What do you think? When Cosmologist talk about the expansion of the universe, it is often phrased as space itself expanding. For instance, interpreting cosmological redshifts as due to the photons being 'stretched' as they pass through expanding space, rather than being due to a doppler shift (since for instance at cosmological distances galaxies can be receding at greater than c and hence the doppler formula breaks down). People use analogies to dots on a balloon or raisins in bread but this seems to imply that the expansion of space (the rubber or the bread) is what carries the galaxies (the dots or raisins) apart. The idea the space expands has been attacked by various people, including the well respected John Peacock. See http://www.roe.ac.uk/~jap/book/additions.html" [Broken], click on the link 'Expanding Space' Do people agree with this? Is Expanding Space a 'dangerous idea' or a necessary interpretation of the GR equations for FRW universes? The maths is not in dispute, but the interpretation seems to be.