John Wheeler’s famous comment “John Wheeler “Black holes have no hair” on Black Holes might have set the ball rolling that information within these infinitely densely packed invisible objects is lost forever. However, over the years, the view about Black Holes is changing with significant contributions by scientists. Three laureates won the Nobel Prize for Physics in 2020 for their discoveries in explaining the most exotic phenomenon in the Universe, Black Holes. This year, the Nobel Prize was awarded to Sir Roger Penrose (one-half) for his work on understanding mathematically that black holes are a direct consequence of Albert Einstein’s General Theory of Relativity and jointly to Reinhard Genzel and Andrea Ghez (other half) for their work on supermassive Black Hole Sagittarius A*. Stephen Hawking is perhaps the most well-known scientist whose contribution to understanding the mysteries behind these invisible objects is timeless. Black Holes, The BBC Reith Lectures, is a beautiful primer on understanding the working of Black Hole from a layman’s perspective. The book is based on two fifteen minutes talk by Stephen Hawking about his lifetime work on this subject with add-on notes by David Shukman. Stephen’s work in understanding the characteristics of the Black Hole is of paramount importance today. His research brings a fresh perspective to the long-held view that no matter can escape black holes. Famous for espousing black holes to remit radiation aptly termed Hawking radiation, understanding the workings of Black Holes could change our understanding of our Universe, especially in quantum mechanics. The book is fantastic assimilation of the scientist’s lectures on this subject. Pic Goodreads
# Understanding Black Holes
Black holes record only mass, state of rotation, and the electric charge. Black holes are formed when giant stars collapse under their mass after exhausting their nuclear fuel and compress to an infinitesimally single point. Stephen Hawking spent most of his time researching this point of singularity. The black holes in unimaginably high that even light cannot escape them. The gravity of black holes sucks everything inside once an object crosses the event horizon, and it is assumed that space and time do not exist at the center of a black hole. Over their billions of years of existence, Stars used the nuclear fusion process to convert hydrogen to helium to support themselves from collapsing against their gravity. The fusion process is the prime energy source in this world when one or more nuclei combine to form one or more different atoms and the generation of subatomic particles. When the nuclear process is exhausted, the stars collapse under their gravity and contract to work with white dwarfs and neutron stars. Based on the game-changing research by scientists S Chandrashekar and Lev Landau, the maximum mass of a white dwarf is 1.4 times the mass of the Sun. However, this doesn’t explain what happens to massive stars with mass greater than 1.4 times than our Sun at the end of their time. What lies ahead leads to the realms of Black Holes and Singularity, where laws of physics don’t apply, diverging from Einstein’s theory of general relativity. Ironically, Roger Penrose won the prize for his seminal work that proved Black Holes directly a consequence of Albert Einstein’s general theory of relativity.
“John Wheeler coined the term Black Hole in 1967”
“Einstein himself did not believe that stars could collapse under their weight and in 1939 published a paper in the journal Annals of Mathematics titled On a Stationary System with Spherical Symmetry Consisting of Many Gravitating Masses wherein he discredited the existence of black holes. Stephen Hawking credits John Wheeler, an American scientist whose work in the late 1950 and 60’s emphasized their existence and importance within the cosmos. Roger Penrose, ground-breaking work which laid out the mathematical evidence towards Black Hole formation and his 1965 article on this topic remains according to the Nobel committee the most significant contribution to the general theory of relativity since Einstein.”
# Singularity, the beginnings of this Universe
The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. In joint press conferences across the globe, EHT researchers revealed that they succeeded, unveiling the first direct visual evidence of the supermassive black hole in the center of Messier 87 and its shadow. The shadow of a black hole seen here is the closest we can come to an image of the black hole itself, a completely dark object from which light cannot escape. The black hole’s boundary — the event horizon from which the EHT takes its name — is around 2.5 times smaller than the shadow it casts and measures just under 40 billion km across. While this may sound large, this ring is only about 40 microarcseconds through — equivalent to measuring the length of a credit card on the surface of the Moon. Although the telescopes making up the EHT are not physically connected, they can synchronize their recorded data with atomic clocks — hydrogen masers — which precisely time their observations. The observations were collected at a wavelength of 1.3 mm during a 2017 global campaign. Each telescope of the EHT produced enormous amounts of data – roughly 350 terabytes per day – which was stored on high-performance helium-filled hard drives. These data were flown to highly specialized supercomputers — known as correlators — at the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory to be combined. They were then painstakingly converted into an image using novel computational tools developed by the collaboration. Above pic of the first-ever photo of a black hole. Source: https://eventhorizontelescope.org/
“Black Holes are formed when massive stars collapse to create invisible dense objects, bringing us to the concept of singularity. Consider a star twice the mass of our Sun compressed to a minimal size. The most enormous known black hole is 500 trillion km away, 40 billion km across, which is 3 million times the size of the Earth but with a mass of 6.5 billion times of Earth. These are supersized black holes, where both Reinhard Genzel and Andrea Ghez jointly won the Nobel prize for their work on understanding the largest known Black Hole within our galaxy, Sagittarius A*of size four million times of that our Sun.
Interestingly, today, scientists believe black holes are at the center of all galaxies within the Cosmos taking the number to billions. Read about other Nobel Prizes for 2020 here.
# Black Holes: The BBC Reith Lectures revisited; Event Horizon: Hotel California & You can never leave but you just might
Compare it as a metaphor to the Eagles evergreen song Hotel California “We are programmed to receive. You can check out any time you like, But you can never leave”
Black Holes that have event horizons are not visible, while naked singularities are without one and visible. Event Horizon is a boundary around the back hole where the gravity is so high that it sucks anything within its presence, even photons. Once inside the event horizon, you can never leave. Hence black holes are not visible but can be indirectly detected through their pull-on neighbouring celestial objects. A fascinating read, Black Holes, a pocket-sized dynamo, traces the evolution of the theoretical framework of Black Holes within the parlance of the scientific community backed by easy-to-understand examples. Examples of a canoe falling over the edge of the Niagara waterfall are akin to entering the event horizon. The causality between an increase in the event horizon area when another matter enters the horizon and Sir Newton’s second law of entropy thermodynamics are winners simplifying a seemingly complex concept. However, Hawking’s two lectures’ triumph lies in the explanation of how information is preserved within the black holes. Recall that Heisenberg’s theory of uncertainty delves that in subatomic states, i.e., the quantum level, it’s difficult to predict the particles’ speeds and positions precisely.
Yet knowing the Quantum State, one can predict both speeds and positions with a certain degree of accuracy. Understanding gravitation as a weak force in our Universe could well be due to multiple dimensions, as proposed by Super String theory with gravity seeping into other dimensions is thought-provoking know-how. Brian Greene, a well-known physicist, is a massive advocate of this scientific reasoning. Whether Black Holes work as time warps, sending the matter to another dimension unknown hitherto to humans, only time will tell. Still, the recent award towards work related to Black Holes is a step in a forward direction. It’s a significant step to understanding the origins of this Universe, giving credence to multiverse theory and parallel universes. In a nutshell, Hawking’s Nobel Prize could practically prove that one can leave the black hole one day. The answer is, how soon can this be done. Deciphering laws governing information within the black holes could lead to a framework that better fuses both the gravitational and quantum aspects of theory, paving the way for the build-up for a United Theory of laws governing physics.
Time is endless. There is no beginning of time and no end of time.