[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:07.10,0:00:09.96,Default,,0000,0000,0000,,What if you could only see one color?
Dialogue: 0,0:00:09.96,0:00:11.58,Default,,0000,0000,0000,,Imagine, for instance,
Dialogue: 0,0:00:11.58,0:00:13.74,Default,,0000,0000,0000,,that you could only see things that were red
Dialogue: 0,0:00:13.74,0:00:14.87,Default,,0000,0000,0000,,and that everything else
Dialogue: 0,0:00:14.87,0:00:17.11,Default,,0000,0000,0000,,was completely invisible to you.
Dialogue: 0,0:00:17.11,0:00:18.14,Default,,0000,0000,0000,,As it turns out,
Dialogue: 0,0:00:18.14,0:00:20.41,Default,,0000,0000,0000,,that's how you live your life all the time
Dialogue: 0,0:00:20.41,0:00:21.92,Default,,0000,0000,0000,,because your eyes can only see
Dialogue: 0,0:00:21.92,0:00:25.08,Default,,0000,0000,0000,,a minuscule part of the full spectrum of light.
Dialogue: 0,0:00:25.08,0:00:28.18,Default,,0000,0000,0000,,Different kinds of light are all around you everyday
Dialogue: 0,0:00:28.18,0:00:30.10,Default,,0000,0000,0000,,but are invisible to the human eye,
Dialogue: 0,0:00:30.10,0:00:32.94,Default,,0000,0000,0000,,from the radio waves that carry your favorite songs,
Dialogue: 0,0:00:32.94,0:00:35.48,Default,,0000,0000,0000,,to the x-rays doctors use to see inside of you,
Dialogue: 0,0:00:35.48,0:00:37.94,Default,,0000,0000,0000,,to the microwaves that heat up your food.
Dialogue: 0,0:00:38.55,0:00:39.68,Default,,0000,0000,0000,,In order to understand
Dialogue: 0,0:00:39.68,0:00:41.24,Default,,0000,0000,0000,,how these can all be light,
Dialogue: 0,0:00:41.24,0:00:42.66,Default,,0000,0000,0000,,we'll need to know a thing or two
Dialogue: 0,0:00:42.66,0:00:44.28,Default,,0000,0000,0000,,about what light is.
Dialogue: 0,0:00:44.28,0:00:46.52,Default,,0000,0000,0000,,Light is electromagnetic radiation
Dialogue: 0,0:00:46.52,0:00:49.04,Default,,0000,0000,0000,,that acts like both a wave and a particle.
Dialogue: 0,0:00:49.04,0:00:52.03,Default,,0000,0000,0000,,Light waves are kind of like waves on the ocean.
Dialogue: 0,0:00:52.03,0:00:53.99,Default,,0000,0000,0000,,There are big waves and small waves,
Dialogue: 0,0:00:53.99,0:00:55.70,Default,,0000,0000,0000,,waves that crash on the shore
Dialogue: 0,0:00:55.70,0:00:57.24,Default,,0000,0000,0000,,one right after the other,
Dialogue: 0,0:00:57.24,0:01:00.16,Default,,0000,0000,0000,,and waves that only roll in every so often.
Dialogue: 0,0:01:00.16,0:01:02.99,Default,,0000,0000,0000,,The size of a wave is called its wavelength,
Dialogue: 0,0:01:02.99,0:01:04.50,Default,,0000,0000,0000,,and how often it comes by
Dialogue: 0,0:01:04.50,0:01:06.39,Default,,0000,0000,0000,,is called its frequency.
Dialogue: 0,0:01:06.79,0:01:08.75,Default,,0000,0000,0000,,Imagine being a boat in that ocean,
Dialogue: 0,0:01:08.75,0:01:11.23,Default,,0000,0000,0000,,bobbing up and down as the waves go by.
Dialogue: 0,0:01:11.23,0:01:13.67,Default,,0000,0000,0000,,If the waves that day have long wavelengths,
Dialogue: 0,0:01:13.67,0:01:15.79,Default,,0000,0000,0000,,they'll make you bob only so often,
Dialogue: 0,0:01:15.79,0:01:17.70,Default,,0000,0000,0000,,or at a low frequency.
Dialogue: 0,0:01:17.70,0:01:20.06,Default,,0000,0000,0000,,If the waves, instead, have short wavelengths,
Dialogue: 0,0:01:20.06,0:01:21.31,Default,,0000,0000,0000,,they'll be close together,
Dialogue: 0,0:01:21.31,0:01:23.54,Default,,0000,0000,0000,,and you'll bob up and down much more often,
Dialogue: 0,0:01:23.54,0:01:25.29,Default,,0000,0000,0000,,at a high frequency.
Dialogue: 0,0:01:25.29,0:01:27.90,Default,,0000,0000,0000,,Different kinds of light are all waves,
Dialogue: 0,0:01:27.90,0:01:30.41,Default,,0000,0000,0000,,they just have different wavelengths and frequencies.
Dialogue: 0,0:01:31.30,0:01:33.20,Default,,0000,0000,0000,,If you know the wavelength or frequency
Dialogue: 0,0:01:33.20,0:01:34.32,Default,,0000,0000,0000,,of a wave of light,
Dialogue: 0,0:01:34.32,0:01:36.79,Default,,0000,0000,0000,,you can also figure out its energy.
Dialogue: 0,0:01:36.79,0:01:39.00,Default,,0000,0000,0000,,Long wavelengths have low energies,
Dialogue: 0,0:01:39.00,0:01:41.23,Default,,0000,0000,0000,,while short wavelengths have high energies.
Dialogue: 0,0:01:41.23,0:01:42.67,Default,,0000,0000,0000,,It's easy to remember
Dialogue: 0,0:01:42.67,0:01:44.73,Default,,0000,0000,0000,,if you think about being in that boat.
Dialogue: 0,0:01:44.73,0:01:46.43,Default,,0000,0000,0000,,If you were out sailing on a day
Dialogue: 0,0:01:46.43,0:01:47.98,Default,,0000,0000,0000,,with short, choppy waves,
Dialogue: 0,0:01:47.98,0:01:50.40,Default,,0000,0000,0000,,you'd probably be pretty high energy yourself,
Dialogue: 0,0:01:50.40,0:01:53.65,Default,,0000,0000,0000,,running around to keep things from falling over.
Dialogue: 0,0:01:53.65,0:01:54.80,Default,,0000,0000,0000,,But on a long wavelength sea,
Dialogue: 0,0:01:54.80,0:01:57.06,Default,,0000,0000,0000,,you'd be rolling along, relaxed,
Dialogue: 0,0:01:57.06,0:01:58.31,Default,,0000,0000,0000,,low energy.
Dialogue: 0,0:01:59.16,0:02:00.70,Default,,0000,0000,0000,,The energy of light tells us
Dialogue: 0,0:02:00.70,0:02:02.64,Default,,0000,0000,0000,,how it will interact with matter,
Dialogue: 0,0:02:02.64,0:02:04.92,Default,,0000,0000,0000,,for example, the cells of our eyes.
Dialogue: 0,0:02:04.92,0:02:07.63,Default,,0000,0000,0000,,When we see, it's because the energy of light
Dialogue: 0,0:02:07.63,0:02:09.59,Default,,0000,0000,0000,,stimulates a receptor in our eye
Dialogue: 0,0:02:09.59,0:02:11.32,Default,,0000,0000,0000,,called the retina.
Dialogue: 0,0:02:11.32,0:02:13.12,Default,,0000,0000,0000,,Our retina are only sensitive to light
Dialogue: 0,0:02:13.12,0:02:15.32,Default,,0000,0000,0000,,with a very small range in energy,
Dialogue: 0,0:02:15.32,0:02:18.48,Default,,0000,0000,0000,,and so we call that range of light visible light.
Dialogue: 0,0:02:18.48,0:02:20.70,Default,,0000,0000,0000,,Inside our retina are special receptors
Dialogue: 0,0:02:20.70,0:02:22.73,Default,,0000,0000,0000,,called rods and cones.
Dialogue: 0,0:02:22.73,0:02:24.57,Default,,0000,0000,0000,,The rods measure brightness,
Dialogue: 0,0:02:24.57,0:02:26.54,Default,,0000,0000,0000,,so we know how much light there is.
Dialogue: 0,0:02:26.54,0:02:29.55,Default,,0000,0000,0000,,The cones are in charge of what color of light we see
Dialogue: 0,0:02:29.55,0:02:31.22,Default,,0000,0000,0000,,because different cones are sensitive
Dialogue: 0,0:02:31.22,0:02:33.43,Default,,0000,0000,0000,,to different energies of light.
Dialogue: 0,0:02:33.43,0:02:35.42,Default,,0000,0000,0000,,Some cones are more excited by light
Dialogue: 0,0:02:35.42,0:02:37.82,Default,,0000,0000,0000,,that is long wavelength and low energy,
Dialogue: 0,0:02:37.82,0:02:39.65,Default,,0000,0000,0000,,and other cones are more excited
Dialogue: 0,0:02:39.65,0:02:42.54,Default,,0000,0000,0000,,by short wavelength, high-energy light.
Dialogue: 0,0:02:42.54,0:02:43.77,Default,,0000,0000,0000,,When light hits our eye,
Dialogue: 0,0:02:43.77,0:02:46.18,Default,,0000,0000,0000,,the relative amount of energy each cone measures
Dialogue: 0,0:02:46.18,0:02:48.98,Default,,0000,0000,0000,,signals our brain to perceive colors.
Dialogue: 0,0:02:48.98,0:02:50.24,Default,,0000,0000,0000,,The rainbow we perceive
Dialogue: 0,0:02:50.24,0:02:53.62,Default,,0000,0000,0000,,is actually visible light in order of its energy.
Dialogue: 0,0:02:53.62,0:02:54.69,Default,,0000,0000,0000,,At one side of the rainbow
Dialogue: 0,0:02:54.69,0:02:57.40,Default,,0000,0000,0000,,is low-energy light we see as red,
Dialogue: 0,0:02:57.40,0:02:59.73,Default,,0000,0000,0000,,and at the other side is high-energy light
Dialogue: 0,0:02:59.73,0:03:01.63,Default,,0000,0000,0000,,we see as blue.
Dialogue: 0,0:03:01.63,0:03:02.81,Default,,0000,0000,0000,,If light shines on us
Dialogue: 0,0:03:02.81,0:03:04.90,Default,,0000,0000,0000,,that has an energy our retina can't measure,
Dialogue: 0,0:03:04.90,0:03:06.78,Default,,0000,0000,0000,,we won't be able to see it.
Dialogue: 0,0:03:07.60,0:03:09.96,Default,,0000,0000,0000,,Light that is too short wavelength or high energy
Dialogue: 0,0:03:09.96,0:03:11.98,Default,,0000,0000,0000,,gets absorbed by the eye's surface
Dialogue: 0,0:03:11.98,0:03:14.13,Default,,0000,0000,0000,,before it can even get to the retina,
Dialogue: 0,0:03:14.13,0:03:16.94,Default,,0000,0000,0000,,and light that is too long wavelength
Dialogue: 0,0:03:16.94,0:03:17.21,Default,,0000,0000,0000,,doesn't have enough energy
Dialogue: 0,0:03:17.21,0:03:19.58,Default,,0000,0000,0000,,to stimulate our retina at all.
Dialogue: 0,0:03:19.58,0:03:21.52,Default,,0000,0000,0000,,The only thing that makes one kind of light
Dialogue: 0,0:03:21.52,0:03:24.27,Default,,0000,0000,0000,,different from another is its wavelength.
Dialogue: 0,0:03:24.27,0:03:26.22,Default,,0000,0000,0000,,Radio waves have long wavelengths,
Dialogue: 0,0:03:26.22,0:03:28.51,Default,,0000,0000,0000,,while x-rays have short wavelengths.
Dialogue: 0,0:03:28.51,0:03:30.98,Default,,0000,0000,0000,,And visible light, the kind you can actually see,
Dialogue: 0,0:03:30.98,0:03:33.15,Default,,0000,0000,0000,,is somewhere in between.
Dialogue: 0,0:03:33.15,0:03:35.21,Default,,0000,0000,0000,,Even though our eyes can't detect light
Dialogue: 0,0:03:35.21,0:03:37.03,Default,,0000,0000,0000,,outside of the visible range,
Dialogue: 0,0:03:37.03,0:03:38.66,Default,,0000,0000,0000,,we can build special detectors
Dialogue: 0,0:03:38.66,0:03:39.62,Default,,0000,0000,0000,,that are stimulated
Dialogue: 0,0:03:39.62,0:03:41.62,Default,,0000,0000,0000,,by these other wavelengths of light,
Dialogue: 0,0:03:41.62,0:03:43.46,Default,,0000,0000,0000,,kind of like digital eyes.
Dialogue: 0,0:03:43.46,0:03:44.64,Default,,0000,0000,0000,,With these devices,
Dialogue: 0,0:03:44.64,0:03:46.46,Default,,0000,0000,0000,,we can measure the light that is there,
Dialogue: 0,0:03:46.46,0:03:48.80,Default,,0000,0000,0000,,even though we can't see it ourselves.
Dialogue: 0,0:03:50.26,0:03:51.82,Default,,0000,0000,0000,,So, take a step back and think about
Dialogue: 0,0:03:51.82,0:03:53.79,Default,,0000,0000,0000,,all of this for a moment.
Dialogue: 0,0:03:53.79,0:03:54.88,Default,,0000,0000,0000,,Even though they seem different,
Dialogue: 0,0:03:54.88,0:03:57.09,Default,,0000,0000,0000,,the warmth you feel from a crackling fire
Dialogue: 0,0:03:57.09,0:03:58.97,Default,,0000,0000,0000,,is the same as the sun shining on you
Dialogue: 0,0:03:58.97,0:04:00.23,Default,,0000,0000,0000,,on a beautiful day,
Dialogue: 0,0:04:00.23,0:04:01.93,Default,,0000,0000,0000,,the same as ultraviolet light
Dialogue: 0,0:04:01.93,0:04:04.42,Default,,0000,0000,0000,,you put on sunscreen to protect yourself from,
Dialogue: 0,0:04:04.42,0:04:05.100,Default,,0000,0000,0000,,the same thing as your TV,
Dialogue: 0,0:04:05.100,0:04:06.90,Default,,0000,0000,0000,,your radio,
Dialogue: 0,0:04:06.90,0:04:08.28,Default,,0000,0000,0000,,and your microwave.
Dialogue: 0,0:04:09.05,0:04:11.48,Default,,0000,0000,0000,,Now, those examples are all things here on Earth,
Dialogue: 0,0:04:11.48,0:04:13.76,Default,,0000,0000,0000,,things you experience in your everyday life,
Dialogue: 0,0:04:13.76,0:04:16.59,Default,,0000,0000,0000,,but here's something even more amazing.
Dialogue: 0,0:04:16.59,0:04:20.12,Default,,0000,0000,0000,,Our universe gives off the full spectrum of light, too.
Dialogue: 0,0:04:20.78,0:04:22.46,Default,,0000,0000,0000,,When you think of the night sky,
Dialogue: 0,0:04:22.46,0:04:24.06,Default,,0000,0000,0000,,you probably think of being able
Dialogue: 0,0:04:24.06,0:04:26.68,Default,,0000,0000,0000,,to see the stars shining with your own eyes,
Dialogue: 0,0:04:26.68,0:04:28.31,Default,,0000,0000,0000,,but that's just visible light,
Dialogue: 0,0:04:28.31,0:04:30.18,Default,,0000,0000,0000,,which you now know is only a tiny part
Dialogue: 0,0:04:30.18,0:04:31.96,Default,,0000,0000,0000,,of the full spectrum.
Dialogue: 0,0:04:31.96,0:04:33.29,Default,,0000,0000,0000,,If we had to draw the universe
Dialogue: 0,0:04:33.29,0:04:35.60,Default,,0000,0000,0000,,and could only use visible light,
Dialogue: 0,0:04:35.60,0:04:37.43,Default,,0000,0000,0000,,it would be like having only one crayon --
Dialogue: 0,0:04:37.43,0:04:38.70,Default,,0000,0000,0000,,pretty sad.
Dialogue: 0,0:04:39.43,0:04:41.50,Default,,0000,0000,0000,,To see the universe in its full spectrum,
Dialogue: 0,0:04:41.50,0:04:43.33,Default,,0000,0000,0000,,we need to have the right eyes,
Dialogue: 0,0:04:43.33,0:04:45.28,Default,,0000,0000,0000,,and that means using special telescopes
Dialogue: 0,0:04:45.28,0:04:48.16,Default,,0000,0000,0000,,that can help us see beyond visible light.
Dialogue: 0,0:04:48.16,0:04:50.50,Default,,0000,0000,0000,,You've probably heard of the Hubble Space Telescope
Dialogue: 0,0:04:50.50,0:04:51.78,Default,,0000,0000,0000,,and seen its beautiful pictures
Dialogue: 0,0:04:51.78,0:04:54.52,Default,,0000,0000,0000,,taken in visible and ultraviolet light.
Dialogue: 0,0:04:54.52,0:04:55.75,Default,,0000,0000,0000,,But you might not know
Dialogue: 0,0:04:55.75,0:04:58.36,Default,,0000,0000,0000,,that there are 20 space telescopes in orbit,
Dialogue: 0,0:04:58.36,0:05:00.14,Default,,0000,0000,0000,,missions that can each see part
Dialogue: 0,0:05:00.14,0:05:01.78,Default,,0000,0000,0000,,of the full spectrum of light.
Dialogue: 0,0:05:02.38,0:05:04.86,Default,,0000,0000,0000,,With telescopes acting as our virtual eyes,
Dialogue: 0,0:05:04.86,0:05:06.61,Default,,0000,0000,0000,,both in space and here on Earth,
Dialogue: 0,0:05:06.61,0:05:09.26,Default,,0000,0000,0000,,we can see some amazing things.
Dialogue: 0,0:05:09.26,0:05:10.79,Default,,0000,0000,0000,,And the coolest thing of all,
Dialogue: 0,0:05:10.79,0:05:13.20,Default,,0000,0000,0000,,no matter the wavelength or energy,
Dialogue: 0,0:05:13.20,0:05:15.70,Default,,0000,0000,0000,,the light that we see out in the distant universe
Dialogue: 0,0:05:15.70,0:05:17.12,Default,,0000,0000,0000,,is the same thing as the light
Dialogue: 0,0:05:17.12,0:05:19.72,Default,,0000,0000,0000,,that we can experience and study here on Earth.
Dialogue: 0,0:05:19.72,0:05:20.99,Default,,0000,0000,0000,,So, since we know the physics
Dialogue: 0,0:05:20.99,0:05:22.28,Default,,0000,0000,0000,,of how x-ray,
Dialogue: 0,0:05:22.28,0:05:23.41,Default,,0000,0000,0000,,ultraviolet light,
Dialogue: 0,0:05:23.41,0:05:25.20,Default,,0000,0000,0000,,or microwaves work here,
Dialogue: 0,0:05:25.20,0:05:28.20,Default,,0000,0000,0000,,we can study the light of a distant star or galaxy
Dialogue: 0,0:05:28.20,0:05:29.70,Default,,0000,0000,0000,,and know what kinds of things
Dialogue: 0,0:05:29.70,0:05:31.50,Default,,0000,0000,0000,,are happening there too.
Dialogue: 0,0:05:31.50,0:05:33.25,Default,,0000,0000,0000,,So, as you go about your daily life,
Dialogue: 0,0:05:33.25,0:05:35.95,Default,,0000,0000,0000,,think beyond what your eyes can and can't see.
Dialogue: 0,0:05:35.95,0:05:38.37,Default,,0000,0000,0000,,Knowing just a little bit about the natural world
Dialogue: 0,0:05:38.37,0:05:40.35,Default,,0000,0000,0000,,can help you perceive the full spectrum
Dialogue: 0,0:05:40.35,0:05:42.25,Default,,0000,0000,0000,,around you all the time.