Glowing spheres that drift through the air for seconds after a lightning strike — centuries of sober eyewitness reports, even one caught on a spectrometer in 2012. Is it real? The energy in a ~10 cm luminous ball is physically plausible, and it’s a genuine open problem — but no single MECHANISM (oxidising silicon vapour? trapped microwaves? plasma?) is confirmed. Slide the reported energy. Verdict: REAL, mechanism unconfirmed.
A ~0.1 m luminous sphere holding ~10²–10³ J has an energy density (~10⁵ J/m³) comparable to other transient plasmas — physically plausible, not impossible. Ball lightning has thousands of consistent eyewitness accounts across cultures and a 2012 Lanzhou spectrum (silicon, iron, calcium lines — supporting the Abrahamson–Dinniss vaporised-soil hypothesis). But no proposed mechanism is confirmed or reliably reproduced. A fail-loud self-check throws unless the energy density sits in the plausible 10³–10⁷ J/m³ window. ◆ VERDICT: REAL phenomenon, UNEXPLAINED mechanism — the honest ‘we don’t know yet’.
The energy-density plausibility is a real sanity check, not a proof of any mechanism. ‘Real’ rests on the weight of consistent observation + one spectrum, not a lab-repeatable result — the honest status is open, and this sphere says so rather than picking a favourite theory.