Archive for August, 2008

According to Loop quantum gravity (LQG), loops are the quantum excitations of the gravitational
field and they are space. Because there is no background space. Only loops over loops and these loops intersect each other just like a net. Interesting fact is that, the points at which loops intersect, i mean at the nodes “quanta of space” ( also called elements of space or grains of space)was found! Two adjacent quanta or elements of space are separated by a surface, and the area of this surface is also quantized. Nodes carry quantum numbers of volume elements and links carry quantum numbers of area elements. These quantum numbers and their algebra looked like the spin angular momentum numbers of elementary particles. So they are called spin network.

Here are few selected articles which should work well to understand spin network.

Useful articles for Quantum Mechanics :

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String 2008 starts today

Today String 2008 is going to start at CERN. This conferense will end on 23rd of this month. Last year it was held in Madrid, Spain. This conference is the largest and most important one on String Theory. Almost 400 physicists are participating. Here is the scheduale. CERN will provide live webcast . Lubos Motl is updating String 2008 in his blog.

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cosmic microwave background radiation (CMB)The Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas within it cools. Thus the universe should be filled with radiation that is literally the remnant heat left over from the Big Bang, called the “cosmic microwave background radiation”, or CMB.

In 1965, two young radio astronomers, Arno Penzias and Robert Wilson, almost accidentally discovered the CMB using a small, well-calibrated horn antenna. It was soon determined that the radiation was diffuse, emanated unifromly from all directions in the sky, and had a temperature of approximately 2.7 Kelvin (ie 2.7 degrees above absolute zero). Initially, they could find no satisfactory explanation for their observations, and considered the possibility that their signal may have been due to some undetermined systematic noise.However, it soon came to their attention through Robert Dicke and Jim Peebles of Princeton that this background radiation had in fact been predicted years earlier by George Gamow as a relic of the evolution of the early Universe. This background of microwaves was in fact the cooled remnant of the primeval fireball – an echo of the Big Bang.

The CMB is nothing but a heavenly hisss…Wanna listen to it? Just click the play button.




1. Mp3- “Berlin Cosmic Microwave Experiment” (BECOME)

2. Image – Nasa

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Gravitational wave is a prediction of Einstein’s General Relativity . Gravitational waves are disturbance in curvature of space-time caused by the motions of matter and they propagate as a wave, traveling outward from a moving object or system of objects. Important examples of systems which emit gravitational waves are binary star systems, where the two stars in the binary are white dwarfs, neutron stars, or black holes.

Gravitational waves propagate through space-time at the same speed of light . It does not only propagate through space but also matter. Here is video on Gravitational wave you will like to enjoy:

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