The universe is vast. There are many galaxies, each containing many stars. In a future with space colonization, each star could support a large population of people leading worthwhile lives. During any given year, we irrecoverably lose an amount of energy that could have powered a civilization like ours for many billions of years.
The prospect of advanced technology only makes the numbers more extreme. Such technology would make it possible to support far more, and better, lives with the same resources.
Nick Bostrom has named this issue astronomical waste. He notes that in a wide range of moral theories — in particular, those based on linear aggregation of value — considerations of astronomical waste outweigh all others....