In 1956 Hugh Everett III published his Ph.D. dissertation titled “The Theory of the Universal Wave Function.” In this paper Everett argued for the relative state formulation of quantum theory and a quantum philosophy, which denied wave collapse. Initially, this interpretation was highly criticized by the physics community, and when Everett visited Niels Bohr in Copenhagen in 1959 Bohr was unimpressed with Everett’s most recent development [1]. In 1957 Everett coined his theory as the Many Worlds Interpretation (MWI) of quantum mechanics. In an attempt to circumvent the problem of defining the mechanism for the state of collapse Everett suggested that all orthogonal relative states are equally valid ontologically. An orthogonal state is one that is mutually exclusive. A system cannot be in two orthogonal states at the same time. As a result of the measurement interaction, the states of the observer have evolved into exclusive states precisely linked to the results of the measurement. At the end of the measurement process the state of the observer is the sum of eigenstate—or a combination of the sums of eigenstates, one sum for each possible value of the eigenvalue. Each sum is the relative state of the observer given the value of the eigenvalue [2]. What this means is that all-possible states are true and exist simultaneously.
Hugh Everett and the Many Worlds Interpretation
Karl Popper on the Many Worlds Interpretation
In a brief section of Karl Popper’s Quantum Theory and the Schism in Physics[1] he discusses his attraction to the Many Worlds Interpretation of quantum physics as well as the reason for his rejection of it. Popper is actually quite pleased with Everett’s three-fold contribution to the field of quantum physics. Despite his attraction to the interpretation he rejects it based on the falsifiability of the symmetry behind the Schrödinger equation.
Popper’s model allows for a theory to be scientific prior to supported evidence. There is no positive case for purporting a theory under his model. There can only be a negative case to falsify it and as long as it may be potentially falsified it is scientific. Thus, a scientific theory could have no evidence or substantiated facts to provide good reasons for why it may be true. What makes this discussion of MWI interesting is that despite Popper’s attraction to MWI it’s not the attraction that makes it scientific, it’s his criterion of falsification.
In favor of MWI:
- The MWI is completely objective in its discussion of quantum mechanics.
- Everett removes the need and occasion to distinguish between ‘classical’ physical systems, like the measurement apparatus, and quantum mechanical systems, like elementary particles. All systems are quantum (including the universe as a whole).
- Everett shows that the collapse of the state vector, something originally thought to be outside of Schrödinger’s theory, can be shown to arise within the universal [Schrödinger] wave function.
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“The Heisenberg Uncertainty Principle was Never Quite Right”
Pioneering experiments have cast doubt on a founding idea of the branch of physics called quantum mechanics.
The Heisenberg uncertainty principle is in part an embodiment of the idea that in the quantum world, the mere act of observing an event changes it.
But the idea had never been put to the test, and a team writing in Physical Review Letters says “weak measurements” prove the rule was never quite right.
That could play havoc with “uncrackable codes” of quantum cryptography.
Quantum mechanics has since its very inception raised a great many philosophical and metaphysical debates about the nature of nature itself.
The experiment requires preparing pairs of “entangled” photons, the particles from which light is made (BBC)
Hugh Everett’s Dissertation: “The Many Worlds Interpretation of Quantum Mechanics”
In 1956 Hugh Everett III published his Ph.D. dissertation titled “The Theory of the Universal Wave Function.” In this paper Everett argued for the relative state formulation of quantum theory and a quantum philosophy, which denied wave collapse. Initially, this interpretation was highly criticized by the physics community and when Everett visited Niels Bohr in Copenhagen in 1959. Bohr was unimpressed with Everett’s most recent development.[1]
In 1957 Everett coined his theory as the Many Worlds Interpretation of quantum mechanics. In an attempt to circumvent the problem of defining the mechanism for the state of collapse, Everett suggested that all orthogonal relative states are equally valid ontologically.[2] What this means is that all possible states are true and exist simultaneously.
We have a problem of using secondary sources. I’ve provided a link below that takes you back to Everett’s original dissertation to read for ourselves.
Why Many Worlds Cannot be Dismissed due to a Lack of Experiencing Other Worlds
The level three multiverse is particular to a certain interpretation of quantum mechanics being Hugh Everett’s Many Worlds Interpretation. It is a mathematically simple model in support of unitary physics. Everything that can happen in the particle realm actually does happen. Each of the many worlds following a split represents one of the possible worlds remaining after the event which led to the split. There are no interactions between these worlds. No observer or inhabitant of them will notice anything about the other worlds.
Everett’s interpretation is not impossible due to the fact that we do not experience the continual splitting of our world. Observers would only view their level one multiverse, but the process of decoherence—which mimics wave function collapse while preserving unitary physics—prevents them from seeing the level three parallel copies of themselves.[1] It is no more contradicted by our failure to experience the splitting than the theory that the earth rotates is contradicted by our failure to experience its movement. [2]
[1] Max Tegmark, “The Multiverse Hierarchy,” arXiv:0905.1283v1 (accessed March 15, 2011), 10.
[2] Some of the commentary is summarized by Karl Popper in Quantum Theory and the Schism in Physics, ed. W.W. Bartley, III (Totowa, NJ: Rowman and Littlefield, 1982): 91-2.
Word of the Week Wednesday: String Theory
Word of the Week: String Theory
Definition: The leading theory of everything, which describes the earliest moments of the universe in which the four fundamental forces of nature (gravity, electromagnetic, strong nuclear, and weak nuclear) were one force. The most fundamental element of reality are cosmic strings, and their vibration determines what particles or forms it takes.
More about the term: The spontaneous breakdown of symmetries[1] in the early universe can produce linear discontinuities in fields, known as cosmic strings. Cosmic strings are also common in modern string theories in which the most fundamental reality are astronomically tiny vibrating strings (either closed or open depending on the interpretation of the mathematics).[2] The combination of the string/scalar landscape with eternal inflation has in turn led to a markedly increased interest in anthropic reasoning. In this multiverse scenario life will evolve only in very rare regions where the local laws of physics just happen to have the properties needed for life, giving a simple explanation for why the observed universe appears to permit the evolutionary conditions for life. It is argued that such anthropic reasoning can give the illusion of intelligent design without the need for any intelligent intervention.[3] There are at least four ways we can understand the different universes described by string landscape.[4]
Word of the Week Wednesday: Decoherence
Word of the Week: Decoherence
Definition: A loss of coherence between the angles of components in a superposition and a loss of information due to environment, which gives the appearance of a wave function collapse.
More about the term: A wave function collapse occurs when the outcome of a quantum state is determined by an observer. An observer can be a concious observer or even the interaction of particles. Instead of a determinate state, decoherence is akin to pulling one string out from an entire knot of strings. Decoherence is a major talking point and factor in multiverse scenarios.
In 1956 Hugh Everett III published his Ph.D. dissertation titled “The Theory of the Universal Wave Function.” In this paper Everett argued for the relative state formulation of quantum theory and a quantum philosophy, which denied wave collapse. Initially, this interpretation was highly criticized by the physics community and when Everett visited Niels Bohr in Copenhagen in 1959 Bohr was unimpressed with Everett’s most recent development.[1]
Quantum Tunneling in Action
I’m sure several of you have heard of quantum tunneling. Vic Stenger is constantly appealing to it in order to explain the origin of the early universe. In a false vacuum quantum fluctuations can occur which allows decay. In a false vacuum the vacuum energy barrier (the Higgs field) doesn’t have enough energy to traverse the field. (Think of a ball sitting on top of a sombrero making an indentation on the top). Even though it cannot traverse the field it can traverse it via tunneling.
What Happens When Particles Collide?
Richard Feynmann, a Nobel Laureate, developed thse diagrams to depict what happens when particles collide with each other. I’ve made a rough diagram with an step by step explanation.
The first incoming particle is a down quark, a building block of the proton. By convention, it is depicted by the straight line.- The down quark emits a gluon and turns into a ‘virtual’ down quark. Virtual particles are intermediate stages that cannot be observed on their own.
- The other incoming particle is an up antiquark. This motion/arrow is moving backwards for reasons having to do with relativity theory.
- The up antiquark and virtual down quark annihilate each other, leaving behind a W boson.
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Quantum Physics: How Small? How Fast? How Long?
Length
Atomic nuclei range from about 10-4 to 10-5 of the size of an atom. If the atom were about the size of a medium-sized airport (say, 3 km) then the nucleus would be about 30 cm, about the size of a basketball. Now imagine the airport, 3 km, having a sphere encompassing it. If you change the basketball to a golf ball you have a rough scale of the hydrogen atom with its central proton. Inside the golf ball are the quarks. Change the scale from the proton being the size of a golf ball to the size of a marble, about 1 cm. The sphere is now the size of the earth’s orbit. The actual size of a proton is about 10-15m. This is equivalent to one femtometer, or one Fermi (1 fm). The smallest distance probed is 10-18m, which is one thousandth of a fermi. The fundamental particles such as quarks are smaller than this.
The radius of the Hubble volume, or known universe, is about fourteen billion light years, which is about 1026m away. The size of your desk is about 1026 times smaller than the universe and only 1018 times larger than the smallest probed distance. The mean distance between the large distance of the universe and the smallest distance probed is 104m, or 10 km. This means that the mean distance of the universe is about six miles.