Wish that was true, but so far nobody has come up with a workable substitute for the mercury. Mercury vapor is quite efficient at emitting copious ultraviolet light when energized by an electrical current passing through it. The special phosphor film on the inside of the tube, when struck by the ultraviolet light, will glow (”fluoresce”) with a visible light. Anything taking the place of the mercury would have to be able to emit similar ultraviolet light with similar efficiency.
Thanks. I wasn’t actually certain of that. Good to know, though!