What is light ? (Atomic Physics Video Series – Part 2)
Light… What is it? What is it made of?
How does it interact with atoms?
The first video of this series discussed the energy of an atom within the scope of the model defined by Niels Bohr. This model describes an atom as being a central nucleus with electrons in circular orbit around it.
In this video, we came to realize that when we talk about the energy of an atom, we are actually discussing the energy of its electrons. We will prove in detail in episode 4 that for a hydrogen atom (1 electron in orbit around a nucleus made of a single proton), the radius of the electron’s orbit is directly linked to the energy of the atom. Change the orbit of the electron, and the energy of the atom changes accordingly.
But how can this be done? How can one change the energy of an atom?
Well, this can be done with light. Light is a carrier of energy. We will see in episode 3 that if the energy carried corresponds exactly to the energy required to move an electron from an orbit to the other, the light will get absorbed by the atom!
It goes both ways: an atom can emit light carrying the exact amount of energy released when an electron moves back from an orbit of high energy to an orbit of low energy.
But before we go in detail about that, it is important to know what light is actually made of:
Is it a wave? Is it a particle?
Click the video below and get the answer!
Enjoy the ride!
This video series aims at providing an introduction to the quantum world to non-scientists and high school students preparing for their high school exams.
If you wish to deepen your understanding, please explore @lemouth 's quantum mechanics series. A relevant chapter to this specific video is Quantization of the electromagnetic radiation and the birth of the photons.
Credits: Friezes and the main illustration are based on illustrations found on Pixabay.
Hi,
I’m @muphy,
My life revolves around music production, teaching sciences, and discovery through travel.
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Finally, I took the time to watch this video. This was on the to-do list... Sorry for the delay. I guess you know how it works with free time :p
This video is actually perfect for the class of students it targets. It is extremely well done, I must say. Very visual (we can say that, cf. the topic :p) and very understandable for students.
I have one (super minor) remark (that you may actually want to ignore). Strictly speaking, the concept of photons was proposed by Einstein to explain the photoelectric effect and proved by Compton who demonstrated the 'particle' behavior of photons. Starting from the Compton experiment in 1923, the concept of photons was finally fully accepted by the scientific community. And the name photon itself was invented by Lewis in 1926.
PS: we say a quantum of energy, don't we, not a quanta? :D
You are right, 1 quantum, 2 quanta, I need to brush up on my Latin, lol!
When I was recording "What is Light", the train of thoughts was written down (i.e. the scenario) but not the text details, (I was kind of improvising): And I remember a little uneasy feeling when saying: He (Einstein) called them photons. I should of said something more like, "later, these were called photons..." During edition, I thought of making a text box correcting this as I do when I say a mistake and discover it later... Yet, it would have just added unnecessary heaviness to the message in the video... so left it that way...
Thank you for your great remark, I didn't really know who invented the term "photon", now I do :-)!
And thank you for watching these videos. It's so cool to get some feedback from an active researcher in this field.
By the way, do you actually carry out research at the LHC? If so, I want to come and visit one day!
(I used to carry out some of my experiments in High Pressure High Temperature X-Ray crystallography at the ESRF synchrotron when I was in academia, and I loved to have these huge multi-billion dollar machines at the service of my fingertips :-) )
I am a theorist, so that strictly speaking, I am not running the machine. But the LHC results are used in my every-day research, I am part of the CMS collaboration (as a theorist), and I am (kind of) regularly going to CERN. For the visit, the best chance may be 2019. The machine will be shut down for upgrades, and there will be ways to go down in there and see the detectors.
Grenoble! This is where I did my PhD (at the LPSC, the former ISN, not too far from the ESRF). When where you there?
2019? I'm in!
I would absolutely love to wonder where the antimatter went near the LHCb, walk around a couple of extra dimension, or maybe bring some dark matter as souvenir thanks to ATLAS or CMS, or swim in a sweet quark-gluon plasma in ALICE .
I did a PhD in solid state chemistry in Bordeaux in the late 90s. During that time, I met a young spanish researcher in Lyon that was very interested in my project, we became good friends (and we still are).
He worked at the ESRF for 4 years after his PhD, so he could opened doors for me, and he did: I was able to get some beam time to carry out some X-Ray crystallography measurements using the synchrotron light. I was also permitted to work at the ILL (on the same campus): There, I used the Inelastic Neutron Diffusion set up to study the phonons spectra in the material I was studying. Fantastic results :-). We even submitted to Nature, but ended up in PRL (which is pretty cool too).
Then, I left for Hiroshima university for 2,5 years. They had a great high pressure high temperature synthesis equipment, allowing me to develop further my subject. I was given access to Spring8 (The Japanese ESRF). For Spring 8, it was like you, I would participate in the interpretation of the data, but not in gathering the data. I also managed to combine my holidays back in France with beam time at the Lure in Paris, to carried out some further crystallography experiments with my Spanish friend.
I remember these years as being a lot of fun. Mind you, even if it is a totally different area, I am having a lot of fun today too :-).
When you write on Steemit, I suppose you discuss the topics explored with the CMS detector in general. What is actually your specific area?
Let's see what I will be able to organize in due time ^^
Except this, I would only say a word: wow! What a story. Why have you left? I supposed you have been kind of forced to by some lack of positions?
I don't write much about CMS to be honest. My interactions with CMS consist of a tiny fraction of my activities. I am more writing about theory papers I read on particle physics, astrophysics and cosmology, my own research once in a while and generalities about my field and physics in general. I could however write about LHC detectors and things like that. Explaining how this works. May be a good idea for a future post :)
I am mostly working on beyond the Standard Model phenomenology, both at the level of the LHC and cosmology/astrophysics (most on the dark matter side). Trying to understand new phenomena, how to see them and why we didn't see them that far. In addition, I am involved in precision calculations for getting better theory predictions (regardless of the theory), and I am finally also a developper of a bunch of computer programs and methods for high-energy physics. As I said above, on my free time, I participate on a CMS analysis once in a while. And this is just for the research part (I won't mention teaching and administration as this answer is already long enough :p ).
Hey @lemouth, The wow is reciprocal!
You are involved in quite a lot of interesting activities too. I wonder many times also what is the reach of the standard model, and where, one day we will see it crack open. However, I have to admit that it is quite an amazing theory in terms of predictive power. A little like in music, the Fender Strat electric guitar, designed in 1954, and never in need of a shape update since: the designers got it right from their first go…
Yeah, I didn’t really leave academia by choice. When I came back from Japan, the plan was that I’d work as an enseignant chercheur in a Physics lab with my buddies in Lyon (Uni Claude Bernard). I even had an office assigned to me and a grant accepted for 1 Million French francs to buy and set up a high pressure high temperature press in the lab, so I could continue working on my research projects. When I came back, budget cuts to research were decided by the government: all new position openings were either cancelled or suspended. Mine was cancelled before I even had worked my first day. I must say, that professionally, this was a painful period in my existence.
I turned to Industry, where I found a job in the Netherlands as a researcher in water chemistry (something quite different!). The 5 first years were interesting: there was a totally new field for me to explore, but the following 6 years were just a waste of time, the topic started to bore me because there was no possible vision for my work in this environment, even with great results. Leaders were just ass-holes, only caring about profitability and not doing anything good for the planet and the community as a whole, and this despite huge opportunities to do so. What is funny, is that my direct boss was in full agreement with that assessment. We both left the company the same year.
So in my early 40s, I started a new professional life, as an independent :-). This mid-life crisis, lead me to carry out a good move: I am really doing what I love now for a living, teaching sciences and producing music. I do have some nostalgia though for my academic years (and definitely not for my industrial ones haha!)
There are strong signs telling we actually need to go beyond. You may like for instance to read this post of mine where I give some of the reasons. However, there is no guarantee new physics is waiting for us at the LHC. Nature may just have fun of us and wait for the building of a more powerful accelerator.
(Therefore, the guitar is better.)
I am said to read your story, but happy also to see you manage to find a way i which you are happy. This is what matters the most!
Your students are lucky to have someone like you as a teacher, not only as I can tell from your blog and videos, but also it is not everyday that someone can benefit from the experience from people who were in contact with the academy.
For the fun, my first PhD student (who was very good) has left physics to work in an IT company in Amsterdam :)
Thanks you so much for your kind words!
I try to be the teacher I would have loved to have when I was in my late teens. And it seems to be working in terms of my student's rising interest for physics and their performances at school :-).
Some of my previous students that hated physics when I started with them made Physics their major at Uni, and they are still excited about it. Mission accomplished!
I am more pessimistic than you are. Although we should keep searching at the maximum of our abilities. We will reach a limit in energies we can produce with accelerators, and some knowledge will always stay out of reach.
Unless we start thinking differently and bigger to get answers to our questions in ultra high energy physics. For example, finding a way to study directly collisions of particles in accretion around a black hole (which I do not see happening soon, lol).
Yet we still have some way to go before technological limits. What will it be in your opinion: 100TeV? 1PeV?
nice
Trying to explain light without understanding and explaining the aether is a futile task. As a result, the current "scientific" explanation of light doesn't do a very good job of explaining the phenomena we see light do.
Like, the double slit experiment. Where, a single photon will go through both slits and interfere with itself. Or, if there is an observer, (at any time, past or future) the photon will only go through one slit.
Nonsense as usual I see.
Yep, materialistic science is nonsense. It has been disproven way too many times, but it it is still staunchly supported by all those college professors.
No, what you are talking about is nonsense. As is always the case, I havent seen you respond with anything resembling a coherent logic based comment in the year or so I've seen you rambling about.
I realize this comment is ad hominem, but it doesn't much matter. You are going around talking about aether. And insulting actual physicists and professors. Complete hog wash.
If what you consider "logic" is that it came from a science book, then you are correct.
In order to understand physics (electrical - magnetics) I have had to throw away all I have learned. To throw out the entire science book used in today's college courses.
What I am saying is more correct than what is "common scientific knowledge", but it won't become apparent for probably a generation.
So, to you, I will always sound like a lunatic.
Here is an example that you should know very well:
Nikola Tesla was in a college class and talked about making an AC motor. The professor said it couldn't be done, and took all that day to explain to the class why it "scientifically" couldn't be done.
Fortunately, Tesla didn't take that to heart, and kept working on creating an AC motor. The results is our modern world.
What I am doing is no less painful.
Lol, Tesla you are not.
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