Re: A glimpse.

[Cliff Parker <cparker@EMPOWERING.COM>]

Ludwik Kowalski wrote:

> The question is HOW TO ACCOMPLISH THIS? How much is
> enough to be worth doing in an introductory course? How much
> is one glimpse? In my case they get a micro-glimpse, or less. But
> this is because my own background is limited to glimpses. And
> this is likely to be typical.
> Ludwik Kowalski

My views on this subject are in a constant state of change and correction
but these are some thoughts.

Students should be exposed to the idea that:

1) Light travels at the same rate in all frames of reference and
therefore...

2) Time is not what they thought it was.  This could be done by discussion
of the meaning of simultaneous events and the effects on clock readings in
the "twin paradox".  The effects of clock operation in satellites and fast
airplanes can illustrate these ideas.

3) Distance is not what they thought it was.  Discussions about what it
means to measure distance may help here.  What is the length of an arrow
in flight compared to at rest.

4) Space is not what they thought it was.  Discussions of the addition of
time to our three dimensions of space to imagine space-time.  The idea
that the moon follows Newton's First Law as it circles the earth in a
"straight" line through bent space-time will lead to new thoughts.  The
elimination of Newton's uncomfortable idea of force at a distance should
be part of this discussion.

5) An analysis of line spectra will lead to quantum explanations.
Electrons changing from one energy level to another without stopping
in-between is very strange.

6) The dual nature of light introduces the possibility that somehow our
measurement effects the thing it is measuring and can begin to show the
very strange nature of things small.

7) Heisenberg's Uncertainty Principle means some things will never be
known.  Many examples exist here the location and momentum of an electron,
diffraction of light, etc.  One application of Heisenberg that I like to
discuss with my classes which I think is correct but have never personally
seen used  is the measurement of an objects temperature.   I make the
provocative claim that we will never have any object reach absolute zero
because if we think we have accomplished this task any attempt to measure
that temperature would increase the temperature above zero K.

Consideration should be given to touching on these topics in a non
threatening atmosphere where students are aware that testing on these
ideas will be kept to a minimum or eliminated completely.  An acquaintance
of mine tells his class that they are going to do "party physics" (just
for fun) when they talk about such things.

Cliff Parker