Physics Wednesday, April 2, 2003. Post by Ricky James
Six weeks ago SFT ran a story about a speech by your favorite physicist and mine, Fotini Markopoulou Kalamara. Fo (oh, to know her so) hoped that gamma rays from sources billions of miles away at the edge of the universe would effectively “defocus” during their trip to Earth as they weaved in and out of the subatomic fabric structure of space itself, down at the so-called Planck scales. She thought this “defocusing” might be observable with NASA’s next generation Gamma-ray Large Area Space Telescope (GLAST) and lead to deep new theoretical insights about the true nature of space and time.
Other astronomers and physicists aren’t waiting for GLAST. Their studies of the best current visible light pictures from the edge of the universe, the so-called Hubble Deep Field photographs, suggest that “fabric-of-space-defocusing” isn’t present at all. They say the Deep Field photos are just too sharp and do not exhibit the blurriness that Fo suggests.
A team led by Roberto Ragazzoni of the Astrophysical Observatory of Arcetri, Italy studied Hubble pictures of a galaxy more than 5 billion light-years away and, separately, an exploding star 42 million light-years distant. “You don’t see a universe that is blurred,” he said. “If you take any Hubble Space Telescope Deep Field image you see sharp images, which is enough to tell us that the light has not been distorted or perturbed by fluctuations in space-time from the source to the observer.” Their research will be published April 10 in the journal Astrophysical Research-Letters. Similar results came a few weeks ago from scientists Richard Lieu and Lloyd Hillman at the University of Alabama in Huntsville. Their examination of galaxies that are at least 4 billion light-years away did not find the expected quantum effect, either. “If time doesn’t become ‘fuzzy’ beneath a Planck interval, this discovery will present problems to several astrophysical and cosmological models, including the Big Bang model of the universe,” Lieu says. One challenge for theorists would be that the instant of the Big Bang would involve an infinitely hot and dense condition — something current theory does not allow.
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