La fusione fra due stelle di neutroni è stata osservata per la prima volta il 17 agosto grazie ai due apparecchi, LIGO negli Stati Uniti e Virgo in Italia, che permettono di individuare le onde gravitazionali. Si tratta di un evento unico, secondo una decina di studi pubblicata contemporaneamente lunedì nelle riviste Nature e Science.
La comunità degli astronomi era in fibrillazione da mesi, ma aveva mantenuto finora il segreto per poter fornire risultati inappuntabili. Lo scontro cosmico permette di svelare o confermare almeno tre tesi sull'universo: per la prima volta c'è la conferma di una "miniera spaziale" in cui sono stati forgiati elementi pesanti come oro, platino e piombo. Inoltre, il telescopio Fermi della NASA ha individuato dopo 1,7 secondi l'emissione di raggi gamma corti, di cui dunque si dimostra l'origine. Infine, la simultaneità delle due ricezioni dà ragione ad Einstein, che più di un secolo fa aveva ipotizzato che le onde gravitazionali viaggiassero alla velocità della luce: lo scarto infatti è minimo, se si considera che l'evento percepito risale a 130 milioni di anni fa. Sulla Terra c'erano ancora i dinosauri.
pon/AFP
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