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Sound waves in the embryonic Universe are revealed for the first time in this image captured by the BOOMERANG  balloon-borne telescope during its maiden voyage around the Antarctic.  The patterns visible in the image are consistent with those that would result from sound waves racing through the early universe, creating the structures that by now have evolved into giant clusters and super-clusters of galaxies. The image records the intense heat that filled the universe just after the Big Bang, which is still present today as a faint glow of microwave radiation that fills the sky. The first evidence of structure in this Cosmic Microwave Background (CMB) was found in 1991 by NASA's Cosmic Background Explorer (COBE) satellite, which mapped the entire sky with high sensitivity but coarse angular resolution (upper left). The BOOMERANG image covers approximately 2.5% of the sky with angular resolution 35 times that of COBE, revealing hundreds of complex structures that are visible as tiny variations -- typically only 100 millionths of a degree (0.0001 C) -- in the temperature of the CMB. Detailed analysis of this image will determine the geometry of the universe to high precision, and will shed light on the nature of the matter and energy that fill the Universe.

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An image of the Primordial Universe. Enormous structures in the early universe which are invisible to the unaided eye become apparent when observed using a telescope sensitive to mm-wave light. This image of approximately 1800 square degrees of the southern sky was taken using the BOOMERANG telescope over a 10 day period from December 1998 - January, 1999. For scale, the apparent size of the moon is indicated on the bottom right of the page. In this picture, we see the distant Universe as it makes its transition from a glowing 2700 deg C plasma to a perfectly transparent gas, approximately 14 billion years ago, a mere 300,000 years after the Big Bang. The color scale of the image has been enhanced to bring out the tiny 100 ppm temperature variations in the primordial plasma. BOOMERANG is the first telescope with the resolution and sensitivity required to image these variations, which have since evolved into giant clusters and superclusters of galaxies today.

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The BOOMERanG maps are based on the HEALPIX pixelization algorithms.

The BOOMERANG Telescope being readied for launch. With Mt. Erebus as a backdrop, NASA/NSBF personnel inflate the 1 million m3 (28 million cubic foot) balloon which will carry the BOOMERANG telescope on its 10 day trip around the Antarctic continent. In order to make its exquisitely sensitive measurements, BOOMERANG is lifted above 99% of the atmosphere to an altitude of 35km (120,000 ft.). The continuous sunlight and stable air currents over Antarctica enable 10 to 20 day long stratospheric balloon flights. This launch was preceded by two months of assembly at McMurdo research station, and half a decade of development and construction by a international team of researchers

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The CMB sky over Mt. Erebus. In this fanciful picture, the CMB sky looms behind the prelaunch preparations of BOOMERANG. The BOOMERANG images of the early universe have been overlaid onto the sky to indicate what size that the fluctuations would appear if a standard 35mm camera were sensitive to microwave light. The color map of the CMB images has been changed here to aesthetically match the rest of the picture. The CMB images and the prelaunch picture are available separately.

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BOOMERANG images determine the geometry of space. By observing the characteristic size of hot and cold spots in the BOOMERANG images, the geometry of space can be determined. Cosmological simulations predict that if our universe has a flat geometry, (in which standard high school geometry applies), then the BOOMERANG images will be dominated by hot and cold spots of around 1 degree in size (bottom center). If, on the other hand, the geometry of space is curved, then the bending of light by this curvature of space will distort the images. If the universe is closed, so that parallel lines converge, then the images will be magnified by this curvature, and structures will appear larger than 1 degree on the sky (bottom left). Conversely, if the universe is open, and parallel lines diverge then structures in the images will appear smaller (bottom right). Comparison with the BOOMERANG image (top) indicates that space is very nearly flat.

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The Spectrum of Primordial Sound. The temperature variations in early universe seen in the BOOMERANG images are due to sound waves in the primordial plasma. The angular spectrum of these images shown here, reveals the characteristic size of the structures that dominate the image. A peak in this spectrum at scales of ~ 1 degree, as is seen here in the BOOMERANG data, indicates that the Universe is nearly spatially flat. The data can be well fit by cosmological models that contain non-baryonic matter in addition to normal, baryonic matter. One such model is indicated by the solid blue curve. A generic feature of such models is the presence of a harmonic series of additional peaks beyond the fundamental peak at ~ 1 degree. The relative height of the second peak at ~ 1/2 degree on the sky varies with the ballance of matter in the Universe contained in normal or baryonic matter and non-baryonic matter.

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Cosmological Results from BOOMERANG compared with Type 1a Supernovae Results. Shown here are limits from BOOMERANG and Type Ia supernovae on the values of the average density of space in matter (OmegaM, on the horizontal axis) which slows the expansion of the Universe, and the density of the so-called Dark Energy of empty space (OmegaLambda, on the vertical axis) which causes the expansion of the universe to accelerate, preventing re collapse. The BOOMERANG results are consistent with cosmological models whose parameters lie within the blue region. This curve is concentrated near the diagonal red line. From this we learn that, according to BOOMERANG data, the Universe is cosmologically flat. As an excellent complement to this, recent results from the study of S1a supernovae are consistent with cosmological models which lie inside of the yellow region. If both measurements are correct, then allowed models lie in the gree overlap region. This overlap region indicates that our universe is cosmologically flat, started with a Big Bang, and will not collapse again

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The micromesh bolometer, reminicent of a spider's web, uses a free-standing micromachined mesh of silicon nitride to absorb millimeter-wave radiation from the cosmic microwave background.  This design uses the minimum amount of material for optimal performance.  Millimeter-wave radiation is absorbed and measured as a minute temperature rise in the mesh by a tiny Germanium thermistor.  Cooling the sensor to three tenths of a degree above absolute zero results in the high sensitivity necessary to create the BOOMERANG maps.

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