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Location: UFOUpDatesList.Com > 2007 > Feb > Feb 21

Satellite Could See Shadow Of Extra Dimensions

From: UFO UpDates - Toronto <ufoupdates.nul>
Date: Wed, 21 Feb 2007 07:27:28 -0500
Fwd Date: Wed, 21 Feb 2007 07:27:28 -0500
Subject: Satellite Could See Shadow Of Extra Dimensions

Source: NewScientist.Com News Service - Sutton, Surrey UK


12 February 2007

Satellite Could See Shadow Of Extra Dimensions

David Shiga

A satellite to be launched next year could see signs of extra
dimensions in the afterglow of the big bang, a new study says.

Some theories =96 such as string theory =96 that attempt to unify
all known forces into a single "theory of everything" posit the
existence of extra spatial dimensions beyond the three familiar

But string theory has proven stubbornly resistant to
experimental tests (although some physicists say it could be
tested in the Large Hadron Collider scheduled to open by the end
of 2007).

Now, Gary Shiu and Bret Underwood, both physicists at the
University of Wisconsin in Madison, US, say the shape of the
extra dimensions could leave an imprint in the afterglow of the
big bang. This glow, called the cosmic microwave background,
reveals the structure of the universe about 370,000 years after
the big bang.

They use a popular model of the universe's early growth called
Dirac-Born-Infeld (DBI) inflation, which is inspired by string
theory. It is one of a class of ideas called braneworld models,
which state that our universe is like a sheet of paper floating
in a higher dimensional space.

Subtle effects

Because we are confined to our 3D universe, we ordinarily have
no way of seeing the extra dimensions. But Shiu and Underwood
show that in this scenario, the big bang's afterglow is affected
by the precise shape that the extra dimensions take.

The effects are subtle, however, and Underwood points out that
other inflation theories that do not require extra dimensions
could probably produce similar signals. So the effects could not
be used on their own as proof that extra dimensions are present.

But if some other evidence is found that the DBI inflation
scenario is correct, the new study shows that the detailed shape
of those extra dimensions could be distinguished by Europe's
Planck satellite, which is set to be launched in July 2008 (see
the blog Precision cosmology with Planck).

Previous work by Shiu and others has indeed shown that DBI
inflation could be distinguished from other scenarios through
another effect on the cosmic microwave background =96 by causing
the measured clumpiness of matter in the early universe to
deviate in a characteristic way from a random distribution.

Single out

"The really exciting thing is that it's possible in principle =96
extra dimensions can actually show up in observations,"
Underwood told New Scientist. "If you know that you're in this
particular model, then these details of the geometry can
actually be seen."

Licia Verde, a cosmic microwave background researcher at the
University of Pennsylvania in Philadelphia, US, says the
predicted effects are big enough to be noticeable by Planck.
"The prospects are exciting," she told New Scientist.

String theorist Robert Myers of the Perimeter Institute for
Theoretical Physics in Waterloo, Canada, cautions, however, that
DBI inflation is just one of many scenarios proposed to explain
the early universe, each of which could produce subtle effects
in the microwave background.

"DBI is one variant which seems to be consistent with what we
know," he told New Scientist. "But it will be very difficult to
use CMB observations alone to single out the correct story."

Journal reference: Physical Review Letters (vol 98, 051301)

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