"Laws of Physics for a Holographic Universe" --New Theories of Space-Time
- Interesting post from The Daily Galaxy
Sent: 5/30/2013 6:02:10 P.M. Eastern Daylight Time
Subj: The Daily Galaxy: News from Planet Earth & Beyond
_The Daily Galaxy: News from Planet Earth & Beyond_
_"Laws of Physics for a Holographic Universe" --New Theories of Space-Time
Posted: 30 May 2013 07:37 AM PDT
Researchers at the _University of Southampton_ (http
(University%20of%20Southampton)&t=h) have taken a significant step in a project to unravel the
secrets of the structure of our Universe. One of the main recent advances in
theoretical physics is the holographic principle. According to this idea,
our Universe may be thought of as a hologram and we would like to
understand how to formulate the laws of physics for such a _holographic Universe_
(http://en.wikipedia.org/wiki/Holographic_principle) .A new paper released by
Professor Skenderis and Dr Marco Caldarelli from the University of
Southampton, Dr Joan Camps from the _University of Cambridge_
2222222 (University%20of%20Cambridge)&t=h) and Dr Blaise Goutéraux from
the _Nordic Institute for Theoretical Physics_
(Nordic%20Institute%20for%20Theoretical%20Physics)&t=h) , Sweden published in _Physical Review D_
(http://publish.aps.org/) , makes connections between negatively _curved
space-time_ (http://en.wikipedia.org/wiki/General_relativity) and _flat space_
(http://en.wikipedia.org/wiki/Minkowski_space) -time. The paper AdS/Ricci-flat
correspondence and the _Gregory-Laflamme instability_
(http://en.wikipedia.org/wiki/Gregory%e2%80%93Laflamme_instability) specifically explains what is known
as the Gregory Laflamme instability, where certain types of black hole break
up into smaller black holes when disturbed – rather like a thin stream of
water breaking into little droplets when you touch it with your finger.
This black hole phenomenon has previously been shown to exist through computer
simulations and this work provides a deeper theoretical explanation.
Space-time is usually understood to describe space existing in three
dimensions, with time playing the role of a fourth dimension and all four coming
together to form a continuum, or a state in which the four elements can't
be distinguished from each other.
Flat space-time and negative space-time describe an environment in which
the Universe is non-compact, with space extending infinitely, forever in
time, in any direction. The gravitational forces, such as the ones produced by
a star, are best described by flat-space time. Negatively curved
space-time describes a Universe filled with negative vacuum energy. The mathematics
of holography is best understood for negatively curved space-times.
Professor Skenderis has developed a mathematic model which finds striking
similarities between flat space-time and negatively curved space-time, with
the latter however formulated in a negative number of dimensions, beyond
our realm of physical perception.
"According to holography, at a fundamental level the universe has one less
dimension than we perceive in everyday life and is governed by laws
similar to electromagnetism," says Skenderis. "The idea is similar to that of
ordinary holograms where a three-dimensional image is encoded in a
two-dimensional surface, such as in the hologram on a credit card, but now it is the
entire Universe that is encoded in such a fashion.
"Our research is ongoing, and we hope to find more connections between
flat space-time, negatively curved space-time and holography. Traditional
theories about how the Universe operates go some way individually to describing
its very nature, but each fall short in different areas. It is our
ultimate goal to find a new combined understanding of the Universe, which works
across the board."
In October 2012, Professor Skenderis was named among 20 other prominent
scientists around the world to receive an award from the New Frontiers in
Astronomy and Cosmology international grant competition. He received $175,000
to explore the question, 'Was there a beginning of time and space?"
The Daily Galaxy via University of Southampton
Image credit: MIT
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_NASA Mission Pinpoints Lost & Hidden Asteroids_
Posted: 30 May 2013 07:58 AM PDT
Data from NASA's _Wide-field Infrared Survey Explorer (WISE)_
(http://wise.ssl.berkeley.edu/) have led to a new and improved family tree for
asteroids in the main belt between Mars and Jupiter. Astronomers used millions of
infrared snapshots from the asteroid-hunting portion of the WISE all-sky
survey, called NEOWISE, to identify 28 new asteroid families. The snapshots
also helped place thousands of previously hidden and uncategorized asteroids
into families for the first time. The findings are a critical step in
understanding the origins of asteroid families, and the collisions thought to
have created these rocky clans."NEOWISE has given us the data for a much
more detailed look at the evolution of asteroids throughout the solar system,"
said Lindley Johnson, the program executive for the Near-Earth Object
Observation Program at NASA Headquarters in Washington. "This will help us
trace the NEOs back to their sources and understand how some of them have
migrated to orbits hazardous to the Earth."
The _main asteroid belt_ (http://en.wikipedia.org/wiki/Asteroid_belt) is a
major source of near-Earth objects (NEOs), which are those asteroids and
comets that come within 28 million miles (45 million kilometers) of Earth's
path around the sun. Some near-Earth objects start out in stable orbits in
the main asteroid belt, until a collision or gravitational disturbance
flings them inward like flippers in a game of pinball.
The NEOWISE team looked at about 120,000 main belt asteroids out of the
approximately 600,000 known. They found that about 38,000 of these objects,
roughly one third of the observed population, could be assigned to 76
families, 28 of which are new. In addition, some asteroids thought to belong to a
particular family were reclassified.
An asteroid family is formed when a collision breaks apart a large parent
body into fragments of various sizes. Some collisions leave giant craters.
For example, the asteroid Vesta's southern hemisphere was excavated by two
large impacts. Other smash-ups are catastrophic, shattering an object into
numerous fragments, as was the case with the _Eos asteroid_
(http://en.wikipedia.org/wiki/Eos_family) family. The cast-off pieces move together in
packs, traveling on the same path around the sun, but over time the pieces
become more and more spread out.
Previous knowledge of asteroid family lineages comes from observations of
their orbits. NEOWISE also looked at the asteroids' reflectivity to
identify family members.
Asteroids in the same family generally have similar mineral composition
and reflect similar amounts of light. Some families consist of
darker-colored, or duller, asteroids, while others are made up of lighter-colored, or
shinier, rocks. It is difficult to distinguish between dark and light
asteroids in visible light. A large, dull asteroid can appear the same as a small,
shiny one. The dark asteroid reflects less light but has more total surface
area, so it appears brighter.
NEOWISE could distinguish between the dark and light asteroids because it
could detct infrared light, which reveals the heat of an object. The larger
the object, the more heat it gives off. When the size of an asteroid can
be measured, its true reflective properties can be determined, and a group
of asteroids once thought to belong to a single family circling the sun in a
similar orbit can be sorted into distinct families.
"We're separating zebras from the gazelles," said Joseph Masiero of
_NASA's Jet Propulsion Laboratory_
(Jet%20Propulsion%20Laboratory)&t=h) in Pasadena, Calif., who is lead author of a report on
the new study that appears in the Astrophysical Journal. "Before, family
members were harder to tell apart because they were traveling in nearby
packs. But now we have a better idea of which asteroid belongs to which
The next step for the team is to learn more about the original parent
bodies that spawned the families.
"It's as if you have shards from a broken vase, and you want to put it
back together to find out what happened," said _Amy Mainzer_
(http://en.wikipedia.org/wiki/Amy_Mainzer) , the NEOWISE principal investigator at JPL. "Why
did the asteroid belt form in the first place and fail to become a planet?
We are piecing together our asteroids' history."
JPL, a division of the _California Institute of Technology_
(California%20Institute%20of%20Technology)&t=h) in Pasadena, managed and
operated WISE for NASA's _Science Mission Directorate_
(http://en.wikipedia.org/wiki/Science_Mission_Directorate) . The spacecraft was put into
hibernation mode in 2011, after completing its main objectives of scanning the
entire sky twice.
The Daily Galaxy via http://www.nasa.gov/wise
Image credit: With thanks to National Space Centre/_SpaceAnswers.com_
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Earth Next Week_
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