The conversation between human and AI assistant.
How fast is universe expanding compared to light speed?
How do astronomers measure the expansion rate of the universe?
One of the main ways is by observing distant objects known as "standard candles," which have a known luminosity. By comparing the observed luminosity of these objects to their predicted luminosity based on their distance, astronomers can determine how far away they are - and therefore how quickly they're moving away from us due to the expansion of the universe.