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The world’s most famous equation E=mc2 on which the bomb is based comes from his theory. One of the greatest scientist of the 20th century, Einstein’s Special theory of relativity revolutionized physics which even challenged the scientists at CERN. The World's Greatest Books, Vol. 12, Modern History Item Preview. Worldsgreatestbo1910nort.pdf download. Internet Archive Books. Scanned in China. Uploaded by Phillip.L on December 23, 2009. SIMILAR ITEMS (based on metadata). Created Date: 4/14/2011 8:12:17 PM.
Inventors Day is celebrated on 29 September by several countries, as it is the birthday of Argentinian inventor László József Bíró, the inventor of the ball-point pen.
From the discovery of the wheel to the launch of the World Wide Web, several key advancements have changed the way the human species lives. To celebrate the day, we look at some of the most important and revolutionary inventions of all time:
Compass
Before the introduction of the compass, destination, position and direction at sea were primarily determined by the sighting of landmarks, along with the observation of the position of stars and celestial bodies.
The compass was invented by the Chinese between the 9th and 11th century. It was originally made from lodestone, a naturally magnetised piece of the mineral magnetite. The earliest Chinese literature reference to magnetism lies in the writings of Wang Xu in the 4th century BC .
Internal combustion engine
The earliest evidence of a crank and connecting rod mechanism dates to the 3rd century AD and the Hierapolis sawmill in Asia Minor, a part of the Roman Empire that has become modern-day Turkey.
The modern form of the internal combustion engine came around in the latter half of the 19th century, which brought with it the Industrial Age. In these engines, the combustion of a fuel releases a high-temperature gas, that expands and exerts force on a piston, thereby moving it.
The invention of the internal combustion engine brought with it a variety of machines, including modern cars and aircraft.
Computer
Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the 'father of the computer', he conceptualised and invented the first mechanical computer in the early 19th century.
The principle of the modern computer was first described by computer scientist Alan Turing, who set out the idea in his seminal 1936 paper, On Computable Numbers.
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. The discovery of penicillin is attributed to Scottish scientist and Nobel laureate Alexander Fleming in 1928. He showed that, if Penicillium rubens were grown in the appropriate substrate, it would exude a substance with antibiotic properties.
Chemists purified it and developed the drug Penicillin, which fights a huge number of bacterial infections in humans without harming the humans themselves. It was being mass produced and advertised by 1944.
Wheel
The wheel was invented in 3500 BC and facilitated agriculture and commerce by enabling the transportation of goods to and from markets. Wheels have transformed our lives, and are used in everything from clocks to vehicles.
World Wide Web
Sir Tim Berners-Lee, a British computer scientist and former Cern employee, is considered the inventor of the Web. On 12 March, 1989, he wrote a proposal for what would eventually become the World Wide Web.
However, in a May 1970 issue of Popular Science magazine, Arthur C Clarke predicted that satellites would one day 'bring the accumulated knowledge of the world to your fingertips' – using a console that would combine the functions of the telephone, photocopier, television and a small computer. He predicted it would eventually allow the transfer of data and video conferencing around the world.
Light bulb
According to historians, two dozen people were instrumental in inventing incandescent lamps throughout the 1800s.
Thomas Edison is credited as the primary inventor because he created a completely functional lighting system, including a generator and wiring as well as a carbon-filament bulb.
Contraception
The Egyptian Ebers Papyrus from 1550 BCE and the Kahun Papyrus from 1850 BCE have within them some of the earliest documented descriptions of birth control. Acacia leaves, honey and lint were placed in the vagina to block sperm.
The birth control movement developed during the 19th and early 20th centuries. Gregory Pincus and John Rock, with help from the Planned Parenthood Federation of America, developed the first birth control pills in the 1950s, such as mestranol/norethynodrel, which became publicly available in the 1960s.
Telephone
Alexander Graham Bell was the first to be awarded a patent for the electric telephone in 1876. The first successful bi-directional transmission of clear speech by Bell and his assistant Thomas Watson was made in March 1876.
The invention quickly took off, and revolutionised global business and communication.
Paper
Paper was invented in ancient China during the Han Dynasty (206 BC-220 AD) and spread slowly to the West via the Silk Road.
Earlier materials used instead of paper, such as papyrus, parchment and palm leaves, were expensive and in short supply, but paper, made from wood and rags, could be processed everywhere and eventually provided a cheaper alternative using large-scale production.
RelatedSo if a black hole isn't so black, and if it's radiating, the big question now becomes how. How does a black hole radiate? Figuring out the answer to this conundrum was Hawking's biggest contribution to physics. We know how to calculate, in quantum field theory, how the vacuum of empty space behaves when space is flat. That is, we can tell you properties of empty space when you're very far away from any masses, like a black hole. What Hawking showed, for the first time, is how to do this in curved space: within a few radii of the event horizon. And what he found was that there was a marked difference in the behavior of the quantum vacuum when a mass was near.
Quantum gravity tries to combine Einstein’s general theory of relativity with quantum mechanics. Quantum corrections to classical gravity are visualized as loop diagrams, as the one shown here in white. The semiclassical approximation that Hawking used involved calculating the quantum field theoretic effects of the vacuum in the background of curved space.
SLAC National Accelerator LabWhen he ran through the math, he found the following properties:
- When you're far from the black hole, it looks like you get the thermal emission of blackbody radiation.
- The temperature of the emission is dependent on the black hole's mass: the lower the mass, the higher the temperature.
- As the black hole emits radiation, it decreases in mass, in exact accord with Einstein's E = mc2. The higher the rate of radiation, the faster the mass loss.
- And as the black hole loses mass, it shrinks and radiates faster. The time a black hole can live is proportional to its mass cubed: the black hole at the Milky Way's center will live some 1020 times longer than a black hole of the Sun's mass.
If you visualize empty space as frothing with particle/antiparticle pairs that pop in-and-out of existence, you'll see radiation coming from the black hole. This visualization is not quite correct, but the fact that it's easy to visualize has its benefits.
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Ulf Leonhardt of the University of St. AndrewsOriginally, Hawking visualized this as particle/antiparticle pairs popping in-and-out of existence, annihilating away to produce radiation. That oversimplified picture was qualitatively good enough to describe the radiation far from the black hole, but it turns out to be incorrect close to the event horizon. It's more accurate to think of the vacuum changing, and of the radiation as being emitted from wherever the curvature of space is relatively large: within a few radii of the black hole itself. Once you get far away, though, everything just appears to be this thermal, blackbody radiation.
Hawking radiation is what inevitably results from the predictions of quantum physics in the curved spacetime surrounding a black hole's event horizon. This visualization is more accurate than the above, since it shows photons as the primary source of radiation rather than particles. However, the emission is due to the curvature of space, not the individual particles, and doesn't all trace back to the event horizon itself.
E. SiegelAll at once, there was a revolution in black holes, and in understanding how quantum fields behave in highly curved space. It opened up the black hole information paradox, as we're now asking where the information encoded on the black hole's event horizon goes when a black hole evaporates? It opens up the (related) problem of black hole firewalls, asking why don't objects get fried by radiation as they cross the event horizon, or whether they in fact do? It tells us there's a relationship between what happens within a volume (in the space enclosed by the event horizon) and the surface encapsulating it (the event horizon itself), which is a potential example of the holographic principle in real life. And it opens the door to additional subtleties that may allow us, for the first time, to probe the effects of quantum gravity if there are any departures from the predictions of General Relativity.
Against a seemingly eternal backdrop of everlasting darkness, a single flash of light will emerge: the evaporation of the final black hole in the Universe.
ortega-pictures / pixabayThe paper that led to all this was simply titled Black Hole Explosions? and was published in Nature back in 1974. It would have been the crowning achievement of a lifetime of research, and Hawking published it when he was merely 32 years old. He had been researching singularities, black holes, baby universes, and the Big Bang for many years, having collaborated with titans like Gary Gibbons, George Ellis, Dennis Sciama, Jim Bardeen, Roger Penrose, Bernard Carr, and Brandon Carter, to name a few. His brilliant work didn't come out of nowhere, but arose out of a combination of a brilliant mind thriving in a fertile academic environment. It's a lesson to us all in how important it is, if we want to have these titanic theoretical advances, to create (and fund) these quality environments where research like this can come to life.
Outside the event horizon of a black hole, General Relativity and quantum field theory are completely sufficient for understanding the physics of what occurs; that is what Hawking radiation is.
NASANearly half a century later, the world mourns his passing, but the legacy of his research lives on. Perhaps this will be the century where there paradoxes are resolved, and the next titanic leaps forward in physics are taken. Regardless of what the future holds, Hawking's legacy is secure, and the most any theorist can hope for is that their theories will be improved in time. As Hawking himself stated:
Any physical theory is always provisional, in the sense that it is only a hypothesis: you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory.
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While the world may have lost one of its great scientific luminaries with Hawking's demise, his impact on our knowledge, understanding, and curiosity will echo throughout the ages.