Nandkumar M Kamat
There is a broad agreement that our universe is 13780 million years old and evolved out of a cosmic explosion called ‘Big Bang”. But what was is it that ‘exploded’? String theory, loop quantum gravity, Multiverse theory, all struggle to provide explanations. None is satisfactory. The only evidence we have of ‘Planck Epoch’, or time equivalent to ten raised to the factor of minus 43 seconds is CBE or cosmic background radiation which is a smoking gun of that “explosion”. Was there an ‘initial singularity’ before the Big Bang? How was that different from the Black holes?
Black holes are in the news because these entities seem so unreal, so monstrous, and mysterious. Stellar, supermassive, and miniature – the black holes come in different flavours. Except miniature black holes, evidence has been found for stellar and supermassive black holes.
Despite almost a century of research, the human mind has not been capable of understanding the meaning of supergravity or quantum gravity. Crunching of the objects can reach such a limit that finally it would not even have any radius – thus becoming a ‘singularity’. Physical matter doesn’t remain physical matter. It is deconstructed and dematerialised. Atoms come apart inside this entity called ‘black hole’. The most important fact is time ‘slows down’.
Black hole is a misnomer. There are no holes in observable universe which is stretched for 92 billion light years. There is dark matter, dark energy, but no holes. Einstein would have called it an invisible tear in space time continuum. A tear in the fabric of space-time made by supergravity. The functions of the large-scale structure of the universe may be determined by such tears.
People have exciting and romantic ideas about ‘black holes’. Science fiction writers, science journalists and writers have romanticised black holes as weird invisible mega vacuum cleaners in space. An outside observer can’t see but can suspect a pocket inside the vacuum cleaner where all the dirt ends.
Black holes are in the news this month because of the claim of ‘photographing” one. But theoretically such tears can’t be photographed because for photography one needs some photons, the quanta of light. And black holes don’t permit escape of any radiation. What astronomers under the Event Horizon Telescope project have done is to stich a computerised map, not a real photograph of the black hole. This image is a map of an annular zone of superhot radiation at the event horizon and the area which doesn’t return any information- the tear or void which has baffled the physicists. It is like looking at an unfathomable deep well, in which you can see the objects falling but can’t see the interior or the ‘bottom’ of the well.
It is the gravitational collapse of stars 20 times heavier than our sun which produce the stellar black holes whereas supermassive black holes exist at the centre of galaxies gobbling up the nearby stars. We are fortunate to be on the outer spiral arm of our Milky Way galaxy, much beyond the danger of being sucked in by the supermassive black hole. Our cosmic address is Earth, Solar system, Orion arm, Milky way, local group, Virgo Cluster, Local Super cluster, the Universe. Our galaxy has an estimated 100 million stellar black holes. Scientist know about many wandering or phantom or rouge black holes but considering the vast distances there is no danger to solar system.
The romantic interest in the “photograph” of the black hole needs to be understood from Einstein’s correct prediction of such an object. The artists who speculated on the idea of the black holes were also pleased to see the image on April 10 produced by a huge international team. The half dozen papers which have come out of the work all list hundreds of co-authors from more than 30 countries indicating how much effort has been put in to get just one “image” right. And indeed, by processing a mountain of electronic and photonic data, writing the special software to integrate it into a cohesive image and finally producing a visual graphical output the international team proved that beautiful theories can produce beautiful results. Scientists and artists are romancing the black holes because these objects challenge human minds.
Black holes gobble mass and trap radiation. As an object approaches the black hole, time slows down and it comes to a standstill near the event horizon. Gravitational waves could be detected due to the collision of two rotating black holes. Such collisions are frequent and create very high temperature and radiation. Such massive collisions are like cosmic scale “earthquakes” sending powerful ripples across the fabric of space and time. The fascinating properties of the black holes have made them popular. Their exotic nature has spawned imagination leading to half a dozen movies but these movies don’t necessarily correspond to the science of black holes.
For common man, understanding cosmic entities like the black holes from the image produced on April 10 is impossible. But they could sense that scientists have found something big and that creates a sense of wonder. Humans need such fuel to maintain their curiosity about the universe and black holes are perfect cosmic bodies which confound human imagination.
The iconic image of black hole has enthused millions of students across the globe. This would surely benefit a healthy growth of astrophysical research. In both arts and sciences – black holes will continue to provide inspiration to generations to come. Therefore romancing the black holes is to be welcomed.