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Cosmological Constant and its Significance

Abdul Najeeb asked via Facebook:

Would you plz explain me what is a cosmological constant? When Einstein snubbed it as the "biggest blunder" in his life, what else is the real importance of the constant? Also what is cosmological acceleration and its’ effect on the constant…plz…but in simple words…plzzzz:)))))

Ans:

The cosmological constant was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe.

image image

Einstein abandoned the concept after the observation of the Hubble redshift indicated that the universe might not be stationary, as he had based his theory on the idea that the universe is unchanging.However, the discovery of cosmic acceleration in the 1990s has renewed interest in a cosmological constant.

{courtesy : Wikipedia}

More details will be added soon

Nature of light, relativity and blackholes

Prasanna asked:

we know light has got dual nature. & blackholes has got enormous gravity from which even light cant escape. how can gravity can influence a mass less stream of particles like gravity?

Ans:

Do you know why solar eclipse is watched with great importance by the scientific community?

OK

Einstein’s theory of General Relativity was proved right(?) when bending of light by masses was observed in reality.

Please go through the links below and hope that you’ll find an answer there.

http://en.wikipedia.org/wiki/General_relativity

http://www.suite101.com/

Wormhole

Deepa asked:

“What is a worm hole?”

Ans:

A wormhole is a hypothetical topological feature of spacetime that would be, fundamentally, a "shortcut" through spacetime.

A wormhole is, in theory, much like a tunnel with two ends each in separate points in [wiki]spacetime[/wiki]. image

There is no observational evidence for [wiki]wormholes[/wiki], but on a theoretical level there are valid solutions to the equations of the theory of general relativity which contain wormholes. The first type of wormhole solution discovered was the Schwarzschild wormhole which would be present in the Schwarzschild metric  describing an eternal black hole, but it was found that this type of wormhole would collapse too quickly for anything to cross from one end to the other. Wormholes which could actually be crossed, known as traversable wormholes, would only be possible if exotic matter with negative energy density could be used to stabilize them

Faster than light Travel
[wiki]Wormholes [/wiki]allow superluminal (faster-than-light) travel by ensuring that the speed of light is not exceeded locally at any time. While traveling through a wormhole, subluminal (slower-than-light) speeds are used. If two points are connected by a wormhole, the time taken to traverse it would be less than the time it would take a light beam to make the journey if it took a path through the space outside the [wiki]wormhole[/wiki]. However, a light beam traveling through the wormhole would always beat the traveler. As an analogy, running around to the opposite side of a mountain at maximum speed may take longer than walking through a tunnel crossing it.

Ref: Wikipedia

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