, or it may be found in state with probability p3, and so on.

Density matrix

Density matrix
Einselection Einselection In quantum mechanics, einselection, short for environment - induced superselection, is a name coined by Wojciech H. Zurek[1] for a process which explains the phenomenon of wavefunction collapse and the emergence of classical descriptions of reality from quantum descriptions. Classicality is an emergent property induced in open quantum systems by their environments. Due to the interaction with the environment, the vast majority of states in the Hilbert space of a quantum open system become highly unstable to entangling interaction with the environment, which in effect monitors selected observables of the system.
Welcome to this week’s installment of the From Eternity to Here book club. Part Four opens with Chapter Twelve, “Black Holes: The Ends of Time.” Excerpt: Unlike boxes full of atoms, we can’t make black holes with the same size but different masses. The size of a black hole is characterized by the “Schwarzschild radius,” which is precisely proportional to its mass. From Eternity to Book Club: Chapter Twelve | Cosmic Variance From Eternity to Book Club: Chapter Twelve | Cosmic Variance