Clarity is what astronomers and the public have come to expect from the
       Hubble Space Telescope. But the sharpness with which Hubble
       photographs distant galaxies has scientists pondering why the pictures are
       not blurry, as some new calculations suggest they should be, and whether
       some basic assumptions about space, time and gravity might have to be
       rethought.

       The photographs, of very distant stars and galaxies, were analyzed to test a
       fundamental aspect of quantum theory, which is a collection of widely held
       ideas about physics at the invisible level of atoms, and how these ideas
       relate to conceptions of physics on the grandest scales of the universe. 

       Conventional thinking is that space and time
       can be thought of together as a sort of foam.
       As light travels through the foam, it ought to be
       disrupted, ever so slightly, such that by the
       time it crosses much of the universe it would
       render only blurry pictures when gathered by a
       precision telescope. Put simple, Hubble ought
       to see a pixilation effect when photographing
       distant objects.

       It does not. Hubble pictures are crisp and
       clear, no matter the distance to the object.

       And that, say two separate teams of
       researchers, might mean there are flaws in
       quantum theory.

       The newest study was led by Roberto
       Ragazzoni of the Astrophysical Observatory of
       Arcetri, Italy and the Max Planck Institute for
       Astronomy in Heidelberg, Germany.
       Ragazzoni told SPACE.com the expected
       quantum effect is like a subtle version of the
       blurring caused by Earth's atmosphere, which
       makes stars twinkle. 

       When light arrives from a distant object,
       Ragazzoni explained, some parts of the light's
       wave should be retarded with respect to
       others, because each would take slightly
       different paths through the foam. Light will
       appear to come from positions around the
       actual source, causing a blur.

       Ragazzoni's team 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."

       The research will be published April 10 in the Astrophysical Journal Letters. 

       Similar results came a few weeks ago from scientists using a slightly different technique at the
       University of Alabama in Huntsville. Richard Lieu and Lloyd Hillman used separate Hubble images
       and a more complex analyzing technique to examine galaxies that are at least 4 billion light-years
       away.

       They did not find the expected quantum effect, either.

       Light is said to move in very small but measurable quanta, or quantum bits. Time is supposed to
       move in correspondingly miniscule quantum bits. The bits fit in with Einstein's theory of general
       relativity, which describes physics at the large scale of the universe. Einstein said time, gravity and
       the fabric of space are different manifestations of the same phenomenon.

       In recent years, theorists have refined all this thinking and determined a pair of quanta -- the Planck
       length (one trillion-trillion-trillionth of a meter) and a similarly miniscule packet of Planck time -- that
       should be the smallest measurable. Below these thresholds, things should become fuzzy: If light's
       travel is quantized, it would in theory be variable in units below the Planck limit.

       "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.

       Other theorists say the new results must
       be taken into account, but they say not
       enough is known about the way light
       does or should behave below the Planck
       interval to draw firm conclusions yet.

       One challenge for theorists, if the studies
       by Lieu and Ragazzoni are on track, is
       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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