The cause for said near-miss was a minor burst of rage, and that rage, in turn, was triggered by the book Backroom Boys - one of the books I bought because Jo Walton recommended it in "What Makes This Book So Great". I fear on this occasion she may have led me (and other readers) up the garden path...
I'd only just started reading Backroom Boys. It seemed cheerful enough, although the significant number of missing apostrophes was already grating my patience into thin slivers. I figured this was probably an issue caused by the transfer to Kindle (when publishers use OCR to generate manuscripts for Kindle, things don't always work very well). But then came this whopper:
You have to pause for a moment there, as the rocket's vertical movement paused, with the forces of lift and gravity briefly equalised, and contemplate the strangeness of the place it was in, (...)Oh wow. That fizzing and bubbling you hear? It's the sound of my blood boiling. This is the sort of throwaway remark that might be only mildly annoying in a second-rate scifi novel. It would be quite annoying in a good science fiction novel. But this is a supposed work of non-fiction, dedicated to celebrating engineers and ingenuity! How dare they!!!
Now, I hope it is very obvious to everyone what is wrong with that sentence, but just in case it's not, let's list all the problems:
1) Gravity is not a force. Gravity is a force field - the force it induces in a body, depending on its mass, is weight.
2) The author does not understand what lift is. Lift tends to be defined as the aerodynamic force perpendicular to the air flow that a body generates. (Sometimes, it can be defined as total upwards force, but that is a bit rarer). On rockets, the things that generate lift are the little steering fins (or any wings that may be attached to the rocket). The main force that pushes rockets upwards is thrust.
3) Let's for the moment assume the author defines "lift" as the total upward force and "gravity" (oh, how I cringe) as the total downward force. Then, guess what: in the moment when the rocket's vertical movement is paused, the two forces are not equal(ised)! In fact, at that precise moment, there is no "lift" at all (regardless of which definition you use: at that point, the rocket is outside the atmosphere / in space, so there is no aerodynamic lift, no thrust, no upward force). There is only the rocket's weight. The only force working on it is the downward force. The reason the vertical movement pauses (for an infinitesemal moment) is that its upward movement is being continually counteracted by the downward force (the weight) - force is mass times acceleration, and the rocket has been accelerating downwards ever since its "lift" (i.e. upward force / combination of thrust and aerodynamic lift) has stopped. If the two forces were equal, then the rocket would fly in a straight line (that's how planes work): it would not fly a parabolic arc.
So, about 1% into the book, the author gets the most fundamental Newtonian physics and the most fundamental language of engineering fatally, embarrassingly, shockingly wrong. I would expect anyone who finished secondary education to know these things, so of course it is disappointing in any book written by an adult. But this isn't just any book - it's a book meant to celebrate engineers and ingenuity. How can it celebrate them if it does not respect their work enough to get even the most basic fundamentals right?
And, more importantly, how am I supposed to trust later chapters, which presumably touch on sciences I know much less about, if I can see that the author didn't have the slightest clue about the topics that I do understand?
I may continue reading, but for now, I seethe...
UPDATE: I have finished reading the book. It was better than that sentence. Click for the review.
No comments:
Post a Comment