1Hi, it's Doug.
2I recently came across this unbelievable video.
3It was taken at a hotel in Texas
4where on the roof of the hotel they have this pool that hangs off the edge
5and it has a glass bottom.
6Look at this.
7Would you go in there?
8Would you trust this glass?
9Someone named Benjamin has a question about glass.
10Let's give him a call now.
11Hi, Doug.
12Hi, Benjamin.
13I have a question for you.
14How's glass made?
15That's a great question.
16It's funny, right?
17Think about just how many objects around you are made of glass.
18Without glass, we'd have no windows,
19no windshields for our cars,
20no drinking glasses or eyeglasses,
21no skyscrapers or smartphones
22and yet it's really not obvious at all where glass comes from.
23Like, if you're sitting there and you have a table or a desk in front of you like this,
24that's wood.
25I'm guessing you know that wood comes from a tree
26or this statue here is carved from stone.
27You know where that comes from.
28But glass?
29Glass is a material that has to be made.
30How do they make it?
31Where does it come from?
32Well, believe it or not,
33glass is made by taking a bunch of sand and getting it so hot that it melts.
34It's one of the most amazing things to watch how it's made
35because in order to melt sand, you have to use a special type of oven that can get super hot.
36It's called a furnace or a kiln.
37Here, you can see someone loading some sand into the furnace.
38Once it gets hot enough, it will melt or become liquid
39and when you get something this hot, you can see it glows just like lava.
40This isn't lava though. It's molten sand.
41And as it cools, it will start to look more familiar to you.
42It becomes solid glass.
43To make a flat sheet of glass like you'd use for a window,
44they melt sand until it's molten
45then they pour it out and roll it into a flat shape like this
46and carefully allow it to cool.
47More fancy objects like a glass vase are even more fun to watch.
48This involves a special skill called glassblowing.
49You can see here it starts with this person taking a big glob of molten sand
50and getting it on the end of a hollow pipe
51then she blows air into the pipe.
52You can actually blow a bubble into it
53which might end up being the open part of the vase.
54The molten glass has a similar thickness as honey.
55They carefully shape it the way they want it and keep turning it and turning it.
56As it cools, it becomes solid.
57Artists can make amazing sculptures with glass.
58Believe it or not, this artist is making a glass swan.
59So that's how glass is made
60but it's kind of weird, isn't it? I mean...
61how did people ever discover that if you melt sand it makes glass?
62We've been making glass for a long time.
63So long ago now that no one knows for sure who was the first person to discover that if you melt sand it makes glass
64but some of the earliest objects made of glass come from ancient Egypt,
65a place covered in desert sand.
66Could it be that someone long ago had a campfire
67and noticed that the heat of their fire melted the sand beneath it?
68No one knows for sure but it's possible.
69That's all for this week's question.
70Thanks, Benjamin, for asking it.