0

Is there any difference between expectation value and average value in quantum mechanics? If there is no difference then why give them different names?

Roger V.
  • 58,522
QM_Search
  • 21
  • If I type "expectation value average value quantum mechanics" into a search engine, I get plenty of hits, which describe this. – Semoi Apr 18 '20 at 10:00
  • Is there a difference in ordinary statistics? Why do you think quantum mechanics is special here? – ACuriousMind Apr 18 '20 at 10:21

2 Answers2

3

It is the same as for statistics and probability theory. Average applies to data. Expectation applies to predictions.

Charles Francis
  • 11,546
  • 4
  • 22
  • 37
0

I agree with @CharlesFrancis answer, but it is worth adding more terminology: expectation value is mathematical average/mean, as opposed to the ensemble average or sample average. See here for more.

Remark: the obligatory reference on statistics is this crash course on statistics, from the Review of Particle Physics.

Roger V.
  • 58,522