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Re: [Phys-L] Edu Videos



On 03/27/2013 04:12 PM, Paul Lulai wrote:
I really like the veritasium videos. I show these, some minute
physics, and the brief chalkboard character videos from the Perimeter
Institute to students in grades 9-12. I watch others myself for fun
and inspiration for teaching ideas.


I just looked at the veritasium video:
Can We Go the Speed of Light? (The Principle of Relativity)
http://www.youtube.com/watch?v=vVKFBaaL4uM

The only 'inspiration" I got was the urge to tear my hair out.
It looked to me like 4 minutes of grossly bad judgment as to
the physics, and worse judgment as to the pedagogy.

First of all, there are multiple reasons why the "Jaywalking" segments
cannot possibly serve any constructive purpose:
1) [general public] -- Calling attention to misconceptions in this
way is a disservice to the viewing public. It is more likely to
reinforce misconceptions than to dispel them.
2) [interviewees] -- It's just plain mean to the interviewees.
For one thing it embarrasses them, and furthermore it is very
likely to consolidate their misconceptions. It requires them
to make a decision, whereupon they are motivated to defend
their decision.
3) In another video, the author claims that he doesn't do it
just to make himself feel good, to build himself up by tearing
other people down ... but I have to wonder.
4) [teachers] -- Anybody who knows the first thing about teaching
knows that students arrive with more misconceptions than anybody
can imagine. We get it. We don't need to be told yet again.
5) Even *IF* you hypothesize that somewhere there is a teacher
or an administrator or a funding agency or a voter or a politician
who doesn't realize how many widespread misconceptions there are,
it is pedagogical malpractice to *begin* with the Jaywalking
segments. It would be better in every way to explain the right
answer -- thoroughly -- *before* giving any airtime to misconceptions.

I put this sort of thing fairly high on the list of cheap, unprofessional
stunts for getting attention. Maybe not as unprofessional as taking off
your clothes, but on the same list.

==========

As for the physics, it shows bad judgment to talk about Einstein's
1905 theory of relativity. As a minor point, the principle of
relativity was set forth by Galileo, almost 300 years before
Einstein came on the scene.

Somewhat more importantly, the ideas of length contraction and
time dilation are *not* due to Einstein. There's a reason why
it's called the FizGerald-Lorentz contraction, not the Einstein
contraction.

Thirdly, those two ideas are not sufficient to explain special
relativity or to resolve the so-called "paradoxes" posed by the
video. You also need the breakdown of simultaneity at a distance,
and even that was known in the literature years earlier (e.g.
Poincaré, 1898).

Fourthly, FWIW, despite what the title of the video suggests,
the principle of relativity and the speed-of-light speed limit
are not the same thing.

Fifthly, it is pedagogical malpractice to teach relativity (or
anything else) in a way that revolves around "paradoxes". The
correctly-stated laws of physics do not contain any paradoxes
that I know of. The only way to present a paradox is to
mis-state the laws of physics, which is a terrible idea,
especially when speaking to non-expert audiences.

If relativity seems weird and paradoxical,
you're doing it wrong.

Sixthly and vastly more importantly, it has been known for
105 of the last 108 years that the wise approach is to define
time, distance, and mass in such a way that they do *NOT*
depend on velocity. (Minkowski, 1908). It is pedagogical
malpractice to talk about contraction and dilation, because
those ideas will have to be unlearned before there can be any
real understanding of special relativity, not to mention any
progress toward further developments such as general relativity.

Please, folks, let's stop pretending that the development of
special relativity _began_ and _ended_ in 1905. Neither of
those things is true, not by a long shot.

Virtually everybody has heard of the "four dimensional space-
time continuum". They have heard that time is the fourth
dimension. Even Buffy the Vampire Slayer uses the idea and
doesn't feel obliged to explain it. I mention this to make
the point that the cognitive workload of introducing this
idea is zero. People don't necessarily take the idea as
seriously as they should, but that's a fixable problem.
If you're going to make a four-minute video, make a video
showing what's really going on in spacetime. It's just
not that tricky.

It is straightforward to explain special relativity without
ever mentioning contraction, dilation, or velocity-dependent
mass.
http://www.av8n.com/physics/spacetime-welcome.htm
Let's be clear: I am not suggesting a better way of explaining
why clocks can't be trusted and rulers can't be trusted. No
indeed. Instead I recommend in the strongest terms defining
length, time, and mass in such a way that they *can* be trusted
... and are velocity-independent. I recommend not mentioning
contraction and dilation at all, period. Such things are
inconsistent with any modern (post-1908) understanding of the
subject.

When are we going to stop teaching physics that is more than
100 years out of date?