LoL. I had the exact same thought [1], but you managed to finish your comment while I was still away reading about aerogel. ;-) Incidentally, there was a "ca

LoL. I had the exact same thought [1], but you managed to finish your comment while I was still away reading about aerogel. ;-) Incidentally, there was a "carbon nanotube aerogel" that (AFAIK) has the exact same composition as this one and is listed at 1.5 mg/cc [2]. Weighing in a vacuum would seem a bit sensationalistic IMO. [1] http://news.ycombinator.com/item?id=4261353 http://news.ycombinator.com/item?id=4261353 [2] http://www.sciencemag.org/content/323/5921/1575.full http://www.sciencemag.org/content/323/5921/1575.full