Understanding Light and Matter Interaction

In the last part, we looked at how photons are emitted and how this creates an emission and absorption spectrum. In this part, we will examine how light or more specifically electromagnetic radiation can interact with matter and what fingerprint these interactions leave behind.

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00:00 Introduction
00:20 Collisional / Pressure Broadening
02:02 Photoelectric Effect
03:12 Thomson Scattering
04:06 Compton Scattering
04:40 Inverse Compton Scattering
05:03 Double and Multiple Compton Scattering
05:21 Raman Scattering
05:37 Rayleigh Scattering
06:22 Mie Scattering
06:52 Doppler Shift
07:18 Refraction
08:37 Reflection
09:40 Pair Production
10:10 Photodisintegration
10:44 Photofission
11:05 Dispersion Measure
11:43 Whistler Mode
12:10 Cherenkov Radiation

[Sulucnumoh]

Dude your stuff is so technical and so densely packed with info I watch ones like this several times to fully absorb. Thanks for all you do. Gnosis

[revcrussell]

I teach this stuff and this is the best explanation of Rayleigh scattering I have ever heard. Missing some important stuff around photoelectric effect (e.g. that the entire photon energy is used to liberate the electron) and pair production (e.g. why it has to occur "near" a nucleus). The way you defined it, photodisintegration and photofission are effectively the same thing.

[Makapolu]

Thank you for the explanations of these different phenomena.

[MrHichammohsen]

I think i should watch this 10 times to really appreciate it! Thank you Gareth for this mind-blowing video.

[dejablueguitar]

Your concepts/insights shine a LOT of light on the EU view of the universe! Love your channel and your content! One of my Top Shelf “gotta watch” content creators and lovers of science!

[chrisfontenot]

This was your Magnus opus. BRAVO, Gentlemen. You're correct, there are other theories to consider.

[SuperSquark]

I'm keeping this as a treat for when I'm more awake.

[mcnaugha]

This should be retitled “The latest lesson for mainstream astronomers and cosmologists” to see if they can resolve these facts with their current explanations for their observations.

[Marcusstratus]

That green image of resonant scattering is amazing

[digbysirchickentf]

Thanks for explaining reflections, makes much more sense now.. cheers.

[philoso]

Thanks Gareth. This episode is quite collective and an eye opening piece. Every second of this video worth hours of my time in searching it alone.

[waelfadlallah]

Excellent explanation!
The beautiful thing about this video that it can be watched more than once. Keep it up :)

[waelfadlallah]

I have one suggestion that is related to what have been discussed till now which is the interaction of light with a complex molecules such as for example the activation of vitamin D in skin by light or the protective effect of sunscreens

[hamdaniyusuf_dani]

Many behaviors of light such as reflection, refraction, diffraction, interference, and polarisation can be demonstrated more clearly using longer wavelength like radio and microwave. That's because the shape of the interacting materials can be easily seen and even manipulated to produce some desired effects.

[keithb]

Another awesome presentation as usual. This is the first and only presentation I have seen that even begins to explain the details involved in a way that can help me understand what I could never understand about flight behavior no matter how many of the other explanations I reviewed and red I admit I cannot keep up with the details and the extreme complexity even though your explanations are excellent and clear and concise. I will have to watch this one probably a couple of dozen times before I begin to really understand.

[stephanieherman]

People told me of the importance of daily meditations and sports. I mean it certainly helps. But it is way more important to watch this video every day :-) Thanks for this great content!

[jezzamobile]

Wow. Very listenable bite-size nuggets giving quite an overview perspective! Top notch 👍

[RIXRADvidz]

because everything you 'see' is a reflection of light

[BarelyScience]

the broadening in frequency width of spectral lines is similar to broadening wave diffraction patterns that appear as light passes through a slit. The larger the slit, the narrower the diffraction lines, likewise, a smaller slit will produce broader a diffraction pattern.

[willembont]

Nice presentation. Well done.
Now, when you state that light is a wave, can you explain what exactly waves?