Black Holes

The term “Black Hole” is of very recent origin coined by John Wheeler, an American scientist.

The graphical description and idea of “A BLACK HOLE” goes back to two hundred years when there were two prevalent and widely accepted theories about light. Light was considered to possess two forms (or natures) namely particle and wave nature. The particle nature of light was favored by Newton.

According to the wave nature, light behaves as a wave. The question that arises is that – Can gravity affect light ? Yes, gravity can affect light if it is considered to behave as particle. Roemer discovered that light has a finite speed, therefore, gravity must have important effect on it.

Gravity is seen to have effect on cricket balls, humans and rockets etc. But light is composed of photons. Photon is a particle which can move upwards constantly against gravity without showing retarding effect. How can then Newtonian gravity affect light?

A star is formed when a light amount of hydrogen starts to collapse on itself due to strong gravitational pull. Eventually due to gravity and increasing pressure the gases heat up and finally hydrogen atoms collide to form helium. The heat released in the process makes the star shine.

Oppenheimer’s work was based on black holes.

He proposed that gravitational field of the star changes the path of light rays it emits in space-time. The light cones are bent slightly inwards near the surface of star. As the star passes its years of life, it contracts and its gravitational field becomes stronger and stronger and finally a time comes when the light cones bend inwards so much that it can no longer escape. This results into nothing but a region in universe which is called a black hole.

The boundary of a black hole is called event horizon. It coincides with the path of light rays that just fail to escape from the black hole.

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Meteor Shower Peaks on Saturday

Earth is about to pass through a stream of dust from Halley's Comet, and this will produce the annual eta Aquarid meteor shower. The shower peaks on Saturday, May 6th, with 10 meteors per hour in the northern hemisphere and as many as 60 meteors per hour in the southern hemisphere. The best time to look is during the hours immediately before sunrise on Saturday morning.

PHOTO OP: On May 7th, the biggest fragment of dying comet 73P/Schwassmann Wachmann 3 will glide by the Ring Nebula in Lyra. The view through backyard telescopes should be wonderful. This is an opportunity for astrophotographers to take some rare photos of a comet and a planetary nebula side by side.

Visit http://spaceweather.com for sky maps and more information.

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Does Universe look same from everywhere?

We have a unique position in the universe. While we observe from our planet, universe seems to be same from all directions. In 1965,Penzias and Robert Wilson, were testing a very sensitive microwave detector. They found that their detector was picking up more noise than it ought to. The noise did not appear to be coming from any particular direction. It was concluded after sometime that the noise was from outside the atmosphere. Infact, it was coming from beyond the solar system.

When one combines general relativity with the uncertainty principle of quantum mechanics, it is possible for both space and time to be finite without any edges or boundaries.

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