What's your favorite superhero power? When we ask this question, a favorite choice is: "Invisibility!" What if you could invent something that could make you invisible?
You don't need to be a superhero when you have science!
Today's Famous Female is Katharine Blodgett, who invented invisibility! Well, kind of. Let's find out more:
Remember our last Famous Females blog about Agnes Pockels, who founded surface science with nothing but household objects in her kitchen? Well, today's famous female built upon her work!
Katharine Blodgett was much luckier in her upbringing. Her private school in New York offered classes to girls and boys equally, and she excelled in math and physics.
She graduated college, got her PhD in physics, and was quickly hired by General Electric (GE), where her father had also worked.
Remember how Agnes Pockels invented a trough to study detergents in water? Then you know that detergents are molecules with a water-loving (hydrophilic) head and a water-fearing (hydrophobic) tail.
Well, Blodgett began working with scientist Irving Langmuir. Langmuir had been improving on Agnes Pockels's trough, and proved that those molecules really don't like to get those tails wet, so they make a layer on top of water only one molecule thick!
Working with Langmuir, Blodgett discovered that you could add layers of oily substances one by one to a solid surface like metal or glass. Kind of like dipping a strawberry into chocolate, letting it dry, then dipping it again.
Here's a video to show how this all works:
Blodgett found that one layer reflected a different color of light than two layers, which was different than three, and so on.
Therefore, you could measure how many layers there were on a surface by matching them up to a color wheel. This color gauge is still used today!
Five years later, she discovered that 44 layers of liquid soap on a plate of glass allowed for 99% of light to pass through without bouncing back in a reflection!
It so happens that 44 layers is four millionths of an inch, which is about one-fourth the average wavelength of white light.
So when light bounced back, the tops of the reflective waves met the bottoms of the incoming waves, and canceled each other out in destructive interference.
Meanwhile, soap is a great conductor of light, so almost all of it passes through with no reflection, making the glass ‘invisible’!
This discovery has led to the glass we now use in cameras, picture frames, computer screens, car windows, eyeglasses, and even submarine periscopes! Gone With the Wind was the first film to use this technology, and knocked audiences socks off when they saw how clear everything looked!
Blodgett was the first woman scientist hired at the GE research lab (1918). She was also the first to be awarded a PhD in physics from Cambridge University (1926).
Look at all the other things her work led to!
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