The lightbulb, right? The good old incandescent lightbulb.
Well, it’s maybe not so good anymore. Or comparatively speaking, at least. New lights that boast better energy use and less waste heat are changing the field for the better — or so some would claim. Others prefer the light and warmth offered by the old-fashioned bulb. No matter which side you’re on, the fact is that there’s more than one way to light a room, and we’re talking all about it in this episode. So settle in, give us a listen… and then maybe get in on the conversation!
Next up: Material toughness.References
Here are some references we used while researching this show:
- A page on lighting inventors from the Smithsonian National Museum of American History.
- A Reuter’s piece on Canada’s (now delayed) roadmap for banning the bulb.
- A Canada Gazette article on the ban.
- Wired article about LED lighting, including Orad’s mention about the US ban.
- A wiki page on Edison.
- Britannica’s entry on Swan.
- A Toronto Star article on the ban.
- A CBC story on the relationship between bulbs and heating bills.
- The US EPA’s Energy Star page on bulbs.
- A post at Treehugger about the L-Prize.
Phil from Cambridge:
I’m listening to your episode on the diversification of species, and I heard you wondering aloud why there are no enormous animals. What’s the limit? Well I’m sure there are plenty of nutritional or biological reasons, but I thought I’d share an interesting physical effect that puts an upper limit on the sizes of all kinds of structures, including skeletons:
This one has to do with scaling. Basically, a skeleton gets heavy faster than it gets sturdy. The weight of any structure, like a bone, is proportional to its volume. That’s the linear dimension cubed. Big bones mean heavy bones. Meanwhile the amount of weight a structure can support is related to pressures, which go like the force per cross-sectional area. That’s the linear dimension *squared*. So as bones get bigger, the weight they support goes up like the square of the length, but the weight they add grows even faster, like the cube!
This means that if you scaled up any animal, you’d eventually reach a point where its bones weigh more than they can support, and its skeleton would collapse. That’s the upper limit. That also explains why sea animals can be larger than land animals– things weigh less in water. The whole thing works in reverse when you talk about very tiny animals. That’s why ants can carry so much weight without collapsing.
Engineers have to take this into account when designing bridges; just because a scale model is sturdy doesn’t mean the real thing will be.
Keep up the great work!
This episode was researched, written, hosted and recorded by Orad Reshef and Jesse Corbeil. Sound editing was done by Jesse Corbeil and Aimee Gillespie.