The COBE satellite was the first to measure fluctuations (signified by blobs of different colors) in the temperature of the cosmic microwave background. Because of its low angular resolution, COBE could detect blobs only bigger than 7 degrees in width. Blobs smaller than that are smeared together, in effect. But newer ground-based measurements, made at places such as Saskatoon in northern Canada, can see much smaller structures. The question of blob size is important for determining whether the universe will continue to expanding forever. (Figure courtesy of Max Tegmark, Institute of Advanced Study, Princeton, NJ.)
This research is described in an paper by M. Tegmark in Physical Review Letters, v. 79, p. 3806 (17 November 1997).
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