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← Does colour exist? | Andrew Parker | TEDxSydney

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Showing Revision 29 created 07/14/2017 by Robert Tucker.

  1. First of all, colour doesn't exist
    in the outside world:

  2. it exists only in the minds
    of animals with eyes.
  3. And we still don't fully understand
  4. how our images of the world
    are put together.
  5. But that's not an issue for nature.
  6. Nature doesn't need
    to understand how things work;
  7. it just gets on with inventing things
    through trial and error, random mutations.
  8. Now I'm going to talk about
    how I came across these two facts,
  9. and how they led me
    to a subject called biomimetics,
  10. which is learning from nature,
  11. taking inspiration from nature
    to effect our commercial products.
  12. This all began about 20 years ago,
  13. working on a group of animals called
    seed shrimps or ostracod crustaceans.
  14. They are fairly obscure animals,
    about the size of a tomato seed,
  15. not very well known, but very, very
    common in Australian waters.
  16. They're well known to produce
    bioluminescent light.
  17. They light up in the dark
    when there's no light to reflect,
  18. and you can find them
    on beaches around Sydney at night,
  19. as you can see in this image here.
  20. That was well known,
  21. but I've often quoted that my research
    began with a flash of green light,
  22. green or blue light, and that's true.
  23. When I was looking at some
    preserved ostracods under a microscope,
  24. I moved them around and started to find
    flashes of blue and green light.
  25. This wasn't known for ostracods,
    so I thought, "What's going on here?"
  26. Also, when I videoed
    live animals during courtship,
  27. they were using these
    iridescent flashes of light
  28. as a courtship display
    to attract each other.
  29. So, I decided to put some ostracods
    in electron microscopes
  30. to find out what's going on.
  31. Here you can see
    the images of a diffraction grating
  32. on the surface of the hairs
  33. that are splitting up white light
    into its component colours.
  34. Diffraction gratings are well known
    in physics and in commerce.
  35. They have a number of uses in technology.
  36. But they weren't known
    in ostracods or animals in general.
  37. Now, the interesting thing here is that,
  38. because they were being used
    as a courtship display,
  39. they had a function.
  40. So they'd evolved
    to be very, very efficient.
  41. Nature had been working on these
    over millions of years,
  42. fine-tuning them to be optimal
    at doing their job.
  43. Now I knew what I was looking for,
  44. I thought, "Where else
    do diffraction gratings occur in nature?"
  45. So I looked at all sorts of animals,
  46. and found them in a range of things.
  47. From worms, as you can see here,
  48. and also on the claws
    of, in this case, a galatheid lobster.
  49. You can see how the colour changes
    with change in direction.
  50. These are the very bright,
    metallic-looking colours
  51. that you find also in hummingbirds
    and beetles, for example.
  52. These are physical structures
    just like bones.
  53. So I thought, "Well, I wonder
    if it occurs in fossils too."
  54. And in fact they did.
  55. We started to look at fossils.
  56. I found them
    in 45-million-year-old beetles
  57. that came out of the rocks
    just looking like living beetles,
  58. sparkling with all their metallic colours;
  59. in 85-million-year-old ammonites
    as you can see here.
  60. You can also see how light is reflecting
  61. from the different layers
    in this reflector.
  62. The layers, they're about 100th
    of a hair's width in size,
  63. really, really tiny nanostructures, even.
  64. The oldest were the Burgess Shale fossils,
  65. 508 million years old
    from the Cambrian period.
  66. This got me thinking, "We can take
    colour back this far in time,
  67. but how far can you go here?
  68. When did colour first begin on earth?"
  69. That led me to search
    for the very first eye that existed.
  70. It turned out to be a trilobite
    that had this very first eye,
  71. a type that you can see here.
  72. You can see one of the ridges
    on one of the eyes, for example.
  73. Really, really good eyes in fact,
  74. they could produce image
    just as well as we can today.
  75. But this animal lived
    521 million years ago.
  76. Before that there was no vision,
    so colour didn't matter.
  77. There was really no such thing as colour,
    just wavelengths of light.
  78. I looked at the animals
    that existed at that time.
  79. The trilobite had really
    armoured parts, hard parts,
  80. and it had a very modern lifestyle.
  81. It moved very quickly,
  82. and it had hard parts
    to tear animals apart.
  83. It was a predator.
  84. It could see animals around it.
  85. But just before that,
    all the animals were soft bodied,
  86. even the predecessor of the trilobite,
  87. and they moved around very slowly
    on the seafloor just bumping into things.
  88. They didn't really interact
    with each other very well.
  89. They did have a light sensor.
  90. The most sophisticated
    light sensor of the time
  91. would have produced
    this image of the world.
  92. This is the best way animals
    could have seen their environment
  93. with such a sensor.
  94. You can see the direction
    where light is coming from,
  95. so you know where up and down is
    in the water column, for example.
  96. But you can't find
    a friend or foe around you.
  97. You can't identify all the other animals
    and see what there is.
  98. Then perhaps the most dramatic event
    in the history of life happened.
  99. One of those light sensors evolved lenses.
  100. Suddenly an image was cast
    on the back of an eye,
  101. the very first image on earth,
  102. which would have looked
    something like this.
  103. You can see all the other
    animals around you.
  104. You can identify what's possibly prey.
  105. Therefore, selection pressures,
    evolutionary pressures,
  106. start acting on that animal
    to evolve swimming parts to get there,
  107. a hard part to tear it apart,
  108. and feed on all of those
    soft-bodied animals,
  109. which are essentially
    chunks of protein waiting to be eaten.
  110. It actually triggered
    the Cambrian explosion,
  111. the Big Bang in evolution,
  112. where all animals
    went from being soft bodied,
  113. like worms and jellyfish,
  114. into having the whole range of bodies
    that you see today,
  115. the whole range of behaviours.
  116. Life suddenly became complex.
  117. Vision was introduced to the world,
    and it was here to stay.
  118. Today, over 95% of animals have eyes,
  119. and vision is the most powerful
    stimulus on earth.
  120. Everywhere you go,
    you leave an image on a retina,
  121. and, from then onwards,
    animals had to be adapted
  122. and could at any time
    be caught by a predator.
  123. Evolution has led to a design process
  124. where trillions upon trillions
    of strands of DNA are mutating,
  125. producing endless designs
    of new types of colours.
  126. They've been working on this
    over millions of years,
  127. hundreds of millions of years
    to produce optimal colours.
  128. A designer in commerce
    would be lucky to get a year
  129. to come up with a new colour.
  130. So, why not just go to nature
    and see what they have to offer,
  131. see if we can copy some of the things?
  132. Even if we don't understand
    how the colours are produced,
  133. that doesn't matter,
  134. just simply copy those nanostructures
    that's there in nature,
  135. then you will have the same colours.
  136. After all, we're working
    towards the same goal:
  137. the effect on the eye.
  138. So let's go to industry now and ask:
  139. "What type of colours would you like?"
  140. "Would you like a very bright colour
    that lights up in the dark,
  141. that even when there's no sunlight,
    you can produce light?"
  142. For example in glow sticks,
  143. or in certain applications
    in farmers' fields,
  144. where, if a crop is attacked by a virus,
  145. it lights up at night to tell the farmer
    where the attack is.
  146. That's exactly what we're doing
    with bioluminescent chemicals.
  147. Bioluminescence is where two chemicals
    interact in the presence of oxygen
  148. and produce light as a by-product.
  149. It's a very efficient light.
  150. Almost all of the energy
    is converted into light,
  151. very little heat, as opposed
    to light bulbs, for example.
  152. Bioluminescence causes the light
    in fireflies or glow worms.
  153. It's very common in the deep sea,
  154. where over 90% of all animals
    produce bioluminescent lights.
  155. Would industry like to have
    pigments, perhaps?
  156. These are really common in nature,
    for example, in this milk snake here.
  157. There's a pigment in this case
    that produces an orange effect.
  158. So, what happens here
    is the molecule is struck by white light
  159. with all the different colours
    or wavelengths.
  160. Most of those wavelengths
    are eaten up and turned into heat,
  161. but the energy remaining
    in those that aren't eaten up
  162. is back-reflected or scattered out
    into the environment,
  163. so you see those colours.
  164. There's another way that nature
    can offer pigments to industry.
  165. That's through chromatophores,
    or colour change cells.
  166. These are cells
    that can expand or contract
  167. and are filled with pigment.
  168. When they expand,
  169. they are large enough
    to be seen as a pixel,
  170. and when they contract,
    they become invisible.
  171. This is the way that chameleons
    change colour, or cuttlefish or squid.
  172. You can imagine packing red, blue
    and green chromatophores together
  173. and expanding and contracting those
    to produce any colour you want to.
  174. Now I'm working with Georgia Tech
  175. to try to produce colour change
    surfaces and materials,
  176. which is great for camouflage
    colours, for example.
  177. We could produce fluorescent colours
    for industry as well,
  178. plenty of those around,
  179. particularly in parrots,
    Australian parrots in particular.
  180. These are head feathers
    from the sulphur-crested cockatoo
  181. that fluoresce.
  182. You'll see there's a picture there
    showing the yellow pigment
  183. and then also showing
    the fluorescence only.
  184. What's happening is that
    the fluorescence is also yellow
  185. and is enhancing
    the effect of the yellow pigment.
  186. I found that some yellow feathers
    are producing fluorescence
  187. and others are not.
  188. In fact, those that
    are used for courtship,
  189. those in areas of the plumage
    used to attract a female,
  190. they've got the fluorescent pigment.
  191. So it's not just incidental
    of a yellow pigment.
  192. Evolution has acted on this
  193. to be very, very efficient
    at producing the yellow light.
  194. Fluorescence results from
    an effect at the atomic level,
  195. where white light comes in,
    including ultraviolet light.
  196. Ultraviolet, which we don't see,
  197. is eaten up and rejected again
    in a longer wavelength.
  198. So some of the high energy
    that is contained in ultraviolet light
  199. is used up when an electron jumps
    into an outer shell.
  200. When the electron immediately
    drops down back to its original shell,
  201. that energy is re-emitted,
    but a little is lost as heat,
  202. so there's less energy,
  203. which means a longer wavelength
    or yellow light, for example.
  204. So we go from ultraviolet light,
    which we don't see,
  205. to yellow light, which we do.
  206. Now, this is my favourite subject,
  207. this is structural colour,
    nature's nanotechnology, if you like.
  208. These are physical structures made
    from completely transparent materials.
  209. It's the architecture at the nanoscale
  210. that's important in determining
    what colour is reflected,
  211. or what type of light effect
    that you can see.
  212. Here we have the spines
    of a sea mouse called Aphrodita
  213. found around Sydney's beaches.
  214. It's a strange-looking animal;
    it looks like a little iridescent mouse.
  215. But it's a marine animal,
  216. and it's covered
    in these iridescent spines.
  217. If you cut through those spines,
  218. you can see these tiny nanotubes
  219. that form what's called
    a photonic crystal fibre.
  220. Photonic crystals were only discovered
    in physics in the 1980s,
  221. and they've since been used in all sorts
    of technological applications.
  222. They're going to revolutionize
    computers in the future
  223. with optical chips
    instead of electronic chips.
  224. These types of photonic crystal fibres
  225. are already used
    in the telecommunications industry.
  226. But we've got designs in nature
    that aren't known in physics,
  227. and we don't fully understand
    how it works in physics yet.
  228. So, let's just copy
    what nature's got for now.
  229. And in fact, I didn't find this one.
  230. This was the first photonic crystal
    found in nature,
  231. which I found in the year 2000.
  232. But we'd have saved
    ourselves a lot of time
  233. if we'd started looking at nature earlier.
  234. Butterflies are really good examples
    of photonic crystals.
  235. A butterfly's wing contains
    about a hundred thousand scales
  236. overlapping like tiles on a roof.
  237. Each of those scales
    are filled with nanostructures
  238. that interact with light waves
    in various ways.
  239. And you'll see by these next slides -
  240. we've got electron micrographs
    showing the fine details on those scales,
  241. again about 100th
    of a hair's width in size -
  242. you'll see how those structures change
  243. almost like the shape
    of a building can change,
  244. but when it's on that nanoscale,
    around the wavelength of light in scale,
  245. then they will change the colour effect.
  246. So you can see these various
    architectures producing different colours,
  247. and they can change the way
    that colour changes.
  248. As you walk around these scales,
  249. you can get a change in colour,
    or you can get constant colour,
  250. you can get very bright scales,
    or you can get duller examples.
  251. A good example
    of a photonic crystal is opal,
  252. the gemstone opal as you can see
    in this top-left picture there.
  253. Opal is filled with tiny nanospheres.
  254. They're close-packed together.
  255. Light rays come in
  256. and bounce around inside this structure
    and interact with each other
  257. to produce these iridescent colours.
  258. But interestingly, I found opal,
    in 2005, in a weevil, an animal.
  259. So, a living thing producing opal.
  260. Well, opal does have
    lots of technological applications
  261. such as it will appear in computer chips.
  262. Industry makes it at high energy costs;
  263. we need high temperatures and pressures.
  264. But nature, animals, are doing this
    at room temperatures and pressures.
  265. They're magically
    mixing together chemicals,
  266. and out comes this perfect opal,
    using very, very low energy.
  267. So, this is something
    we're trying to do at moment.
  268. We're trying to image these scales
    in living weevils
  269. to work out how they're
    making these devices,
  270. and see if we can copy it
    and bring this process to industry.
  271. Some optical devices in nature
    don't produce any colour at all.
  272. In fact the opposite:
  273. they prevent any kind of reflections,
  274. all the light passes through a surface,
  275. such as I found on the eye
    of this 45-million-year-old fly
  276. preserved in amber.
  277. This very fine structure
    you can just about see
  278. in this electron micrograph,
    these very fine striations.
  279. When I made this onto a perspex surface,
    as you can see in the bottom right,
  280. in the centre there,
    you've got this structure,
  281. and you can see how the reflections
    are being cut down.
  282. It allows all the light to pass through
    instead of being reflected.
  283. If you put this onto a glass window,
  284. you'd no longer see
    reflections of yourself.
  285. But put onto solar panels,
    we get a 10% increase in energy capture.
  286. Now, several years ago,
  287. I started to expand my interest
    in biomimetics, in optics or colour,
  288. into other subjects,
  289. such as looking at strong materials
    in beetles or mantis shrimps,
  290. looking at glues that work underwater,
  291. designs of buildings based
    on natural animals and plants,
  292. and also air-conditioning systems,
    such as found in termite mounds,
  293. to put into buildings,
  294. which require very little power.
  295. One thing that really grabbed me is water.
  296. Just quickly, here's an example
    of a Namibian beetle,
  297. where I found a structure
  298. that collects water from desert fogs
    very, very efficiently.
  299. It's now being put into
    air-conditioning systems
  300. to extract the water out and to recycle.
  301. But nature is telling us
  302. that there's a whole airborne
    source of water to tap into,
  303. which animals and plants
    are doing in deserts, for example.
  304. That's what I'm working on now
    in collaboration with MIT,
  305. and we hope to get
    the first devices out into Africa
  306. to collect water for drinking
    and medicine quite soon.
  307. So, unfortunately, I can't reveal exactly
    the plans that I have next.
  308. We've got some very exciting things
    coming up, particularly next year,
  309. but at least I've been able to give you
    an introduction to the subject
  310. and say where it all began,
  311. which was 520 million years ago.
  312. Thank you very much.
  313. (Applause)