Quantum Physics

Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science.

Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale.

Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values (quantization); objects have characteristics of both particles and waves (wave–particle duality); and there are limits to how accurately the value of a physical quantity can be predicted prior to its measurement, given a complete set of initial conditions (the uncertainty principle).

Quantum mechanics arose gradually from theories to explain observations that could not be reconciled with classical physics, such as Max Planck's solution in 1900 to the black-body radiation problem, and the correspondence between energy and frequency in Albert Einstein's 1905 paper, which explained the photoelectric effect. These early attempts to understand microscopic phenomena, now known as the "old quantum theory", led to the full development of quantum mechanics in the mid-1920s by Niels Bohr, Erwin Schrödinger, Werner Heisenberg, Max Born, Paul Dirac and others. The modern theory is formulated in various specially developed mathematical formalisms. In one of them, a mathematical entity called the wave function provides information, in the form of probability amplitudes, about what measurements of a particle's energy, momentum, and other physical properties may yield.

Source: Quantum mechanics (wikipedia.org)

The First Quantum Field Theory | Space Time

Viewers like you help make PBS (Thank you 😃) . Support your local PBS Member Station here: https://to.pbs.org/DonateSPACE Quantum Electrodynamics is the first true Quantum Field Theory. Part 2 in our series on Quantum Field Theory. Signup for your free trial to The Great Courses Plus here: http

Why Are Quasiparticles So Spectacularly WEIRD?

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The Ultraviolet Catastrophe Experiment

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Physics Nobel rewards 'spooky science' of entanglement

This year's Nobel Prize in Physics rewards research into quantum mechanics - the science that describes nature at the smallest scales. The award goes to Frenchman Alain Aspect, American John Clauser and Austrian Anton Zeilinger.

Why Is 1/137 One of the Greatest Unsolved Problems In Physics?

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Why Isn’t The Nucleus Ripped Apart?

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A Real Life Quantum Delayed Choice Experiment

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Zeno's Paradox & The Quantum Zeno Effect

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What Happens Inside a Proton?

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Feynman's Infinite Quantum Paths

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How the Higgs Mechanism Give Things Mass

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Quantum Locking Will Blow Your Mind—How Does it Work?

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Large hadron collider: A revamp that could revolutionise physics

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Shock result in particle experiment could spark physics revolution

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What If Charge is NOT Fundamental?

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Will We Discover Cosmic Strings From the Big Bang?

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Is The Wave Function The Building Block of Reality?

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What is the quantum apocalypse and should we be scared?

Imagine a world where encrypted, secret files are suddenly cracked open - something known as "the quantum apocalypse". Put very simply, quantum computers work completely differently from the computers developed over the past century.

Is ACTION The Most Fundamental Property in Physics?

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Neutrino result heralds new chapter in physics

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Will Constructor Theory REWRITE Physics?

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Why Magnetic Monopoles SHOULD Exist

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Is The Future Predetermined By Quantum Mechanics?

PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACE ↓ More info below ↓ Einstein’s special theory of relativity combines space and time into one dynamic, unified entity - spacetime. But if time is connected to space, could the univ

Electrons DO NOT Spin

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A Better Way To Picture Atoms

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Muon g-2 experiment finds strong evidence for new physics

The first results from the Muon g-2 experiment hosted at Fermilab show fundamental particles called muons behaving in a way not predicted by the Standard Model of particle physics. Announced on April 7, 2021, these results confirm and strengthen the findings of an earlier experiment of the same name

Why the Muon g-2 Results Are So Exciting!

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Muons: 'Strong' evidence found for a new force of nature

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Electroweak Theory and the Origin of the Fundamental Forces

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An atomic marker hidden in plain sight

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Tricking the perfect code machine

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Scientists have performed successful teleportation on atoms for the first time, the journal Nature reports. The feat was achieved by two teams of researchers working independently on the problem in the US and Austria.

Team's quantum object is biggest by factor of billions

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Quantum trick for pressure-sensitive mobile devices

Hand-held devices could soon have pressure-sensitive touch-screens and keys, thanks to a UK firm's material that exploits a quantum physics trick. The technology allows, for example, scrolling down a long list or webpage faster as more pressure is applied.

Quantum physics explanation for smell gains traction

The theory that our sense of smell has its basis in quantum physics events is gaining traction, say researchers. The idea remains controversial, but scientists reporting at the American Physical Society meeting in Dallas, US, are slowly unpicking how it could work.

Quantum mechanics rule 'bent' in classic experiment

Researchers have bent one of the most basic rules of quantum mechanics, a counterintuitive branch of physics that deals with atomic-scale interactions. Its "complementarity" rule asserts that it is impossible to observe light behaving as both a wave and a particle, though it is strictly both.

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Quantum computing device hints at powerful future

One of the most complex efforts toward a quantum computer has been shown off at the American Physical Society meeting in Dallas in the US. It uses the strange "quantum states" of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

Majorana particle glimpsed in lab

Scientists think they may finally have seen evidence for a famously elusive quarry in particle physics. The Majorana fermion was first predicted 75 years ago - a particle that could be its own anti-particle.

Imaginary time

Imaginary time is a mathematical representation of time which appears in some approaches to special relativity and quantum mechanics. It finds uses in connecting quantum mechanics with statistical mechanics and in certain cosmological theories.

How long is a piece of string?

Alan Davies leaves behind his role in the TV quiz show QI to explore the world of quantum mechanics for the BBC science programme Horizon. The stand-up comic admits to deliberately failing at physics so he wouldn't have to take the O-level.

Higgs boson 'hints' also seen by US lab

A US particle machine has seen possible hints of the Higgs boson, it has emerged, after reports this week of similar glimpses at Europe's Large Hadron Collider (LHC) laboratory.The Higgs boson sub-atomic particle is a missing cornerstone in the accepted theory of particle physics.

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The late philosopher Robert Nozick, talking about the deep question of why there is something rather than nothing, quipped: "Someone who proposes a non-strange answer shows he didn't understand the question.

Antimatter Tevatron mystery gains ground

US particle physicists are inching closer to determining why the Universe exists in its current form, made overwhelmingly of matter. Physics suggests equal amounts of matter and antimatter should have been made in the Big Bang.

Quantum Leap: Information Teleported between Ions at a Distance

Quantum entanglement, whereby two or more objects are linked by an unseen connection, has some famously spooky effects. As quantum researcher Anton Zeilinger has said, entanglement can be thought of as a pair of dice that always land on the same number.

Physics of life: The dawn of quantum biology

The key to practical quantum computing and high-efficiency solar cells may lie in the messy green world outside the physics lab. On the face of it, quantum effects and living organisms seem to occupy utterly different realms.

Bridging the gap to quantum world

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Antihydrogen undergoes its first-ever measurement

The antimatter version of the hydrogen atom - antihydrogen - could soon finally give up its secrets. Scientists expect that antihydrogen will have exactly the same properties as hydrogen; but after 80 years, the test is only just becoming possible.

Neutrino 'ghost particle' sized up by astronomers

Scientists have made their most accurate measurement yet of the mass of a mysterious neutrino particle. Neutrinos are sometimes known as "ghost particles" because they interact so weakly with other forms of matter.

Neutrino particle 'flips to all flavours'

An important breakthrough may be imminent in the study of neutrinos. The multinational T2K project in Japan says it has seen indications in its data that these elementary particles can flip to any of their three types.

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