Yeah. I think the 10-20b is based off of stronger carbon nanotubes. But I think we have strong enough nanotubes at the moment. However, the stronger they get, the fewer we have to use, and the cheaper it will be.
You don't even need to build all the way to orbit or even space. A 20km tall tower made out of ordinary steel with a launch accelerator built into it would dramatically reduce the cost to orbit.
My understanding is that they are now strong enough, but we can't make them long enough. We have no way to "weld" them together after their creation to make longer tubes without sacrificing their integrity.
