Carbonado compared to carbon‑12, relative to typical diamonds). Carbonado exhibits strong luminescence (photoluminescence and cathodoluminescence) induced by nitrogen and by vacancies existing in the crystal lattice. Luminescence halos are present around radioactive inclusions, and it is suggested that the radiation damage occurred after formation of the carbonados, an observation perhaps pertinent to the radiation hypothesis listed below. The origin of carbonado is controversial. Some proposed hypotheses are as follows: None of these hypotheses for carbonado formation had come into wide acceptance in the scientific literature by 2008. Supporters of an extraterrestrial origin of carbonados propose that their material source was a
What Is Life song offers "little overall coherence between words and music". In a 2010 poll to find the "10 Best George Harrison Songs", AOL Radio listeners voted "What Is Life" third behind "My Sweet Lord" and "Blow Away". A similar list by Michael Galluci of Ultimate Classic Rock placed it second (behind "My Sweet Lord"), as Galluci wrote of the track having "a giant pop hook as its guide" as well as "the catchiest chorus Harrison ever penned".<ref name="Gallucci/UCR">Michael Gallucci, "Top 10 George Harrison Songs", Ultimate Classic Rock (retrieved 28 March 2014).</ref> In 2009, Matt Melis of Consequence of Sound listed it