yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

The Real Reason Flames Don't Have Shadows


less than 1m read
·Nov 10, 2024

Uh, why don't flames have shadows? Like, I mean, hello, it's kind of freaky. But it has everything to do with what a hydrocarbon flame is. When you look at a candle flame, the part you can see is not a gas, and it's not a plasma, believe it or not.

The part you can see is a solid. A flame is a chemical salad full of wax and oxygen molecules that are burning. Carbon dioxide and water vapor are products of the combustion, as well as hot air and unburnt solid fuel particles that are so hot they're glowing incandescently. That's where the light comes from.

But all of this stuff is not very crowded. In fact, a flame is about only a quarter as dense as the surrounding air. So, light can pass right on through. Whatever shadow is created can be easily filled in by the glow of the flame itself.

What the flame mainly does to light can be revealed by using a light that is brighter than the flame. Light travels at different speeds through media that have different densities. So, passing from the hot flame to the cooler air, we get ghostly distortions of intensity that are the only evidence that anything's there.

More Articles

View All
THE MOST EXPENSIVE HOME IN THE WORLD ($250,000,000)
This is the most expensive home in the world at $250 million. It’s also the tallest residential building in the world, to the point where you could actually see the curvature of the Earth right from your living room. And today, you’ll get to see exactly w…
The Path to $100B by Paul Buchheit
It is now my great pleasure to introduce my longtime colleague at Y Combinator, Paul Buchheit. Paul is known for a lot of things, not the least of which is his wisdom in all things when it comes to startups. But he’s also, of course, the creator of Gmail,…
Executive and legislative disagreements with the Supreme Court | Khan Academy
In many videos already, we have talked about our three branches of government in the United States. But what we’re going to do in this video is focus a little bit more on the judicial branch. As we’ve talked about, the judicial branch’s main goal is to be…
The Key to Living a Longer Life | Breakthrough
NIR Barzilai has been studying a group of exceptionally healthy hundred year olds, or centenarians. “Hi Milton, so nice meeting you!” He believes they’re a model for how we can all age. “Come on in fellas!” One of the interesting things with those cen…
Paycheck Squabble | Wicked Tuna
What do you think of a nice tuna check when we go in? Oh right, one out. All right. I think we were fishing every day, really. Hmm, so far in this trip, we’ve already lost two paychecks. And to top it off, I still haven’t been paid for the first three fi…
How Billionaires Foolproof Their Wealth
Most people think that making money is hard, but that’s false. Making money is actually relatively easy. The hard part is keeping and transferring wealth across generations. This is what most people have a lot of trouble with, so let’s fix that by learnin…