No, this isn’t a sequel. If you haven’t read What If? (The Original) you can read this one first with no regrets. If you have read The Original, you may conclude that Randall Monroe will never see the bottom of his bucket of absurd questions.
Will you, like me, be thrilled and delighted by his approach? Take this easy method of finding out: Read below; decide on that basis. Here is the opening hypothetical question.
What if the Solar System were full of soup out to Jupiter ?
"If the Solar System were full of soup out to Jupiter, things might be okay for some people for a few minutes. Then, for the next half hour, things would definitely not be okay for anyone. After that, time would end. Filling the Solar System would take about 2 × 10^39 liters of soup. If the soup is tomato, that works out to about 10^42 calories worth, more energy than the Sun has put out over its entire lifetime. The soup would be so heavy that nothing would be able to escape its enormous gravitational pull; it would be a black hole. The event horizon of the black hole, the region where the pull is too strong for light to escape, would extend to the orbit of Uranus. Pluto would be outside the event horizon at first, but that doesn’t mean it would escape. It would just have a chance to broadcast out a radio message before being vacuumed up."
"…If you were floating between the planets, away from Earth’s gravity, you’d actually be okay for a little while, which is kind of weird. Even if the soup didn’t kill you, you’d still be inside a black hole. Shouldn’t you die instantly from . . . something? Strangely enough, no! Normally, when you get close to a black hole, tidal forces tear you apart. But tidal forces are weaker for larger black holes, and the Jupiter Soup black hole would be about 1/500th the mass of the Milky Way."
"…From the point of view of an unlucky observer inside our black hole, it would take about half an hour for the soup and everything in it to fall to the center. After that, our definition of time—and our understanding of physics in general—breaks down."
No, this “answer” doesn’t end at this point. There are further considerations. Do you want to proceed? Then enjoy this book (my local library has several copies!).
There are long answers and short ones. If this is a money machine for Munroe, then it is in good working order because he is getting plenty of help from his readers. Here is a “short” question and part of Munroe’s “short” response:
Q: "What would happen if the Earth’s rotation were sped up until a day only lasted one second? —Dylan
A: “That would be apocalyptic, but there would be a brief period every two weeks when it would be even more apocalyptic. The Earth rotates, [citation needed] which means its midsection is being flung outward by centrifugal force. This centrifugal force isn’t strong enough to overcome gravity and tear the Earth apart, but it’s enough to flatten the Earth slightly and make it so you weigh almost a pound less at the equator than you do at the poles. [*] If the Earth (and everything on it) were suddenly sped up so that a day only lasted one second, the Earth wouldn’t even last a single day. [*] The equator would be moving at over 10 percent of the speed of light. Centrifugal force would become much stronger than gravity, and the material that makes up the Earth would be flung outward. You wouldn’t die instantly—you might survive for a few milliseconds or even seconds. That might not seem like much, but compared to the speed at which you’d die in other What If scenarios involving relativistic speeds, it’s pretty long. The Earth’s crust and mantle would break apart into building-size chunks. By the time a second [*] had passed, the atmosphere would have spread out too thin to breathe—although even at the relatively stationary poles, you probably wouldn’t survive long enough to asphyxiate. In the first few seconds, the expansion would shatter the crust into spinning fragments and kill just about everyone on the planet, but that’s relatively peaceful compared to what would happen next."
"…Everything would be moving at relativistic speeds, but each piece of the crust would be moving at close to the same speed as its neighbors, so there wouldn’t be any immediate relativistic collisions. This means things would be relatively calm . . . until the disk hit something. The first obstacle would be the belt of satellites around the Earth. After 40 milliseconds, the International Space Station (ISS) would be struck by the edge of the expanding atmosphere and instantly vaporized. More satellites would follow. After a second and a half, the disk would reach the belt of geostationary satellites orbiting above the equator. Each one would release a violent burst of gamma rays as the Earth consumed it. The debris from the Earth would slice outward like an expanding buzz saw. The disk would take about 10 seconds to pass the Moon, another hour to spread past the Sun, and would span the Solar System within a day or two. Each time the disk engulfed an asteroid, it would spray a flood of energy in all directions, eventually sterilizing every surface in the Solar System."