Schrodinger's Cat


Schrodinger's Cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schršdinger in 1935. It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. The scenario presents a cat that is randomly put in a state where alive and dead are both possibilities, requiring further observation to determine which. The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics. In the course of developing this experiment, Schrodinger coined the term Verschrankung (entanglement). Read more ...




In the News ...





'Dead or alive' cat in physics top 10   BBC - December 13, 2016
The detection of ripples in space-time and a famous cat-based paradox are featured in a list of the physics advances of 2016. The discovery of gravitational waves, announced in February, was declared breakthrough of the year. But the top 10 list, compiled by Physics World magazine, also features a new twist on the much-loved Schrodinger's Cat paradox. It also included the detection of a planet around our nearest star. The winning discovery was the result of work by the Ligo collaboration, which involved more than 80 institutions worldwide.




'Schroedinger's cat' molecules give rise to exquisitely detailed movies   BBC - September 21, 2016
One of the most famous mind-twisters of the quantum world is the thought experiment known as "Schroedinger's Cat," in which a cat placed in a box and potentially exposed to poison is simultaneously dead and alive until someone opens the box and peeks inside.




Doubling down on Schrodinger's cat   PhysOrg - May 26, 2016

Yale physicists have given Schrodinger's famous cat a second box to play in, and the result may help further the quest for reliable quantum computing. Schršdinger's cat is a well-known paradox that applies the concept of superposition in quantum physics to objects encountered in everyday life. The idea is that a cat is placed in a sealed box with a radioactive source and a poison that will be triggered if an atom of the radioactive substance decays. Quantum physics suggests that the cat is both alive and dead (a superposition of states), until someone opens the box and, in doing so, changes the quantum state. This hypothetical experiment, envisioned by one of the founding fathers of quantum mechanics in 1935, has found vivid analogies in laboratories in recent years. Scientists can now place a wave-packet of light composed of hundreds of particles simultaneously in two distinctly different states. Each state corresponds to an ordinary (classical) form of light abundant in nature.




Quantum Cheshire Cat effect may be explained by standard quantum mechanics   PhysOrg - June 13, 2015
"A grin without a cat" is how Lewis Carroll describes the Cheshire Cat's mysterious way of disappearing while leaving its grin behind in his 1865 classic, Alice in Wonderland. The fanciful character raises a question that has captured physicists' attention over the past few years: can an object be separated from its properties? However, in a new paper published in the New Journal of Physics has questioned this interpretation of the results. Instead of a particle being separated from its properties, they suggest that the results can be explained by a standard quantum effect, quantum interference, in which an individual particle interferes with itself due to its wave-like properties.




Schrodinger's cat gets a reality check   PhysOrg - February 12, 2015
It's a century-old debate: what is the meaning of the wave function, the central object of quantum mechanics? Is Schršdinger's cat really dead and alive? Physicist Erwin Schršdinger's famous thought experiment was designed to show how, if quantum mechanics is taken literally and to its ultimate implications, even macroscopic systems, like cats, would be in such "superpositions" of states - such as the cat being both dead and alive - which is an apparently absurd conclusion.




Researchers describe the wave-function of Schroedinger's cat   PhysOrg - February 3, 2015

Schrodinger's cat highlights a long-standing dilemma in quantum mechanics: is the cat really alive and dead, or is the weirdness just in our head? Researchers at The University of Queensland have now made major progress in answering this question. Using four-dimensional states of photons, and subjecting them to very precise measurements, they ruled out the popular view that describing the cat as dead and alive is just due to a lack of knowledge about its real state. As with all objects in quantum physics, the cat is described by the quantum wave-function. Schrodinger's cat really is in a state of being both alive and dead.




Schrodinger's Cat Comes into View with Strange Physics   Live Science - August 27, 2014

The cats represent the famous Schrodinger cat paradox, in which a quantum cat closed in a box can be dead and alive at the same time. The dark and light cat body outlines are images of an etched piece of silicon. They arise due to destructive and constructive quantum interference, respectively. In this experiment the photons that interact with the silicon are not detected, while the images are obtained by detecting only photons that never interact with the object. By sending green, red and yellow laser beams down a path to detector, researchers have shed light on the famous physics idea known as the Schrodinger's cat thought experiment. For physicists, Schrodinger's cat involves picturing a cat, in a box, with a vial of poison that can kill the cat if it opens. Over any given period there's a 50-50 chance the poison vial will open, and a person who opens the box after a given time and looks at the cat will then observe that it is either dead or alive. Most people would say that even before you open the box, before you can see the cat, it's still in either one state or the other, either dead or alive.




Bizarre 'Schrodinger's Cat' Comes Alive in New Experiments   Yahoo - July 22, 2013

The strangeness of the world of the very small that allows a particle to be in two states at once may extend to larger scales, two new studies reveal. If the research proves true, that would bolster the validity of a thought experiment suggesting a cat can be both alive and dead at the same time. The idea, called Schrodinger's Cat after the physicist, Erwin Schrodinger, who proposed it in 1935, goes like this: Put a cat in a box with a vial of poison gas. The vial opens when a tiny piece of radioactive metal emits an alpha particle (the nucleus of a helium atom) as it decays. Emitting an alpha particle is a quantum-mechanical process, which means that whether it happens in any given stretch of time is basically random. Quantum mechanics says that it's impossible to know whether the radioactive decay has happened (and the cat is dead) unless one measures it - that is, unless the alpha particle interacts with the environment in some way that an observer can see. Until that happens, the alpha particle is emitted and not emitted at the same time. The cat is both dead and alive, a state called superposition. Opening the box is a measurement - one sees the effect of an alpha particle as the dead cat, or the absence of an alpha particle as a live one.




PHYSICS INDEX


ASTRONOMY INDEX


PHYSICAL SCIENCES INDEX


ALPHABETICAL INDEX


CRYSTALINKS HOME PAGE


PSYCHIC READING WITH ELLIE


2012 THE ALCHEMY OF TIME