<Tr> <Td> Nuclear fusion </Td> <Td> Spectroscopy </Td> <Td> Stellar evolution </Td> <Td> How the stars shine and how metals formed </Td> </Tr> <Tr> <Td> The Big Bang </Td> <Td> Hubble Space Telescope, COBE </Td> <Td> Expanding universe </Td> <Td> Age of the Universe </Td> </Tr> <Tr> <Td> Quantum fluctuations </Td> <Td> </Td> <Td> Cosmic inflation </Td> <Td> Flatness problem </Td> </Tr> <Tr> <Td> Gravitational collapse </Td> <Td> X-ray astronomy </Td> <Td> General relativity </Td> <Td> Black holes at the center of Andromeda galaxy </Td> </Tr>

What is a description of how closely measurements are to each other