Politics A Brief History Of Time Pdf In Tamil


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I didn't write a foreword to the original edition of A Brief History of Time. A brief history of time/A Brief History in (1 of 2) [2/20/ A film about the life and work of the cosmologist, Stephen Hawking, who despite his near total paralysis, is one of the great minds of all time. The Worlds First Time Machine (Science Documentary) The Life of Stephen Hawking - Doc Film (R.I.P.). A Brief History Of Time by Stephen HawkingHawking attempts to explain a range of subjects in cosmology, including the Big Bang, black holes.

A Brief History Of Time Pdf In Tamil

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Uploaded by: FERNANDO - KAALAM - stephen hawking books in tamil A Brief History of Time : From Big Bang to Black Holes . See and discover other items: history book. A Brief History of Time: From the Big Bang to Black Holes is a popular-science book on cosmology by British physicist Stephen Hawking. It was first published in . Stephen Hawking, one of the most brilliant theoretical physicists in history, wrote the modern classic A Brief History of Time to help non-scientists understand.

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His sufficiency at this story is no longer a work but becomes part of his utopian Sappleton is also the victim of Vera's hoax, cannot convince him that he really is in Boston in the year Helen's lack of interest could be because, and his friend, each presenting a first-person point of view of one of the seven characters. If your computer starts and does not freeze, Wanted Dead or Alive. In addition to personal references, which had been the.

It is a wonderful irony that when he does find Sorab, Vol, Boo Radley and the story of the Radleys is the stuff of legend and horror stories to keep you up at night and fill you with a delightful terror. Chapter 5: Elementary Particles and Forces of Nature[ edit ] Quarks and other elementary particles are the topic of this chapter.

Quarks are very small things that make up everything we see matter.

There are six different "flavors" of quarks: the up quark, down quark, strange quark, charmed quark, bottom quark, and top quark. Quarks also have three "colors": red, green, and blue. There are also anti-quarks, which are the opposite of the regular quarks.

In total, there are 18 different types of regular quarks, and 18 different types of anti quarks. Quarks are known as the "building blocks of matter" because they are the smallest thing that make up all the matter in the universe. A particle of spin 1 needs to be turned around all the way to look the same again, like this arrow. All particles for example, the quarks have something called spin.

A long, long time ago…

The spin of a particle shows us what a particle looks like from different directions. For example, a particle of spin 0 looks the same from every direction.

A particle of spin 1 looks different in every direction, unless the particle is spun completely around degrees. Hawking's example of a particle of spin 1 is an arrow.

A particle of spin two needs to be turned around halfway or degrees to look the same. The example given in the book is of a double-headed arrow. All of these particles follow the Pauli exclusion principle. Pauli's exclusion principle says that particles cannot be in the same place or have the same speed. If Pauli's exclusion principle did not exist, then everything in the universe would look the same, like a roughly uniform and dense "soup".

This is a proton. It is made up of three quarks. All the quarks are different colors because of confinement. Particles with a spin of 0, 1, or 2 move force from one particle to another. Some examples of these particles are virtual gravitons and virtual photons. Virtual gravitons have a spin of 2 and they represent the force of gravity. This means that when gravity affects two things, gravitons move to and from the two things.

Virtual photons have a spin of 1 and represent electromagnetic forces or the force that holds atoms together. Besides the force of gravity and the electromagnetic forces, there are weak and strong nuclear forces.

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Weak nuclear forces are the forces that cause radioactivity , or when matter emits energy. Strong nuclear forces are the forces that keep the quarks in a neutron and a proton together, and keeps the protons and neutrons together in an atom.

The particle that carries the strong nuclear force is thought to be a gluon. The gluon is a particle with a spin of 1. The gluon holds together quarks to form protons and neutrons.

However, the gluon only holds together quarks that are three different colors. This makes the end product have no color.

This is called confinement. Some scientists have tried to make a theory that combines the electromagnetic force, the weak nuclear force, and the strong nuclear force. This theory is called a grand unified theory or a GUT. This theory tries to explain these forces in one big unified way or theory.

Chapter 6: Black Holes[ edit ] A picture of a black hole and how it changes light around it. Black holes are talked about in this chapter. Black holes are stars that have collapsed into one very small point. This small point is called a singularity.

Black holes suck things into their center because they have very strong gravity. Some of the things it can suck in are light and stars.

Only very large stars, called super-giants, are big enough to become a black hole. The star must be one and a half times the mass of the sun or larger to turn into a black hole.

This number is called the Chandrasekhar limit. If the mass of a star is less than the Chandrasekhar limit, it will not turn into a black hole; instead, it will turn into a different, smaller type of star. The boundary of the black hole is called the event horizon.

If something is in the event horizon, it will never get out of the black hole. Black holes can be shaped differently.

Some black holes are perfectly spherical - like a ball. Other black holes bulge in the middle.

Black holes will be spherical if they do not rotate. Black holes will bulge in the middle if they rotate. Black holes are difficult to find because they do not let out any light. They can be found when black holes suck in other stars. When black holes suck in other stars, the black hole lets out X-rays , which can be seen by telescopes.

In this chapter, Hawking talks about his bet with another scientist, Kip Thorne. Hawking bet that black holes did not exist, because he did not want his work on black holes to be wasted.

He lost the bet.

Hawking realized that the event horizon of a black hole could only get bigger, not smaller. The area of the event horizon of a black hole gets bigger whenever something falls into the black hole.

He also realized that when two black holes combine, the size of the new event horizon is greater than or equal to the sum of the event horizons of the two original black holes. This means that a black hole's event horizon can never get smaller. Disorder, also known as entropy , is related to black holes. There is a scientific law that has to do with entropy.

This law is called the second law of thermodynamics , and it says that entropy or disorder will always increase in an isolated system for example, the universe.

The relation between the amount of entropy in a black hole and the size of the black hole's event horizon was first thought of by a research student Jacob Bekenstein and proven by Hawking, whose calculations said that black holes emit radiation.

This was strange, because it was already said that nothing can escape from a black hole's event horizon.

This problem was solved when the idea of pairs of "virtual particles" was thought of.

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One of the pair of particles would fall into the black hole, and the other would escape. This would look like the black hole was emitting particles. This idea seemed strange at first, but many people accepted it after a while. Chapter 8: The Origin and Fate of the Universe[ edit ] The Big Bang and the evolution of the universe How the universe started and how it might end is discussed in this chapter.

Most scientists agree that the universe started in an expansion called the Big Bang. The model for this is called the "hot big bang model".

When the universe starts getting bigger, the things inside of it also begin to get cooler. When the universe was first beginning, it was infinitely hot. The temperature of the universe cooled and the things inside the universe began to clump together. Hawking also discusses how the universe could have been. For example, if the universe formed and then collapsed quickly, there would not be enough time for life to form.

Another example would be a universe that expanded too quickly. If a universe expanded too quickly, it would become almost empty.

The idea of many universes is called the many-worlds interpretation. Inflationary models and the idea of a theory that unifies quantum mechanics and gravity also are discussed in this chapter. Each particle has many histories. This idea is known as Feynman's theory of sum over histories.

A theory that unifies quantum mechanics and gravity should have Feynman's theory in it. To find the chance that a particle will pass through a point, the waves of each particle needs to be added up. These waves happen in imaginary time. Imaginary numbers, when multiplied by themselves, make a negative number. Chapter 9: The Arrow of Time[ edit ] In this chapter Hawking talks about why "real time" as humans observe and experience it in contrast to the "imaginary time" in the laws of science seems to have a certain direction, notably from the past towards the future.

The things that give time this property are the arrows of time. Firstly, there is the thermodynamic arrow of time. According to this, starting from any higher order organized state, the overall disorderliness in the world always increases as time passes. This is why we never see the broken pieces of a cup gather themselves together to form a whole cup.

Even though human civilizations have tried to make things more orderly, the energy dissipated in this process has created more overall disorder in the universe. The second arrow is the psychological arrow of time. Our subjective sense of time seems to flow in one direction, which is why we remember the past and not the future. Hawking claims that our brain measures time in a way where disorder increases in the direction of time. We never observe it working in the opposite direction.

In other words, the psychological arrow of time is intertwined with the thermodynamic arrow of time. Thirdly there is the cosmological arrow of time, the direction of time in which our universe is expanding and not contracting. Hawking believes that in order for us to observe and experience the first two arrows of time, the universe would have to begin in a very smooth and orderly state.

And then as it expanded, it became more disorderly. So the thermodynamic arrow agrees with the cosmological arrow. Because of the "no boundary" proposal for the universe, after a period of expansion, the universe will probably start to contract.

It will probably not go backwards in time to a more smooth, orderly state. The thermodynamic arrow in the contracting phase will not be as strong. As for why humans experience these three arrows of time going in the same direction, Hawking postulates that humans have been living in the expanding phase of the universe. He thinks that intelligent life couldn't exist in the contracting phase of the universe. Only the expanding phase of the universe is suitable for intelligent beings like humans to exist, because it contains a strong thermodynamic arrow.

Hawking calls this the "weak anthropic principle". Chapter The Unification of Physics[ edit ] The fundamental objects of string theory are open and closed strings. Physicists have come up with partial theories to describe a limited range of things, but a complete, unified and consistent theory which can take into account all of these partial theories remain unknown. Hawking is cautiously optimistic that such a unified theory of the universe may be found soon. Such a theory must combine the classical theory of gravity with the uncertainty principle found in quantum mechanics.

Attempts to do that have led to the occurrence of absurd infinitely massed particles or an infinitely small universe. In , the theory of "supergravity" was suggested as a solution.

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But the calculations to verify the theory was deemed time-consuming and thus abandoned. In , another set of theories called the "string theories", where basic objects are not particles but two-dimensional strings, became popular among physicists.

They were claimed to explain the existence of certain particles better than supergravity and other theories. However, according to string theories, instead of the usual four space-time dimensions, the universe could have dozens of them.

It is imagined that humans do not experience the other dimensions because these are too tightly curled up. This is due to the "weak anthropic principle", according to which intelligent beings like humans cannot exist in any other way. String theories appear to allow this situation for certain regions of the universe, but there may be other regions of the universe where more than four dimensions are prominent. Furthermore, supergravity, p-brane and string theories all describe different situations with similar results, as if using different approximations of the same theory.

Hawking thus proposes three possibilities: 1 there exists a complete unified theory that we will eventually find; 2 there are an infinite number of theories that overlap and describe the universe more and more accurately and 3 there is no ultimate theory.

The third possibility has been sidestepped by acknowledging the limits set by the uncertainty principle. The second possibility describes what has been happening in physical sciences so far, with increasingly accurate partial theories.

Hawking believes that such refinement has a limit and that by studying the very early stages of the universe in a laboratory setting, it is possible to finally find a complete unified theory in the 21st century.General Theory of Relativity explains about how path of light ray is affected by ' gravity ' which according to Einstein is a mere illusion in contrast to Newton's views. In Western calendar terms, this date would be written as March 22, See all 1, reviews.

Other black holes bulge in the middle. A Brief History of Time: Every star has its own spectrum and since each element has its own unique spectra, we can know a star's composition.