Tag - Losing Energy

How Light Travels Across the Universe Without Losing Energy

A pulsar inside a supernova bubble. (NASA/ESA/G. Dubner et al.)One evening in my light-polluted San Diego backyard, I had my telescope set up for astrophotography and aimed it at an incredibly distant galaxy. As the first image appeared on my tablet screen, my wife, Cristina, came over."That’s the Pinwheel Galaxy," I told her—named for its...