A fantastic video was just released by the youtube channel Kurzgesagt about the gravity well around Earth.
The terminology used there reflects what I see as a very modern trend of assigning new “simple” terminology to complex concepts, and walking the listener through newfangled jargon that follows from those selections. This was very much pioneered by xkcd, and the power of the technique generally explains why the author went through so much pain-staking effort to write Thing Explainer. But I want to keep myself tied to the most standard terms, so let me be perfect clear that this video is performing the task of equating
Prison Earth = Gravity Well
If I were to categorize the type of narrative here, I would say it’s a once-through statement of facts. It popularizes the basic details of rocket science into something that is emotionally relate-able. Indeed, it feels like the universe is our jailer when presented along that particular perspective, and that strikes a cord. In doing this, it goes over Newtonian universal gravitation, which is cool. It also does some very fact-oriented rehearsals of physics concepts that feel so forced that it becomes its own new kind of jargon. The concept of debt, for instance, is based purely in energy accounting.
Deeper Relationships in the Anthropic Principle
Debt and imprisonment are words that have emotional consequences, but the method employed in the video is to ignore the scientific validity of those feelings and let the impact fall however it will. But even speaking in purely scientific terms, I think we must face the emotional consequences of the fact that we are trapped on a planet, and those consequences are not what people often give credit for.
In fact, there is something of tremendous relevance that is not addressed in the video.
Atmospheric escape is another concept which seems unrelated. But if we are considering the meaning inherit in Earth’s gravity well, it is anything but irrelevant. Bear with me for a bit, as I try to craft the story in the appropriate emotional terms.
We owe a debt to the universe in the sense of energy account, but we also owe a debt in other forms — the fact that it gave our biosphere time and stability sufficient to grow us. Strikingly, these are two sides to the same coin. The energetic debt in the physical sense provided the credit on our balance sheet that funded our biological growth. The energetic debt held in our hydrogen, doing this allowed our DNA to become wealthy.
If this sounds like an outrageous story to you, then that means you understood it. The reality that we live in has deep connections that dive far back into our history. The properties of the world we live in are connected to our own selves via the anthropic principle. Here is a post I recently wrote on the mechanics at work in this story:
That essay probably isn’t as easy to follow, and certain much more difficult than the basics of the gravity well. I don’t think the connection is intuitive, because it is just so difficult to explain what the analogies of “height” of walls and “length” of our legs are.
The Blues of Chemical Existence
Why do rockets need to be big in order to get into space? It’s a perfectly valid question, but most scientists and engineers will give you a tautological answer. It’s because of the reaction energies involved… okay yes, facts are facts, but there are so many problems with that as an answer to the question.
Let’s start by stating that rockets are the pinnacle of the performance we can get from chemical-based engines. If not, we would be using some other propellant combinations — easy enough of a proof there.
Now, given that, we are left needing to explain why the application of these high-performance engines not only necessitates the highest-performance we have available, but stresses them to the very limit of what technology could accomplish. In other words, why is Earth a good prison? This would all be much easier if we had been born in a crappy prison, like Mars. Therein lies a large part of your answer, that Mars is a crappy place to live, just like it’s a crappy place to keep humans trapped on it. These 2 facts are not unrelated.
If you’re sharp, you should have noticed that we have failed to fully answer the 2nd part of the question. Sure, we gave an answer, but there’s a free variable. Why should the biological cutoff be anywhere near the rocket cutoff? Biology and rockets apparently have nothing to do with each other. Oh, but they do…
We are chemical beings first and foremost. Chemical connections hold us together, they also hold rockets together, and they provide the reaction energies for rockets. Rocketry is hard because we needed Hydrogen to evolve. If the prison of our gravity well was less-good, then our atmosphere would have boiled off of our planet, and we would have never evolved.
Meekness and Purpose
Space exploration seems different to me when seen under this light. The challenges of rocket travel are not arbitrary when I think of it in this way. Rockets do not just happen to be hard, they are fundamentally hard, they must be hard.
I’m sure this pattern repeats itself over-and-again many times in patterns found throughout the tree of life, shaped by evolution. If a chick’s egg wasn’t hard enough, it would break out too early and die. Time must be permitted for the organism to develop before it can break open its shell.
There’s also something insulting about the current realities of space. If there was ever a definitional problem to prove our determination and capabilities, it would be space travel. This is because our walls are the very walls that helped to incubate us throughout our development.
Our legs are, in a certain way, perfectly matched to the size of the wall. We can reach plausibly toward the top of it, but we can not summit it without a great amount of scampering, loosing our breath, and believing that we might not make it in the process.
If there were a litmus test to determine whether we are something unique, or just another species among the tree of life, this may be it. The size of the challenge is absolutely dripping with meaning going back 4 billion years.