Author Topic: Knowledge Byte: Schrodinger's cat and quantum mechanics  (Read 2521 times)

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Knowledge Byte: Schrodinger's cat and quantum mechanics
« on: February 03, 2014, 14:53:09 PM »
Knowledge Byte: Schrodinger's cat and quantum mechanics

Published: Jan. 31, 2014 Updated: 2:10 p.m.

We got a quick overview of one of the most enduring paradox questions in quantum theory: Schrodinger's cat. Is it alive? Is it dead? Both, or neither. It may just be sleeping.

Austrian physicist Erwin Schrodinger developed the thought experiment as a means to discuss issues with other theories involving quantum mechanics.

Jeff Tollaksen, co-director of the Chapman University Institute for Quantum Studies, and institute member and professor Ali Nayeri, help explain the paradox:

• There is a cat in a sealed box. It is not known whether the cat is alive or dead. Some people nowadays prefer to use the concepts of “awake or asleep” as a more humane approach to the theoretical animal in question.

• Inside the theoretical box is also a device containing a substance or a source of radiation. The device is attached to a Geiger counter, which measures radioactive activity and determines whether or not an atom is in a state of decay.

The device, if activated, will trigger a reaction that will break a tube that, in previous explanations, contained poison. Nowadays, the tube contains something that will make the cat sleep. If the atoms are stable, the device will not be activated. If even one atom has decayed, the device is activated.

• Schrodinger posed the scenario to deal with an interpretation of quantum mechanics involving observations that says that until something, such as an atom, is observed, it may in principle exist in multiple states because each outcome is equally possible and valid. So, with an atom, it could be decayed or not decayed, simultaneously, until an observation proves otherwise.
This interpretation is based on observational and research principles saying there is a 50 percent chance that either outcome is probable. By taking the information that is relevant to all probable outcomes, either assumption can be made prior to observation. And each assumption is correct until shown otherwise.

• Schrodinger used the cat in a box example to pose a more practical application of argument, saying that the cat will be alive or dead – whether or not it is observed – rather than in an undetermined state until someone looks at it. The thought experiment shows the limitation of the observation-based interpretation by showing at what stage one can stop the use of quantum mechanics in ascertaining an outcome.
Although not meant to be an enduring concept in Schrodinger's research and work, the cat paradox has been continually used in ongoing discussions about a variety of theories in quantum mechanics.

For example, one such discussion that utilizes the cat paradox is the Many Worlds theory of quantum mechanics, where the universe splits to permit different quantum states – so in one world the cat is alive and in the other split world the cat is dead.

In Knowledge Bytes, the Register offers insight, ideas and information from university experts.