Re: When was the observer effect (physics) first observed?

On 15/08/2024 18:42, Martin Harran wrote:

It seems to have been first formally stated by Heisenberg in 1958 his
book "The Physicist's Conception of Nature" but I would have thought
that it would have been noted earlier than that.
 The reason I'm asking is that Teilhard de Chardin effectively
describes it in his foreword to 'The Phenomenon of Man' - "Object and
subject marry and mutually transform each other in the act of
knowledge; and from now on man willy-nilly finds his own image stamped
on all he looks at."
 Teilhard wrote that somewhere in the last 1920s/early 30s which more
or less coincides with the early days of QM. I'm wondering if Teilhard
was reflecting what those involved in QM were already talking about or
whether he arrived at this under his own steam.
 

One example of the observer effect occurs with the use of mercury thermometers. If you use a mercury thermometer to measure the temperature of a flask of water, what you measure is the weighted mean temperature of the water and the mercury (and other bits of the system), as heat flows from one to the other to equilibriate the temperature.
The observer effect, in one form or another, may well have been one of those things that "everyone knew". One specific example, the Hawthorne Effect, was named in 1953. In electronics it's called the probe effect.
--
alias Ernest Major