Why is it still possible to observe galaxies billions of light years away although the intensity drops inversely proportional to the square of the distance?
Among those who love physics, you are young people with independent scientific minds. But I can not answer this question at the moment, otherwise pan quantum theory will be more brutally blocked. I wish you a lot of breakthroughs.
Because we have exceptionally sensitive cameras, and can (with space-borne telescopes) stare in a given direction for an arbitrarily long period - and so collect sufficient photons.