Monday, December 2, 2013

Irreversible loss of information

Physicist Sean M. Carroll writes:
This year we give thanks for an idea that establishes a direct connection between the concepts of “energy” and “information”: Landauer’s Principle. ...

Landauer’s Principle states that irreversible loss of information — whether it’s erasing a notebook or swiping a computer disk — is necessarily accompanied by an increase in entropy. Charles Bennett puts it in relatively precise terms:
Any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information bearing degrees of freedom of the information processing apparatus or its environment.
The principle captures the broad idea that “information is physical.”
Okay, fine, but various big-shot physicists foolishly insist that information is always preserved. They have to deny information loss in order to argue for many-worlds (MWI) and black hole firewalls.

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