OK!!
Scientists Propose Test Of String Theory Based On Neutral Hydrogen Absorption
ScienceDaily (Jan. 28, 2008) — Ancient light absorbed by neutral hydrogen atoms could be used to test certain predictions of string theory, say cosmologists at the University of Illinois. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon.
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See also:
Space & Time
Cosmic Rays
Cosmology
Astrophysics
Matter & Energy
Albert Einstein
Physics
Nature of Water
Reference
Physical cosmology
Cosmic microwave background radiation
Shape of the Universe
Subatomic particle
String theory -- a theory whose fundamental building blocks are tiny one-dimensional filaments called strings -- is the leading contender for a "theory of everything." Such a theory would unify all four fundamental forces of nature (the strong and weak nuclear forces, electromagnetism, and gravity). But finding ways to test string theory has been difficult.
Now, cosmologists at the U. of I. say absorption features in the 21-centimeter spectrum of neutral hydrogen atoms could be used for such a test.
"High-redshift, 21-centimeter observations provide a rare observational window in which to test string theory, constrain its parameters and show whether or not it makes sense to embed a type of inflation -- called brane inflation -- into string theory," said Benjamin Wandelt, a professor of physics and of astronomy at the U. of I.
"If we embed brane inflation into string theory, a network of cosmic strings is predicted to form," Wandelt said. "We can test this prediction by looking for the impact this cosmic string network would have on the density of neutral hydrogen in the universe."
Wandelt and graduate student Rishi Khatri describe their proposed test in a paper accepted for publication in the journal Physical Review Letters.
About 400,000 years after the Big Bang, the universe consisted of a thick shell of neutral hydrogen atoms (each composed of a single proton orbited by a single electron) illuminated by what became known as the cosmic microwave background.
Because neutral hydrogen atoms readily absorb electromagnetic radiation with a wavelength of 21 centimeters, the cosmic microwave background carries a signature of density perturbations in the hydrogen shell, which should be observable today, Wandelt said.
Cosmic strings are filaments of infinite length. Their composition can be loosely compared to the boundaries of ice crystals in frozen water.
When water in a bowl begins to freeze, ice crystals will grow at different points in the bowl, with random orientations. When the ice crystals meet, they usually will not be aligned to one another. The boundary between two such misaligned crystals is called a discontinuity or a defect.
Cosmic strings are defects in space. A network of strings is predicted by string theory (and also by other supersymmetric theories known as Grand Unified Theories, which aspire to unify all known forces of nature except gravity) to have been produced in the early universe, but has not been detected so far. Cosmic strings produce characteristic fluctuations in the gas density through which they move, a signature of which will be imprinted on the 21-centimeter radiation.
The cosmic string network predicted to occur with brane inflation could be tested by looking for the corresponding fluctuations in the 21-centimeter radiation.
Like the cosmic microwave background, the cosmological 21-centimeter radiation has been stretched as the universe has expanded. Today, this relic radiation has a wavelength closer to 21 meters, putting it in the long-wavelength radio portion of the electromagnetic spectrum.
To precisely measure perturbations in the spectra would require an array of radio telescopes with a collective area of more than 1,000 square kilometers. Such an array could be built using current technology, Wandelt said, but would be prohibitively expensive.
If such an enormous array were eventually constructed, measurements of perturbations in the density of neutral hydrogen atoms could also reveal the value of string tension, a fundamental parameter in string theory, Wandelt said. "And that would tell us about the energy scale at which quantum gravity begins to become important."
Funding was provided by the Alexander von Humboldt Foundation.
Adapted from materials provided by University of Illinois at Urbana-Champaign, via EurekAlert!, a service of AAAS.
Need to cite this story in your essay, paper, or report? Use one of the following formats:
APA
MLA University of Illinois at Urbana-Champaign (2008, January 28). Scientists Propose Test Of String Theory Based On Neutral Hydrogen Absorption. ScienceDaily. Retrieved January 28, 2008, from http://www.sciencedaily.com /releases/2008/01/080128113207.htm
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thumbs down! aw, you bunch of slow witted retards! now im gonna put double the amount!
OK!!
Scientists Propose Test Of String Theory Based On Neutral Hydrogen Absorption
ScienceDaily (Jan. 28, 2008) — Ancient light absorbed by neutral hydrogen atoms could be used to test certain predictions of string theory, say cosmologists at the University of Illinois. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon.
--------------------------------------------------------------------------------
See also:
Space & Time
Cosmic Rays
Cosmology
Astrophysics
Matter & Energy
Albert Einstein
Physics
Nature of Water
Reference
Physical cosmology
Cosmic microwave background radiation
Shape of the Universe
Subatomic particle
String theory -- a theory whose fundamental building blocks are tiny one-dimensional filaments called strings -- is the leading contender for a "theory of everything." Such a theory would unify all four fundamental forces of nature (the strong and weak nuclear forces, electromagnetism, and gravity). But finding ways to test string theory has been difficult.
Now, cosmologists at the U. of I. say absorption features in the 21-centimeter spectrum of neutral hydrogen atoms could be used for such a test.
"High-redshift, 21-centimeter observations provide a rare observational window in which to test string theory, constrain its parameters and show whether or not it makes sense to embed a type of inflation -- called brane inflation -- into string theory," said Benjamin Wandelt, a professor of physics and of astronomy at the U. of I.
"If we embed brane inflation into string theory, a network of cosmic strings is predicted to form," Wandelt said. "We can test this prediction by looking for the impact this cosmic string network would have on the density of neutral hydrogen in the universe."
Wandelt and graduate student Rishi Khatri describe their proposed test in a paper accepted for publication in the journal Physical Review Letters.
About 400,000 years after the Big Bang, the universe consisted of a thick shell of neutral hydrogen atoms (each composed of a single proton orbited by a single electron) illuminated by what became known as the cosmic microwave background.
Because neutral hydrogen atoms readily absorb electromagnetic radiation with a wavelength of 21 centimeters, the cosmic microwave background carries a signature of density perturbations in the hydrogen shell, which should be observable today, Wandelt said.
Cosmic strings are filaments of infinite length. Their composition can be loosely compared to the boundaries of ice crystals in frozen water.
When water in a bowl begins to freeze, ice crystals will grow at different points in the bowl, with random orientations. When the ice crystals meet, they usually will not be aligned to one another. The boundary between two such misaligned crystals is called a discontinuity or a defect.
Cosmic strings are defects in space. A network of strings is predicted by string theory (and also by other supersymmetric theories known as Grand Unified Theories, which aspire to unify all known forces of nature except gravity) to have been produced in the early universe, but has not been detected so far. Cosmic strings produce characteristic fluctuations in the gas density through which they move, a signature of which will be imprinted on the 21-centimeter radiation.
The cosmic string network predicted to occur with brane inflation could be tested by looking for the corresponding fluctuations in the 21-centimeter radiation.
Like the cosmic microwave background, the cosmological 21-centimeter radiation has been stretched as the universe has expanded. Today, this relic radiation has a wavelength closer to 21 meters, putting it in the long-wavelength radio portion of the electromagnetic spectrum.
To precisely measure perturbations in the spectra would require an array of radio telescopes with a collective area of more than 1,000 square kilometers. Such an array could be built using current technology, Wandelt said, but would be prohibitively expensive.
If such an enormous array were eventually constructed, measurements of perturbations in the density of neutral hydrogen atoms could also reveal the value of string tension, a fundamental parameter in string theory, Wandelt said. "And that would tell us about the energy scale at which quantum gravity begins to become important."
Funding was provided by the Alexander von Humboldt Foundation.
Adapted from materials provided by University of Illinois at Urbana-Champaign, via EurekAlert!, a service of AAAS.
Need to cite this story in your essay, paper, or report? Use one of the following formats:
APA
MLA University of Illinois at Urbana-Champaign (2008, January 28). Scientists Propose Test Of String Theory Based On Neutral Hydrogen Absorption. ScienceDaily. Retrieved January 28, 2008, from http://www.sciencedaily.com /releases/2008/01/080128113207.htm
Related Stories
--------------------------------------------------------------------------------
Examination Of Radiation Left From Birth Of Universe Could Alter Theories (Apr. 3, 2007) — Using relic radiation from the birth of the universe, astrophysicists at the University of Illinois have proposed a new way of measuring the fine-structure constant in the past, and comparing it with ... > read more
Theoretical Physicists Develop Test For String Theory (Jan. 25, 2007) — For decades, many scientists have criticized string theory, pointing out that it does not make predictions by which it can be tested. Now, researchers at Carnegie Mellon University; the University of ... > read more
Scientists Find Faint Objects With Hubble That May Have Ended The Universe's 'Dark Ages' (Jan. 10, 2003) — Researchers using NASA's Hubble Space Telescope reported they are seeing the conclusion of the cosmic epoch called the "Dark Ages," a time about a billion years after the big bang when ... > read more
Ultracold Plasmas Are A Chilling Puzzle (Dec. 11, 2001) — Researchers at the National Institute of Standards and Technology’s Physics Laboratory have created “ultracold” plasmas—with the electrons about a degree above absolute ... > read more
New Insights Into Open String Theory (Jul. 4, 2002) — Theoretical physicist Lennaert Huiszoon has described a new family of strings in research conducted at the National Institute for Nuclear Physics and High Energy Physics. He investigated so-called ... > read more