[Bored chemist]

And in this article, no mention of diffraction is found.

Does it mention beer?
Are you surprised that not all articles mention all words?

[hamdani yusuf (OP)]

This article shows the difference between Reflection,-Refraction,-and-Diffraction.

Why did you post it?

To remind you that not every kind of wave spreading is called diffraction.

[Bored chemist]

This article shows the difference between Reflection,-Refraction,-and-Diffraction.

Why did you post it?

To remind you that not every kind of wave spreading is called diffraction.

How did you come to the mistaken conclusion that I had said, or even thought, that it was?

[hamdani yusuf (OP)]

How did you come to the mistaken conclusion that I had said, or even thought, that it was?

From your previous posts.

Why do you call it diffraction?

It was called diffraction before I was born.

How much is the divergence caused by diffraction,

It depends.

All light beams are (eventually) divergent- because of diffraction.

[Bored chemist]

There is no logical path from what I said to what you seem to think it means.
Diffraction was called diffraction long before I was born.
So it isn't me who called it diffraction.

Whether a beam of light is spread more by diffraction than by the curvature of the mirror will depend on circumstances.
The spread is determined both by the mirror and by how narrow the beam is.
If you make the beam narrow enough it will result in more spreading than the mirror.

Any beam of light starts off converging, diverging or parallel.
But a converging beam comes to a focus (like I showed in the picture) and then diverges.
A diverging beam is already diverging.
So the only possibility that is left is a parallel beam.
but that diverges too- because of diffraction.
So, diffraction means that all beams diverge in the end.

You need to get to grips with the fact that it is you who doesn't understand science- because you refuse to study it.

[hamdani yusuf (OP)]

The spread is determined both by the mirror and by how narrow the beam is.
If you make the beam narrow enough it will result in more spreading than the mirror.

I've seen many people confused between diffraction and interference. But you are the first one I know to confuse between diffraction and curved mirror reflection.

https://en.wikipedia.org/wiki/Diffraction
Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening. It is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. Italian scientist Francesco Maria Grimaldi coined the word diffraction and was the first to record accurate observations of the phenomenon in 1660.

You seem to refer to this formula when saying that narrower light beam spread more.

But you need to remember that d here is the width of the slit, not the width of the light beam itself. In my example above, the width of the incoming slit is much wider than the width of the light beam. The light beam doesn't interact with the edges of the slit.

[Bored chemist]

But you are the first one I know to confuse between diffraction and curved mirror reflection.

THE ONLY ONE WHO IS CONFUSED IS YOU.

[Bored chemist]

But you need to remember that d here is the width of the slit, not the width of the light beam itself. In my example above, the width of the incoming slit is much wider than the width of the light beam. The light beam doesn't interact with the edges of the slit.

The problem isn't what I need to remember. The thing here isn't that I have forgotten that you said that the beam is smaller than the hole in the mirror.
The problem is that you have forgotten what that means. How did the light get made into a beam?

Imagine a beam of visible  light from a distant star comes in through my large open window and hits a perfectly flat mirror exactly 1 cm in diameter and is reflected to form a circular spot of light on a screen at a distance of 1 metre.
How big is the spot of light?
Is it
(1) smaller than 1cm
(2) exactly 1 cm
(3) bigger than 1cm?


The thing here isn't that I have forgotten that you said that the beam is smaller than the hole in the mirror.
The problem is that you have forgotten what that means.

[hamdani yusuf (OP)]

But you are the first one I know to confuse between diffraction and curved mirror reflection.

THE ONLY ONE WHO IS CONFUSED IS YOU.

Somehow you think that flat mirrors don't have the problem.

It would be a math problem if the mirror was a polygon.

Why does it stop being math problem when the number of sides of the polygon is increased toward infinity, i. e. becomes a  circle?

Because it stops working.
If a beam of light hits a curved surface, it's no longer a beam.

[Bored chemist]

But you are the first one I know to confuse between diffraction and curved mirror reflection.

THE ONLY ONE WHO IS CONFUSED IS YOU.

Somehow you think that flat mirrors don't have the problem.

It would be a math problem if the mirror was a polygon.

Why does it stop being math problem when the number of sides of the polygon is increased toward infinity, i. e. becomes a  circle?

Because it stops working.
If a beam of light hits a curved surface, it's no longer a beam.

I started off by pointing out the most obvious reason that you are wrong.
Have you accepted that you are wrong yet?

[hamdani yusuf (OP)]

I started off by pointing out the most obvious reason that you are wrong.

What's obvious is that you are being inconsistent. You bring up diffraction problem to curved mirror to dismiss the solution, while at the same time ignoring diffraction for flat mirror.

[hamdani yusuf (OP)]

perfectly flat mirror exactly 1 cm in diameter

I'm not sure if you refer to mathematical abstractions or real physical model.

[hamdani yusuf (OP)]

My research 25 years ago was presented as mathematical problem instead of physical one. At the end of the paper I mentioned the connection with complex numbers. The video above reminds me of that.

[Bored chemist]

while at the same time ignoring diffraction for flat mirror.

The whole point of this

Imagine a beam of visible  light from a distant star comes in through my large open window and hits a perfectly flat mirror exactly 1 cm in diameter and is reflected to form a circular spot of light on a screen at a distance of 1 metre.
How big is the spot of light?
Is it
(1) smaller than 1cm
(2) exactly 1 cm
(3) bigger than 1cm?

was to get you to realise that diffraction also applies to flat mirrors.
Unfortunately, you failed to answer it.
Because you didn't do the work, you now still don't understand.

If you don't want to understand, why do you keep asking?
Are you a troll?

[Bored chemist]

I'm not sure if you refer to mathematical abstractions or real physical model.

Imagine...

[hamdani yusuf (OP)]

was to get you to realise that diffraction also applies to flat mirrors.

Then why did you write this?

It would be a math problem if the mirror was a polygon.

And this?

If the beam has a finite width (and diffraction means it will have) them you need to consider the "focussing" effect of the curved mirror.
Essentially the light will be scattered in every direction.
Incidentally, unless the mirror has infinite mass, the wavelength will also be scrambled.

Your last sentence above is especially suspicious.

[hamdani yusuf (OP)]

There is no angle using a circle, the light remains linear.

It seems I missed reading this comment. What do you mean by "the light remains linear"?

[Bored chemist]

Your last sentence above is especially suspicious.

Did it lead you to suspect that I know more than you?

If someone who makes a living as a scientist says something about science, it is worth considering that it is correct, rather than assuming that it isn't.

[Bored chemist]

Then why did you write this?

I was making the point that maths problems don't have to obey the laws of physics.

[hamdani yusuf (OP)]

Your last sentence above is especially suspicious.

Did it lead you to suspect that I know more than you?

If someone who makes a living as a scientist says something about science, it is worth considering that it is correct, rather than assuming that it isn't.

That's a logical fallacy called appeal to authority.
It is possible that you're overrated.

Incidentally, unless the mirror has infinite mass, the wavelength will also be scrambled.

It implies that the mirror has infinite mass, the wavelength will not be scrambled.