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While a space elevator doesn't contradict any fundamental limits of physics, that doesn't mean it's actually possible to build one. There is no reason to be cer

While a space elevator doesn't contradict any fundamental limits of physics, that doesn't mean it's actually possible to build one. There is no reason to be certain that it's actually possible to create a material that has the required characteristics in terms of tensile strength to support it's own weight, plus the weight of the elevator, plus the weight of all the additional cabling. It also has to endure the huge temperature differences that it will experience along its length and from day to night and from season to season. This is especially true considering that you don't need something that barely holds - you need something that you know will hold up to many times more weight than it needs to, so that it can be safe: the potential energy such a thing would store would be enough to dig into hundreds of meters of rock all around the world, if it ever crashed. So, you have to ensure there is no realistic chance of it ever crashing. It also has to be highly non-fragile in other ways, so that a madman with a bomb or a freak collision with an airplane or a meteor (especially likely in the thin upper layers of the atmosphere) won't bring it all down. This combination of properties may well be completely impossible to actually achieve in a material. Even if there is no obvious basic law of physics that it would break, that doesn't mean that it wouldn't break other, harder to touch, derived laws.

Jolter 1y ago
A terrorist attack on a space elevator happens to figure in the first episode of the TV series Foundation. https://foundation.fandom.com/wiki/Bombing_of_the_Star_Bridge https://foundation.fandom.com/wiki/Bombing_of_the_Star_Bridg... It’s about as devastating as you would expect.
- lproven 1y ago
  That's odd. The first episode was the only one I watched and I don't remember that bit. It might have grabbed me. A terrorist attack on a space elevator is a pivotal plot point in Blue Mars by Kim Stanley Robinson, which IMHO is a better work in basically every way than Asimov's magnum opus.
  - Metacelsus 1y ago
    Doesn't the space elevator attack happen in Red Mars not Blue Mars?
    - p_l 1y ago
      There's a terrorist attack, sorta, in latter book, but Red Mars was admittedly a legitimate military strike, as was destruction of Phobos.
    - lproven 1y ago
      I happily defer. I've reread the trilogy 6 times now and they do all blur together a bit. You look to be right: https://www.kimstanleyrobinson.info/content/space-elevator https://www.kimstanleyrobinson.info/content/space-elevator And I'm not the only one to notice the cross-reference: https://www.reddit.com/r/kimstanleyrobinson/comments/pv6zh9/space_elevator_in_apple_tv_foundation/ https://www.reddit.com/r/kimstanleyrobinson/comments/pv6zh9/...
  - CaptainOfCoit 1y ago
    > That's odd. The first episode was the only one I watched and I don't remember that bit. It might have grabbed me. I think it's the first episode of season 2 or 3, not the first season. I remember someone else mentioning it, but I've only seen season 1 and don't recall that either.
    - mechanicum 1y ago
      Definitely S01E01, @ ~55-58 minutes. I just watched it.
      - lproven 1y ago
        Huh. OK then. I was not taken by it and don't really want to watch it again, or the whole thing, so I will take your word.
- Frotag 1y ago
  Terrorists-attacking-elevator is something that comes up multiple times in Gundam 00. Probably as an allusion to 9/11 (resistance to a growing superpower), but the in-universe explanations are pretty interesting too. The elevators were developed for cheap space travel but unsurprisingly centralized the world's economic development around the owner countries. ie the other countries became increasingly reliant on them and the world segmented into (three) blocs. But the owner countries became increasingly protective / paranoid, leading to cold-war era developments where each of them secretly researched fancy space weapons and stockpiled more and more military assets around the elevators. So some of the attacks were by poorer countries lashing out. Some attacks were to expose the military assets being hidden in the elevator (outlawed by intl treaty). Though most were probably just excuses to show things like giant robots vs death star.
icetank 1y ago
The issue of the line falling back to earth is solved by putting the base of the elevator on water. If the top part of the elevator was cut of you could even detonate charges along the line to make sure all pieces fall into water.
- 0xEF 1y ago
  Are we to assume they would be falling straight down? Because I'm pretty sure that's wrong. I'm not a physicist, though, and am happy to be corrected because every time the Space Elevator comes up, I want to know what happens when catastrophic failure occurs and how we'd mitigate that.
  - speed_spread 1y ago
    It would become a giant whip falling faster and faster round the equator.
  - devilsdata 1y ago
    https://en.wikipedia.org/wiki/Space_elevator https://en.wikipedia.org/wiki/Space_elevator > Above GEO, the centrifugal force is stronger than gravity, causing objects attached to the cable there to pull upward on it. [...] On the cable below geostationary orbit, downward gravity would be greater than the upward centrifugal force, so the apparent gravity would pull objects attached to the cable downward. So, without defensive countermeasures, the Space Elevator would indeed whip around the Earth. But honestly, if I were designing such a thing, it would have break points, and maybe even a whinch at the base, to pull the line in. I'd also build it over water, and not over a population centre. But I'm only a software engineer– it's likely a lot more challenging than this.
  - LorenPechtel 1y ago
    If you blow the cable apart at a few important points the mass that falls either hits fairly near downrange from the tether, or does not hit at all. Have a group of range safety officers for the charges and a law that when on duty they are expected to shoot any politician that contacts them. (I'm thinking of Fukushima. We need to vent the reactor or it will blow! You can't vent until the city has been evacuated. The reactor didn't listen to the politicians.)
gtowey 1y ago
I'm wondering if it's one of those paradoxes where by the time we are technologically capable of building one, we won't actually need it.

Jolter 1y ago

A terrorist attack on a space elevator happens to figure in the first episode of the TV series Foundation. https://foundation.fandom.com/wiki/Bombing_of_the_Star_Bridge https://foundation.fandom.com/wiki/Bombing_of_the_Star_Bridg... It’s about as devastating as you would expect.

lproven 1y ago
That's odd. The first episode was the only one I watched and I don't remember that bit. It might have grabbed me. A terrorist attack on a space elevator is a pivotal plot point in Blue Mars by Kim Stanley Robinson, which IMHO is a better work in basically every way than Asimov's magnum opus.
- Metacelsus 1y ago
  Doesn't the space elevator attack happen in Red Mars not Blue Mars?
  - p_l 1y ago
    There's a terrorist attack, sorta, in latter book, but Red Mars was admittedly a legitimate military strike, as was destruction of Phobos.
  - lproven 1y ago
    I happily defer. I've reread the trilogy 6 times now and they do all blur together a bit. You look to be right: https://www.kimstanleyrobinson.info/content/space-elevator https://www.kimstanleyrobinson.info/content/space-elevator And I'm not the only one to notice the cross-reference: https://www.reddit.com/r/kimstanleyrobinson/comments/pv6zh9/space_elevator_in_apple_tv_foundation/ https://www.reddit.com/r/kimstanleyrobinson/comments/pv6zh9/...
- CaptainOfCoit 1y ago
  > That's odd. The first episode was the only one I watched and I don't remember that bit. It might have grabbed me. I think it's the first episode of season 2 or 3, not the first season. I remember someone else mentioning it, but I've only seen season 1 and don't recall that either.
  - mechanicum 1y ago
    Definitely S01E01, @ ~55-58 minutes. I just watched it.
    - lproven 1y ago
      Huh. OK then. I was not taken by it and don't really want to watch it again, or the whole thing, so I will take your word.
Frotag 1y ago
Terrorists-attacking-elevator is something that comes up multiple times in Gundam 00. Probably as an allusion to 9/11 (resistance to a growing superpower), but the in-universe explanations are pretty interesting too. The elevators were developed for cheap space travel but unsurprisingly centralized the world's economic development around the owner countries. ie the other countries became increasingly reliant on them and the world segmented into (three) blocs. But the owner countries became increasingly protective / paranoid, leading to cold-war era developments where each of them secretly researched fancy space weapons and stockpiled more and more military assets around the elevators. So some of the attacks were by poorer countries lashing out. Some attacks were to expose the military assets being hidden in the elevator (outlawed by intl treaty). Though most were probably just excuses to show things like giant robots vs death star.

icetank 1y ago

The issue of the line falling back to earth is solved by putting the base of the elevator on water. If the top part of the elevator was cut of you could even detonate charges along the line to make sure all pieces fall into water.

0xEF 1y ago
Are we to assume they would be falling straight down? Because I'm pretty sure that's wrong. I'm not a physicist, though, and am happy to be corrected because every time the Space Elevator comes up, I want to know what happens when catastrophic failure occurs and how we'd mitigate that.
- speed_spread 1y ago
  It would become a giant whip falling faster and faster round the equator.
- devilsdata 1y ago
  https://en.wikipedia.org/wiki/Space_elevator https://en.wikipedia.org/wiki/Space_elevator > Above GEO, the centrifugal force is stronger than gravity, causing objects attached to the cable there to pull upward on it. [...] On the cable below geostationary orbit, downward gravity would be greater than the upward centrifugal force, so the apparent gravity would pull objects attached to the cable downward. So, without defensive countermeasures, the Space Elevator would indeed whip around the Earth. But honestly, if I were designing such a thing, it would have break points, and maybe even a whinch at the base, to pull the line in. I'd also build it over water, and not over a population centre. But I'm only a software engineer– it's likely a lot more challenging than this.
- LorenPechtel 1y ago
  If you blow the cable apart at a few important points the mass that falls either hits fairly near downrange from the tether, or does not hit at all. Have a group of range safety officers for the charges and a law that when on duty they are expected to shoot any politician that contacts them. (I'm thinking of Fukushima. We need to vent the reactor or it will blow! You can't vent until the city has been evacuated. The reactor didn't listen to the politicians.)

gtowey 1y ago

I'm wondering if it's one of those paradoxes where by the time we are technologically capable of building one, we won't actually need it.