indistinguishability

Meanings

1. 1
   noun

   the quality or state of being impossible to distinguish from something else

   The near indistinguishability of the two signatures made the forgery difficult to detect.

2. 2
   noun

   in quantum physics, the principle that exchanging identical particles produces no physically observable new state

   Electron indistinguishability requires the wave function to respect exchange symmetry.

From indistinguishable + -ity: in- ("not") + distinguish + -able + -ity. Distinguish comes through Old French distinguer from Latin distinguere ("separate, mark off"). Physics later adopted the noun for the principle that exchanging identical particles creates no observable difference.

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