| Okay! |
| So, today I am going to talk about the flight of the bumblebee. |
| Many years ago, scientists believed that the flight of the bumblebee defied the law of physics. |
| They took the weight of a bumblebee and its wing area into account and did some calculations. |
| They found, from an aerodynamic point of the view, |
| the way a bumblebee flies doesn't make any sense. |
| In fact, scientists believed that bumblebees couldn't even fly. |
| That's why there is a famous quote, "Aerodynamically, the bumblebee shouldn't be able to fly", |
| "but the bumblebee doesn't know it so it goes on flying anyway". |
| Now you must be wondering how come we still see bumblebees flying around amidst the flowers. |
| It turned out that scientists were wrong. |
| The big misconception about bumblebee flight is the belief that bumblebees flap their wings up and down. |
| In addition, the fluid dynamics behind the flight of a bumblebee are different from those that allow a plane to fly. |
| An airplane's wing forces air down, |
| which in turn pushes its wing upward. |
| For bumblebees, it isn't so simple. |
| They flap their wings back and forth. |
| As a bumblebee takes flight, |
| the angle to the wing creates vortices in the air like small hurricanes. |
| The eyes of those vortices have lower pressure than the surrounding air and suck the wing upwards. |
| This is what gives the bumblebee the extra bit of lift it needs to buzz around from flower to flower. |
| It's just like if you move a spoon through a cup of coffee; |
| you'll see the flow swirl around the sharp edge. |
| If you move the spoon quickly, |
| you'll actually see a dimple at the center of the vortex caused by the lower pressure. |
| Amazing, right? |
| But this is not what amazes me the most. |
| What I am most intrigued by is how these bees are able to find the most efficient route between flowers. |
| You see, bumblebees foraging for nectar in flowers are like salesmen traveling between towns. |
| Both seek the optimal route to minimize their travel costs. |
| In order to find out how they achieve this, |
| a team of researchers conducted an experiment. |
| They trained the bees to forage nectar from five blue artificial flowers. |
| Each artificial flower had a yellow landing platform and a single drop of sucrose, |
| just enough to fill one-fifth of a bumblebee's tank capacity. |
| This ensured that the bees would visit all five flowers on each foraging route. |
| The researchers arranged the flowers in a pentagon and spaced them 50 meters apart. |
| This distance is more than three times as far as bumblebees can see, |
| so the bees must actively fly around to locate their next target. |
| A motion-triggered Webcam was attached to each flower to record the bees' visits. |
| Then, every day for a month, each bee was freed to forage for 7 hours. |
| At first, the bumblebees visited the flower nearest to their nest, |
| and then the next closest flower. |
| It appeared that the bees kept track- that is, they remembered - |
| the total distance traveled on each foraging trip. |
| They tried new routes to increase their efficiency, |
| and if a route was shorter, they used this route instead. |
| If not, they abandoned it. |
| As their experience increased, |
| the bumblebees were able to select the most efficient path to visit the flowers. |