[FPSPACE] FW: Centauri Dreams - GLAST: Expect to Be Surprised

[LARRY KLAES]

>From: Centauri Dreams <gilster at mindspring.com>
>Reply-To: Centauri Dreams <gilster at mindspring.com>
>Subject: Centauri Dreams
>Date: Wed, 14 May 2008 14:03:26 -0500 (CDT)
>
>Centauri Dreams
>
>///////////////////////////////////////////
>GLAST: Expect to Be Surprised
>
>Posted: 13 May 2008 02:57 PM CDT

>http://www.centauri-dreams.org/?p=1874
>
>
>With the GLAST mission near launch, keep in mind the possibilities of this 
>unique observatory in terms of findings that could revolutionize our view 
>of distant events. GLAST (Gamma-Ray Large Area Space Telescope) will be 
>looking at things weve only recently learned about, such as the enigmatic 
>gamma-ray bursts (GRBs) now flagged by the Swift satellite and quickly 
>pinpointed for the use of Earth-based observatories. We know were pushing 
>into uncharted waters given that GLAST represents a major step forward over 
>all previous satellites designed to study gamma ray events. And major new 
>instruments usually deliver new classes of objects.
>
>Because of the increase in GLASTs sensitivity over earlier tools like the 
>EGRET instrument on NASAs Compton Gamma-ray Observatory (CGRO), the 
>satellite may find thousands of new point sources. And we have plenty of 
>questions already on the table. Gamma-ray bursts, for example, may be the 
>result of black hole mergers, or the merger of a black hole and a neutron 
>star. But its also thought that some are markers for the collapse of a 
>massive star into a black hole. What types of stars, then, become GRBs, and 
>why? What is the mechanism for producing the initial gamma rays in the 
>burst? Because GRBs seem to come in numerous varieties, their study offers 
>fertile ground for years of research.
>
>Or consider dark matter, the leading candidate for which is the 
>hypothetical weakly interacting massive particle (WIMP). Gamma rays may 
>also derive from WIMPS, which according to supersymmetry theory act as 
>their own antimatter particles, annihilating when they interact with each 
>other, and in the process releasing gamma rays and secondary particles. The 
>signature of such annihilations is potentially observable with GLASTs Large 
>Area Telescope (LAT), assuming that dark matter is indeed composed of 
>WIMPs. Its continuous stream of gamma rays should differ markedly from the 
>milliseconds-to-minutes time frame of GRBs.
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>Image: According to supersymmetry, dark-matter particles known as 
>neutralinos (which are often called WIMPs) annihilate each other, creating 
>a cascade of particles and radiation that includes medium-energy gamma 
>rays. If neutralinos exist, the LAT might see the gamma rays associated 
>with their demise. Credit: Sky  Telescope / Gregg Dinderman.
>
>One other fascinating possibility in range of this observatory is the 
>question of the speed of light in a vacuum. The special theory of 
>relativity pins the speed of electromagnetic radiation to 299,792,458 
>meters (186,282.4 miles) per second, and it would be assumed that gamma-ray 
>photons should move at the same speed. Some models of quantum gravity, 
>however, predict that the speed of very-high-energy gamma rays may vary 
>slightly from other forms of light, the result of the turbulence of 
>spacetime at quantum scales. GLAST can thus test a prediction that could 
>nudge us, if only slightly, toward a merger of general relativity and 
>quantum mechanics.
>
>GLAST is now at Cape Canaveral with a planned launch in early June, having 
>been moved to the Hazardous Processing Facility near Kennedy Space Center 
>for fueling. I suppose its human nature that manned missions are what snare 
>media attention, but this observatory may turn out to be one of the most 
>significant weve launched in terms of probing out to the edges of physics 
>and cosmology. Dark matter may not make CNN, nor will many gamma-ray 
>bursts, but if GLAST can offer up some answers, we may get a far better 
>read on how the universe functions, and if were really lucky, some clues to 
>future propulsion possibilities.
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