Man science is so much more fun when you aren't forced to do it for school.

I feel more enlightened after watching this. It really shed some light on this topic. Perhaps I am slightly brighter today than I was yesterday. It kinda turns me on

This just became my most favorite episode of all crash course series. Analogies are perfect. So simple to understand.

That must have been the best explanation of electron shells I heard so far.

Been watching CrashCourse since highschool and now that I'm a teacher, I still love coming back to these videos :)

I love this show. Thanks to everyone who keep this going.

MOAR. Just binge watched all episodes(up till light, which is the last episode as of now), took notes, googled stuff I didn't understand, fast forwarded stuff which I knew well and re-played stuff that was awesome. WANT MOAR! Awesome job :D

You just did an entire video on light without mentioning photons. I'm impressed.

This ten-minute video made me understand atomic structure where two semesters of chemistry failed. Thank you, Crash Course! Love what you do!

Omg I want that periodic table at 5:22 as a poster on my wall... Make it happen plesh!!!! P.S: You explain how light is emitted faster than my physics teacher did... OVER ONE YEAR .__.

One of the best educational videos I've ever seen. Love you, CrashCourse team!

This episode was so awesome. Well.... They're all awesome... But this episode was awesome

This was the hardest to grasp episode yet, but a fantastic and critical one. Also the Green brothers on the moped was awesome.

I'm excited about the next episode! Distance throughout the universe has always fascinated me. Thats for your expertise, Phil!

You just said everything I was thought in a month

I have been using Crash Course videos in my daughter's history, science and A&P classes for the last two years. This teacher is the best. He explains the information about light with just the right balance of energy and calm (he is very easy to follow, others tend to go too fast for even me to understand 🤯). Well done.

That was very well explained, I am learning about spectroscopy, and this video helps me to understand the concept better. Thank you

I love how Phil injects his love for this stuff into every word he says. Also, Crash Course just taught everyone a month's worth of college Gen Chem in ten minutes, and it actually made sense. I love you guys!

Best episode of the whole series! I was totally blown away!

What is (visible) light? It is a wave, period. At last, somebody who can explain this clearly. Inspired by the video from Phil Plait, I would highlight the following: Photon: Each photon is an oscillating wave which push and pull the electric field as it propagate in free space - creating local increase and decrease of electric field pressure - the same way as sound wave propagating by pushing and pulling on air molecules. Fourrier Series for light Our eye perceive exactly one octave, the red being equivalent to bass and blue equivalent to higher pitch instrument. According to Fourrier series, any wave that is not sinusoidal (produced by an object circulating around a sphere) can be simulated by adding a few sinusoidal wave which have integer multiple of the fundamental. For example, a square wave at 60 Hz can be simulated as follow: a*60 Hz + b*180 Hz + c*180 Hz where a, b and c is the intensity (how loud the volume is set) for each of these frequency. Changing these coefficients (and adding also the even numbered) would produce saw tooth or any other waveform. Brief, when a wave is not a pure sinusoidal shape, then it contains harmonics, which is small amount of wave with frequency exactly double, triple, etc. The color detectors in our eye may react when a wave of exactly double or half the frequency hit them. That may explain why light going up after blue appear as purple ; the red detector become activated. What are electrons Atoms are not like as small solar system with proton/neutron in the center and electron rotating around like the planets around the sun. The electrons are "something" which wiggle randomly "around" very fast, like a bouncing rubber ball inside a metal or glass sphere . Humming bird vision The uncertainty principle is related to our incapacity to figure out how much faster this "thing" called electron oscillate compared to our measurement devices. Predicting where is an electron with the present technology is like asking to a human to predict the location of the wing of a hummingbird. We just see a blurry cloud. But a hummingbird eye and brain is about 10 time faster than our visual system, so they see the beating of their wing when looking at them self in a mirror. Dangerous cliff Our distant ancestors, the Jellyfish, wisely selected the visible light to get the 4K clear vision that we enjoy today. Like all engineering decision, this choice represent a compromise between conflicting factors. Using a lower frequency, like the infrared, give more blurry picture, as any desert snake can tell you. Using higher frequency gives more clear picture, but can be used only on clear day time. Furthermore, the ultraviolet light (and X ray and gamma ray) is ionizing. It's energy is so high that electrons are kicked off atom and long molecules chain break apart. With UV light, the DNA data bank receive kicks in the teeth and cells forget how to behave politely in pluri-cellular society, which is perceived on the macroscopic scale as cancer.

Everything mentioned I already knew, but it was illustrated in way that made me appreciate the science so much more. Love the staircase analogy!

Phenomenal content. I am in awe by the quality of how well this is written, animated, narrated and directed. I will be showing this to my students.

This is one of the most informative and accurate videos on the physics of light that I have seen, and I've seen quite a few from private youtubers and universities. I'm happy that he did NOT mention photons, or particle properties of light, but just the wave properties, he is more correct then other people. That being said the video is not 100% accurate

phil you are an absolute legend ! your passion & enthusiasm is INCREDIBLY infectious !

Its really amazing . This lecture has proved very useful in clearing my concepts and many doubts as well. I really felt educated on the subject. Thanks a lot and stay blessed.

Loved this episode!! One of my favs.

This is the best video on KZfaq for this subject, and I've watched many. Thanks!!

CrashCourse This is one of the most concise, thorough explanations of the wave nature of light I've ever seen, with just enough mention of the actual structure of atoms to highlight how integral spectroscopy is to understanding the universe. Outstanding work, Phil and all the CC team!

It's insane thinking about how we are just extreme luck and that if a certain chemicals never existed we may never of existed. Keep up the good work Crash Course :3

my mind is always blown when I learn how it is we know things about our universe. Science is awesome

I don't know if you are going to read this Phil, but anyways I would like to thank you very much for this series. You managed to make astronomy more interesting to the masses, and you did it by not making it too hard to understand. I am a civil engineer and I love astronomy,physics and math. So I felt very happy to see this, and I hope we have more episodes of Crash Course Astronomy. (also recomended to some friends interested in astronomy to watch this ASAP!) A big fan of yours, André Gomes

I wish this guy was my teacher at college...

Wow, just wow! This is getting better and better. Thank you Phil and the whole CrashCourse team for all the videos.

This has been my favourite crash course yet! It has just been so immersive and entertaining.

A lot of stuff that I didn't know. Thanks for this amazing channel.

I have watched almost every video of every series of C.C. and the Astronomy series is by far my favorite. This episode was especially awesome because it helped me appreciate how astronomers gain knowledge of the universe. The visuals and explanation of light, atoms and their correlation were the best I've seen.

This dude is such a great communicator.

This was very enlightening.

I love this Crash Course so much! Astronomy, guys. It's the best.

I love Crash Course Astronomy. It reminds me of things that I've learned but forgot and teaches me new things that are awesome.

This was a brilliant episode. Very well written. Thanks for making it!

this guy is amazing. i should start crashcourse astronomy even though im not studying anything envolves with astronomy. his just brilliant.

Phil really knows how to cast light on issues. He is very enlightened in the field of astronomy. He also makes it fun to learn about astronomy, with his lighthearted jokes. Thank you for helping lighten the burden of everyday life with your entertainment. Boom.

I'm rewatching these series. And I just remembered how eye opening about science this particular episode is. Very, very great one. So much so, I've spent my last 2 hours, maticilously translating it to a very good Turkish. People should watch this in every possible language.

Was the left one slightly darker?

I love crash course!!! They make everything so much easier and interesting!

I've been waiting for this youtube video for years! Light is so awesome and so hard to conceptualize. Very well done, thanks!

Finally, glad that I have a clue now on how does scientists find what's in an object billions of miles away! Thanks a ton for making it so easy to understand.

This episode was very illuminating.

Episodes like this are the reason I love CC Astronomy. Phil, keep up the excellent work. You are awesome.

Best lectures in this channel comes from this guy Easy simple and can draw some light on complex subjects without letting much-needed information slip

This show is just superb! Never get tired of watching these episodes!

8:36 was a beautiful performance.

Just a small correction: we didnt evolve to see the light which the sun emits most strongly (it emits electro magnetic waves outside our visible spectrum too, and granted it is not as strongly, it probably would be useful to see and differentiate the wide band of IR that the sun emits, which is much wider than our visible spectrum); we evolved to see the light frequencies that water lets through instead of absorbing. Considering where we come from, there wouldnt be much point, evolutionary speaking, to waste energy on being able to detect light waves that wouldnt penetrate water anyway. So water is very much the key in the evolutionary "decision" for what light we can see, and not what light is "emitted the strongest by the sun". If we had evolved on land instead of water, then no doubt our visible spectrum would look different and be expanded a fair bit into the IR section.

This show is the best. Thank you all who were involved in it. This is why the internet is so cool. I would have never learned so much about space in such a fun way.

I already know a lot of this stuff, but this series is so well made, I can't help myself but watch it. Phill is so charismatic, you can't not love him. Wish bloke like him taught in my class, I can guarantee a lot more of my former class mates would have been into science.

This series is AWESOME!!! I never knew how interested I was in astronomy until discovering this series. I’m totally blown away by all the great info in this course! Really wish they would’ve taught this interesting stuff in high school. 👍

7:13 Soooooooo many puzzle pieces just fell into place.

The best explanation of light I have ever seen. Thanks Professor Plait.

sir today i have learned a lot from you. Thanks a lot. look forward to learn more.

godddddd...jesus.........i'm living for these 3 channels...1..crashcourse....2....it's okay to be smart....and 3...kurzgesagt in a nutshel.......................love these 3 channels............guys keep making more stuff like this ,,,i feel so powerful and enlightened when i watch these kind of videos.............much appreciation,,love and respect from india,,,

0:19 The first thing I thought of for that hint: He's obviously waving and waving is a form of greeting someone, saying hi is also a form of greeting someone, and if we look up high, we see the sun, and the sun produces light?

Loved this explanation and how applicable this is to several different fields. It's so timeless

I just rewatched this. Being in physics now, learning about electricity and magnetism, really opens my eyes to this video. Awesome!

This blew my mind... wow

"Can you tell the difference between these two squares?" Me: yeah "Your eyes probably can't see a difference..." Me:🤔

Awesome video. It's so fundamental, this should have been shown earlier in the series!

Good job Phil. Thanks to all for putting this together. Facinating stuff.

"here"s a hint" then proceed to wave. fucking brilliant, i laughed more than i should have ^^

@ 7:32 photoshop tells me that those are the exact same colour youtube processing does this sort of stuff to preserve bandwidth

Just wanted to thank you for this video which has clarified a lot of information that I sort of knew and understood but then structured it into a coherent logical sequence. Crash Course is phenomenal for those that wish to learn more about...anything really. Merci beaucoup !

Simply one of the best channels on KZfaq, period.

Its a course in astronomy. I just came here 24 videos ago to learn about right ascention and declination.

Just getting educated at 6:48 before I've even eaten👍

This is astonishingly helpful! THANK YOU

This is the best series on Crash Course! Thank you, and keep up the good work!

I learned a lot from this video

At the quantum level though, light is actually a particle... and a wave.

Awesome explanation of light - particularly admired the graphic, explanation of the role of the electron and, as always, Dr Plait's enthusiasm and captivating delivery.

i love this show. so much info in 10 mins. keep going

The guy on the motorcycle looked like hank green

This video is enLIGHTening. Heheh.. Sorry everyone..

So far, this is my most favorite episode in Crash Course Astronomy. Thanks, Mr. Plait and Crash Course's team. :)

i LOVED this episode, thanks a lot, hope this show continues a long time on, i never get tired of it!

Dammnn!! Watched this at 2am here, who knew science could be this interesting 😂 Thanks to Phil! And cc.

How does the electron decide whether to stay on their step or go down and emit energy?

This is great for homeschool. Cool demonstration with the electric stove

I've never seen a video that explains this more beautifully. I just wish he had went more in depth on photons.

The square on the left was a bit darker of a shade, or at least that's how it looks to me without looking at rgb values.

So.. u could technicly find out length, distans, mass, health, etc About any person only by capturing, analysing and seeing their electro magnetic lights?

Thank you very much, Phil Plait and the others at _CrashCourse_ Astronomy, for making this video! Honestly, I knew most of the physics of light and the Doppler effect from elementary school but I did not realise the importance of light in astronomy. Literally everything we do in astronomy and everything we know about the Universe depends on light/radiation in one way or the other. I do have a question after watching this video. You said that an atoms of an object emit different wave lengths of light, containing different levels of energy, depending on how hot the object. How can we differentiate between a cooler object which emits a shorter wave length than a hotter object of another element? What happens when wave length and the element compensate for each other? How can we tell the difference between a hotter object that of element A from a cooler object of element B if they emit the same wave length of light?

This episode was very well done! (Most episodes usually are, but I really enjoyed this one in particular!)

7:35 Is it weird that I can somehow tell that the box on the left is a darker shade than the box on the right

How can light be real if our eyes arent real? - Jaden The Philosopher

This is the best, clearest explanation of spectroscopy I have found so far. Very well written Phil.

These videos are amazing, keep them coming!

I want that periodic table, where can I download it?

I just love the fact that this man never feels the need to shoehorn 'comedy' into his presentations. Plait don't need no pyrotechnics. Just him and the facts is all the magic we need. (Can't say the same about Craig over at CrashCourse Politics. How many failed attempts at dry humor does it take to realize you're consistently coming across as a cantankerous mope?) Phil Plait For President!

One of the best explanation I've heard so far, thanks!

So clear and succinct! I love the host! Slow, clear and engaging!!