- ALBUQUERQUE, N.M. -
Researchers
from the U.S. Department of Energy's Los Alamos National Laboratory and
the University of South Carolina have provided a hypothesis that
"black
holes" in space are not holes at all, but instead are more akin to
bubbles.
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- Researcher Emil Mottola of Los Alamos' Theoretical
Division
today presented a new explanation for black holes at the American Physical
Society annual meeting in Albuquerque, N.M. Pawel Mazur of the University
of South Carolina is Mottola's co-author. The researchers' explanation
redefines black holes not as "holes" in space where matter and
light inexplicably disappear into another dimension, but rather as
spherical
voids surrounded by an extremely durable form of matter never before
experienced
on Earth. Mazur and Mottola call the extraordinary objects
Gravastars.
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- The Gravastar explanation for black holes helps provide
answers to some of the daunting questions raised by traditional black-hole
descriptions. Based on earlier-held astrophysical explanations, black holes
form in space when stars reach the end of their lives and collapse in on
themselves. According to black hole theory, the matter from these dying
stars occupies a tiny amount of space - a mere pinpoint - and creates a
mind-boggling gravitational field so powerful that nothing can escape,
not even light.
-
- Mottola and Pawel suggest that while some degree of
collapsing
does take place in a dying star, the collapse proceeds only to a certain
point. At that point, the intense gravity of the dying star transforms
the star's matter into an entirely new phase. Mottolla describes this phase
as similar to a Bose-Einstein condensate, a phase of matter recently
observed
in a laboratory setting and the subject of scientific excitement in the
past few years.
-
- On Earth, a Bose-Einstein condensate forms when matter
is plunged to very low temperatures approaching Absolute Zero, the
theoretical
temperature at which all atomic motion - the motion of electrons, protons
and all other subatomic particles within an individual atom - is believed
to cease. When matter is cooled sufficiently to become a Bose-Einstein
condensate, the atoms that make up the matter enter a strange new phase.
The atoms all reach the same energy state, or quantum state, and they
coalesce
into a blob of material called a "super atom." The properties
of Bose-Einstein condensates are the subject of intense study and many
physicists are working to understand them.
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- Mottola and Mazur believe that dying stars collapse to
the "Event Horizon" - in essence the point of no return for
objects
entering the gravitational field of a black hole. At this point, the matter
in the dying star transforms to a new state of matter that forms a
Gravastar.
According to the two researchers, the dying star's matter creates an
ultra-thin,
ultra-cold, ultra-dark shell of material that is virtually indestructible.
The new form of gravitational energy in the interior is akin to a
Bose-Einstien
condensate, although it appears on the inside to be a bubble of vacuum,
hence the term Gra (vitational) Va (cuum) Star, or Gravastar.
-
- "Since this new form of matter is very durable,
but somewhat flexible, like a bubble, anything that became trapped by its
intense gravity and smashed into it would be obliterated and then
assimilated
into the shell of the Gravastar," Mottola said. "However, any
matter in the vicinity that fell onto the surface could be re-emitted as
another form of energy, which would make Gravastars potentially much more
powerful emitters of radiation than black holes, which simply swallow the
material."
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- The space trapped inside the Gravastar's shell is a
similarly
uncanny conceptually. The interior of the Gravastar would be totally warped
space-time (the traditional three dimensions plus time). According to the
researchers, this interior space would exert an outward force on the shell,
adding to its durability.
-
- Although unconventional, Mottola and Mazur's Gravastar
explanation for black holes does solve at least one serious quandary
created
by black hole theory. Under a black-hole scenario, the amount of entropy
created in a black hole would become nearly infinite. Physicists have
struggled
for years to account for the huge entropy of black holes, and largely have
failed. Unlike their black hole counterparts, Gravastars would have a very
low entropy.
-
- Mottola and Mazur continue to refine their theory and
are working on a concept behind rotating Gravastars. They even suggest
that the universe we now know and live in may be the interior of a
Gravastar.
-
- "These are fascinating concepts to think
about,"
Mottola said. "I look forward to exploring this hypothesis
further."
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- Los Alamos National Laboratory is operated by the
University
of California for the U.S. Department of Energy.
-
- For more Los Alamos news releases, visit World Wide Web
site http://www.lanl.gov/external/n
ews/releases
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