Extinctions usually caused by impact, not radiation
While this is possible, i think that nearly all extinctions have been linked with impact craters.
While cosmology is interesting for the information it can provide about nuclear processes, from the point of view of risk impactors, both cometary and asteroidal, appear to be present a far more serious threat.
The big problem is finding the next continent killer, whether that is an asteroid or comet. Solving this problem appears to have the highest pay-back.
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