WWe all have those thoughts, the ones that come to us in the wee hours of the night. Who I am? Why are we here? What would happen if my cell phone ran on vacuum tubes? Randall Munroe has the answer to, well, just one of those questions, but also the answers to a bunch of others gathered at And yes? 2: Additional serious scientific answers to absurd hypothetical questions. Yeah, that’s a T-Rex eating a plane. In the excerpt below, Munroe examines what it would take to transport an average-sized human in a chair over Australia’s tallest skyscraper, using only the power of pigeons. a lot and a lot of pigeons
Taken from And yes? 2 by Randall Munroe. Copyright © 2022 by Randall Munroe. Retrieved with permission from Riverhead, an imprint and division of Penguin Random House LLC, New York. All rights reserved. No part of this excerpt may be reproduced or reprinted without the written permission of the publisher.
How many pigeons would it take to lift an average person and a launch chair to the height of Australia’s Q1 skyscraper?
In a 2013 study, researchers at the Nanjing University of Aeronautics and Astronautics, led by Ting Ting Liu, trained pigeons to fly to a perch while wearing a weighted harness. They found that the average pigeon in their study could take off and fly straight up while carrying 124 grams, about 25 percent of its body weight.
The researchers determined that pigeons could fly better if weights were placed under their bodies, rather than on their backs, so you’d probably want pigeons to lift your chair from above instead of holding it from below.
Let’s say your chair and harnesses weigh 5 kilograms and you weigh 65 kilograms. If you used the pigeons from the 2013 study, it would take a flock of about 600 to pick up your chair and fly up with it.
Unfortunately, flying with a load is a lot of work. The pigeons in the 2013 study were able to carry a load 1.4 meters straight up onto a perch, but probably wouldn’t have been able to fly much higher than that. Even untrammeled pigeons can only sustain strenuous vertical flight for a few seconds. A 1965 study measured a rate of climb of 2.5 m/s for untethered pigeons,* so even if we are optimistic, it seems unlikely that pigeons will be able to lift your chair more than 5 meters.†
No problem, you might think. If 600 pigeons can lift you the first 5 meters, then you only need to bring another 600 with you, like the second stage of a rocket, to carry you the next 5 meters when the first flock gets tired. You can bring another 600 for the 5 meters after that and so on. Q1 is 322 meters high, so about 40,000 pigeons should be able to get you to the top, right?
No. There is a problem with this idea.
Since a pigeon can carry only a quarter of its body weight, it takes four flying pigeons to carry a resting pigeon. That means that each “stage” will need at least four times as many pigeons as the previous one. Raising a person can only take 600 pigeons, but raising a person Y 600 resting pigeons would take another 3,000 pigeons.
This exponential growth means that a 9-stage vehicle, capable of lifting you 45 meters, would need almost 300 million pigeons, roughly the same world population. Reaching the midpoint would require 1.6 × 1025 pigeons, which would weigh about 8 × 1024 kilograms, more than the Earth itself. At that time, the pigeons would not be pulled downward by Earth’s gravity; the Earth would be pulled upwards by the gravity of the pigeons.
The full 65-stage craft to get to the top of Q1 would weigh 3.5 × 1046 kilograms. It’s not just more pigeons than there are on Earth, it’s more mass than there is in the galaxy.
You could make things more efficient by reusing pigeons. In the 2013 study, the researchers gave the pigeons 30 seconds to rest on the perch before lowering them for another test. If each “stage” is two seconds long and the pigeons refresh after 30 seconds, you could fly arbitrarily high with a 15-stage ship, but that would still require trillions of pigeons.
A better approach might be to avoid taking the pigeons with you. After all, the pigeons can climb to the top of the skyscraper by themselves, so you’d better send them ahead to wait for you there instead of having their friends take them with you. If you could train them well enough, you could make them slide to the proper height, then grab and pull yourself up for a few seconds when you reach their altitude. Keep in mind that pigeons can’t grab and carry things with their feet, so they’ll need small harnesses with aircraft carrier-style hooks to intercept it.
With this arrangement, you may be able to fly to the top of the tower with only a few tens of thousands of well-trained pigeons. You should probably make sure you have some sort of safety system in place that prevents you from diving in every time a hawk flies by and scares away the pigeons.
The ship would not only be more dangerous than an elevator, but it would also be much more difficult to choose its destination. could you plan to go to the top of Q1, but once you take off… you’ll be completely under the control of anyone with a bag of seeds.
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