Imagine a star giving off light for a split second of time, and the photons of light from this exact point in time are travelling through the universe in all directions like an expanding bubble. Is this the correct way of imagining light? If the light travels 10 million light years away and reaches, for example, our Moon, it would appear brighter than if viewed from another moon a further 100 million LY away. What about a billion LY away? Is there a point when the light becomes completely undetectable? If I liken if to my computer monitor.... An image taken next to the star has 1,000,000 bright pixels. An image taken from 10 million LY away has 300,000 bright pixels. An image taken from 100 million LY away has 50,000 bright pixels. An image taken from 1 billion LY away has 1,000 bright pixels. etc Am I right in thinking there will be a distance from which only 1 pixel is bright, and a distance even further where no pixels are light remaining? Where the photons are so spread out that they are undetectable?