One centre, and something going out from it in every direction at once. Stand in front of a hot stove in a cold room: the heat does not travel in a single line towards you, it fills the space all around. Or look at a bicycle wheel: every spoke starts at the middle and runs . Whatever radiate is talking about — heat, light, cracks in glass, streets on a map, or the confidence coming off a person — that same picture can be held underneath it: a middle point, and the thing spreading out from it on all sides.
From the word’s history
Wiktionary records radiate as a learned borrowing from Latin radiātus, from radius 'a spoke, a ray'. The spoke of a wheel is literally a line running out from a hub, which sits very close to the picture the modern word still carries.
Wiktionary 記載 radiate 借自拉丁文 radiātus，來自 radius「輻條、光線」。輻條本來就是一根從輪心往外走的線，這跟今天 radiate 仍然帶著的畫面幾乎重疊。
Wiktionary (kaikki:3f6f69a190036ae4:763106495) — Latin radiātus, perfect passive participle of radiō, from radius ("a spoke, ray")
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