[alright1234 (OP)]

Then why is Fresnel's diffraction mechanism used currently in college text books?

(1) Fresnel diffraction does not require an aether.

This statement is incorrect since Fresnel's diffraction is based on a ether, composed of matter.

[alancalverd]

The Fresnel equations are purely geometric and apply to all waves, in a medium or no medium, since they do not invoke any explicit properties of a medium.

One can only assume that the "college textbooks" at Harvard are out of date or written by someone who never understood Fresnel's mathematics.

[Kryptid]

This statement is incorrect since Fresnel's diffraction is based on a ether, composed of matter.

If that's true, then provide a quote from a modern textbook that supports that claim.

[Bored chemist]

Then why is Fresnel's diffraction mechanism used currently in college text books?

(1) Fresnel diffraction does not require an aether.

This statement is incorrect since Fresnel's diffraction is based on a ether, composed of matter.

I know Wiki isn't the ultimate reference, but how come the page about this
 https://en.wikipedia.org/wiki/Fresnel_diffraction
doesn't mention ether?

It seems that Fresnel diffraction does just fine without it.

[alright1234 (OP)]

"APPLICATIONS OF HUYGENS' PRINCIPLE TO THE PHENOMENA OF DIFFRACTION

43. Having determined the resultant of any number of trains of light-waves. I shall now show how by the aid of these interference formulae and by the principle of Huygens alone it is possible to explain, and even to compute, all the phenomena of diffraction. This principle, which I consider as a rigorous deduction from the basal hypothesis, may be expressed thus: The vibrations at each point in the wave-front may be considered as the sum of the elementary motions which at any one instant are sent to that point from all parts of this same wave in any one of its pervious* positions, each of these parts acting independently the one of the other. It follows from the principle of the superposition of small motions that the vibrations produced at any point in an elastic fluid" (Fresnel, § 43).

[Bored chemist]

Showing that the maths which applies to waves in an elastic fluid is similar to the maths used in the propagation of light does not show that the propagation of light takes place in an elastic fluid.

[alright1234 (OP)]

"21. If we call λ the length of a light-wave, that is to say, the distance between two points in the ether where vibrations of the same kind are occurring at the same time" (Fresnel, § 21).

Make another wish.

[Bored chemist]

"21. If we call λ the length of a light-wave, that is to say, the distance between two points in the ether where vibrations of the same kind are occurring at the same time" (Fresnel, § 21).

Make another wish.

What?
Nobody is questioning the fact that Huygens and Fresnel thought there wan ether.
So, obviously, they wrote stuff in terms of what was thought at the time.

Both of them were safely dead before the MM experiment showed that there was no ether.

What you have shown is that science moved on.
Why don't you move with it?

[alright1234 (OP)]

They did not move on since Fresnel's diffraction mechanism is still used in college physics text books.

[Bored chemist]

They did not move on since Fresnel's diffraction mechanism is still used in college physics text books.

But... and this is the bit you missed... the mechanism and calculations still work without the ether.
So, when we found out that the ether isn't real, we stopped including that bit in the books.

What else would you expect to have happened?

[alright1234 (OP)]

The ether is part of the mechanism that effect is being represented with the mathematics.

[Bored chemist]

The ether is part of the mechanism that effect is being represented with the mathematics.

Yes, but the maths works just fine without it.

[alright1234 (OP)]

How can the mathematics work without a mechanism?

[Bored chemist]

How can the mathematics work without a mechanism?

What is 6 times 7?
Quite a lot of maths applies to things that have little or no physical meaning.

You might need a mechanism to understand things; maths doesn't.

[alright1234 (OP)]

You cannot apply mathematics to an entity that you have no idea what the mechanism or structure is.

[Kryptid]

"APPLICATIONS OF HUYGENS' PRINCIPLE TO THE PHENOMENA OF DIFFRACTION

43. Having determined the resultant of any number of trains of light-waves. I shall now show how by the aid of these interference formulae and by the principle of Huygens alone it is possible to explain, and even to compute, all the phenomena of diffraction. This principle, which I consider as a rigorous deduction from the basal hypothesis, may be expressed thus: The vibrations at each point in the wave-front may be considered as the sum of the elementary motions which at any one instant are sent to that point from all parts of this same wave in any one of its pervious* positions, each of these parts acting independently the one of the other. It follows from the principle of the superposition of small motions that the vibrations produced at any point in an elastic fluid" (Fresnel, § 43).

What is your source for this? What year was this published in? Before you answer, remember that I specifically asked for a quote from a modern textbook. If you got this from a textbook published before the year 2000, I consider that a failure of the very simple task I gave you.

You cannot apply mathematics to an entity that you have no idea what the mechanism or structure is.

Of course you can. You don't have to know what makes the Sun hot in order to measure its temperature.

[alright1234 (OP)]

"APPLICATIONS OF HUYGENS' PRINCIPLE TO THE PHENOMENA OF DIFFRACTION

43. Having determined the resultant of any number of trains of light-waves. I shall now show how by the aid of these interference formulae and by the principle of Huygens alone it is possible to explain, and even to compute, all the phenomena of diffraction. This principle, which I consider as a rigorous deduction from the basal hypothesis, may be expressed thus: The vibrations at each point in the wave-front may be considered as the sum of the elementary motions which at any one instant are sent to that point from all parts of this same wave in any one of its pervious* positions, each of these parts acting independently the one of the other. It follows from the principle of the superposition of small motions that the vibrations produced at any point in an elastic fluid" (Fresnel, § 43).

What is your source for this? What year was this published in? Before you answer, remember that I specifically asked for a quote from a modern textbook. If you got this from a textbook published before the year 2000, I consider that a failure of the very simple task I gave you.

You cannot apply mathematics to an entity that you have no idea what the mechanism or structure is.

Of course you can. You don't have to know what makes the Sun hot in order to measure its temperature.

Fresnel, Augustin. Memorie su la Diffraction de la Lumiere. French Academy of Science. 1819.

Fresnel is using wave interference yet there is no ether that forms the waves. So you cannot mathematically depict something that does not physically exist.

[Kryptid]

Fresnel, Augustin. Memorie su la Diffraction de la Lumiere. French Academy of Science. 1819.

So I was right. You failed. Try again.

So you cannot mathematically depict something that does not physically exist.

Engineers do this all the time whenever they design something that hasn't been built yet.

[alright1234 (OP)]

Fresnel, Augustin. Memorie su la Diffraction de la Lumiere. French Academy of Science. 1819.

So I was right. You failed. Try again.

So you cannot mathematically depict something that does not physically exist.

Engineers do this all the time whenever they design something that hasn't been built yet.

Like the Apollo 11 mission?

[Kryptid]

Like the Apollo 11 mission?

Red herring fallacy.