Specifically , luminosity is proportional to radius squared .
具体来说，光度与半径的平方呈正比。
Specifically , the luminosity of a star is proportional to temperature to the fourth power .
具体来说，恒星的光度与温度的四次方呈正比。
In principle , one can trace that history back in cosmic time by observing a so-called standard candle , a class of astronomical object whose intrinsic luminosity is uniform .
原理上，我们可以通过观测所谓的标准烛光（一种天体，它的绝对光度是相同的）来追溯宇宙内的历史。
And if octopuses , cuttlefish and squid-and some of their predators and prey-can see polarized light so keenly , are they also using it , as they use color and luminosity , to actively create camouflage ?
