May 20, 2007

Cosmic Mirror

picture of a black holeYou are walking tired and thirsty on an unforgiving desert. Water is not to be found anywhere near. Broken hearted, you suddenly seem to spot an oasis. You rub your eyes, pinch your skin, but yes it is an oasis indeed. Oh NO, its only a mirage, an illusion that played tricks on you. You are crestfallen!

A situation like above occurs quite commonly. Here, for example, the air in the immediate vicinity of the hot sands are much lighter in comparison to that of the above. Just as light bends, due to refraction (changes at the interface, due to differing refractive indices of the medium), when a ray of light is made to pass through water from air, it bends (one can see it using lasers or using a straight rod which appears bent). A similar situation occur in deserts and in very cold climates.

Objects having mass, distort the space time curvature just in a similar way an iron ball would do to a piece of cloth, whose four corners are tied to four poles. There would be an indentation in the middle of the cloth. If one releases a small ball at one of its corners, the ball will proceed towards the dent, in a spiral way. Encircling, it will finally end up in the center. This is what we call gravity, and orbits (paths, the ball traces) have been proposed so that the ball doesn't end up with the ball at the center.

Now imagine a black hole, a very massive and dense object, with such a strong gravitational pull, that even light can not escape its fatal attraction. Thus it it is invisible. The gravitational pull near its surface will be maximum, while the pull will fade out away from it, inversely proportional to the square of the distance (of measurement). Hence we can visualize a situation akin to the mirage illusion already stated. Near the black hole the gravity (space time curvature) is densest, whereas gravity away from it is less so. This reminds us the analogy of refraction we saw with respect to light (electro-magnetic radiation). Thus, you certainly can expect to find gravitational mirrors (total internal reflection) in black holes.

The black hole won't belch out any of its secrets, as theory of quantum gravity prohibits it: it will only show the observer's curious face in its own mirror. Could there be a Grand Unified Theory now? Or, how about combing your hair using this MIRROR?

1 comment:

amiya said...

I think it's important to mention 'microlensing' in this regard. It is known that the gravitational pull bends light. Thus, if a heavy (massive) object lies before a background object, the strong gravitational pull of the former will magnify the image of the latter. It is more efficient in studying distant galaxies compared to 'radiovelocity' method which uses Doppler effect. More about this at: