The original version of this story appeared in Quanta Magazine.
For a molecule of RNA, the world is a dangerous place. Unlike DNA, which can persist for millions of years in its remarkably stable, double-stranded form, RNA isn’t built to last—not even within the cell that made it. Unless it’s protectively tethered to a larger molecule, RNA can degrade in minutes or less. And outside a cell? Forget about it. Voracious, RNA-destroying enzymes are everywhere, secreted by all forms of life as a defense against viruses that spell out their genetic identity in RNA code.
There is one way RNA can survive outside a cell unscathed: in a tiny, protective bubble.