(I think) I know that massless particles can only exist traveling at(adsbygoogle = window.adsbygoogle || []).push({}); c, but I find it somehow counter-intuitive (like many other real things... :D ) Would anyone please be so kind to confirm that, for instance, a gamma photon generated by the radioactive decay of a stationary isotope is already "born" at light speed, with zero "acceleration time"? And, when this gamma ray interacts with matter and produces a pair of massive particles (let's say an electron and a positron), what is the initial speed of these massive particles?

By the way, then a deconfined gluon (yes, I know, this is impossible, but let's say for the sake of the argument) would be instanly "propelled" atctoo, wouldn't it?

Thanks for your patience! :)

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# Are all massless particles "born" at light speed?

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