3Blue1Brown - 2023-09-01
Shining polarized light into sugar water reveals diagonal stripes of color. Why? Next video: https://youtu.be/aXRTczANuIs Steve Mould's video on the topic: https://youtu.be/975r9a7FMqc Help fund future projects: https://www.patreon.com/3blue1brown An equally valuable form of support is to simply share the videos. Thanks to Quinn Brodsky for setting up the demo and to the MIT Physics Instructional Resources Lab for their help and materials, especially Josh Wolfe and Caleb Bonyun. Thanks to these viewers for their contributions to translations German: Josh, jns-v Hebrew: Omer Tuchfeld Hungarian: MrExpert Indonesian: akhyarr Italian: Gabboronco Korean: @tebaioioo, Juhyung Persian: ah.202 Russian: fedor, ilevinson Spanish: Marcelo Lynch ------------------ These animations are largely made using a custom Python library, manim. See the FAQ comments here: https://3b1b.co/faq#manim https://github.com/3b1b/manim https://github.com/ManimCommunity/manim/ All code for specific videos is visible here: https://github.com/3b1b/videos/ The music is by Vincent Rubinetti. https://www.vincentrubinetti.com https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown https://open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. If you're reading the bottom of a video description, I'm guessing you're more interested than the average viewer in lessons here. It would mean a lot to me if you chose to stay up to date on new ones, either by subscribing here on YouTube or otherwise following on whichever platform below you check most regularly. Mailing list: https://3blue1brown.substack.com Twitter: https://twitter.com/3blue1brown Instagram: https://www.instagram.com/3blue1brown Reddit: https://www.reddit.com/r/3blue1brown Facebook: https://www.facebook.com/3blue1brown Patreon: https://patreon.com/3blue1brown Website: https://www.3blue1brown.com
Fun fact: Measuring the angle between the two filters can provide an estimation of the amount of sugar in the solution. This trick is applied to precisely evaluate the amount of sugar in wine grapes and must.
These animations are awesome!
Is that the brix percentage?
@@seth094978 I think Brix measurement is based on refraction properties rather than polarization. But I am far from being an expert in this field.. Let's wait if someone can clarify this point..
@@seth094978 He is refering to a polarimeter, which uses a specific light frequency (to avoid the phenomenon shown in the video). As far as I know, °Brix (degrees, not %) is usually measured with a refractometer, but you can convert the concentration measured with a polarimeter to °Brix
Could we use this technique create a non invasive glucose monitor for diabetics?
@@ricgreen1 I don't think so, you would still need a blood sample for the polarimeter, and blood has many other substances in it that would prevent this from working.
Love to see Grant branching out. He's truly made an impact on all online education, not just math! ❤
Omg yes this is getting into chemistry and enantiomers! Super excited to hear the math behind this
The universe is made with complex math, so his expertise will be amazing if he breaks into physics and similar subjects.
@PowerhouseCell Wait you're the guy who makes biology videos with Manim! Love your channel!
Basically, maths is behind all, so u understand math, u understand all.
@@arvinderbali Maybe, but "maths" has been proven by Godel to be "incomplete" and therefore it seems unlikely that the universe is "incomplete." So there must be more to the universe than "maths."
Hey folks, Quinn here. Lots of people have been asking how they can make this demo themselves, so here’s how I built it:
Materials:
⁃ Table sugar (sucrose)
⁃ Water
⁃ A glass tube that you can fill and seal, although it would be cool to experiment with different materials for the tube, since different material = different index of refraction. More on this in part 3 of the video. The tube should be long enough so that you can actually see the effect from the sides - our tube is 1 meter long, but you’d probably be able to see the effect with a ~0.5m tube. You also might want to make sure the tube is easy to open so you can clean it. See “Things to consider” for more. For the mini-demo, I just used a drinking glass! [FYI, the tube in this demo was custom-made for the MIT Physics Department. I’m not sure exactly where it came from or what type of glass it is exactly…]
⁃ A source of white, unpolarized light. We used a Dedo lamp, and if you make the demo as big as we did, you need a pretty powerful light source. For the mini-demo, I used my phone’s flashlight!
⁃ Two linear polarizing filters. You can get ‘em online pretty easily!
Directions:
⁃ For our demo, we made a sugar solution of 300g of sugar per 400g of water. So, you should measure the volume of your tube and scale this ratio accordingly.
⁃ Boil the water and mix in the sugar until it’s dissolved.
⁃ Let the solution cool, then fill the tube with solution. Close up the tube.
⁃ Place the light source so it’s shining down the length of the tube, then place a filter between the light and the tube.
⁃ Place the other filter at the end of the tube.
⁃ Voila! You can rotate the first filter to see the whole spiral move up and down the tube, or you can rotate the last filter to see the color coming out of the end of the tube (and through the last filter) change.
Things to consider:
⁃ You really want the tube to be clean before you start, since the solution can get moldy. If you look up close, you’ll actually see little floating things in the solution - those are some bacterial friends :)
⁃ We try to replace the sugar solution frequently so that the demo is clearer.
⁃ The shorter the tube is, the more concentrated you want the sugar solution to be in order to see a similar effect.
⁃ The amount of rotation of the polarization angle is proportional to the concentration of the solution (this is called the specific rotation!)
⁃ The light might get hot the longer you keep it on, so be careful! As always, observe sensible safety procedures.
⁃ You could do this with different sugars! Glucose would also rotate light to the right, but slightly less than sucrose. Fructose rotates light to the left!
If you recreate this/do something else cool with it, I’d love to see!
Only 47 Likes and no replies? Thanks for this and for taking the time to build this!
It’s likely borosilicate glass, most scientific glass is. You’re likely able to find a local glass blower who could make the fillable tube but the caps might require some thought. Could just superglue a small glass plate to the ends 🤔
Ordered filters to try this at home!
Quinn, thank you so much for what you've built here. I greatly enjoyed this video, and it has rekindled my interest in studying optics.
Is LED light on your phone actually white light? When you split it, do you end up with the three specific wavelengths of light corresponding to wavelengths from each LED making up the white light? Either way, I think that would be a cool follow up to this. Use different light sources and see the effect. If you did use three wavelengths (rgb), how sharp would the drop from one colour to the next be? Would you get twisted lines around the tube for each colour or would there be areas dominated by each colour with gradient transitions?
I've studied light/matter interactions for 20 years, published papers and such, and had never seen this before. I was pleasantly surprised! I wouldn't have thought you'd see light via the side. How great
The more you learn the more you realize you know next to NOTHING
Gene Simmons from Kiss said next to the same thing about women. The more you think you know about women, the less you really know. And that is one guy, who has likely been with a lot of different women in his life.
do you mind sharing what your research is in and your link on google scholar? I do research in optics
the lamp is set off the axis
I did research in optics. This should be obvious to you if this was your profession.
I'm an optical engineer. I have solid intuitions about light. I still said "what?!" out-loud involuntarily when the lights dropped the first time.
What an amazing video!
it truly is an amazing video
Right there with you (optical and opto-mechanical) the angle is weird. You just don't anticipate the "rotation" to be so slow...
Any chance this will replace separate RGB diodes someday?
@@KeithSmith42 Diodes replaced this actually. It's how LCD screens work.
@@userJohnSmith So before RGB pixels were single tubes that used a filter to output the desired wavelength? I thought diodes replaced electron gun-based CRT screens
I first saw this in 1973, in Walter Lewin's class on vibrations & waves at MIT. Damn, he was a great lecturer.
True, and yet as great as he was, Lewin still turned out to be misusing his role like a creep in the end.
Lewin is the best❤❤
What a beautiful demo setup!
Hello @Nighthawkinlight ! Love your channel !
This is like being at the center of the research table of grant, listening to the ideas and just absolutely loving your time learning. This is exactly what college/higher education needs to be, collaborative on a world level. Ofcourse, i am only a viewer and not a collaborator, but it just feels insanely amazing to be able to listen to this information
I 100% agree. As someone who's experienced maths olympiad camps my favourite part is the collaboration.
A landmark in science communication. Thank you and congratulations.
Just some lads making videos.......................................................................................................................... !
Part 2 is available now: https://youtu.be/aXRTczANuIs?si=m6DgY1ogMrwTRrUP
Some viewers have asked about how to make this demo for themselves, and Quinn kindly wrote up the description below.
Materials:
⁃ Table sugar (sucrose)
⁃ Water
⁃ A glass tube that you can fill and seal, although it would be cool to experiment with different materials for the tube, since different material = different index of refraction. More on this in part 3 of the video. The tube should be long enough so that you can actually see the effect from the sides - our tube is 1 meter long, but you’d probably be able to see the effect with a ~0.5m tube. You also might want to make sure the tube is easy to open so you can clean it. See “Things to consider” for more. For the mini-demo, I just used a drinking glass! [FYI, the tube in this demo was custom-made for the MIT Physics Department. I’m not sure exactly where it came from or what type of glass it is exactly…]
⁃ A source of white, unpolarized light. We used a Dedo lamp, and if you make the demo as big as we did, you need a pretty powerful light source. For the mini-demo, I used my phone’s flashlight!
⁃ Two linear polarizing filters. You can get ‘em online pretty easily!
Directions:
⁃ For our demo, we made a sugar solution of 300g of sugar per 400g of water. So, you should measure the volume of your tube and scale this ratio accordingly.
⁃ Boil the water and mix in the sugar until it’s dissolved.
⁃ Let the solution cool, then fill the tube with solution. Close up the tube.
⁃ Place the light source so it’s shining down the length of the tube, then place a filter between the light and the tube.
⁃ Place the other filter at the end of the tube.
⁃ Voila! You can rotate the first filter to see the whole spiral move up and down the tube, or you can rotate the last filter to see the color coming out of the end of the tube change.
Things to consider:
⁃ You really want the tube to be clean before you start, since the solution can get moldy. If you look up close, you’ll actually see little floating things in the solution - those are some bacterial friends :)
⁃ We try to replace the sugar solution frequently so that the demo is clearer.
⁃ The shorter the tube is, the more concentrated you want the sugar solution to be in order to see a similar effect.
⁃ The amount of rotation of the polarization angle is proportional to the concentration of the solution (this is called the specific rotation!)
⁃ The light might get hot the longer you keep it on, so be careful! As always, observe sensible safety procedures.
⁃ You could do this with different sugars! Glucose would also rotate light to the right, but slightly less than sucrose. Fructose rotates light to the left!
❤
You should pin this.
Hey there, I have a fundamental correction to the visuals in this video. The polarizing filters are oriented incorrectly. When the polarizer is vertical, it will transmit horizontal and reflect vertical. It’s a common misconception, if you would like to hear more I would be happy to share! (I am an electrical engineer with a passion for light haha)
PS these are some amazing quality videos!
+1 to this, it's hard to test with visible light polarizers, but you can find educational material that does it with ~10cm wavelength. The idea is that the electrons can move in the direction of the line filter can move sufficiently along this direction that the dissipate the energy of the light polarized in the same direction right ?
@@MatthiasBussonnier but please, fix your English first, I am not understanding what you are asking exactly
The visualisations is on another level. I am incredibly impressed by how you can create these moving 3D animations to show super complicated concepts.
Im a chemist. the dependence of angle of polarization by a chiral molecule on frequency of light is a very useful phenomenon which gives rise to cotton effect. Different molecules and even parts of a molecule have a different signature and thus the plot of angular dispersion vs. freq can help identify a molecule and functional or structural motifs. See Circular Dichorism spectroscopy
How does the chirality cause the twisting even though the molecules might be in any orientation? My intuition would be ones facing the opposite direction cause it to twist the opposite way, but clearly that's not the case here
@@ENCHANTMEN_ I'd love to know too -- I don't have the intuition for this at all.
I'm trying to use my hands to represent chirality / circular polarization, with my thumbs representing the direction of travel and the curl of my fingers as the twist. It seems to make sense -- if you had an equal number of left hand and right hand chiral sugars (represented as both right and left hands with the thumbs pointing in the same direction) then the twist would cancel out.
But it's also really easy to get the direction of twist to cancel out with one hand. Just turn your thumb to point the other direction.
So what's different about pointing your hand in the opposite direction, and light hitting the sugar molecule from a different angle (ie the opposite side)?
@@ENCHANTMEN_ The light does not just interact with a single molecule, so you can consider an average of all the molecules that the light interacts with being equivalent to averaging one molecule over all orientations.
A chiral molecule averaged over all orientations cannot be superimposed a similar average for the other enantiomer - essentially the average is still chiral.
Plane polarised light can be equivalently described as a balanced sum of right and left helically polarised light.
The sample will interact differently with right and left helically (circularly) polarised light, which leads to the twist in the polarisation plane.
I remember learning about chirality in Chemistry 201. Most of the time I'm mostly along for the ride, but today it did feel intuitive. Learning from you has completely changed my view of mathematics, and I thank you for that.
I came to this video as someone who only vaguely remembers some HS optical physics so I didn't expect to be too intrigued. Instead, that animation and explanation moved mo to the verge of tears. So beautiful and curiosity-enabling
A day with a 3blue1brown video is always great but a day with 2 uploads is exceptional!
I am a British Physics teacher working in China. I really appreciate the questions you ask and how you ask them/ explore ways of answering. gets to the core of what we are trying to encourage in our students.
Great work
What made you move to China and work there?
I just learned about optical isomerism in A-level chemistry, and I'm not sure if it's related to this video.
@@Ninjaeule97 The question really is "why would I ever move back?" :)
Lovely students, interesting culture, many varied daily challenges, the money is pretty good.
@@user-qu5on8mg1h from what I recall of my chem I think it is very much linked...
@@iainmackenzieUK Glad that you enjoy your life there. I just haven't heared of many westerns move to Asia and choose China instead of one of the more democratic (and wealthier) countries in that region. So I had to ask.
This is such a great video with the way it's setting up other discussions. Thank you for making physics accessible!!!
As always, your visualizations are beautiful in their elegance and simplicity, and really help to explain the concepts. Well done.
Steve Mould and Grant Sanderson has the best therapy voice of all time. ;)
You have such a gift at explaining complicated subjects in interesting and engaging ways. Thanks for another excellent video!
Having played around with a lot of polarizing filters and looked through a ton of information about how it works with scattering, I have built up an intuition, and I am really excited to see how you make it easier to understand.
I insist. This guy deserves the Nobel Prize in Education. And given that it doesn't exist, he also deserves it to be created.
Incredible collaboration, another video gem packed with knowledge and clean understandable explanation, thank you!
I saw this video as one of the great documents some immense scientist from the 19th century left as his legacy. What youre doing is just incredible, a friend of mine and I literally chose our graduation courses (Mathematics for him, Mech. Eng. for me), greatly thanks to your influence during our high school. Thank you for your ridiculously amazing work!
I have never seen this phenomenon before, which is a surprise because I love Steve’s videos. What a beautiful phenomenon that’s quite easy to replicate! Seeing this in science class as a kid would have seemed like magic.
This is such a lovely video. The explanation, the slow build-up to the problem expressed at the beginning, and the music... sooo good
This is the first physics video I have seen from this channel.
This is a phenomenon occurring due to optical activity of sugar. Known as optical isomerism. If a compound is optically active , it will bend light to a certain degree. I don’t know why this wasn’t mentioned in the video.
Oh nice, glad to see a new 3B1B video!
the visualizations add so much depth to the explanations, actually awesome stuff.
Great video, Grant! This is a really interesting topic. I loved Steve Mould's introduction of this phenomenon. Quinn Brodsky did a fantastic job with that setup! I love the mesh of the visceral demo and your animations. I can't wait to watch all of your videos on this!
Grant is trying something new, adding a bit of physics experiments to the recipe! Glad to see that the channel is looking towards a bit of variety. Not that the usual maths animations were bad, they were exceptional as ever, but this is great to exploit the viz towards more intertwined maths and physics, I love it. Keep it up, Grant!
Thanks for lighting me to this new knowledge.
in the subtitles it says "coloours which end up more perpendicular to the filter, pass through only very weekly" and I'd like to thank you for taking all this time to do this experiment
Neat video, can't wait for more of the series!
My feeling for question 3 could be due to the tube acting like a prism, scattering different light at slightly different directions, magnified by the lens effect of the cylindrical tube.
I am very much using this video in my classes, and my heart jumped a little when I saw you could do the demo yourself! We are adding optics back into our curriculum (highschool physics) and this will be so interesting to see
This is way beyond any highschool or AP course
Guy is such a good story teller
What a fabulous demo. I would have loved to see this kind of display when I was taking college physics. The coordination between the rotation angle of the polarization, the brightness of the output color, all coordinated. Brilliant. This reminded me strongly of Feyneman's book, QED. Thanks Grant!
Very nice topic! When Math meets Physics, things get interesting :)
3blue1brown never disappoints. The videos are always of high quality, it's borderline rare,
Plus this guy is a great source of inspiration, just that, well done.
Hello from a guy in France.
These visualizations are absolutely top notch!
This video is amazing. I love your videos in general, but this is the most amazingest you've done, imo.
Subtitle nitpick at 6:04: s/weekly/weakly/
Very much looking forward to the next video 👍
Holy mother of god this is great! Optics was one of my weakest subjects in physics. It felt like a lot of it was just "this is how it is." I'm so excited to follow this series. I feel embarrassed, though, that as someone with a degree in chemistry that I didn't even consider the chirality of the sugar. I've used polarimeters in lab! Duh!
beautiful and fascinating ; well done ; looking forward to the rest of this indeed
These animations and narration are sublime.
Wow! I’ve loved your videos for quite some time, @3blue1brown, but I’ve never felt so excited as just now seeing this teaser. I did a PhD and postdoc in optics 20 years ago, in areas very close what you’ve shown here. This is the clearest and most beautiful video I’ve seen on this topic and I am already learning something I didn’t know before. Thank you so much for everything that you for maths and physics education around the globe!
3b1b physics videos are a delight to see
@SteveMould - 2023-09-01
Can't wait for the final video! As always, your animations add so much clarity.
@berkekus7053 - 2023-09-01
Comment under steve mould for sale
@GooogleGoglee - 2023-09-01
❤
@didodido883 - 2023-09-01
They do.
@d.mort. - 2023-09-01
Hey Steve, Dave here.
I think a wonderful follow up to this video would be about why the polarizers in this video are in the wrong direction and the reasons behind the common misconception. I am an electrical engineer with a passion for light, I would be happy to collaborate!
@gregorywitcher5618 - 2023-09-01
helically twisted clarity, my favorite.