# Biggest Constructs possible today. **URL:** \ **Category:** Factual Questions\ **Created:** [October 4, 2009, 8:56pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587 "2009-10-04T20:56:45Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Lust4Life](https://avatars.discourse-cdn.com/v4/letter/l/ecc23a/32.png) [@Lust4Life](https://boards.straightdope.com/u/Lust4Life)\ **Post date:** [October 4, 2009, 8:56pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/1 "2009-10-04T20:56:45Z")
If money were no object and we can use any technology reasonably available,any materials plus the plant that is actually in existance today, what would be the biggest Dome, highest tower and wall that we could build? Usefullness and purpose are irrelevant. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [October 4, 2009, 9:13pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/2 "2009-10-04T21:13:19Z")
A PBS documentary on supertall skyscrapers a few years ago asked exactly that question. If price is no object and if you’re not concerned about terrorist attack or economic usefulness, several civil engineers on the show said you can build just about as high as you want to go. In this as in so many other things, Frank Lloyd Wright was a true visionary: [The Illinois - Wikipedia](http://en.wikipedia.org/wiki/The_Illinois) And consider this: [Space elevator - Wikipedia](http://en.wikipedia.org/wiki/Space_elevator) ---
**Author:** ![ChrisBooth12](https://avatars.discourse-cdn.com/v4/letter/c/e95f7d/32.png) [@ChrisBooth12](https://boards.straightdope.com/u/ChrisBooth12)\ **Post date:** [October 4, 2009, 9:49pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/3 "2009-10-04T21:49:12Z")
An elevator to space would be easy. I mean its just the carbon nano links are a bitch/expensive to make. I think with current tech a space elevator would cost more then the entire planets GDP, we justneed to work on getting the nanotubes cheaper ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [October 4, 2009, 10:32pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/4 "2009-10-04T22:32:07Z")
The [X-seed 4000](http://en.wikipedia.org/wiki/X-Seed_4000) was designed to be 4,000m high. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [October 4, 2009, 10:33pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/5 "2009-10-04T22:33:26Z")
A slightly less extreme example would be building a skyscraper out of commercially available graphite fiber. In principle it could be ridiculously high- 40 or 50 kilometers- but at current prices would cost several trillion dollars. I’ve posted before that I’m a little uncertain as to claims that tensegrity structures, such as geodesic domes, can be _limitless_ in size. I don’t know how to reconcile that claim with limitations such as the square-cube law. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [October 4, 2009, 10:39pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/6 "2009-10-04T22:39:20Z")
A building 1/2 mile high already exists. [Burj Khalifa - Wikipedia](http://en.wikipedia.org/wiki/Burj_Dubai) ---
**Author:** ![appleciders](https://avatars.discourse-cdn.com/v4/letter/a/85f322/32.png) [@appleciders](https://boards.straightdope.com/u/appleciders)\ **Post date:** [October 4, 2009, 10:40pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/7 "2009-10-04T22:40:02Z")
> [@ChrisBooth12](#): > > An elevator to space would be easy. I mean its just the carbon nano links are a bitch/expensive to make. I think with current tech a space elevator would cost more then the entire planets GDP, we justneed to work on getting the nanotubes cheaper I think I’ve read reports on the feasibility of space elevators that the weight-strength ratio of carbon nanotubes that concluded that even those would be unable to support their own weight over the distance needed for a space elevator, let alone lift any cargo. May have been an Asimov or Clarke essay. I’ll see if I can dig it up. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [October 4, 2009, 11:20pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/8 "2009-10-04T23:20:18Z")
> [@appleciders](#): > > I think I’ve read reports on the feasibility of space elevators that the weight-strength ratio of carbon nanotubes that concluded that even those would be unable to support their own weight over the distance needed for a space elevator, let alone lift any cargo. May have been an Asimov or Clarke essay. I’ll see if I can dig it up. Remember that even if a straight cable couldn’t support its weight, you could still use a tapered cable, thicker at the geosynch point than the ends. You could build a space elevator out of the same steel cable used to build suspension bridges IF the cable was a thousand miles thick at geosynch and tapered down to a thread. So it’s more a question of how strong the cable needs to be practical. Proposals exist for the first version to be a ribbon only microns thick but capable of lifting a few hundred kilos at the Earth end. So you taper the ribbon by making it millimeters thick in orbit ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [October 4, 2009, 11:28pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/9 "2009-10-04T23:28:23Z")
> [@Tapioca\_Dextrin](#): > > The [X-seed 4000](http://en.wikipedia.org/wiki/X-Seed_4000) was designed to be 4,000m high. Leave it to the Japanese to build a replica of Mount Fuji, only larger. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 5, 2009, 1:39am UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/10 "2009-10-05T01:39:42Z")
So far as I know, the biggest device ever planned to be built is the [Laser Interferometer Space Antenna](http://lisa.nasa.gov/), an equilateral triangle with sides 5 million km long. It kind of stretches the definition of a single thing, since it’s composed of three separate spacecraft connected only by laser beams, but I would maintain that it should count, since a single LISA spacecraft, or even two of them, is completely useless-- You need all three for it to work. It’s expected to be about ten years away from launch, and has been for the past decade, so it’s an open question whether it ever actually will be, but it’s certainly possible. ---
**Author:** ![Lust4Life](https://avatars.discourse-cdn.com/v4/letter/l/ecc23a/32.png) [@Lust4Life](https://boards.straightdope.com/u/Lust4Life)\ **Post date:** [October 5, 2009, 10:13am UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/11 "2009-10-05T10:13:49Z")
Ref the Space Elevator,I don’t think that counts as technology thats reasonably available. ---
**Author:** ![hammos1](https://avatars.discourse-cdn.com/v4/letter/h/ba8739/32.png) [@hammos1](https://boards.straightdope.com/u/hammos1)\ **Post date:** [October 5, 2009, 12:35pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/12 "2009-10-05T12:35:55Z")
The pyramids of Egypt certainly count as buildings, even though they’re largely just piles of rock. There doesn’t seem to be any reason why you couldn’t build such a structure to the height of a large mountain, several miles in height. The ultimate limiting factor would be the ability of the earth’s crust to support the weight. ---
**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\ **Post date:** [October 5, 2009, 1:31pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/13 "2009-10-05T13:31:39Z")
> [@hammos1](#): > > The pyramids of Egypt certainly count as buildings, even though they’re largely just piles of rock. There doesn’t seem to be any reason why you couldn’t build such a structure to the height of a large mountain, several miles in height. The ultimate limiting factor would be the ability of the earth’s crust to support the weight. In that case, could we pick a large mountain that already exists, and carve it down until it’s a building? Kind of like NORAD’s bunker, but taken to its full conclusion. I have a feeling that would be cheating, according to the OP. ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [October 5, 2009, 2:04pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/14 "2009-10-05T14:04:24Z")
Also, see post #4 😉 ---
**Author:** ![pan1](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pan1](https://boards.straightdope.com/u/pan1)\ **Post date:** [October 5, 2009, 2:12pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/15 "2009-10-05T14:12:12Z")
A space elevator IS currently available technology. But, we’re looking for ways to make it cheaper before we do it. A steel cable is feasible but would be large and expensive. We’re hoping to get the carbon fiber tech to the point where we could make a small and less expensive cable. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [October 5, 2009, 2:23pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/16 "2009-10-05T14:23:32Z")
Maybe someone in this thread can tell me how a space elevator can work. If you have a cable tethered to the ground, with another end in orbit, you’re supposed to attach wheels and drive the cargo into orbit, right? How does this not pull down the counterweight? Any force pulling up the cargo must try to pull down the cable. I think there’s something I’m missing. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [October 5, 2009, 2:56pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/17 "2009-10-05T14:56:37Z")
> [@Cardinal](#): > > Maybe someone in this thread can tell me how a space elevator can work. If you have a cable tethered to the ground, with another end in orbit, you’re supposed to attach wheels and drive the cargo into orbit, right? How does this not pull down the counterweight? Any force pulling up the cargo must try to pull down the cable. I think there’s something I’m missing. The proposals I’ve seen have the cable have a net upward force, prevented from rising up by being anchored to the ground. So the payload simply reduces the upward force. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [October 5, 2009, 4:37pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/18 "2009-10-05T16:37:17Z")
Teacher nerd: It has a tension upward. If it had a net force up it would be accelerating up. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [October 8, 2009, 5:09pm UTC](https://boards.straightdope.com/t/biggest-constructs-possible-today/512587/19 "2009-10-08T17:09:25Z")
> [@Cardinal](#): > > Maybe someone in this thread can tell me how a space elevator can work. If you have a cable tethered to the ground, with another end in orbit, you’re supposed to attach wheels and drive the cargo into orbit, right? How does this not pull down the counterweight? Any force pulling up the cargo must try to pull down the cable. I think there’s something I’m missing. Because the mass of your payload is insignificant when compared against the forces acting on the space elevator. Realistically, I would say mile-high skyscrapers are about the maximum at current technology. Or about twice as tall as the Burj Dubai. Any bigger than that, you start getting into exotic materials or construction methods that I’m not sure are feasible.