Advanced science, Astrophysics, International, Technical

Stephen Hawking: The supernova of cosmology

In 1974, by predicting the apparently paradoxical concept of radiation emanating from black holes, Hawking reminded us that mass and energy are two sides of the same coin.

Stephen-Hawking5

We humans are a recent phenomenon in the Universe that is very old, mostly imperceptible and beyond our comprehension. Had it not been for great scientists like Isaac Newton, Albert Einstein, Edwin Hubble, Karl Schwarzschild, Subrahmanyan Chandrasekhar, Stephen Hawking and many more who unlocked the enduring mysteries of the boundless Universe, it would have been a struggle for lesser mortals like us getting our bearings straightened about our place in the cosmos. Their ground-breaking work, forever, changed our view of the “heavens.”

Postulated in 1687, Newton’s law of gravity was a beautiful synthesis between terrestrial and celestial phenomenon, reaching across the vast expanse of the Universe. It allows us to study the waltzing motion of the planets, moons, stars and other objects in the sky with clockwork precision.

Einstein’s special relativity, published in 1905, tells us that time is not only elastic, it is also the fourth component of the spacetime fabric of the Universe. Ten years later, his general relativity redefined gravity as matter’s response to the curving of spacetime caused by surrounding massive objects.

In 1916, Schwarzschild found that the solution of Einstein’s general relativity equations characterized something that confounds common sense ‒ an unfathomable hole drilled in the superstructure of the Universe. Today, we call this voracious gravitational sinkhole a black hole, a single point of zero volume and infinite density.

Much to Einstein’s consternation, in 1929, Hubble discovered that the Universe is expanding in size. His “constant” enabled us to estimate the age of the Universe. In 1930, Chandrasekhar’s calculations indicated that when a massive star runs out of fuel, it would blow itself apart in a spectacular but violent explosion and then collapse into a black hole.

Black holes were discovered in 1971, when astronomers detected a hint of radio wave emissions coming from an object in the constellation Cygnus. The emissions were later interpreted as the fingerprint of the black hole Cygnus X-1. Since then, numerous black holes, including supermassive ones, have been detected in our own Galaxy ‒ The Milky Way, and elsewhere in the Universe. According to NASA, supermassive black holes are growing faster than the rate at which stars are being formed in their galaxies.

Cloaked behind the event horizon, which is not a physical barrier but just an information barrier, it must seem that there is no way of getting mass from the black hole back out into outer space. No way, that is, not until the British physicist Stephen Hawking, arguably one of the greatest minds in scientific history, joined the Big League of Cosmology in the mid-twentieth century. With his seminal contributions to the fields of astrophysics, general relativity, quantum gravity and black holes, he raised the field of cosmology from a niche topic to a well-developed subject in the forefront of science.

In 1974, by predicting the apparently paradoxical concept of radiation emanating from black holes, Hawking reminded us that mass and energy are two sides of the same coin. He was able to show that a black hole, like any other body whose temperature is not absolute zero, emits energy in the form of radiation, energy now known as Hawking Radiation.

The continual emission of radiation causes the black hole to shrink in mass. In other words, black holes “evaporate,” although the time it takes for a solar-mass black hole to evaporate completely is immensely long ‒ vastly larger than the age of the Universe, which is 13.7 billion years. The implications are nonetheless important ‒ even black holes evolve and die.

One of the Gordian knots of cosmology is the missing mass of the Universe. There is irrefutable evidence that visible matter accounts for only four percent of the Universe’s mass. The remaining 96 percent is invisible of which 73 percent is attributed to a pervasive “dark energy,” believed to be manifestation of an extremely powerful repulsive force that is causing the expansion of the Universe to accelerate. The additional 23 percent is thought to be dark matter whose origin obviously is the many black holes spread throughout the cosmos. However, their total mass does not add up to account for all the dark matter.

To address this issue, in 1971, Hawking advanced the idea that in the intergalactic space, there may be “mini” black holes with very small masses ‒ much smaller than the mass of the Earth ‒ yet numerous enough to account for most of the unaccounted dark matter. He hypothesized that they may have been formed during the first instants of chaos following the Big Bang when matter existed in a hot, soupy plasma. Since mini black holes have not been detected so far, Hawking lamented: “This is a pity, because if they had, I would have got a Nobel Prize.”

During the 1980s, Hawking devoted much of his time contributing to the theory of cosmic inflation ‒ the expansion of the Universe at an exponential pace before settling down to expand at a slower pace. In particular, he demonstrated how minuscule variations in the distribution of matter during this period of expansion, known as the Planck era, helped shape the spread of galaxies in the Universe.

As noted above, the core remnant of a high-mass star would eventually collapse all the way to a point ‒ a so-called singularity. Having said that, singularities are places where laws of physics break down. Consequently, some very strange things may occur near them. As suggested by Hawking, these strange things could be, for instance, gateway to other universes, or time travel, but none has been proved, and certainly none has been observed. These suggestions cause serious problems for many of our cherished laws of physics, including causality ‒ the idea that cause should precede the effect, which runs into immediate problem if time travel is possible ‒ and energy conservation, which is violated if matter can hop from one universe to another through a black hole.

While scientists know Hawking for his work on cosmology, millions of others know him because of his book “A Brief History of Time.” His lucid explanation of the mechanism leading to the creation of the Universe, our place in it, how we got there, where did space and time come from, and where we might be going made the notoriously difficult subject of cosmology more understandable to the layperson.
In a follow-up book titled “The Grand Design,” Hawking outlines his consuming quest for the long-dreamed-of “Theory of Everything,” the quantum theory of gravity. Such a theory would unify the two pillars of twentieth century physics, general relativity and quantum theory.

Known as the M-Theory (M stands for Mother-of-All), it would enable us to understand all phenomena in space-time, especially the first split second of cosmic creation, when everything was unimaginably small and densely packed.

Hawking was about as pure an atheist as one can be. He dismissed the existence of an omnipotent by noting that “regularities in the motion of astronomical bodies such as the sun, the moon, and the planets suggested that they were governed by fixed laws rather than being subjected to the arbitrary whims of gods and demons.” Nevertheless, in December 2016, he had a surprising but cordial encounter with Pope Francis at a convention on Big Bang in Rome.

Besides being a genius, Hawking’s celebrity status derives from his spunk in the face of physical adversity. Born on 8 January 1942 in Oxford, England, Hawking was diagnosed with a debilitating, incurable neuromuscular disorder, commonly known as motor neurone disease (MND), when he was just 21 years old. Although doctors predicted that he has only two more years to live, he lived another 55 years and died on 14 March, 2018. There are some interesting anecdotal coincidences. Hawking was born on the 300th anniversary of Galileo’s death and died on the 139th anniversary of Einstein’s birth. Following his cremation, his ashes will be interred on 15th June 2018 in Westminster Abbey’s nave, next to the grave of Isaac Newton and close to Charles Darwin.

Instead of ruing about his mortality, Hawking considered his illness as a blessing, allowing him, in his own words, “to focus more resolutely on what he could do with his life.” Indeed, with a crumpled, voiceless body ensconced in a wheelchair, he soared and established an exalted scientific reputation as the most recognizable scientist of the modern era. The name of this supernova of cosmology will be engraved in the sands of time as long as humanity lives.

The writer, Quamrul Haider, is a Professor of Physics at Fordham University, New York

 

Cultural, International, Technical

Einstein’s incredible burst of creativity in 1905

einstein3Three ages of Einstein

Albert Einstein, the iconic physicist of the twentieth century, was born at a time when prevailing physical science was deemed inadequate and incapable of explaining emerging scientific evidence and, worst of all, there was nothing in the horizon to replace it. The scientific establishment of the day was complacent with this impasse. When Max Planck, the future pioneer of quantum concept, approached his professor in Munich in 1879 at the age of 21 and expressed his desire to pursue a career in physics, he was told by the patronising professor that ‘it is hardly worth entering physics anymore’ because there was nothing important left to discover!

Albert Einstein, an Ashkenazi Jew (secular in religious outlook), was born on Friday, 14 March 1879 in the historic city of Ulm, Kingdom of Wurttemberg, in the then German Empire. His father, being an engineer and a salesman, gave little Einstein every encouragement and adequate technical backing to pursue a technical career. He was very inquisitive and tenacious. Nothing he would consider as unattainable. As a child he wondered if he could ride on a beam of light! He said about himself years later, ‘God gave me the stubbornness of a mule’.

As a child he was not a prodigy by any means. As a strong headed boy, he intensely disliked strict disciplinarian life, either at school or at home. But he would pursue his curiosity, his objective with passion and energy. Years later, he said, “Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning”.

At the age of nine, when he was sent by his parents to Luitpold Gymnasium (a strict discipline focussed school) in Munich, he was not happy at all. He intensely disliked ‘rote learning’ method at the school with no opportunity for creative thinking. However, he pursued his studies there until the age 16 (1895) to keep parents happy. But then to avoid compulsory military service in Germany, he left the school, went to his parents in Italy at the end of 1895. After spending few months with his parents in Italy, he was persuaded by his parents to continue with his secondary education in science at a Cantonal school in Zurich, Switzerland. He renounced his German citizenship in 1896, so that he would never be called for military service in Germany. He completed his studies and then graduated with a teaching diploma in physics and mathematics in 1900. All these years, from 1895 to 1900, he was stateless. He acquired Swiss citizenship in 1901 after completing five years of residence there.

Aspiring to take up a career in physics, particularly at a university, at that time was not easy. He scaled down his ambition and for nearly two years, he even tried to get a school teaching post, but without success. Eventually on the recommendation of the father of his close friend, he managed to get a humble position at the Swiss Patent Office in Bern, capital of Switzerland, in 1902 as a ‘Technical Expert – Third Class’. Although the position was lowly, but the salary was quite handsome. This job, according to him, brought an end to ‘the annoying business of starving’.

He moved to Bern in 1902 and lived there until 1907. Initially, as a bachelor, he rented a room beyond the river Aare, which meanders across the capital city of Bern. After he got married in 1903, he rented a two-bedroom apartment on the second floor of 49 Kramgasse at the picturesque Old Town part of Bern. The cobbled street of Kramgasse, with the famous clock tower on one side and the river Aare, some three hundred meters away (about two hundred meters from 49 Kramgasse) on the other, was one of the most beautiful streets in Bern. At the end of Kramgasse, a historic bridge led to the other side of the river. From the street level, a series of steps, some 200 of them, led to the river banks. Einstein used to sit and contemplate by the river in summer evenings as the rippling sound of crystal clear water cascaded down the shallow river.

Einstein used to leave his apartment just before eight o’clock in the morning for a 10-minute walk to the imposing Patent Office building. He said later in his life that his work as a Patent Clerk was only for 48 hour a week, and he had one additional day to spare! At work he had to look at the design details of electrical devices submitted by budding inventors. This required him to scrutinise details and identify any possible flaws. These traits and critical thinking honed his talent for future research in physics.

What inspired Einstein to write his first ground breaking paper in 1905 advancing the proposal on the quantum theory of light was Max Planck’s paper detailing the solution of the blackbody problem with an outline of hitherto unheard of quantum concept of emission and absorption of light a few years back. Einstein read the paper and was completely overwhelmed by this radical concept of Max Planck. Einstein carried forward that quantum idea and produced a paper on photoelectric effects of light with the title “On a Heuristic Point of View Concerning the Production and Transformation of Light” for the journal ‘Annalen der Physik’, world’s leading physics journal in Germany, and posted it on 17 March 1905. Max Planck happened to be the adviser on theoretical physics to that journal at that time. Despite Planck’s reservation with Einstein’s mind-boggling concept of particulate nature of light, sweeping away the age-old concept of wave nature of light, he allowed the paper to be published simply because of its radical nature.

Einstein produced altogether four papers between this date of 17 of March and 30 of July,1905. The second one was from his Ph.D. dissertation where he set out a way of determining the sizes of atoms. The third one was the explanation of Brownian motion of atoms and molecules. The fourth one was, as Einstein himself admitted, a rough draft on “On the Electrodynamics of Moving Bodies” giving details of the concepts of space and time. Max Planck read all of these papers, but when he read the last paper, he was simply blown away. Although Einstein did not call it ‘the theory of relativity’, Max Planck called it so and the title stuck with it ever since.

einstein_2 (2)

Before the year was over, Einstein produced another paper, which contained a small equation, E = mc2 (actually the equation was E= mc2/(√(1-q2/c2) where q was the speed of the body and c was the speed of light. If q was much smaller than c, then the term inside the square root became very close to 1 and hence E = mc2). This equation came to be known as the mass-energy equivalence with which Einstein became synonymous. Also, during the same year, he reviewed as many as 21 technical books for this Annalen der Physik journal!

No other scientist, except Isaac Newton, had ever produced as many groundbreaking monumental papers in such quick succession as Einstein did in 1905. He was only 26 at that time. Isaac Newton, an Englishman, at the age of 23 produced the gravitational law and advanced the theory of light, all in 1666! Oh, he also laid the foundation for calculus in the same year! It is amazing to note that these two prodigal physicists dealt with the same physical problems – theory of gravity and theory of light – with incredible ingenuity.

Einstein received Nobel Prize in Physics in 1921 for his work on photoelectric effects of light. His work on special theory of relativity (followed by general theory of relativity in 1916) could also have warranted another Nobel Prize, but the concept was so profound and radical that even the Nobel Committee found it challenging without any supporting evidence! His mass-energy equivalence could have been another candidate for Nobel Prize. He laid foundations of two major planks of modern physics – quantum mechanics and theory of relativity, all in a single year of 1905!

 

  • A. Rahman is an author and a columnist