Bean bags are awesome. But I see a few people out there who are standing, we've got some over here, and standing takes more work than lounging. Using the Live Strong Organization's online database of weight loss resources, you can calculate that by the time I'm done with this speech, those of you who are standing will have burned 7.5 more calories than those of you who are bean-bagging it. (Laughter) Okay, here's a question, speaking of weight loss, specifically weight, this speech is live. I'm actually here in front of you guys, we're all here together. But this speech is being recorded and it will become a video that people can access all over the world on computers, mobile devices, televisions. I weight about 190 pounds. How much will the video weigh? Asking questions like that is what I do every week on my channel Vsauce. For the last two years, I have been asking really fun questions, mind-boggling questions, and approaching them as sincerely as I can, celebrating scientific concepts and scientists. And I research and write and produce and host and edit and upload and run the social media all by myself, but it's not lonely, because Vsauce has more than 2 million subscribers, and every month, my videos are seen by more than 20 million people. Yeah. (Applause) It's very exciting. I've found that asking a strange question is a great way to get people in, not just people, but fans. And fans are different than just viewers or an audience, because fans want to come back. They subscribe to you on YouTube and they want to watch everything you've made and everything you plan to make in the future because we are curious people and sparking curiosity is great bait. It's a great way to catch a human. And once you've caught them, you have this captive audience that you can, with the goal in mind of answering the question, accidentally teach a lot of things to. So, let's take a look at some of my videos. Here are eight of them. But down here in the lower-right corner, "What Color is a Mirror?" When people see that, it's very difficult not to click, because you think, "Come on, are you serious? How could you possibly answer that question?" Well, so far, 7.6 million people have watched this five-minute video about what color a mirror is. And in that episode, I answer the question and I get a chance to explain what would normally be kind of dry topics: optics, diffuse versus specular reflection, how light works, how light works on the retina, and even the etymology of color terms like white and black. Okay, spoiler alert: mirrors are not clear, they are not silvery, like they're often illustrated. Mirrors, technically speaking, are just a tiny, tiny, little bit ... green. You can demonstrate this by putting two mirrors next to each other, facing so they reflect back and forth forever. Look down that infinite reflection, and it will get dimmer, because some light is lost or absorbed every time, but it will also become greener, because green light, that is light of a wavelength that we perceive as green, is best reflected by most mirrors. Okay, so, how much does a video weigh? Well, when you stream a video onto your computer, that information is temporarily stored using electrons. And the number of electrons on your device won't actually increase or decrease. But it takes energy to store them in one place, and, thanks to our friend Albert Einstein, we know that energy and mass are related. Okay, so here's the thing: let's say you're watching a YouTube video at a really nice resolution, 720p. Assuming a typical bit rate, we can figure that a minute of YouTube video is going to need to involve about 10 million electrons on your device. Plugging all those electrons and the energy it takes to hold them in the correct place for you to see the video, into that formula, we can figure out that one minute of YouTube video increases the mass of your computer by about 10 to the negative 19th grams. Written out, it looks like this. (Whistle) That's like nothing. You could call that nothing, and you wouldn't really get in trouble, because the best scales we've ever invented that we could try to use to actually to detect that change are only accurate to 10 to the negative 9th grams. So, we can't measure it, but we can, like we just did, calculate it. And that's really cool because when I was a kid, my school had two shelves of science books. That was really cool, but I read all of them within, like, two grades, and it was hard to get more books because books are heavy, you need space for them and moving books around is tougher than what we can do today. With numbers that small, I can fit thousands of books on my own little personal electronic reader. I can stream hours and hours and days and days of YouTube video without my computer ever getting measurably heavier. And as information becomes that light, it becomes a lot more democratic, meaning that more teachers and presenters and creators and viewers than ever before can be involved. Right now, on YouTube, there is an explosion of content like this happening. The three Vsauce channels are down there in the corner. But everyone else, all together, collectively, their views dwarf what I can do alone or with the people that I work with, and that is really, really exciting. It turns out that tapping into people's curiosity and responsibly answering their questions is a brilliant way to build fans and an audience and get in viewers. It's even a great way for brands and companies to build trust. So, calculating the weight of a video is kind of a funny question, but I cannot wait to see what we ask and answer next. As always, thanks for watching. (Applause)