8: Is MIT's LuminAR Lamp the future of computing? Watch
Natan Linder of the Fluid Interfaces group at the MIT Media Lab explains why his LuminAR lamp may help change the way individuals access the internet More and more of our waking hours are spent in spaces sprinkled with electronic devices - a digital camera here, an electronic book reader there and smart phones as far as the eye can see.
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#1 Oct 24, 2010
HOW UNIVERSE Note the high energy gamma-ray
Allow me to greet you firstly, and to ask you for your health, family and love. If they are good, it might mean that also business, profit, success or anything will be very god.
For millions of years the Earth is being constantly bombarded by particles from space: mikrometeoritima, high energy nuclei of atoms, photons and neutrinos. Cosmic high energy photons (X-rays and gamma rays) and cosmic neutrinos made plenty of useful information about faraway exotic objects. This realization, in the last decade, spurred the development of new astronomy: X-ray astronomy, gamma-astronomy and neutrino astronomy. High energy gamma-astronomy today is the best area of astroparticle physics. Her main instrument is Čerenkovljev telescope - a device for indirect observation visokoenergijskih cosmic gamma-rays through Čerenkovljevog radiation in the atmosphere create showers of particles.
Showers of particles in the atmosphere
We now know that stars like our Sun are not the only sources of radiation in space. The sun emits visible light and heat as a result of thermonuclear fusion of hydrogen into helium. Such sources are called thermal sources. There is, however, a multitude of cosmic sources of radiation that are nonthermal. Their radiation is not the result of thermonuclear fusion, but completely different in physical processes. Nonthermal sources emit various types astročestica: electromagnetic radiation of all frequencies (from radio waves to gamma-rays), cosmic rays (high energy atomic nuclei), astrophysical neutrinos and gravitational waves. Most are associated with compact cosmic objects: neutron stars and black holes.
Astročestice very high energies, mainly protons (nuclei of hydrogen atoms) and the cosmic gamma-rays coming to Earth regularly, but are stopped in the upper atmosphere. So the atmosphere, the thin air layer planet, protects life on Earth from harmful radiation. On the other hand, thanks to the atmosphere from the surface of the Earth we can observe the high energy protons and cosmic gamma-rays.We can do it indirectly through the large showers of particles in the atmosphere.
#2 Oct 24, 2010
High energy proton or cosmic gamma-ray collisions in the upper layer of the atmosphere with the atomic nuclei of nitrogen or oxygen. The result of that crash has not only broken the atomic nucleus, but also a brand new pair visokoenergijskih particles. It is like two trucks in a crash resulting two new cars which was not before the collision. The pair of material particles from pure energy, or formation of pairs is a common event in visokoenergijskoj physics. It describes the famous Einstein's equation, the equivalence of mass and energy.
Two new particle, particles and antiparticle in fact, arising in the first collision of cosmic rays with atomic nuclei have more than enough energy to repeat the process of forming pairs. And this is a story repeated many times. In a very short time after the first collision caused a cascade or shower of secondary particles. The number of newly created secondary particles, mostly electrons and positrons, depends on energy of primary cosmic particles, but may be a few million to as much as a hundred billion.
Spray secondary charged particles in the atmosphere began cosmic gamma-ray (left) and cosmic protons (right). Both cuff extending twenty miles through the atmosphere, but the right has a wider cross-development and irregular structure.
Čerenkovljevo radiation in the atmosphere
Many of the charged particles in the rain have so much great energy to move at nearly the speed of light. For such particles are said to be ultrarelativističke. As the speed of light in matter is less than the speed of light in vacuum (the speed limit in nature) then ultrarelativističke particles may be faster than light in the air. In fact, most of the electrons and positrons in the pouring rain, and is faster than light in the air. This fact has an interesting consequence, which is very similar to the sound impact and breaking the sound barrier.
If the source is stationary in relation to the listener, then the sound wave spreads equally in all directions. Wavefront then the concentric spherical surfaces. If the sound source moves then the wave fronts are no longer concentric spherical surfaces. The higher the speed to the ball surface to be more compressed in the direction of motion of sound sources. When the speed reaches the speed of sound sources of all the spherical surfaces touching at the point source. Then a shock wave - a disorder that is moving in the direction of compressed wave fronts. At the beginning of the shock wave potoji strong pressure changes, temperature and air density. When the source velocity exceeds the speed of sound then the new wavefront intersecting with a previously generated fronts. Formed into a cone whose top source of sound. This cone is called Mach cone. Disorder that travels with the surface of the Mach cone shock wave.
Wavefront compaction in the direction of motion of the sound source (left). Source reaches the speed of sound in the medium - breaking the sound barrier (middle). Speed of sound sources exceeds the speed of sound in the medium so that a Mach cone whose surface the shock wave front (right).
Charged particles that are moving through the transparent media faster than the speed of light in the medium creates a shock wave of electromagnetic nature. Such a shock wave called Čerenkovljevom light, the Russian physicist Pavel Cerenkov (1904-1990), who discovered and first explored this phenomenon.Čerenkovlj eva light generated by electrons and positrons in the showers of particles in the atmosphere is visible and ultraviolet light of specific characteristics as. Čerenkovljeve flash of light lasts for a very short, only a few seconds milijarditih parts. In addition, the light is very focused, removed from the axis of the cuff for a maximum of one degree. Because of these properties Čerenkovljeva light can be used for observation of cosmic radiation.
#3 Oct 24, 2010
Telescopes that indirectly, through Čerenkovljeve light, observe cosmic gamazrake call Čerenkovljevim telescopes. Čerenkovljev telescope consists of segmented mirrors ten meters in diameter and segmented camera from a few hundred fotosenzora. The mirror reflects the camera telescope Čerenkovljeve of light from the storm, a fast electronic camera records the image of the cuff.Today Čerenkovljevljevi telescopes capture typically a few hundred images per minute. However, most of these pictures did not come from cosmic gamazraka.
The typical appearance of flies in the camera Čerenkovljevog telescope for cosmic gamma-ray (left) and the cosmic proton (right). Image corresponding to gamma-ray has the shape of an ellipse whose major axis is directed toward the center of the camera, while an image that corresponds to the proton has an irregular shape.
The vast majority of the showers of particles in the atmosphere produce cosmic rays - charged particles, mainly protons and light atomic nuclei, which come from outer space. Only every hundredth or even thousandth Spray (depending on which part of the sky the telescope is focused) derived from the cosmic gamma-rays.Therefore, the main problem high energy gamma-astronomy recognition of images that correspond to gamma-rays. This is not an easy task, but not impossible. Eventually they developed and improved methods of analysis which can not only detect gamma-events but also to determine the energy and direction of the incident cosmic gamma-rays.
High energy gamma-astronomy
From the first idea that Čerenkovljeva light from showers of particles in the atmosphere used for the observation of gamma-rays to detect the first cosmic gamma-sources have passed nearly thirty years. That time continuously develop observational tools and data analysis methods. Finally, 1989. The Crab Nebula was observed in high energy gamma-field. It was the first reliably detected galactic high energy gamma-source. Therefore, in 1989.considered to be the beginning of high energy gamma-astronomy.Three years later, discovered the first izvangalaktički high energy gamma-source. It was an active galactic nucleus of MKN 421stBoth sources revealed Whipple Collaboration, Čerenkovljevim Whipple telescope situated in Arizona.
Collaboration Whipple later grew into a collaboration with VERITAS Čerenkovljeva four large telescopes in Arizona. Despite the pioneering discoveries of the group, VERITAS today no longer has a leadership role in visokoenergijskoj gamma-astronomy.There are two assumed the role of the European Collaboration: MAGIC and HESS. The two MAGIC telescopes are located along the African coast, the Canary island of La Palma, and four HESS telescopes in Africa, in Namibia. Both groups have begun working together on future large telescope system Čerenkovljevih CTA, one of the key projects of astroparticle physics in the next decade.
Čerenkovljevi telescopes MAGIC AND MAGIC II and in the Observatory Roque de los Muchachos on the Canary island of La Palma, 2200 m above sea level. In the background is an optical telescope, currently the largest in the world, GranTeCan or GTC.
Thank you very much indeed, Please I will like you to accept this token with good faith as this is from the bottom of my heart. Thanks and God bless you and your family.
Hope to hear from you soon.
Your' s Faithfully,
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