By Karl S. Kruszelnicki
At the end of the 20th Century, Time magazine voted Albert Einstein to be the Man of The Century. Albert was the dude who came up with all that really weird Relativity stuff - and he was your genuine certified Mega Brain. After all, we are told that he even won the Nobel Prize for his work in Relativity. On the other hand, generations of school kids have consoled themselves over their poor school marks with the belief that Einstein failed at school. Some motivational speakers also make this claim - but this claim is as wrong as the claim about the Nobel Prize.
First, Einstein did not win the 1921 Nobel Prize in Physics for his work on Relativity. Let's back up a little. Back in 1905, Einstein had the biggest year of his life. He wrote, with the help of his wife, Mileva, five ground-breaking papers that, according to the Encyclopaedia Britannica "forever changed Man's view of the Universe". Any scientist would have been proud to write even one of these magnificent papers - but Albert published five of them in one year!
One paper, of course, dealt with Relativity - what happens to objects as they move relative to other objects. Another paper proved that atoms and molecules had to exist, based on the fact that you could see tiny particles jigging around when you looked at a drop of water through a microscope. A third paper looked at a strange property of light - the Photoelectric Effect. Plants and solar cells do the Photoelectric Effect, when they turn light into electricity. His paper explained the Photoelectric Effect.
Relativity may have captured the public's consciousness, but it was the unglamorous Photoelectric Effect that got him the Nobel Prize. Well, that's one myth out of the way.
Second, Einstein definitely did not fail at high school. Einstein was born on 14 March in Ulm, in Germany, in 1879. The next year, his family moved to Munich. At the age of 7, he started school in Munich. At the age of 9, he entered the Luitpold-Gymnasium. By the age of 12 he was studying calculus. Now this was very advanced, because the students would normally study calculus when they were 15 years old. He was very good at the sciences. But, because the 19th-century German education system was very harsh and regimented, he didn't really develop his non-mathematical skills (such as history, languages, music and geography). In fact, it was his mother, not his school, who encouraged him to study the violin - and he did quite well at that as well.
In 1895, he sat the entrance examinations to get into the prestigious Federal Polytechnic School (or Academy) in Zurich, Switzerland. He was 16, two years younger than his fellow applicants. He did outstandingly well in physics and mathematics, but failed the non-science subjects, doing especially badly in French - so he was not accepted. So in that same year, he continued his studies at the Canton school in Aargau (also called Aarau). He studied well, and this time, he passed the entry exams into the Federal Polytechnic School.
So the next year, he finally started studying at the Federal Polytechnic in Zurich (even though he was now one year younger than most of his fellow students). Also in the year 1896, even though he was only 16 years old, he wrote a brilliant essay that led directly to his later work in relativity.
So he definitely did not fail his high school, and definitely was not a poor student.
So how did the myth that he failed high school start?
Easy. In 1896, which was Einstein's last year at the school in Aargau, the school's system of marking was reversed.
A grading of "6", which had previously been the lowest mark, was now the highest mark. And so, a grading of "1", which had been the highest mark, was now the lowest mark.
And so, anybody looking up Einstein's grades would see that he had scored lots of grades around "1" - which under the new marking scheme, meant a "fail".
And that means that schoolkids can't use that mythconception as a crutch any more - they'll just have to work harder...source:http://www.abc.net.au/science/articles/2004/06/23/1115185.htm?site=science/greatmomentsinscience
Friday, April 9, 2010
Proof that Albert Einstein's black holes do exist, claim scientists
Astronomers believe they have come up with concrete proof for the existence of black holes. By Richard Alleyne, Science Correspondent
Ever since Albert Einstein came up with his general theory of relativity, black holes has been central to our knowledge of the Universe.
Now experts say they have shown that the theoretical phenomenon, whose gravitational pull is thought to hold galaxies together, exist "beyond any reasonable doubt".
The team of scientists spent 16 years studying the existence of a super massive black hole thought to be at the centre of our galaxy, the Milky Way.
While the black hole itself is invisible to the eye, the team proved its existence by tracking the motions of 28 stars circling around it.
Just as swirling leaves caught in a gust of wind can provide clues about air currents, so the stars' movements reveal information about forces at work at the galactic centre.
The observations show that the stars orbit a central concentration of mass four million times greater than that of the Sun, claim the team from the Max-Planck Institute for Extraterrestrial Physics in Garching, near Munich, Germany.
"Undoubtedly the most spectacular aspect of our long term study is that it has delivered what is now considered to be the best empirical evidence that super-massive black holes do really exist," said study leader Professor Reinhard Genzel.
"The stellar orbits in the galactic centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt."
The astronomers were also able to measure with great accuracy how far the Earth is from the centre of the galaxy - a distance of 27,000 light years.
Usually the central region of the Milky Way is hard to see because the view from Earth is blocked by interstellar dust.
To overcome this problem, the astronomers, who published their findings in the Astrophysical Journal, focused on infrared light wavelengths that can penetrate the dust clouds.
The galaxy's central mass, long suspected of being a giant black hole, is known as "Sagittarius A star".
The European Southern Observatory study, which began in 1992, was made using the 3.5 metre (11ft) New Technology Telescope at the La Silla observatory and the Very Large Telescope - an array of four 8.2 metre (26ft) telescopes at the Paranal observatory. Both operate from the Atacama desert in Chile.
The team, who found that one particular star made a full orbit of the black hole in the 16 year study, now hope to use even more powerful telescopes to further test Einstein's theories.
A black hole is a theoretical region of space in which the gravitational field is so powerful that nothing, not even electromagnetic radiation (visible light), can escape its pull. They are believed to be the remnants of burnt out suns.
While the idea of a black hole dates back as far as 1783, it was only after Einstein published his general relativity theory in 1916 that the modern concept was introduced by the German physicist Karl Scharzchild. The actual phrase black hole was not, however, coined until 1968. source:http://www.telegraph.co.uk/science/science-news/3690822/Proof-that-Albert-Einsteins-black-holes-do-exist-claim-scientists.html
Ever since Albert Einstein came up with his general theory of relativity, black holes has been central to our knowledge of the Universe.
Now experts say they have shown that the theoretical phenomenon, whose gravitational pull is thought to hold galaxies together, exist "beyond any reasonable doubt".
The team of scientists spent 16 years studying the existence of a super massive black hole thought to be at the centre of our galaxy, the Milky Way.
While the black hole itself is invisible to the eye, the team proved its existence by tracking the motions of 28 stars circling around it.
Just as swirling leaves caught in a gust of wind can provide clues about air currents, so the stars' movements reveal information about forces at work at the galactic centre.
The observations show that the stars orbit a central concentration of mass four million times greater than that of the Sun, claim the team from the Max-Planck Institute for Extraterrestrial Physics in Garching, near Munich, Germany.
"Undoubtedly the most spectacular aspect of our long term study is that it has delivered what is now considered to be the best empirical evidence that super-massive black holes do really exist," said study leader Professor Reinhard Genzel.
"The stellar orbits in the galactic centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt."
The astronomers were also able to measure with great accuracy how far the Earth is from the centre of the galaxy - a distance of 27,000 light years.
Usually the central region of the Milky Way is hard to see because the view from Earth is blocked by interstellar dust.
To overcome this problem, the astronomers, who published their findings in the Astrophysical Journal, focused on infrared light wavelengths that can penetrate the dust clouds.
The galaxy's central mass, long suspected of being a giant black hole, is known as "Sagittarius A star".
The European Southern Observatory study, which began in 1992, was made using the 3.5 metre (11ft) New Technology Telescope at the La Silla observatory and the Very Large Telescope - an array of four 8.2 metre (26ft) telescopes at the Paranal observatory. Both operate from the Atacama desert in Chile.
The team, who found that one particular star made a full orbit of the black hole in the 16 year study, now hope to use even more powerful telescopes to further test Einstein's theories.
A black hole is a theoretical region of space in which the gravitational field is so powerful that nothing, not even electromagnetic radiation (visible light), can escape its pull. They are believed to be the remnants of burnt out suns.
While the idea of a black hole dates back as far as 1783, it was only after Einstein published his general relativity theory in 1916 that the modern concept was introduced by the German physicist Karl Scharzchild. The actual phrase black hole was not, however, coined until 1968. source:http://www.telegraph.co.uk/science/science-news/3690822/Proof-that-Albert-Einsteins-black-holes-do-exist-claim-scientists.html
Black Holes and Beyond
Einstein's general theory of relativity describes gravity as a curvature of spacetime caused by the presence of matter. If the curvature is fairly weak, Newton's laws of gravity can explain most of what is observed. For example, the regular motions of the planets. Very massive or dense objects generate much stronger gravity. The most compact objects imaginable are predicted by General Relativity to have such strong gravity that nothing, not even light, can escape their grip.
Scientists today call such an object a black hole. Why black? Though the history of the term is interesting, the main reason is that no light can escape from inside a black hole: it has, in effect, disappeared from the visible universe.
Do black holes actually exist? Most physicists believe they do, basing their views on a growing body of observations. In fact, present theories of how the cosmos began rest in part on Einstein's work and predict the existence of both singularities and the black holes that contain them. Yet Einstein himself vigorously denied their reality, believing, as did most of his contemporaries, that black holes were a mere mathematical curiosity. He died in 1955, before the term "black hole" was coined or understood and observational evidence for black holes began to mount.
Why Study Black Holes?
Here are some good reasons:
1. Human curiosity: they are among the most bizzare objects thought to exist in the universe.
2. They should be strong sources of gravitational waves.
3. As such, black holes should reveal much about gravity, a fundamental force in the cosmos.
4. Confirmation that they exist will strengthen confidence in current models of cosmic evolution, from the Big Bang to the present universe.
source:http://archive.ncsa.illinois.edu/Cyberia/NumRel/BlackHoles.html
Scientists today call such an object a black hole. Why black? Though the history of the term is interesting, the main reason is that no light can escape from inside a black hole: it has, in effect, disappeared from the visible universe.
Do black holes actually exist? Most physicists believe they do, basing their views on a growing body of observations. In fact, present theories of how the cosmos began rest in part on Einstein's work and predict the existence of both singularities and the black holes that contain them. Yet Einstein himself vigorously denied their reality, believing, as did most of his contemporaries, that black holes were a mere mathematical curiosity. He died in 1955, before the term "black hole" was coined or understood and observational evidence for black holes began to mount.
Why Study Black Holes?
Here are some good reasons:
1. Human curiosity: they are among the most bizzare objects thought to exist in the universe.
2. They should be strong sources of gravitational waves.
3. As such, black holes should reveal much about gravity, a fundamental force in the cosmos.
4. Confirmation that they exist will strengthen confidence in current models of cosmic evolution, from the Big Bang to the present universe.
source:http://archive.ncsa.illinois.edu/Cyberia/NumRel/BlackHoles.html
The Black Hole
Three Hundred Years of Gravitation, Black Holes and Time Warps: Einstein's Outrageous Legacy
A black hole in space has a gravitational force so strong that nothing can escape from it, not even light. Hence no one can see a black hole, but astronomers are convinced they exist. An early intellectual precursor to the concept of black holes may be found in John Michell's dark stars. Michell noted in 1783 that if bodies with densities not less than the Sun's, and hundreds of times greater in diameter, really existed, gravity would prevent their light particles from reaching us. Their existence might be inferred from the motions of luminous bodies around them. Michell's idea was ignored even before wave theory, in which gravity does not act on light, overthrew the particle theory from which he reasoned.
Collapsed stars make another intellectual precursor to black holes. After 1915 and Einstein's relativity theory, gravity again could act on light. In the 1930s, Subrahmanyan Chandrasekhar, recently arrived from India to study in England, modeled stellar structures. He found that stars of less than 1.4 solar mass shrink until they become white dwarfs, but more massive stars continue contracting. The British astrophysicist Arthur Eddington noted that at high compression, gravity would be so great that radiation could not escape, a situation he regarded as absurd. Others accepted Chandrasekhar's mathematics but believed that continuous or catastrophic mass ejection would act as a universal regulating mechanism to bring stars below the critical mass. Also, massive stars might evolve into stars composed of neutrons. In 1939, however, the American physicist J. Robert Oppenheimer established a mass limit for neutron stars (see Kurchatov, Igor Vasilievich, and J. Robert Oppenheimer). When it has exhausted thermonuclear sources of energy, a sufficiently heavy star will collapse indefinitely, unless it can reduce its mass.
World War II and then the hydrogen bomb project diverted research away from stellar structure. Nuclear weapons programs, though, did develop a deeper understanding of physics and more powerful computational techniques, and in the 1960s, computer programs that simulated bomb explosions were modified to simulate implosions of stars. A renewed theoretical assault followed on “black holes,” as they were named by the American nuclear physicist John Wheeler in 1967. In contrast to collapsed or frozen stars, black holes are now known to be dynamic, evolving, energy-storing, and energy-releasing objects.
Read more: black hole - Three Hundred Years of Gravitation, Black Holes and Time Warps: Einstein's Outrageous Legacy http://science.jrank.org/pages/48888/black-hole.html#ixzz0kYZasflH
Because no light escapes from black holes, detection of them requires observing manifestations of their gravitational attraction. From a companion star, a black hole captures and heats gas to millions of degrees, hot enough to emit X rays. Because the Earth's atmosphere absorbs X rays, devices to detect them must be lofted on rockets or satellites. A few black holes probably have been found, although other explanations of the observational data are possible.
In another predicted manifestation, two black holes spiral together, gyrate wildly while coalescing, and then become steady. Outward ripples of curvature of spacetime, also called gravitational waves, would carry an unequivocal black-hole signature. Gravitational waves should propagate through matter, diminishing in intensity with distance. On Earth, they should create tides the size of an atom's nucleus, in contrast to lunar tides of about a meter. Gravitational-wave detectors may be operational early in the twenty-first century.
Meanwhile, without benefit of prediction and intent, we may already have observed manifestations of black holes. Extraordinarily strong radio emissions from both the centers of galaxies and from quasars (compact, highly luminous objects) may be powered by the rotational energy of gigantic black holes, either coalesced from many stars or from the implosion of a single supermassive rotating star a hundred million times heavier than our sun. Other possible explanations for radio galaxies and quasars, however, do not require black holes.
source:http://science.jrank.org/pages/48888/black-hole.html
A black hole in space has a gravitational force so strong that nothing can escape from it, not even light. Hence no one can see a black hole, but astronomers are convinced they exist. An early intellectual precursor to the concept of black holes may be found in John Michell's dark stars. Michell noted in 1783 that if bodies with densities not less than the Sun's, and hundreds of times greater in diameter, really existed, gravity would prevent their light particles from reaching us. Their existence might be inferred from the motions of luminous bodies around them. Michell's idea was ignored even before wave theory, in which gravity does not act on light, overthrew the particle theory from which he reasoned.
Collapsed stars make another intellectual precursor to black holes. After 1915 and Einstein's relativity theory, gravity again could act on light. In the 1930s, Subrahmanyan Chandrasekhar, recently arrived from India to study in England, modeled stellar structures. He found that stars of less than 1.4 solar mass shrink until they become white dwarfs, but more massive stars continue contracting. The British astrophysicist Arthur Eddington noted that at high compression, gravity would be so great that radiation could not escape, a situation he regarded as absurd. Others accepted Chandrasekhar's mathematics but believed that continuous or catastrophic mass ejection would act as a universal regulating mechanism to bring stars below the critical mass. Also, massive stars might evolve into stars composed of neutrons. In 1939, however, the American physicist J. Robert Oppenheimer established a mass limit for neutron stars (see Kurchatov, Igor Vasilievich, and J. Robert Oppenheimer). When it has exhausted thermonuclear sources of energy, a sufficiently heavy star will collapse indefinitely, unless it can reduce its mass.
World War II and then the hydrogen bomb project diverted research away from stellar structure. Nuclear weapons programs, though, did develop a deeper understanding of physics and more powerful computational techniques, and in the 1960s, computer programs that simulated bomb explosions were modified to simulate implosions of stars. A renewed theoretical assault followed on “black holes,” as they were named by the American nuclear physicist John Wheeler in 1967. In contrast to collapsed or frozen stars, black holes are now known to be dynamic, evolving, energy-storing, and energy-releasing objects.
Read more: black hole - Three Hundred Years of Gravitation, Black Holes and Time Warps: Einstein's Outrageous Legacy http://science.jrank.org/pages/48888/black-hole.html#ixzz0kYZasflH
Because no light escapes from black holes, detection of them requires observing manifestations of their gravitational attraction. From a companion star, a black hole captures and heats gas to millions of degrees, hot enough to emit X rays. Because the Earth's atmosphere absorbs X rays, devices to detect them must be lofted on rockets or satellites. A few black holes probably have been found, although other explanations of the observational data are possible.
In another predicted manifestation, two black holes spiral together, gyrate wildly while coalescing, and then become steady. Outward ripples of curvature of spacetime, also called gravitational waves, would carry an unequivocal black-hole signature. Gravitational waves should propagate through matter, diminishing in intensity with distance. On Earth, they should create tides the size of an atom's nucleus, in contrast to lunar tides of about a meter. Gravitational-wave detectors may be operational early in the twenty-first century.
Meanwhile, without benefit of prediction and intent, we may already have observed manifestations of black holes. Extraordinarily strong radio emissions from both the centers of galaxies and from quasars (compact, highly luminous objects) may be powered by the rotational energy of gigantic black holes, either coalesced from many stars or from the implosion of a single supermassive rotating star a hundred million times heavier than our sun. Other possible explanations for radio galaxies and quasars, however, do not require black holes.
source:http://science.jrank.org/pages/48888/black-hole.html
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