# The truth is in there - Maxwell gives us the speed of light

- a Filk on "X as in Fox" by Cecilia Eng -

Once we believed in the speed of the light,
and experiments show that what we thought is right,
But we search our math for another sight,

'Cause we hope that the truth is in there.

When we measure the speed of something somehow,
we can only check against the distance, but now
we'll show that we get it from Maxwell', and wow!

We will know that the truth is in there!

First we take a sheet of charge at hand,
then we move it by an unseen command,
and nabla rot B shows the field where we stand,

And we know that the truth is in there.

Now that formula says, our field's everywhere,
when about the electrics we never care,
but that can't be true, for our world's still there,

And we know that the truth is in there.

Since nabla rot E is -dB/dt,
a field can never change at once all that we see,
It takes some time, which gives us the v,

And we guess that the truth is in there.

So now we take a small square far from the sheet,
when we check the change in B, it then shows quite neat,
It is width times the speed times B, which we need,

To see that the truth is in there.

For we also know that an electric field,
round a loop is (as Stokes will quickly yield),
Just the length of the loop times the strength of the field,

That's a clue that the truth is in there.

For now we take both and make the loop small,
so the length in a field is its width, and we call,
"E is v times B", which gives us all

To believe that the truth is in there.

We then do the same for nabla rot B,
But there's a c squared so we easily see,
E is also c squared times (B divided by v),

And we see that the truth is in there.

For with these we can easily tell,
that v must be c which we like so damn well,
For now we are sure we're right when we yell,

We know that the truth is in there!

So what do we know from this funny tale?
The strength of the fields leads us through the veil,
and gives us the speed of light without fail,

So we see that the truth is in there!

Now we only need to measure the attraction of charge,
and then the attraction of flowing charge,
and the root of their quotient might be quite large,

But it gives us the truth that's in there.
The invariant truth that's in there.

Jepp, that's a way to get the speed of light from the Maxwell equations and the knowledge that our world still exists :)

I hope you enjoyed reading the song as much as I enjoyed writing it! Willkommen im Weltenwald!
((λ()'Dr.ArneBab))