| Topic: |
Science > Physics |
| User: |
"Mike Helland" |
| Date: |
04 Aug 2004 02:37:48 PM |
| Object: |
Re: How to make measurements of a particle |
Gregory L. Hansen wrote:
In article <ad157aec.0408040551.7641bc9f@posting.google.com>,
Mike Helland <mhelland@techmocracy.net> wrote:
The HUP states that when you measure the position of a particle with
some degree of certainty your ability to measure the momentum of
that
particle will be limited to another degree of certainty.
The particle being measured can be an electron and the measuring
tool
can be some photons. Right? It thats not right, please correct me.
Ok, so, can anyone point me to an accessible text on how exactly how
the measurements are made, all the way through setting up the
experiment, describing what happens, and then ending up with the
numbers?
If you could point me to web page or maybe explain it here, that
would
be great.
Thanks.
I can't think of any cases where light was actually used to measure
the
positions of electrons.
Oh. Thats sort of a bummer.
So... if I were to come up with a model that would simulate the
measuring of an electron's position and momentum with the goal of
demonstrating HUP, even if I were successful there has been no
experimental evidence yet that would even support the accuracy of the
model?
.
|
|
| User: "Gregory L. Hansen" |
|
| Title: Re: How to make measurements of a particle |
04 Aug 2004 03:28:52 PM |
|
|
In article <cerduc$9md@odbk17.prod.google.com>,
Mike Helland <mhelland@techmocracy.net> wrote:
Gregory L. Hansen wrote:
In article <ad157aec.0408040551.7641bc9f@posting.google.com>,
Mike Helland <mhelland@techmocracy.net> wrote:
The HUP states that when you measure the position of a particle with
some degree of certainty your ability to measure the momentum of
that
particle will be limited to another degree of certainty.
The particle being measured can be an electron and the measuring
tool
can be some photons. Right? It thats not right, please correct me.
Ok, so, can anyone point me to an accessible text on how exactly how
the measurements are made, all the way through setting up the
experiment, describing what happens, and then ending up with the
numbers?
If you could point me to web page or maybe explain it here, that
would
be great.
Thanks.
I can't think of any cases where light was actually used to measure
the
positions of electrons.
Oh. Thats sort of a bummer.
So... if I were to come up with a model that would simulate the
measuring of an electron's position and momentum with the goal of
demonstrating HUP, even if I were successful there has been no
experimental evidence yet that would even support the accuracy of the
model?
Depends on what you consider to be evidence. The unanswered question in
classical atomic physics was why doesn't the electron radiate away all its
energy and spiral into the nucleus? The answer is that it has, and the
size of the electron orbit is a compromise between the size (uncertainty
in position) and the momentum. The uncertainty principle will give you
exactly the Bohr radius of the hydrogen atom, which is the standard
deviation of the electron wavefunction.
Electrons are also routinely diffracted from things, or diffracted through
thin films. The diffraction patterns are captured on film or another
recording medium, and interpreted to determine crystal structures and
other material properties.
Uncertainty principles exists in any wave mechanics, there's nothing
peculiarly quantum mechanical about that. And the Schroedinger wave
equation is a wave equation. You could say that any evidence that quantum
mechanics describes the things that particles do is evidence that the
particles have wave properties including uncertainty relations.
But I don't know of any experiment that directly addresses what you have
in mind. Maybe something exists that I don't know about, but it's not
part of the standard QM culture.
--
"The main, if not the only, function of the word aether has been to
furnish a nominative case to the verb 'to undulate'."
-- the Earl of Salisbury, 1894
.
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