ethan@utastro.UUCP (Ethan Vishniac) (01/14/85)
[] I've been out for a couple of weeks. Just before I left I saved a message from Martin Taylor which read as follows >In answering another question, Ethan Vishniac pointed out that in an >inflationary universe, distant parts of the universe are now seeing >one another for the second time because of slowing of the general >expansion. This seems odd to me, in that the further one looks, the >older one sees. Yet signals from the very edge were also observed a very >long time ago. Do we not get a doubling, like the image in a curved >mirror? If so, there presumably is a region of time that we see over >a range of distances, like the focus of that mirror.... If not, why not? Allow me to clarify. Nothing I said was meant to imply a doubling of images. The universe was opaque beyond a certain epoch (the epoch of recombination as it is usually called) due to electron scattering. The epoch of inflation occurred long before the epoch of recombination. Therefore the light we see comes from a volume of space which is much smaller than the causally connected volume that contains our universe. If we could effectively detect kinds of radiation that propagate without difficulty through the early universe (gravitational radiation is the only one I can think of) i then it would be possible to detect radiation emitted from the edge of the causally connected volume. The hitch is that inflation drastically redshifts pre-existing radiation so that this gravitational radiation would have such a large wavelength as to be undetectable. [This is a generic disclaimer. It contains all the benefits of the higher priced variety without the expense.] "Don't argue with a fool. Ethan Vishniac Borrow money from him." {charm,ut-sally,ut-ngp,noao}!utastro!ethan Department of Astronomy University of Texas Austin, Texas 78712