This video is about Bell’s Theorem, one of the most fascinating results in 20th century physics. Even though Albert Einstein (together with collaborators in the EPR Paradox paper) wanted to show that quantum mechanics must be incomplete because it was nonlocal (he didn’t like “spooky action at a distance”), John Bell managed to prove that any local real hidden variable theory would have to satisfy certain simple statistical properties that quantum mechanical experiments (and the theory that describes them) violate.

## Tag: Quantum Mechanics

## Modern Physics with Numerical Methods

This is an open-source, modern physics textbook typically for the third semester students majoring in engineering, physics or chemistry. An emphasis is placed on fundamental principles as well as numerical solutions to equations where no analytical solutions exist. The content begins with optics and uses that as a stepping stone to wave phenomena and quantum systems.

## Is the Multiverse Physics, Philosophy, or Something else Entirely?

The idea of the multiverse — or the theoretical possibility of infinite parallel universes–straddles a strange world between science fiction and a plausible hypothesis.

## The Higgs Mechanism Explained

Quantum Field Theory is generally accepted as an accurate description of the subatomic universe. However until recently this theory had one giant hole in it. The particles it describes had no mass! The Higgs field and the Higgs mechanism were proposed long ago in order to give particles mass, but it was only in 2012 that the existence of the field was proved with the discovery of the Higgs boson by the Large Hadron Collider.

## Time Crystals!

In this episode of the Space Time Journal Club Matt discusses how two independent research teams created their own Time Crystals, a form of matter that breaks time translational symmetry and could be used in quantum computers.

## Understanding the Uncertainty Principle with Quantum Fourier Series

But this intuitive, mechanical reality is emergent from underlying reality in which the particles that form matter arise from of the combination of an infinity of possible properties. And forget matter – the vacuum itself is the sum of infinite possible particles. If we fully unravel this idea we’ll be on the verge of tackling things like Hawking radiation. But as you’ll see today, in that unraveling we are led, unavoidably, to Heisenberg’s uncertainty principle.

## Zero-Point Energy Demystified

Let’s talk about the mysterious zero-point energy and what it really can, and really can’t do.

## The Vacuum Catastrophe

Let’s talk about vacuum energy from a theoretical standpoint. From the perspective of quantum field theory, every point in space is represented by a quantum oscillator; one for each elementary particle type. Higher energy oscillations represent the presence of real particles. However even the lowest possible energy oscillation – the one corresponding to the absence of particles – has some energy.

## The Nature of Nothing

How do we study nothing? An empty jar still contains something: molecules of air and a bath of infrared light from its warm environment. But what if we suck out every last molecule of air, chill the jar to absolute zero, and shield it from all external radiation? The jar would contain only empty space, but it turns out that empty space is far from nothing.

## Absolute Cold

Many experimental physicists have spent their careers trying to cool things to absolute zero. This state of absolute cold is the zero-point on the Kelvin temperature scale, corresponding to -273.15 Celsius. Using lasers and magnetic fields, we’ve now managed to cool certain substances to less than a billionth of a Kelvin. Doing so has revealed some bizarre quantum states of matter. But quantum mechanics may also prevent us from ever reaching absolute zero.