[Bored chemist]

How do you think science work? It looks like your understanding is different than mine.

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OK, now, when you get to the experiment and you analyse the data and it just tells you "what happened is exactly what was predicted" where do you publish the results?
Is there a journal of "stating the obvious" or " stuff that anyone who understands the field would have guessed"?

[Bored chemist]

A simple Google search for limitations of Huygens' principle gives these answers.

Being able to read this (especially the bit in brackets) gives you an insight into why it's irrelevant.

Huygens' construction works (within it's field of applicability).

[alancalverd]

It works well enough that people have used it in the design of everything from microscopes to space telescopes, and I have used it in radio navigation (wavelength around 1000 m) and x-ray crystallography (10^-7 m). 

Even though some textbooks make a pig's ear of their derivation, if you use Huygens correctly as I have shown in this discussion, it predicts all the diffraction patterns you (and I) have seen.

And remember it's not a "principle" but a geometric construction. It does model the rectilinear propagation of light if you understand what you are doing with it. It does not purport to explain anything - it's geometry, not physics.

The folk who have found its "failings" seem to have all fallen into the trap of calling it a principle and thus deluding themselves into thinking it might predict things that it can't.  The only tool I can think of that can really do two unrelated tasks well is the Kalashnikov rifle, which incorporates a beer bottle opener, by design. 

[hamdani yusuf (OP)]

Being able to read this (especially the bit in brackets) gives you an insight into why it's irrelevant.
Quote from: Bored chemist on Today at 10:35:00
Huygens' construction works (within it's field of applicability).

If we follow your assertion above, we would find no need for better alternatives to geocentric and phlogiston models.

[hamdani yusuf (OP)]

Not sure that's true of any scientific thory given that science has only been around for a few centuries.

Have you read about Dalton's model?

[hamdani yusuf (OP)]

It works well enough that people have used it in the design of everything from microscopes to space telescopes, and I have used it in radio navigation (wavelength around 1000 m) and x-ray crystallography (10-7 m). 

Even though some textbooks make a pig's ear of their derivation, if you use Huygens correctly as I have shown in this discussion, it predicts all the diffraction patterns you (and I) have seen.

Geocentric model works well enough for many applications.

Which textbooks do you think explain it correctly?

How does it explain non-diffractive edges?

[hamdani yusuf (OP)]

And remember it's not a "principle" but a geometric construction. It does model the rectilinear propagation of light if you understand what you are doing with it. It does not purport to explain anything - it's geometry, not physics.

The folk who have found its "failings" seem to have all fallen into the trap of calling it a principle and thus deluding themselves into thinking it might predict things that it can't.  The only tool I can think of that can really do two unrelated tasks well is the Kalashnikov rifle, which incorporates a beer bottle opener, by design.

It's correctly called Huygen's principle.
https://en.m.wikipedia.org/wiki/Huygens%E2%80%93Fresnel_principle

every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere.[1] The sum of these spherical wavelets forms a new wavefront.

The principle can be mathematically expressed.

Not every principle represents physical reality.

My disagreement is in applying the principle for all kinds of waves, and assuming that light behaves just like mechanical waves. Using surface water wave analogy to introduce the concept of wave diffraction for light is fine as long as the limitations and differences are also clearly mentioned.

[alancalverd]

Whatever you call it, the construction still gives you the correct answer AFAIK for all wave systems. There is no point in using an analogy to describe something you can see anyway. This silliness seems to have arisen in the 1980s with the advent of wave tanks in school laboratories and the general loss of rigor in the science curriculum.

[Bored chemist]

If we follow your assertion above, we would find no need for better alternatives to geocentric and phlogiston models.

That conclusion is a non sequitur.

Have you read about Dalton's model?

Yes; it was pre-scientific, and it showed.

How does it explain non-diffractive edges?

You still have to tell us what these are.

[hamdani yusuf (OP)]

Have you read about Dalton's model?

Yes; it was pre-scientific, and it showed.

Is Bohr's model pre-scientific?

[hamdani yusuf (OP)]

How does it explain non-diffractive edges?

You still have to tell us what these are.

I better show you.

video #4 Non-diffractive Obstacle

I have uploaded new video showing diffraction in microwave frequency.

Basically, the experiment result leads us to conclude that diffraction comes from the material blocking the microwave path. When the obstruction is opaque enough, we find no diffraction. It's similar to my experiment using laser showing non-diffractive obstruction.

This result is not widely known yet.
 

[Bored chemist]

Some theories which survived for thousands years turned out to be false.

Not sure that's true of any scientific thory given that science has only been around for a few centuries.

Is Bohr's model pre-scientific?

Why would it be relevant since it hasn't survived for thousands of years?

[hamdani yusuf (OP)]

Whatever you call it, the construction still gives you the correct answer AFAIK for all wave systems. There is no point in using an analogy to describe something you can see anyway. This silliness seems to have arisen in the 1980s with the advent of wave tanks in school laboratories and the general loss of rigor in the science curriculum.

There are some significant differences between light wave and mechanical waves like sound, water surface,  or slinky. Light wave propagates fastest in vacuum, while mechanical waves need a medium.

[hamdani yusuf (OP)]

Some theories which survived for thousands years turned out to be false.

Not sure that's true of any scientific thory given that science has only been around for a few centuries.

Is Bohr's model pre-scientific?

Why would it be relevant since it hasn't survived for thousands of years?

because you said this about Dalton's model.

Yes; it was pre-scientific, and it showed.

[theThinker]

Whatever you call it, the construction still gives you the correct answer AFAIK for all wave systems. There is no point in using an analogy to describe something you can see anyway. This silliness seems to have arisen in the 1980s with the advent of wave tanks in school laboratories and the general loss of rigor in the science curriculum.

There are some significant differences between light wave and mechanical waves like sound, water surface,  or slinky. Light wave propagates fastest in vacuum, while mechanical waves need a medium.

There are not just "some significant differences" between light wave and mechanical waves like sound, water surface, etc...The difference is like the difference between heaven and hell!

Light in contemporary physics assumes it propagates through "empty" space whereas all mechanical waves are waves in material mediums. The difference has no comparison. Light would be just another wave only if we reintroduce the luminiferous aether of space, but mainstream physics is not willing to consider this alternative.   

[Kryptid]

Light would be just another wave only if we reintroduce the luminiferous aether of space, but mainstream physics is not willing to consider this alternative. 

It was considered. When experiment failed to find it, it was abandoned.

[evan_au]

A bit of a tangent...

light in contemporary physics assumes it propagates through "empty" space whereas all mechanical waves...

Gravitational waves also travel through empty space.

why do a lot of people confuse between interference and diffraction?

When people talk about interference & diffraction, they are talking about continuous waves.

The gravitational wave events we can detect today are transients*
- But their path can still be bent by massive objects in space (eg black holes, galaxies or galaxy clusters)
- And their arrival times on Earth phase-shifted relative to each other
- Would you call this interference or diffraction?

Astronomers have looked for gravitationally-lensed gravitational wave events, without success:
https://www.ligo.org/science/Publication-O3aLensing/

*We might be able to detect more continuous gravitational waves when LISA is launched. Then the distinction between interference and diffraction might become more relevant.
https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna

This tangent was triggered by a conversation on a rather quirky astronomy podcast:
https://spacenutspodcast.com/podcast/space-nuts-or-astronomy-space-and-science-news/episode/03-space-nuts-best-of-2022-first-image-from-the-jwst

[theThinker]

@evan-au, I only have elementary physics background - gravitational waves are way beyond me.

But if you want an "opinion", I can easily provide one. 

[hamdani yusuf (OP)]

When people talk about interference & diffraction, they are talking about continuous waves.

The gravitational wave events we can detect today are transients*
- But their path can still be bent by massive objects in space (eg black holes, galaxies or galaxy clusters)
- And their arrival times on Earth phase-shifted relative to each other
- Would you call this interference or diffraction?

As I explained in my video, the distinguishing characteristic of interference is the existence of dark area produced by destructive interference. While defining characteristic of diffraction is bright spot on the shadow area.
Some experimental setups may have both of them, such as single slit and double slit experiments.
Some other experiments only show one of them, while some others show none of them.

[Bored chemist]

because you said this about Dalton's model.

I know I said that.
So what?

You said "Some theories which survived for thousands years turned out to be false.".
And that may be true.
But they were not scientific theories, so they are barely relevant on a science site.