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Materials that can interact with electromagnetic radiation based on their structure?
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That's so… meta.
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Sorry, had to.
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But we're talking about metamaterials today!
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Actually we've talked about them before, and me talking about us talking about them
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is in fact…
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Meta.
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Ok I'll stop.
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But I just figured that since it's been over four years, three sets, and one channel
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name change ago, we might look at them again and see where the field of metamaterials is
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now.
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First off we should get a pretty firm grip on what exactly metamaterials are.
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Conventional materials interact with electromagnetic radiation like light or radio waves based
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on the properties of the material.
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We're used to how glass bends light or how gold reflects light and so on, and in our
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everyday encounters with these objects we know what to expect because there's nothing
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special about these materials usually.
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Unless some crazed engineer replaced them with metamaterials, then things can get pretty
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unnatural.
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Take that gold for example.
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You're used to seeing it all shiny and yellowish and even on the nanoscale that's still true
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for gold.
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Unless an engineer were to alter the surface of the gold, making nanoscale structures that
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changed how the light behaves.
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Then the gold could be green or red instead of the usual yellowish tint.
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Nothing about the gold's chemical properties have changed, it's still good old Au, atomic
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number 79.
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But the structures on its surface can change how we see it.
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These special structures take gold from a conventional material to a metamaterial.
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You might be more familiar with the concept than you realize.
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One Stanford engineer likens metamaterials to TV antennae of old.
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To adjust the image quality you would wiggle the antennae around until the geometry interacted
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with the radio waves better.
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But the waves carrying TV broadcasts back in the day were centimeters to meters long,
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so the antennas that interacted with them were relatively big.
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If you want your material to interact with electromagnetic waves that are microns to
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nanometers, then the shapes are going to have to be just a fraction of those wavelengths.
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You can start getting pretty creative with these nanoscale shapes.
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You could make lenses that don't rely on the material properties of precisely shaped
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glass to bend light, and instead use metamaterials whose geometry focuses the light the same
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way, but without the difficulty of shaping a lense, or the weight of bulky glass.
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With metamaterials I could have glasses lenses that are 100 times thinner than a strand of
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hair, but still do the same job as these old coke-bottle bottoms of mine.
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Or you could start mixing materials up to make different structures, or mixing structures
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up to control electromagnetic waves in any arbitrarily complex way you want.
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Obviously this has huge implications for a lot of fields that deal with electromagnetic
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waves.
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For example there are machines called synchrotrons which use magnets to whip electrons around
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and around in a circle until they give off X-rays that are then used for various experiments.
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Synchrotrons are usually the size of buildings, but using 10 million precisely etched shapes
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in lithium tantalate crystal, researchers were able to coax infrared light in a circle,
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causing positive and negative charges in the crystal that gave off terahertz radiation,
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waves that are between infrared and microwaves.
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The crystal was just half a square millimeter in size, but it was mimicking what you normally
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need a whole building to do!
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Magnetic fields can be manipulated with metamaterials too, and researchers at the university of
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sussex just demonstrated a way to make one magnet connect to another without the other
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magnetic connecting back.
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A magnetic diode.This could make wireless power transfer like cell phone charging much
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more efficient because power would only flow one way.
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And of course light bending materials open up the possibility of, wait for it… invisibility.
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But explaining how that works is a whole video of it's own.
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Just know that with metamaterials, the possibilities are really only limited by how small we can
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make the structures and your imagination.
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Pretty meta.
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If you interested in strange and unique sciences, subscribe to Seeker and check out this video
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on another way scientists are hacking nature.
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And fun fact before you go, Meta materials are only possible thanks to the same technology
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we use to make our nanoscale integrated circuits in today's electronics.