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Magnetism and electrostatics explained in terms of relativity, rather than
vice versa. And even I followed it when I skipped the actual math. :-)
http://physics.weber.edu/schroeder/mrr/MRRtalk.html
--
Darren New, San Diego CA, USA (PST)
Understanding the structure of the universe
via religion is like understanding the
structure of computers via Tron.
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Darren New wrote:
> Magnetism and electrostatics explained in terms of relativity, rather
> than vice versa. And even I followed it when I skipped the actual math. :-)
>
> http://physics.weber.edu/schroeder/mrr/MRRtalk.html
>
Indeed, wonderfully concise and clear. Should be required reading for
all physics freshers
John
--
"Eppur si muove" - Galileo Galilei
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On 24-8-2009 20:21, Darren New wrote:
> Magnetism and electrostatics explained in terms of relativity, rather
> than vice versa. And even I followed it when I skipped the actual math. :-)
>
> http://physics.weber.edu/schroeder/mrr/MRRtalk.html
>
It is 20 years ago but this is what I remember from one of the great
teachers of theoretical physics in Amsterdam that I had the pleasure of
attending the lectures of (Gerard Bauerle).
- let's assume we have a universe with 3 space-like coordinates and one
time coordinate
- what happens of we have a vector in this space that has to be
invariant to rotations?
- Surprise: what we have now on the blackboard are Maxwell's equations.
Ok, it took a number of hours to introduce the mathematics, but then we
had in 10 minutes shown that in such a universe fields move at a fixed
speed, aka lightspeed. General relativity was another 5 minutes work.
I'll read this page later. I have to do other things now :( but he
starts with relativity assumed and works from there. Gerard started with
a clean board.
Take home message for me (although I might not do his derivation
justice): light is simply a property of space, not something that is
added later.
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Darren New schrieb:
> http://physics.weber.edu/schroeder/mrr/MRRtalk.html
That's cool indeed! Somehow turns the picture of electromagnetism
upside-down (or rather, as it appears to me, puts it the right way round
onto its feet at last).
Makes the universe a tad simpler and easier to understand again.
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andrel schrieb:
> - let's assume we have a universe with 3 space-like coordinates and one
> time coordinate
> - what happens of we have a vector in this space that has to be
> invariant to rotations?
> - Surprise: what we have now on the blackboard are Maxwell's equations.
Sounds like an interesting approach, too.
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Or is space a property of light? I don't know the math but I doubt if we
can make space
fundamental -- thought I suppose we have to if we want to start with
geometry.;)
If I remember correctly, Einstein started with the behavior of light.
But I suppose that must
involve space (a coordinate system) so ... hmmm.... Interesting but
confusing topic.
David
andrel wrote:
> Take home message for me (although I might not do his derivation
> justice): light is simply a property of space, not something that is
> added later.
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David H. Burns wrote:
> thought I suppose we have to if we want to start with geometry.;)
Most things along those lines start with topology, not geometry, and then
find that geometry comes from topology if you restrict the topology to local
interactions.
> If I remember correctly, Einstein started with the behavior of light.
I recall that too. Basically, "c" showed up in a bunch of physics as a
constant without reference to the movement of the experimental setup.
--
Darren New, San Diego CA, USA (PST)
Understanding the structure of the universe
via religion is like understanding the
structure of computers via Tron.
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Yes and I used to think that it was Einstein who showed the velocity of
light to be constant
in all frames of reference. But it wasn't he started with that. I was
not able to find where
this idea actually came from. Any ideas?
David
Darren New wrote:
> I recall that too. Basically, "c" showed up in a bunch of physics as a
> constant without reference to the movement of the experimental setup.
>
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David H. Burns schrieb:
> Yes and I used to think that it was Einstein who showed the velocity of
> light to be constant
> in all frames of reference. But it wasn't he started with that. I was
> not able to find where
> this idea actually came from. Any ideas?
Been around a while. People looking for the "aether" though which light
waves were assumed to propagate, by measuring subtle changes in the
difference of c depending on direction (a) parallel to the earth's
movement on its orbit and (b) orthogonal to it, found that these subtle
changes were apparently... well, /very/ subtle indeed. Actually too
subtle to be measured, if there were any at all. At any rate, "aether"
theory would have predicted a lot more.
That's how this whole "no absolute frame of reference" thing started.
By the way, Einstein did /not/ show that light was travelling at
constant speed - that was Maxwell - nor did he show that this was the
case for every frame of reference - that was the experimenters (who
didn't really show it for /every/ frame of reference of course, but for
enough FoR to provide reason enough to seriously toy around with this idea).
All Einstein did was do just that: Take the "c appears to be constant in
all frames of reference" as a given for argument's sake, and see what
weird predictions he'd wind up with.
It was only the experimenters who showed that Einstein was right in his
predictions, and therefore it is prudent to assume that he was also
right in his initial presumptions.
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andrel <a_l### [at] hotmail com> wrote:
> - let's assume we have a universe with 3 space-like coordinates and one
> time coordinate
> - what happens of we have a vector in this space that has to be
> invariant to rotations?
> - Surprise: what we have now on the blackboard are Maxwell's equations.
That's a really fascinating approach. I should take the time to really learn
some of this, but it certainly helps to have an inspiring teacher. I just met
this guy a couple weeks back, and speaking of people who dabble in
relativity...
http://scholar.google.com/scholar?start=10&q=harry+ringermacher&hl=en
("Engineering warp drives" is my favorite, though I haven't looked at the actual
paper.)
But then I think he's a bit of an exception:
http://oldmerf.us.mensa.org/awards/copper_black/pastwinners/2003winner.php
He looks the part at least.
- Ricky
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