PRECISION IN COSMOLOGY.

PRECISION IN COSMOLOGY. David Kaiser has an essay in the London Review of Books (February 17) in which he recounts the changes in cosmology since he began studying it some 20 years ago. Back then one of his undergraduate teachers announced on the first day that the students “could use the equation ‘1=10’, since most quantities of interest had comparable uncertainties.” After that, satellites and the Hubble Space Telescope collected masses of data. Now cosmologists can say that the universe we know is 13.75 billion years old and the estimated error is plus or minus 0.8 per cent. Kaiser says that cosmologists can now argue on the basis of “high-precision” data.