Fizyka dla każdego

김예진 Kim Ye Jin (KYJ)

Hi, I’m one of the students who listen to your lecture in yesterday.
I sat in the front row and  played the role of “moon” during the lecture.
I don’t know if you’ll remember me.
I can not speak English well. Please read to consider that.
I learn about the surge in physical time these days.
I learned about the constructive interference and destructive interference.
And I was curious. Since light is a type of wave, constructive interference and destructive interference occur, then light can be also offset?
Of course, because the light is proceeding continuously, Shortly after the cancellation, the light continues and will appear again in its original form.
But Think again, Light is a particle, and a form of energy. Therefore, it would not be possible to disappear by the law of conservation of energy?
At that moment, Where the light energy is going?
If the energy is converted into other forms, Is it possible that light disappear?
In other words, In fact, by using the destructive interference, and If we change the light energy in a different form through the operation of the surroundings, The light could disappear?
We can see an object through the reflection of light. If so, it would be applied to objects?

What all I have said so far is just my imagination. so it may be absurd question.
But I'm really curious about it.

Thanks for reading. thank you.

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Grzegorz Karwasz (GK)

Hi 김예진

You put very good questions.
1. Interference of light was observed by Young (in 1808) when he summed two beams, coming from the same light divided into two by apertures. He observed dark and white lines on the screen. The essential point is, that light is a wave, changing very rapidly (10-17 s). To have a permanent black-white lines the two beams mus be identical, i.e. to oscillate with the same frequency.
Now, with lasers, it is easier to do.

2. The dark line is when the two beams arrive exactly opposite: one is maximum and other is minimum. So the light can be offset.

This happens also with jet engines of military aeroplanes flying over Gunsan. You hear them loud the whole day, but in the night they have some system that makes interference of sound waves and they fly close without being heard. Later I will send you a paper on this subject.

3. What happens with the energy is a good question: I do not know and I must think. Ligth delivers its energy when it is stopped (i.e. absorbed). But I have to think on it more.

4. Light is a particle in a sense, that its energy is sent in small portions. I include you a picture in which I explain it to Polish secondary school students. Some people say that photon is just a small portion of the electromagnetic wave. Photon CAN be considered a particle, but it has no mass and you can not stop it (it always travels with the velocity of light and dies, when it stops).

5. By interference of light you can make objects invisible. Scientists work on such materials: these materials have special construction and are called meta-materials. For this moment it is still science-fiction, but maybe during your life it will come true.

https://en.wikipedia.org/wiki/Metamaterial_cloaking

Write me with more questions if you like and thank you for playing Moon.

Best greetings
Grzegorz Karwasz        

    

 

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GK

Dear Kim Ye Jin,

how are you? Sorry for not writing earlier, but this is the beginning
of the academic year in Poland and I have a lot of work with my Polish
students.

I asked several my colleagues, professors, on the interference of
light and nobody is able to answer. You have found a really difficult
question! In normal interference, it means coming from two small
apertures, in dark place there s no energy and in bight place there is
double of energy. The sum is conserved.

I give you a link to such an experiment with electrons (which also
behave as a wave).
https://www.youtube.com/watch?v=tZwm9CKE-60
(Hitachi experiment diffraction electrons)

Your question will wait for answer.

Later today I will put on internet some pictures from my lecture.

http://dydaktyka.fizyka.umk.pl/nowa_strona/?q=node/586

It will be night in Korea, so please have a look on them tomorrow.

Best greetings
Prof. Grzegorz Karwasz

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KYJ

Thank you so much for your care.
I try to find the answer, too.

I saw the writing of Korean doctors at the University of Tokyo.
It was related to the energy shift of the destructive interference.
I seem to find the answer if I explore more about it.
Of course, not sure :). But obviously I seem to be able to get a lot of things.

If I find the answer, I want to tell you well.
But I am worried my English was terrible.

I would also expect that you will find the answer.
Thanks and respect you always.

Best greetings

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GK

Dear Kim Ye Jin,

as you see from the new page
http://dydaktyka.fizyka.umk.pl/nowa_strona/?q=node/591
we found the solution of the problem you asked. But it was not easy. The explanation is long and comes from the best laboratory in the world. So you question was really difficult. Congratulations for this!

Tell also you parents, that I made you congratulations.

Physics is such a subject, that principal laws, like conservation of energy are always fulfilled. Theoreticians find these solutions in one way, experimentalists see that laser mirrors behave in another way, that the energy is conserved. What is great in Physics that theory agrees with experiments.

You have talent for Physics, but many professions, like medicine, are also important.

If it happens that you come to Europe, please visit Poland. I will show you my laboratories in Atomic Physics.

If you give me the postal address (for example of your school) I will send You a disk on Modern Physics.
http://dydaktyka.fizyka.umk.pl/Physics_is_fun/html/index-en.html

Best regards to Your Parents
Grzegorz Karwasz
 

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KYJ

I just watched the video you sent.

I am delighted to finally resolve the question.

 

I really thank you. :) 

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