Technological Overhang In Exploration

Or, "An Obvious Fact That Bears Repeating"

Or, "The Solar System Is Already Yours, You Just Don't Feel It Yet"

At the time I'm writing this (February 2024 AD) there's a great deal of exploration and physical expansion that could be done by humans, but hasn't been: Suppose we measure how far a human could travel round-trip1 in one lifetime2 using their generation's technology, via the Euclidean distance | r - rplace of birth |, where r is the position of the furthest point they reach and rplace of birth is where they were born. We can use Jupiter's 5.5AU furthest-from-sun distance3 to make a very crude and very conservative estimate of the current value at 5.5 + 1 = 6.5 AU. Meanwhile, the greatest distance-from-birth anyone has actually achieved is still the 0.0026AU of the Apollo astronauts. That's a factor of 2,500 remaining to be crossed - a huge technological overhang in exploration.4 Consider too that at the start of the twentieth century, the highest achievable value was just twice Earth's radius, or 12,800km. From the development of rocket propulsion, silicon computing, and nuclear power, we had a roughly 6.5AU / (12800 km) ≈ 76,000-fold increase in human-achievable distance within a single lifespan!

Our situation puts me in mind of a housecat living in a large estate, which doesn't notice when its owner leaves the door ajar one morning because it's so used to padding around inside. All that is required is the decision to go. The difference between us and the cat is the size and significance of the field outside. To be alive so early in history that even the "first guy on Mars" title remains unclaimed - what a deep, tantalizing past we live in! What a young age! It's like being in Sumer when they were just starting to hand out cuneiform sheep receipts, when everything that would ever be written was still yet to be written.

Future generations will regard our time with the same quiet awe, and envy the glory that lies before us. Let's go take it.

Thanks to Snigdha Roy, Jonathan Kornich, Diana Leung, Raymond Russell for reading drafts.

1To borrow a line from The Prestige, it's not enough to just send someone into the howling wilderness - you have to bring them back. Even colonization missions are just taking wilderness and converting it to non-wilderness.

2Let's say the median lifetime of their generation. If you solve human death by aging, you open up new star systems.

3"Apoapsis" / "periapsis" is a really poor way of saying "furthest point" / "nearest point" - I can never remember which is which, because I'm not Greek, and just pronouncing "apoapsis" feels like trying to spit out a congealed ball of vowels. Modifying the second half of the word just makes things more confused. "Aphelion"? "Apogee"? Am I going to be asked to put up with "Apoareon" too?

4It's true that the overhang is far smaller if measured by the surface area of all the untrod large rocky bodies in the solar system — that's about twice the Earth's area, or six times our dry land — but it'll be larger if measured by accessible volume in space, which is what matters in the long run for a species with portable power sources. Anyway, the interior of Antarctica has plenty of land where the human footstep count is zero, yet not many people dream of being an Antarctic explorer anymore. Novelty has an appeal all its own.