SH.jpgStephen William Hawking, born 8 January 1942, is an English theoretical physicist and cosmologist, whose scientific books and public appearances have made him an academic celebrity. He is known for his contributions to the fields of cosmology and quantum gravity, especially in the context of black holes. Hawking's key scientific works to date have included providing, with Roger Penrose, theorems regarding gravitational singularities in the framework of general relativity, and the theoretical prediction that black holes should emit radiation, which is today known as Hawking radiation (or sometimes as Bekenstein-Hawking radiation). He has also achieved success with works of popular science in which he discusses his own theories and cosmology in general; these include the runaway best seller A Brief History of Time, which stayed on the British Sunday Times best-sellers list for a record-breaking 237 weeks.  Hawking has a motor neuron disease that is related to amyotrophic lateral sclerosis, a condition that has progressed over the years and has left him almost completely paralyzed.

 

70 years ago, Stephen was born. It was not just his wisdom and appearance to make him famous, but his birth date was already related to someone big in science past (for those who choose to believe in such connections - I do not).  While Stephen was born on January 8th 1942, Galileo Galilei died exactly 300 years before (January 8th, 1642 - which is the same year when great Isaac Newton was born too).

 

In 1952, when he was ten, Stephen began his secondary education at the St. Albans School, connected with the cathedral and academically of high quality. Unlike many of the great physicists, Hawking did not turn in an outstanding classroom performance. His creative energy was spent on constructing working models of trains, boats, and airplanes, and on inventing immensely elaborate games. "I think these games, as well as the trains, boats, and airplanes, came from an urge to know how things worked and to control them," he wrote later in an autobiographical note. Stephen's preference was for mathematics and physics, but his father disapproved of the mathematics, which he claimed was preparation only for teaching. Chemistry took the place of mathematics, and his limited mathematical training was a handicap in Hawking's subsequent research, based on the formidable mathematics of general relativity. But when he was later facing the adversities of disease, and increasingly unable to write in the formal language of mathematics (that is, with equations), he had to start all over again and find what was for him a better route to the physical message.

 

In 1959, at age seventeen, Hawking went to Oxford on a scholarship to University College. As this was Oxford, rowing was a sport with a long and serious tradition. Hawking did not have the burly physique required to handle an oar, but with his loud voice and fascination with being in control of events, he was suited for the position of coxswain, the member of the team who sits in the stern of the boat, shouts instructions, and steers. With first-class degree, he moved to Cambrige.  At Cambridge, Hawking began his career as a theoretical astrophysicist and cosmologist. His intention was to obtain his Ph.D. under Fred Hoyle, then Britain's best-known cosmologist. Instead, he was assigned to Dennis Sciama, of whom he had never heard. At first, Hawking was annoyed not to be studying under the famous Hoyle, but then he began to appreciate the friendly and stimulating environment Sciama created for his students.

 

Soon after Hawking had joined Sciama and his talented band of students, he was devastated by the news that he had the incurable disorder known as amyotrophic lateral sclerosis (ALS) which is also known as Lou Gehrig's disease (US) or motor neuron disease (UK). This disorder attacks the nerve cells that control voluntary muscular activity. Thought and memory processes are unaffected, but muscles throughout the body atrophy, leading finally to general paralysis. The doctor who made the diagnosis gave him a grim prognosis - two years to live.  Hawking's first reaction to his disease was the most natural one - deep depression.  His escape - isolation and operatic music of Wagner.

 

Hawking lifted himself out of depression partly by the strength of his will and determination, and partly with the help of others - mainly from Jane Wilde, an extraordinary young woman who became Hawking’s fiance.

 

They met at a party in 1963, soon after Hawking’s ALS symptoms began to appear. By the summer of 1965, Hawking had completed his Ph.D. thesis and won a research fellowship in theoretical physics at Gonville and Caius College, Cambridge.

 

Jane and Stephen were married in July 1965. Their first child, Robert, was born in 1967.

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Hawking's first research project centered on black holes.  A black hole can be as big as the solar system, or as small as an atom, or anything between; its behavior depends only on its mass and rate of spin (and on its electric charge, but that is generally comparatively small). Even though they are usually macroscopic in size, they are as standardized physically as elementary particles, which are also characterized by mass, spin, and charge. Up to a point, black-hole theory follows from Einstein's theory of general relativity, which describes the gravitational extremity that exists within the hole. The theory reveals that the gravitational field in the hole is so powerful that anything, including light, coming closer than a certain critical radius called the "event horizon" falls into the hole and is lost forever. General relativity tells us everything we need to know about black holes except for the physical situation at the center of the hole. There, relativity theory prescribes a point called a "singularity", where the density and spacetime curvature are infinite. Hawking and Roger Penrose, sometimes working in collaboration, defined the problem of black-hole singularities during the period from 1965 to 1970. Hawking and Penrose worked well as team. Hawking has a penetrating physical intuition, while Penrose has the mastery of the mathematics of general relativity that Hawking lacks. The theory of black holes was well established in the 1960s by Hawking, Penrose, and others, before any observations were reported that they actually existed. Then in the early 1970s a case was made that an x-ray-emitting object called Cygnus X-1, located in the constellation Cygnus, was a black hole paired with a massive star. In 1974, Hawking and other astrophysicists were about 80% certain that Cygnus X-1 actually involved a black hole, but as an "insurance policy", Hawking made a bet with Kip Thorne that Cygnus X-1 did not harbor a black hole. By 1990, confidence in the Cygnus X-1 black hole had risen to about 95 percent and Hawking cheerfully paid off the bet.

 

Still, Hawking's best-known contribution to astrophysics is a theory that slightly contradicts the blackness of black holes.  The mechanism by which black holes shed their blackness relies on the concept, which originated with Dirac, that electrons have antielectron counterparts called positrons. When an electron meets a positron, they annihilate each other, and gamma-ray photons are produced. The inverse of this process, in which a gamma ray photon obtained from some suitable energy source produces an electron-positron pair, is also possible. Hawking's idea was that the members of a virtual pair could become real and one of them observable if they were produced in the vicinity of a black hole. One might be captured by the hole and become a real particle or antiparticle, while the other, also real, might escape and be seen as emitted radiation. To the extent that these emissions occur, the hole is not literally black. Energy is required to create the particle-antiparticle pairs, and that energy comes from the black hole's gravitational field. As the energy of the field is diminished, the hole shrinks in size and eventually disappears. Emission of black-hole radiation, called "Hawking radiation", is a very inefficient and slow process. Hawking remained convinced that the equations of black hole thermodynamics together with the no-hair theorem led to the conclusion that quantum information may be destroyed. The implications Hawking had opined led to the Susskind-Hawking battle, where Leonard Susskind and Gerard 't Hooft publicly "declared war" on Hawking's solution, with Susskind publishing a popular book about the debate in 2008 (The Black Hole War: My battle with Stephen Hawking to make the world safe for quantum mechanics). The book carefully notes that the "war" was purely a scientific one, and that at a personal level, the participants remained friends.

 

In 1982, with medical expenses and children's school fees looming, Hawking decided to write a short "book about the universe". He would write the book for a popular audience, and hope that it would also be popular in the other sense. It certainly was; sales of the book soared into a realm no science book had ever reached. Hawking's fragile life, and the book project, almost came to an end in the summer of 1985. Hawking was visiting the European center for nuclear research (CERN) in Geneva to conduct research and complete his writing task, while Jane traveled in Germany. Suddenly one night Hawking's nurse found him suffocating from a blockage of the windpipe brought on by an attack of pneumonia. Quick action by a Geneva doctor, who happened to be familiar with Hawking's condition through a television program, saved his life. Jane was hastily summoned, and she agreed with the doctors that Hawking's only hope for longterm survival was a radical procedure called a tracheotomy, involving cutting into the windpipe and implanting a breathing device. The tracheotomy restored Hawking's breathing, but also deprived him of what little use he still had of his vocal cords.  Several weeks after the tracheotomy, Hawking was at home again in Cambridge. The medical bills were now overwhelming, and Jane was forced to appeal to foundations and charitable organizations for help. She was efficient, relentless, and finally successful in raising the necessary funds. At about the same time, Hawking's voice problem was solved by a California computer programmer who supplied a program that allows Hawking to choose words and make sentences on a computer monitor with slight movements of his hand. Once a sentence is constructed, it is pronounced by a voice synthesizer. With his financial and medical problems again under control, Hawking returned to his research and to the book, which was nearing completion. It now had a title, A Brief History of Time, and an explanatory subtitle, From the Big Bang to Black Holes.

 

But in spite of all the fame and fortune, or perhaps because of it, the Hawking enterprise has failed in one important respect. The husband and wife senior partners in that enterprise have broken up after 25 years of marriage. In 1990, Stephen left Jane to live with one of his nurses, Elaine Mason. She left her husband, David, who, as it happened, had designed the computer hardware mounted on Stephen’s wheelchair. The Hawkings have three children, the Masons two. The marriage had shown signs of strain before the separation though. Religion was also a contentious issue in the marriage. Jane is deeply religious, while Stephen, like Einstein, is an atheist in the sense that he has no place for a personal God in his universe. As he put it in a television documentary, "We are such insignificant creatures on a minor planet of a very average star in the outer suburbs of one of a thousand million galaxies. So it is difficult to believe in a God that would care about us or even notice our existence."   In October 2006, Hawking filed for divorce from his second wife amid claims by former nurses that she had abused him. No wonder then, when New Scientist magazine asked him what he thinks about most, he answered: "Women. They are a complete mystery."

 

His actual synthesizer voice was used on parts of the Pink Floyd song "Keep Talking" from the 1994 album The Division Bell.

 

 

Hawking was in the news in July 2004 for presenting a new theory about black holes which goes against his own long-held belief about their behavior, thus losing a bet he made with Kip Thorne and John Preskill. Classically, it can be shown that information crossing the event horizon of a black hole is lost to our universe, and that thus all black holes are identical beyond their mass, electrical charge and angular velocity (the "no hair theorem"). The problem with this theorem is that it implies the black hole will emit the same radiation regardless of what goes into it, and as a consequence that if a pure quantum state is thrown into a black hole, an "ordinary" mixed state will be returned. This runs counter to the rules of quantum mechanics and is known as the black hole information paradox.

 

Hawking has been one of the leaders in the search for a quantum gravity unification. He advocates using the version of quantum mechanics invented by Richard Feynman, in which the actual path for an event is calculated by summing all possible paths for the event, each being characterized by a different phase. He also includes a special treatment of the time dimension by giving it an abstract mathematical identity technically called "imaginary"

 

Along with Thomas Hertog at CERN, in 2006 Hawking proposed a theory of "top-down cosmology", which says that the universe had no unique initial state, and therefore it is inappropriate for physicists to attempt to formulate a theory that predicts the universe's current configuration from one particular initial state. Top-down cosmology posits that in some sense, the present "selects" the past from a superposition of many possible histories. In doing so, the theory suggests a possible resolution of the fine-tuning question: It is inevitable that we find our universe's present physical constants, as the current universe "selects" only those past histories that led to the present conditions. In this way, top-down cosmology provides an anthropic explanation for why we find ourselves in a universe that allows matter and life, without invoking an ensemble of multiple universes.

 

In 2007, he became the first quadriplegic to float in zero-gravity. This was the first time in forty years that he moved freely, without his wheelchair. A bit of a futurist, Hawking was quoted before the flight saying: "Many people have asked me why I am taking this flight. I am doing it for many reasons. First of all, I believe that life on Earth is at an ever-increasing risk of being wiped out by a disaster such as sudden nuclear war, a genetically engineered virus, or other dangers. I think the human race has no future if it doesn't go into space. I therefore want to encourage public interest in space".

 

In 2008, Stephen Hawking theorized on the existence of extraterrestrial life, believing that "primitive life is very common and intelligent life is fairly rare."   He believes alien life not only certainly exists on planets but perhaps even in other places, like within stars or even floating in outer space. He also warns that a few of these species might be intelligent and threaten Earth. Contact with such species might be devastating for humanity: "If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans," he said. He advocated that, rather than try to establish contact, humans should try to avoid contact with alien life forms.

 

Hawking contrasted religion and science in 2010, saying: "There is a fundamental difference between religion, which is based on authority, [and] science, which is based on observation and reason. Science will win because it works."

 

In early 2012, his name made headlines as he announced he was looking for person to maintain his speech system.  Some additional details about this black box can be found here.

 

Man who got stricken by illness, but who lived (and still lives) life at full.  Happy birthday Stephen!

 

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P.S.  As this is 21st century, you can't have birthday without webcast... Same applies here - click here for details.

 

Credits: Wikipedia, William Cropper, Philip Gibbs, Iain Heath (LEGO picture above)