Black Hole and its recent ripples in news and on social media!!!

Black Hole and its recent ripples in news and on social media!!! 12 Apr 2019

Before any details let me explain what a ‘Black Hole’ is?

It is a celestial body which have immense gravitation attraction so much so that anything falling to it will be swallowed and will never be able to come out. Its gravitational attraction comes from profoundly dense mass matter.

Black Hole are spherical in shape and is expected to be spinning, dragging spacetime continuum like honey around spinning spoon. ‘Spacetime continuum’ is a concept where time along with three cartesian coordinates is considered as dimension. So, anyone hypothetically traveling in this spinning region of spacetime will be completely confused that whether he is traveling through time or space or both.

Light which help us in seeing things as it get reflected from object and form its image on our eyes retina will also be swallowed by it just like any other object. It means we can never really see a black hole directly. Light that misses the black hole, but passes very close to it will be deflected onto a new course path through space which is known as ‘bending of light’.

Around a hole there is a position of no return, called the event horizon. This is a point where the escape velocity (speed needed to get out) required for any body is equal to the speed of light. Beyond this point escape velocity becomes larger than the speed of light and since nothing can travel faster than the speed of light, nothing can escape.

Further, we don’t know what happens at the centre of a black hole. Our current theories break down because they can’t deal with infinitely dense objects. So, physicists are trying to develop new theories of gravity to answer what lies at the bottom and whether they lead anywhere. This point is called a singularity which is thought to exist at the centre of every black hole.

The next question which arises is how do we know about them? Well sure enough we can’t see anything inside a black hole but the region around it behave in a manner that only black hole can cause. So, the presence of a black hole can be inferred by tracking the movement of a group of stars or gases that orbit a region in space. For example after observing the motion of nearby stars for 16 years, in 2008 astronomers found compelling evidence that a supermassive black hole of more than 4 million solar masses is located near the Sagittarius A* region in the center of the Milky Way galaxy.

The last question I would like to answer is what is this “Event Horizon Telescope” which have very recently revealed first ever picture of “Black Hole”?

In an attempt to directly look at black hole and take a picture of it how looks like. Scientist uses the concept that the gases around the black hole just outside, which is swirling around it gets heated as it falls into the black hole. This produces light which can be picked up by telescopes. Now taking picture of this surrounding area (Shadow of) from this far is not easy. Its really, really small on the sky. its like we are trying to take a picture of an orange on the moon.” So, if we really want to take a good resolution picture of it we need a very large telescope as large as possible. That’s where scientist came up with idea of creating a virtual earth-size telescope by collecting telescope data from different parts of earth and combing that using supercomputer to create a single picture which is equivalent of being taken from earth size telescope. “Event Horizon Telescope” is one such example. The telescope being used in this doesn’t have a set of mirrors in a tube like our amateur telescope. Instead, it uses radio receivers to detect electromagnetic waves. There are six such observatories in Mexico, Hawaii, Arizona, Chile, and Spain aimed their eyes into sky and staring at M87, which is the biggest galaxy in the center of the Virgo cluster. Functioning as one Earth-sized telescope, the network can resolve objects just one-ten thousandth the angular size of what Hubble can see.

This is a ground breaking work in many sense because It has been able to picture a black hole which measures 40 billion km across - three million times the size of the Earth. It is 500 million trillion km away from us. And It has a mass of 6.5 billion times that of the Sun. The image shows an intensely bright “ring of fire”, it is surrounding a perfectly circular dark hole. The bright halo is caused by superheated gas falling into the hole. This establishes Einstein General Theory of Relativity after 100 of years of its conceptualization by direct measurement opening door for more ground breaking inventions to come.

Picture: This is supermassive black hole inside the core of the supergiant elliptical galaxy Messier 87 in the constellation Virgo. The black hole was the first to be directly imaged (Event Horizon Telescope, released April 10, 2019).