Who Invented the Z Transform

Jul 01, 2005 31 Replies

Actually Maxwell introduced the concept of displacement current. And with this modification the system became complete. He certainly based his work on Gauss, Faraday, and Ampere. But before he did his modification to Ampere's law, the only theoretical way to produce a magnetic field was to have a current (charges in motion). He added the notion that a time varing electric field also produced a magnetic field. He set up an experiement where a constant current was charging a capacitor and noted that a magnetic field existed in between the plates of the cap where there was clearly no current flowing. He also noted that this magnetic field had the same total flux as the field surounding the conductors leading to and from the capacitor.

While Einstein used the Lorentz transform, he changed the reasoning behind its usage and its actual interpretation. However people still call the Lorentz transform a "Lorentz" transform. Einstein's greatest work was in GR. SR is pretty easy to follow, but Einstein had the forthought to choose the proper two axioms (velocity of light is constant in vacuo and physics is the same everywhere) and show that Maxwell's wave equation is invariant under Lorentz transformation. GR took a lot more vision and the use of tensors. The biggest contributor would be Poincare'.

His work on GR cost him 11 years of work after SR and his marriage. Other scientists warned him to not work on gravity since it is too hard. Not to take away from Hilbert's mathematical ability, I never seen his work mentioned in relativity books saying that he predated Einstein.

And his Nobel Prize in 1921 was not for relativity, but for explaining the photoelectric effect, essentially laying the foundation for quantum mechanics.

Jerry

It was Heviside who wrote the vector form of Maxwells equations - the ones we recognise - not Maxwell.

Shytot

I suppose the OP was referring to Hilbert's action principle (for gravitation as a consequence of space-time curvature). According to Misner, Thorne, and Wheeler (see section 21.2 of their book _Gravitation_) Hilbert published this all of 5 days before Einstein published his field equation, but in their words "animated by Einstein's earlier work". The Einstein field equation (for empty space-time at least) follows from Hilbert's principle, which is basically the principle of least action applied to a Lagrangian proportional to the Ricci curvature scalar. I don't think there's any doubt that credit for the field equation (and so for general relativity) belongs solely to Einstein, but Hilbert's work also seems to me to be worth noting.

Hope that clears things up.

Robert E. Beaudoin

(snip)

I haven't seen a copy for many years. The story I used to hear was that only three people really understood the book.

-- glen

Hello Robert,

Thanks for the response. My interpretation of the OP's statement was Hilbert beat Einstein to the result and then Einstein stole all of the glory. Hilbert's approach is certainly notewothy since least action principles abound in physics and alternative mathematical methods often prove to be illuminating on their own[1]. However I suspect Hilbert was familiar with Einstein's result and therefore not only had the problem but also had the solution. This is quite different than working out a solution where the destination is unknown. But even if Hilbert found this solution without knowing the field equation (a great feat the principle of equivalence is bypassed yielding a theory without an obvious physical basis (The few references I've found so far give little to no detail). I don't have Wheeler handy. Einstein's approach is rooted in a physical basis. And today most who study his work celebrate his acheivements.

Clay

[1] Hamilton's modification to the LaGrangian method of classical mechanics turns out to be the usual approach in quantum mechanics.

Hi Clay,

Just in case it wasn't clear: I agree with you on all of this.

Bob Beaudoin

Hi,

I read somewhere that when Maxwell died, there were twenty "Maxwell's equations", and that it was Oliver Heaviside who reduced those down to the current-day four equations.

See Ya', [-Rick-]

Maxwell's equations were originally four _sets_ of integral equations, one in each set for one axis in space, for a total of 12. He also expresses the relations in quaternions and vector analysis (curl and all that). Dover has an unabridged two-volume set of "A Treatise on Electricity and Magnetism". I bought mine long ago. The set was $4. Reading it gives one much respect for the ancients.

Jerry

There are also Maxwell's relations which are fundamental in thermodynamics. The story has it that an eminent physicist, active in thermodynamics, once did a review of Maxwell's work which included a line that "Maxwell also did some work in electromagnetism".

...

The reviewer of Fred Astaire's Hollywood screen test opined that Astaire would be passable and added, "and he can dance a bit, too."

Jerry

I just watched him with Judy Garland in "Easter Parade" yesterday. I never really knew what "dancing like Fred Astaire" meant until I saw that movie. (And the costumes!!! ...)

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