Kelly and Zach Weinersmith discuss space elevators in their book Soonish. The summary of the downsides is:
* If would need to be the most precisely engineered thing we've every produced just to stand a chance of being good enough.
* Because of that, it will be particularly sensitive to wear and tear. How the maintenance would work is an open question.
* It will probably attract terrorists like crazy.
* It needs to never get struck by lightning. It is a particularly attractive lightning rod.
* It generally should avoid bad weather. Whatever it is attached to on Earth needs to be able to move. When moving it you have to avoid not only the bad weather but everything in space, too.
* If the cable breaks, bad things could happen. Bad things can range from burning up in the atmosphere to it whipping around in space damaging satellites, or anything else.
I love the idea of space elevators, but I agree that it probably won't be practical on earth for a long time if ever.
> It needs to never get struck by lightning. It is a particularly attractive lightning rod.
Haven't buildings solved this problem with lightning rods?
On another note, I am personally fascinated by space elevators which is why I am somewhat interested in going back to the moon where we can build a space elevator with today's tech, avoid all of these problems, and have a large body of resources to build/fuel spaceships with.
Yeah, I've never seen a reasonable explanation for that either. If the car is a Faraday cage, and the cable is conductive and grounded, what's the problem?
The only thing I can think of is that all that energy unloaded into cable at once might ablate some of it, causing it to no longer be able to handle the tension.
The tether near the counterweight (in orbit) experiences the greatest stress. This means it needs to be thicker, which means more weight...which means more stress. The ratio at which stress/weight climbs is determined by density and tensile strength. Basically only one material we know of meets these requirements, and manufacturing at scale is far away.
Once you figure out how to make them en masse, now you have to figure out how to secure the strands into a bundle.
Less of a challenge than warp drive, but still...quite hard.
I'm not sure a space elevator is 'impossible' in the way that faster-than-light communication is. I suspect they argued that the engineering challenges will never be solved - which is a fair argument.
IIRC Specifically there are no materials we can currently produce (at that scale) which would be capable of supporting the weight of the cable alone. Let alone cars that ride along it.
"That [rocketry pioneer] Professor Goddard, with his 'chair' in Clark College and the countenancing of the Smithsonian Institution, does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react -- to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools."
That's a colorful quote from a NYT editorial in the 1920s arguing that getting rockets into space would not only be impossible, but obviously so. When Musk announced his intentions to autonomously land and rapidly reuse rockets it was mostly dismissed. Certainly companies, full of world class engineers, that had been launching rockets since before he was born probably knew a bit more about what is or not possible than some programmer with an undergrad in physics and negligible real life aerospace experience, right? Then it became, 'We've looked into it already, of course. It's perhaps theoretically possible, but it's a complete waste of money and in way economical.' Then it became, 'Shit we're a decade behind technologically!'
There are a practically infinite number of ways for why any given nontrivial thing might not be possible, and quite a bit fewer ways that it can be possible. So it's generally quite easy to formulate compelling and intelligent arguments against the viability of something (not that my little paraphrasings above were intended to be intelligent). But these arguments are not necessarily as meaningful, or productive, as they might seem. Think of how much of our technology today would have seemed impossible, or extreme long-term future tech, not that long ago -- even to those most qualified to make such judgement. This of course does not mean anything is possible, but it does mean we'd likely be a much more backwards civilization if not for the headstrong visionaries among us doing what conventional knowledge told us ought not be able to be done.
Anyone here remember that thread and can link it back here? Thanks