Re: Critical size (or Mass?) of the particle at which Macro transitions to Micro (Ref: Double Slit Experiment)
- From: "Materion" <materion@xxxxxxx>
- Date: 19 Apr 2006 05:21:48 -0700
Hello Ravindra. You wrote:
I think I got some clarity with the probability waves explanation and
at the same time got some more questions as well...
Lets assume that the electrons are fired one after the other in the
double slit experiment...Probability waves explain the interfernce
pattern observed and the reasoning goes that the probability wave of a
single electron would travel through both the slits and hence it
interferes causing an interference pattern.
The wave indeed travels through both slits but the electron passes
through one or the other, cf. Bell's quotation in his 1986 paper "Six
possible worlds of quantum mechanics":
"De Broglie showed in detail how the motion of a particle, passing
through just one of two holes in screen, could be influenced by waves
propagating through both holes. And so influenced that the particle
does not go where the waves cancel out, but is attracted to where they
cooperate. This idea seems to me so natural and simple, to resolve the
wave-particle dilemma in such a clear and ordinary way, that it is a
great mystery to me that it was so generally ignored."
When we put a detector at
one of the slits ( either direct / indirect detection of the electron),
the interference pattern is not found because the probability wave
sharpened into the slit where we detected this electron...Till here it
is fine...
It's not the detector's presence that destroys the interference
pattern, it is the impulse of the photons fired by the detector that
knocks the electron out of phase with the wave.
Case 1. Lets say we repeat the same experiment ( thought experiment!)
with needles fired one after another...Going by the same probability
wave explanation should we identify interference pattern with needles?
( lets say I chose all the required distances, slit separation width,
screen size all of those etc., hypothetically) ...
Yes, if the rotating needles stay in phase with the wave.
OR
Case 2. We dont observe interfernce because I can clearly see with my
eyes which slit the needle is passing through ( it is visible) without
any need of detectors!!
The photons we detect with our eyes coming off the path of the needle
do not have enough impulse to knock the needle out of phase with the
pilot wave. The interference pattern is not destroyed.
Case 3. Lets say I repeat Case 2 with needles but now in a closed
chamber and I cannot see till the entire experiment is over so that
Case 2 is no longer valid. Now will I see the interference pattern?
Yes, like in case 2.
If yes, then I have some more questions:
a. In case of electrons it is understood that a detector presence /
presence of light disturbs/alters the probability wave of an electron (
Using uncertainity principle)
It is indeed the presence of light that alters the probability wave of
the electron, not the detector's presence.
b. But in the case of needles, I am not using any detector but is
clearly visible to the naked eye to see the needle as to which slit it
is passing thorugh...So how can the mere act of seeing without any
presence of detectors etc., alter the probability wave of needles?
Well, the mere act of observing with your eyes does not alter the
probability wave of such macro-sized objects. Detecting the path of the
needles with other needles would.
--
Arjen Dijksman
-------------------
Wire grid and needle with angle theta: | | | |/| | | | | |
State vector of plane rotating needle steered by wave with phase phi:
|theta> = exp(i*phi) cos(theta) |0> + sin(theta) |1>
|0> = state vector for undetected needle (theta = 0)
|1> = state vector for detected needle (theta = pi/2)
More on http://materion.free.fr
.
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- Critical size (or Mass?) of the particle at which Macro transitions to Micro (Ref: Double Slit Experiment)
- From: Ravindra
- Re: Critical size (or Mass?) of the particle at which Macro transitions to Micro (Ref: Double Slit Experiment)
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- Re: Critical size (or Mass?) of the particle at which Macro transitions to Micro (Ref: Double Slit Experiment)
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- Re: Critical size (or Mass?) of the particle at which Macro transitions to Micro (Ref: Double Slit Experiment)
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