We all have those thoughts, the ones that come to us in the small hours of the night. Who am I? Why are we here? What if my cellphone ran on vacuum tubes instead? Randall Munroe has the answer to, well, only one of those questions, but also the answers to a whole bunch of others collected together into What If? 2: Additional Serious Scientific Answers to Absurd Hypothetical Questions. Yes, that is a T-Rex eating an airplane. In the excerpt below Munroe examines what it would take to haul an average sized human in a chair over Australia's tallest skyscraper, using only the power of pigeons. Lots and lots of pigeons.

Excerpted from What If? 2 by Randall Munroe. Copyright © 2022 by Randall Munroe. Excerpted by permission of 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 permission in writing from the publisher.

How many pigeons would it require in order to lift the 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 up to a perch while wearing a weighted harness. They found that the average pigeon in their study could take off and fly upward while carrying 124 grams, about 25 percent of its body weight.

The researchers determined that the pigeons could fly better if the weights were slung below their bodies, rather than on their backs, so you would probably want pigeons to lift your chair from above rather than support it from below.

Let’s suppose 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 of them to lift your chair and fly upward 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 upward to a perch, but they probably wouldn’t have been able to fly too much higher than that. Even unencumbered pigeons can only maintain strenuous vertical flight for a few seconds. One 1965 study measured a climb rate of 2.5 m/s for unencumbered pigeons,* so even if we’re being optimistic, it seems unlikely that pigeons could lift your chair more than 5 meters.†