Who Proposed The Idea of Black Hole?

The black hole is a great source of mystery and inspiration for scientists and writers alike. These are abnormalities in space where the gravity is so strong that not even light, traveling at an enormous speed of 300,000 km/sec, can escape.

How did the idea of black hole come about?

In 1915, more than a hundred years ago, Albert Einstein published a theory of space and time or "spacetime" in which one of the crucial predictions was the bending of light as it approached a massy body, like the sun or a black hole.

That light bent in the presence of mass was confirmed in an experiment led by English astronomer Arthur Eddington in 1919. After this observation, Einstein's general relativity was taken more seriously, as it resurrected the original idea of black hole – which was published way back in 1784!

It was English astronomer John Michell who suggested the existence of a body so big that even light could not escape. As a result, such an object could not be seen directly but its gravitational effects on nearby bodies could be measured.

At that time, the term black hole did not exist. Astronomers instead used the term "dark stars" which is a pretty cool name to describe a stellar body hiding in plain sight.

In 1916, Karl Schwarzschild used Einstein's field equations of general relativity to calculate the radius up to which any object of mass must be "cramped" to make it a black hole. This is called the Schwarzschild radius.

For example: Earth crushed to the size of a pea would turn into a black hole.

Although the theory of general relativity implied the existence of a monstrous space object capable of trapping light in its grasp, Einstein wrote in a paper that a star would "never shrink" to zero size.

When will black hole form

A new development occurred in 1930. Indian physicist Subrahmanyan Chandrasekhar calculated how a star could actually shrink or collapse if it "ran out of hydrogen" or other nuclear fuels to burn.

Consequently, there come various stages in the star's life cycle. Upon collapse, the star may become a white dwarf - like our sun will - too feeble to burn bright in our skies.

Chandrasekhar predicted that a white dwarf with mass greater than "a limit" will be subject to further gravitational collapse, evolving into a different type of stellar remnant - a denser neutron star.

What would it take to form a black hole then? In 1939, American physicist Robert Oppenheimer produced a paper titled, "On Continued Gravitational Attraction" and in it calculated that a star would have to be at least three times as massive as the sun to become black hole.

Birth of black hole

The paper by Oppenheimer was the key factor in the rejuvenation of astrophysical research in the United States in the 1950s - mainly by John Archibald Wheeler.

In fact, the term black hole was coined in 1967 by Wheeler during a talk he gave at the NASA Goddard Institute of Space Studies. Not even light could escape from it, it was undetectable - hence, "black" hole.

One also could not tell from the outside what was inside the black hole. This means that the black hole contains a lot of information which is hidden from the outside world and Wheeler called this, "A Black Hole Has No Hair".

But in 1971, English mathematical physicist Roger Penrose described a way for information to be transferred from rotating black hole to an outside particle. Three years later, another method for the same was provided by cosmologist Stephen Hawking, as in Hawking radiation.

At around the same time in America, physicist Kip Thorne, one of Wheeler's doctoral students, developed the general relativistic theory of thin accretion disks around black holes, a flattened band of spinning matter around the event horizon.

Something you may have already seen in artist's impressions of the black hole:

Thorne compiled many theoretical results about the black holes in a 1994 book for non-scientists, titled Black Holes and Time Warps. It was a widely recognized book on the subject and translated into six languages.

Cut to present

The phenomenon of black hole captured the attention of some of the greatest minds in history and continues to surprise us even more in mainstream media.

Most recently, in the 2014 film "Interstellar" by director Christopher Nolan. Physicist Kip Thorne was also closely involved in the making and acted as executive producer.

Interstellar was a huge success - the science fiction movie project not only generated a fortune at the box office but also a new public interest regarding the black holes.

In 2019, the first picture of a black hole in Messier 87 was released based on data from 2017. It was compiled by the event horizon telescope - a collective effort of scientists from over 20 countries made it possible to see the distant space object by converting the entire planet Earth into a giant virtual telescope!

The image of black hole confirmed how lucky we are as a species at this particular time, with the capacity of the human mind to comprehend the universe, to have built all the science and technology to see it in glorious action.

On a fun ending note, black holes have come a long way - from gigantic mass eating monsters in space to the shape of a doughnut!

10 differences between astrology and astronomy

1. Every newspaper in the world has a daily column on astrology. How many papers carry even a weekly column on astronomy? – this is a major, disappointing difference between the two fields, as pointed out by Carl Sagan.

2. Astronomy is a practical science built upon technical skills such as in observation, mathematics and computer programming. Astrology does not demand such complicated knowledge.

3. If you delete all of human history, astronomy will come up again in exactly the same manner since it is based upon facts and figures. Whereas, astrology is a product of the human imagination and will acquire different shapes and forms.

4. There is a Nobel Prize for astronomers who make great advances to our understanding of the universe – astronomy being a branch of physics. In astrology, there is no such honor.

5. According to astrology, the position of a planet such as Saturn can trigger a life changing influence on an individual located on some corner of the Earth. Astronomy denies this claim.

6. After decades of research, astronomy has reached to the conclusion that life on earth is made from elements that were forged in the core of dying stars – a poetically beautiful truth. Astrology could not have reached to this sophisticated result.

7. Historians say that astrology is 2,500 years old. On the contrary, astronomy is vastly older. The first human beings depended on astronomical events for various activities, such as in agriculture and navigation. This developed into questions like, "What's out there?" and into inventions like the telescope.

8. Hence, astronomy is a natural tendency (aka curiosity) whereas astrology is derived, from observations and results in astronomy. Astrology is something that people turn to thinking it would have answers to life's problems.

9. Astronomy is a healthy activity for kids to get involved in. Astrophotography is one way to get started. Whereas, a sincere belief in astrology puts children inside boxes and they grow up asking dumb questions like, "What's your star sign?" to measure compatibility.

10. Reading astrology may be comforting to some people, but at only a superficial level. On the contrary, astronomy appeals to the very core of a person and may inspire them to paint a timeless piece like the "starry night".

Five Quotes By Freeman Dyson On Religion

Freeman Dyson (1923-2020) was no ordinary physicist. In a letter of recommendation to Robert Oppenheimer, Nobel laureate Hans Bethe wrote in praise of Dyson: "He is the best student I have ever had or observed."

Dyson was unusual in that he won the Templeton Prize in 2000, which is given annually in the field of spirituality, recognizing achievements at the intersection of science and religion. Dyson was pleasantly surprised by this honor.

Yes, Dyson was openly religious.

But his God was a kind of meta-scientific, collective consciousness. As someone who regarded the universe as a manifestation of God, Dyson said: The many accidents of physics and astronomy that have worked together to our benefit, it almost seems as if the Universe must in some sense have known that we were coming.

Dyson partially disagreed with fellow physicist Steven Weinberg's view that "with or without religion, good people can behave well and bad people can do evil; but for good people to do evil – that takes religion" and added: "For bad people to do good things – that also takes religion."

Following are 5 quotes by Freeman Dyson on science, religion and life:

1. Both as a scientist and as a religious person, I am accustomed to living with uncertainty. Science is exciting because it is full of unsolved mysteries, and religion is exciting for the same reason. The greatest unsolved mysteries are the mysteries of our existence as conscious beings in a small corner of a vast universe.

2. To talk about the end of science is just as foolish as to talk about the end of religion. Science and religion are both still close to their beginnings, with no ends in sight. Science and religion are both destined to grow and change in the millennia that lie ahead of us, perhaps solving some old mysteries, certainly discovering new mysteries of which we yet have no inkling.

3. Science and religion are two windows that people look through, trying to understand the big universe outside, trying to understand why we are here. The two windows give different views, but they look out at the same universe. Both views are one-sided, neither is complete.

4. Without discipline there can be no greatness. Without diversity there can be no freedom. Greatness for the enterprise, freedom for the individual — these are the two themes, contrasting but not incompatible, that make up the history of science and the history of religion.

5. Over periods of 10,000 years the distinctions between Western and Eastern and African cultures lose all meaning. Over a time span of 100,000 years we are all Africans. And over a time span of 300 million years we are all amphibians, waddling uncertainly out of dried-up ponds onto the alien and hostile land.

As a scientist, Dyson made several important contributions to the field of astrophysics that also bear his name, including concepts like Dyson tree and Dyson eternal intelligence, which find repetitive use in the realm of science fiction.

Dyson was Professor Emeritus in the Institute for Advanced Study in Princeton, remembered by friends and colleagues as shy and polite, with a refreshing view of the world. Physicist Geoffrey Ingram Taylor described Dyson as "the best mathematician in England."

5 Science Quotes By Robert Oppenheimer

Robert Oppenheimer was an American physicist who is often called the father of the atomic bomb. Despite making significant contributions to the fields of quantum mechanics and astrophysics, Oppenheimer is famously remembered for his role in the Manhattan project.

From an early age, Oppenheimer was interested in arts and sciences. He wrote poetry and enjoyed solving physics problems. In a letter to his bother, dated 14 October 1929 Oppenheimer admitted: "It is occasionally true, that I need physics more than friends."

Oppenheimer is also known as a defender and promoter of science in the post war world. He toured Europe and Asia, giving lectures on the history of science, the role of science in society and the nature of the universe.

Regarding his part in the Los Alamos laboratory, Oppenheimer said: "You cannot stop such a thing if you are a scientist. It is good to find out how the world works. It is good to turn over to mankind the greatest possible power to control the world, and to deal with it according to its lights and its values."

At the same time, Oppenheimer was aware of the increasing political misuse of scientific discoveries, which is why, he joined Albert Einstein and Bertrand Russell in establishing the World Academy of Art and Science. It was started to discuss the major concerns of humanity.

Following are five quotes by J. Robert Oppenheimer on science:

1. Science is not everything, but science is very beautiful. (last published words, 1966)

2. There is no place for dogma in science. The scientist is free, and must be free to ask any question, to doubt any assertion, to seek for any evidence, to correct any errors. (1949)

3. Science is the basis for radically new technological developments. Most people, when they think of science as a good thing, when they think of it as worthy of encouragement, have in mind that the conditions of their life have been altered just by such technology, of which they may be reluctant to be deprived. (1948)

4. It is a profound and necessary truth that the deep things in science are not found because they are useful; they are found because it was possible to find them.

5. Science starts with a preconception, with common sense. It moves on to observation, is marked by the discovery of paradox, and is then concerned with the correction of preconception. It moves then to further observation and for more refined experiment. (1958)

Oppenheimer was a polymath who obtained a PhD degree aged only 23, under the guidance of physicist Max Born. He served as the director of the Institute for Advanced Study in Princeton, where Einstein was a resident scholar.

Under his directorship, Oppenheimer brought together the most brilliant minds of his time such as Bohr, Fermi, Dirac, Bethe and Feynman. In 1963, Oppenheimer was recognized by the president of United States with Enrico Fermi award.

A biographical film by Christopher Nolan is scheduled to be released this year, starring actor Cillian Murphy as Robert Oppenheimer. It is based on the book, American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer.

Who Was Alexander Friedmann?

Alexander Friedmann (1888–1925) was a Russian scientist who was the first to propose the theory of expanding universe, discovering a set of equations, now called Friedmann equations – before dying prematurely aged only 37.

Not only that, Friedmann also gave lectures on aeronautics for pilots and flew aircraft during the first world war. His students included such distinguished scientists as George Gamow and Vladimir Fock.

Early years

Friedmann was born to a very artistic household – his father was a professional ballet dancer while his mother was a trained pianist. From an early age, he was interested in the arts, sciences and politics. When he was 17, Friedmann was a student leader at his high school.

In 1907, when Friedmann had freshly joined the St Petersburg university for a physics degree, his father passed away suddenly. Consequently, Friedmann had to work part time as a tutor, earning a small salary that would support his education.

Friedmann received a bachelor's degree in 1910 and quickly joined Saint Petersburg Mining Institute as a lecturer.

Training

By 1913, Friedmann also completed his master’s degree and began taking part in flight lessons to study meteorology. This training came handy during the first World War, because Friedmann decided to volunteer in the air force. He was soon involved in bomb raids.

Friedmann used his physics knowledge in modelling bombing targets and helped other pilots too. Considering his aviation, scientific and leadership skills, Friedmann was promoted to the topmost position in an airplane factory.

His love of the pure sciences encouraged Friedmann to exchange letters, while fighting the war, with mathematician Vladimir Steklov – a friend from college days, in order to stay updated on new activities in the world of physics.

A new theory

German-born physicist Albert Einstein published a ground-breaking theory of gravity in 1916 that made him a celebrity figure. After the world war was over, Friedmann regretted participating, "I achieved what I set out to do, but what’s the use of it all now?" Friedmann decided to return his focus on physics.

In 1919, Arthur Eddington confirmed Einstein's theory by observing how stars near the sun were displaced from their original positions, due to curvature by mass. Friedmann wrote to Paul Ehrenfest a year later regarding his interest in the general theory of relativity.

In June of 1922, Friedmann introduced his own idea that the entire universe’s curvature could be a function of time.

Friedmann solved the field equations in general relativity to suggest three cases: 1) The universe could be expanding over time. 2) The universe could be shrinking over time or 3) The universe’s curvature could change periodically over time.

Revolt

Einstein, a supporter of steady state theory, did not view Friedmann’s evolving universe work favorably. Friedmann immediately wrote a letter to Albert Einstein requesting him to reconsider.

He wrote: “Should you find the calculations presented in my letter correct, please be so kind as to inform the editors of the Zeitschrift für Physik about it, and publish a correction to your statement.”

The letter reached Berlin, but since Einstein was touring Japan at the time, he did not read it until six months later. In 1923, Einstein admitted his error and wrote to Zeitschrift für Physik:

“My earlier criticism was based on an error in my calculations. I consider that Mr Friedmann’s results are correct and shed new light.”

Friedmann gained a widespread recognition in the scientific community as a result of proving Einstein wrong. He was invited to colleges across Europe to explain his findings.

Sadly, Friedmann died in 1925 because of a misdiagnosed typhoid fever. He was only 37 years old. Friedmann's theory was verified by Edwin Hubble 4 years later, who discovered red shift in the galaxies – implying an expanding universe.

Summing up

If Alexander Friedmann were alive in 1929 when Hubble found evidence for a changing universe, he should have won the Nobel Prize in physics. He was an adventurous man who did the most amazing work in the last few years of his life.

Friedmann received many honors after death, including a crater on the Moon which is named after him. Also, a prestigious Friedmann Prize is awarded once every three years to a single scientist for outstanding work done in cosmology.

Why You Should Read Astrophysics For People In A Hurry?

Human beings have been fascinated by the cosmos since time immemorial. Our current understanding of the universe comes from centuries of wonder, observation and experiment. One cannot help but ask – is there a single book that has laid out all the scientific progress in a clear and concise manner?

Enter American astrophysicist Neil deGrasse Tyson with his bestselling book Astrophysics for people in a hurry. You may have dozens or more questions about our place in the universe, how it works, etc. and if you're looking for one book to know them all, one book to find them and in the curiosity bind them, this book is it.

What's so great about this one book is how vast and far it goes in describing the intricate workings of the universe. From the beginning of time to its possible end. With Tyson's playful sense of humor and elaborate report on the ins and outs of the cosmos, Astrophysics for people in a hurry is a joy to read.

The book takes you on a journey to 14 billion years back when all of space and time began. It explains practical astrophysics as well as theoretical, Einstein's blunder, cosmic microwave background, how dwarf galaxies far outnumber the normal, why Titanium is used on telescope domes, etc. in impressive detail.

On top of that, the book is written by one of the most famous scientists of our times – Neil deGrasse Tyson, who is the director of the Hayden planetarium in New York city, whose love for space sciences is contagious, as well as his appearances on television are loved by one and all. Thus, for any science and astronomy enthusiast, the 2017 book is a prized possession.

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Tyson's Astrophysics for people in a hurry is a collection of his essays that appeared in Natural History magazine at various times from 1997 to 2007. Although marketed as a book for beginners, some knowledge of physics will be of genuine help – even so, it is a great place to start learning more about the ever changing field of astrophysics.

So whether you are a high school student or just starting out college, a young working professional or someone in their sixties, Astrophysics for people in a hurry is the one book you turn to in order to discover thorough answers to why and how of the universe. It is a highly recommended addition to your library!

Five Quotes By Stephen Hawking On Religion

Stephen Hawking was one of the most brilliant minds of the 20th century who made fundamental contributions to the theory of black holes. Hawking is well known to the general public by his record-breaking book A brief history of time, which sold over 25 million copies.

Hawking (1942–2018) was given just a few years to live in his twenties, as he was struck by the paralyzing motor neuron disease in 1963. Not only did he beat the odds, but also revolutionized physics for next half a century.

When Hawking ended his bestselling book with the sentence: If we discover the theory of everything... it would be the ultimate triumph of human reason, for then we would know the mind of God, he raised quite a few eyebrows. Hawking later explained that he had used the word "God" figuratively.

On numerous occasions, Hawking had commented that even if God were to be real, he would be bound by the rules of physics. Therefore, is the idea of an all powerful creator even necessary, Hawking wondered often.

For example, Hawking told New Scientist in 2007: (1) I'm not religious in the normal sense. I believe that the universe is governed by the laws of science. The laws may have been decreed by God, but God does not intervene to break the laws.

In 2011, Hawking would go on to say: (2) We are each free to believe what we want and it is my view that the simplest explanation is there is no God. There is probably no heaven, and no afterlife either. We have this one life to appreciate the grand design of the universe, and for that, I am extremely grateful.

And it is true that Hawking lived life to the fullest. His life threatening disease did not hinder his goals and aspirations. Hawking said, I believe that disabled people should concentrate on things that their handicap doesn’t prevent them from doing and not regret those they can’t do.

In an interview to The Guardian, Hawking remarked on the question of death: (3) I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers. That is a fairy story for people afraid of the dark.

On the question of creation, Hawking is clear: (4) Because there is a law such as gravity, the universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the universe going.

It may be a coincidence but Stephen Hawking was born on the same day that Galileo Galilei died in 1642. It was Galileo, the father of modern physics, who laid the foundations of science and religion debate, building upon his inner contradictions as a deeply religious man.

Hawking continued the great legacy more than 300 years later. According to him, there is a fundamental difference between religion, which is based on authority and science, which is based on observation and reason. This is also the view held by such greats as Dirac and Feynman. 

(5) We are just an advanced breed of monkeys—Hawking adds—on a minor planet of a very average star. We are so insignificant that I cannot believe the whole universe exists for our benefit (which is the view that religion has). But we can understand the Universe, and that makes us something very special.

5 Niels Bohr Quotes On Quantum Mechanics

Niels Bohr was a Danish physicist who made pioneering contributions to understanding atomic structure and quantum theory, for which Bohr was recognized with a Nobel Prize in 1922. Bohr was an active participant in the new quantum theory revolution that shook the foundations of classical physics.

Einstein, who was not ready to accept Heisenberg's uncertainty principle, as one of the cornerstones of modern physics, commented: God does not play dice with the universe. Bohr made peace with the uncertainty principle by developing the principle of complementarity.

According to complementarity, particles have certain pairs of interdependent properties that cannot all be observed or measured simultaneously. For example: position and momentum make such a pair.

Bohr regarded complementarity as an essential feature of quantum mechanics. It is said that Bohr replied to Einstein, who preferred the determinism of classical physics over the probabilistic new quantum physics: (1) "Stop telling God what to do."

In 1920, Bohr met Heisenberg for the first time. Bohr said, (2) What is it that we humans depend on? We depend on our words... Our task is to communicate experience and ideas to others. But when it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images and establishing mental connections.

Some physicists depended on mathematical analysis to make sense of the quantum world. However, Bohr was not satisfied. (3) Even the mathematical framework helps nothing, I (Bohr) would first like to understand how Nature avoids the contradictions. (1927)

Bohr said further: Our experience in recent years has brought light to the insufficiency of our simple mechanical conceptions and, as a consequence, has shaken the foundation on which the customary interpretation of observation was based.

We can still use the objectifying language of classical physics to make statements about observable facts. But we can say nothing about the atoms themselves.

In the 1927 Solvay conference, Bohr and Einstein went head-to-head on the metaphysical and philosophical implications of quantum mechanics. Two legends, one defending the new-age probabilistic physics and another fighting for classical determinism. At the end, it was Bohr who emerged victorious and successfully established the probabilistic character of quantum measurement.

Niels Bohr wrote in 1934: (4) Isolated material particles are abstractions, their properties being definable and observable only through their interaction with other systems. Everything we call real is made of things that cannot be regarded as real.

In a 1952 conversation with Heisenberg and Pauli in Copenhagen, Bohr quipped: (5) "Those who are not shocked when they first come across quantum theory cannot possibly have understood it." This was most likely a reference to Einstein, who not only contributed to the new theory but also immediately taken aback by its bizarre results.

Richard Feynman Explains The Circle of Life

Nobel prize winning American scientist, Richard Feynman, was fascinated by simple things. From rubber band to fire, Feynman was delighted to explain the physics of day to day items in easy and poetic language. Here, Feynman described the life cycle of a tree as an example to illustrate that life comes full circle.

Where does the structure of the tree come from? To find out, we must start at the beginning. It is understood that seed sown in the ground will develop shoot of the plant, as it reaches out for the sunlight. At the same time, a root spreads deep in the soil searching for water.

Capillary action helps bring water up into the roots when the soil has higher concentration of water than the root cells. It is like putting a wick in oil lamp. But capillary action can only pull water up a small distance, when the plant is small.

In a mature tree, liquid water flows into the woody stem and then into green leaves where photosynthesis will occur. How does it work against the effects of gravity? The answer is cohesive forces that help to move water to the furthest leaf.

In the green leaves, some part of the water is used for photosynthesis. The other part, due to heat from sunlight, escapes into the atmosphere as water in gaseous form. In fact, if you wrap a plastic bag around a leaf, you can actually see vapor condense inside the bag.

Since molecules of water in the root and stem stick tightly to one another because of cohesion, the vapors which escape from the leaves, kind of pull the remaining water, as a single unit, upward behind them. This process is called transpiration.

Going back to, where does the structure of the tree come from? Feynman comments: it is generally thought that plants grow out of the ground. However, apart from water and vital nutrients, the ground does not contribute in the building up of the tree.

Mass of the tree is primarily carbon and where does that come from? The atmosphere, but not in pure form, it comes as carbon dioxide. (In its lifetime, a tree soaks up tons of carbon dioxide from the air, which is why it is advised to plant more trees).

The absorbed carbon dioxide is reduced to pure carbon when acted upon by the sunlight. Trees utilize these carbon molecules to construct their body tissues, for example in the stem. The useless oxygen molecules, on the other hand, are spit back into the air.

Thus, a combination of water, air and light as they come from the ground, atmosphere and sun respectively, mediate the flowering and growth of the tree.

There is a beautiful end to the story. The tree is used as a fuel for combustion. When pieces of wood are rubbed, for example, heat is built up by friction and that leads to reunification of carbon molecules in the tree with oxygen molecules in the air, generating a "tremendous catastrophe" as Feynman puts it, fire.

If you think about it, this light and heat of the fire is the light and heat of the sun, that went in! Feynman says: it is kind of a "stored sun", that is coming out when you burn a log. Isn't it wonderful how nature manages to come back in a full circle?