Plasma balls have sat on desks for as long as we can remember, filled with low-pressure gas that lights up in thin, branching strands when a high-voltage electrode inside the glass gets going. Those strands look lively, yet they always end somewhere, either at the glass wall or at a second electrode. The Action Lab recently showed a different arrangement: a continuous ring of glowing plasma that floats inside a sealed xenon globe and never touches any solid conductor.

Researchers at Texas A&M University have shaped a soft gel that keeps common hydrated salts from leaking so a building can soak up daytime warmth and let it out again after the sun sets. Salt hydrates already hold a large amount of heat for their size because they change from solid crystals to liquid and back again, absorbing energy during the melt and giving it back during the freeze.