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Stephen Hawking

Stephen Hawking Quotes

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Famous Stephen Hawking Quotes

“When people ask me if a god created the universe, I tell them that the question itself makes no sense. Time didn’t exist before the big bang, so there is no time for god to make the universe in. It’s like asking directions to the edge of the earth; The Earth is a sphere; it doesn’t have an edge; so looking for it is a futile exercise. We are each free to believe what we want, and it’s my view that the simplest explanation is; there is no god. No one created our universe,and no one directs our fate. This leads me to a profound realization; 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.”

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Author:Stephen Hawking
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“There are only two types of waves that can travel across the universe bringing us information about things far away: electromagnetic waves (which include light, X-rays, gamma rays, microwaves, radio waves…); and gravitational waves. Electromagnetic waves consist of oscillating electric and magnetic forces that travel at light speed. When they impinge on charged particles, such as the electrons in a radio or TV antenna, they shake the particles back and forth, depositing in the particles the information the waves carry. That information can then be amplified and fed into a loudspeaker or on to a TV screen for humans to comprehend. Gravitational waves, according to Einstein, consist of an oscillatory space warp: an oscillating stretch and squeeze of space. In 1972 Rainer (Rai) Weiss at the Massachusetts Institute of Technology had invented a gravitational-wave detector, in which mirrors hanging inside the corner and ends of an L-shaped vacuum pipe are pushed apart along one leg of the L by the stretch of space, and pushed together along the other leg by the squeeze of space. Rai proposed using laser beams to measure the oscillating pattern of this stretch and squeeze. The laser light could extract a gravitational wave’s information, and the signal could then be amplified and fed into a computer for human comprehension. The study of the universe with electromagnetic telescopes (electromagnetic astronomy) was initiated by Galileo, when he built a small optical telescope, pointed it at Jupiter and discovered Jupiter’s four largest moons. During the 400 years since then, electromagnetic astronomy has completely revolutionised our understanding of the universe.”

PhysicsElectromagnetic WavesGravitational Waves
Book:Brief Answers to the Big Questions
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“On September 14, 2015, the LIGO gravitational-wave detectors (built by a 1,000-person project that Rai and I and Ronald Drever co-founded, and Barry Barish organised, assembled and led) registered their first gravitational waves. By comparing the wave patterns with predictions from computer simulations, our team concluded that the waves were produced when two heavy black holes, 1.3 billion light years from Earth, collided. This was the beginning of gravitational-wave astronomy. Our team had achieved, for gravitational waves, what Galileo achieved for electromagnetic waves. I am confident that, over the coming several decades, the next generation of gravitational-wave astronomers will use these waves not only to test Stephen’s laws of black hole physics, but also to detect and monitor gravitational waves from the singular birth of our universe, and thereby test Stephen’s and others’ ideas about how our universe came to be. During our glorious year of 1974–5, while I was dithering over gravitational waves, and Stephen was leading our merged group in black hole research, Stephen himself had an insight even more radical than his discovery of Hawking radiation. He gave a compelling, almost airtight proof that, when a black hole forms and “and then subsequently evaporates away completely by emitting radiation, the information that went into the black hole cannot come back out. Information is inevitably lost.”

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Book:Brief Answers to the Big Questions
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“It is cer­tain­ly for­tu­nate for us that the num­bers (of quarks and antiquarks) are un­equal be­cause, if they had been the same, near­ly all the quarks and an­ti­quarks would have an­ni­hi­lat­ed each oth­er in the ear­ly uni­verse and left a uni­verse filled with ra­di­ation but hard­ly any mat­ter. There would then have been no galax­ies, stars, or plan­ets on which hu­man life could have de­vel­oped.”

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Book:A Brief History of Time
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“We have developed from the geocentric cosmologies of Ptolemy and his forebears, through the heliocentric cosmology of Copernicus and Galileo, to the modern picture in which the earth is a medium-sized planet orbiting around an average star in the outer suburbs of an ordinary spiral galaxy, which is itself only one of about a million million galaxies in the observable universe.”

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Book:A Brief History of Time
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“When we invented fire, we messed up repeatedly, then invented the fire extinguisher. With more powerful technologies such as nuclear weapons, synthetic biology and strong artificial intelligence, we should instead plan ahead and aim to get things right the first time, because it may be the only chance we will get. Our future is a race between the growing power of our technology and the wisdom with which we use it. Let’s make sure that wisdom wins.”

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Book:Brief Answers to the Big Questions
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“The realization that time can behave like another direction of space means one can get rid of the problem of time having a beginning, in a similar way in which we got rid of the edge of the world. Suppose the beginning of the universe was like the South Pole of the earth, with degrees of latitude playing the role of time. As one moves north, the circles of constant latitude, representing the size of the universe, would expand. The universe would start as a point at the South Pole, but the South Pole is much like any other point. To ask what happened before the beginning of the universe would become a meaningless question, because there is nothing south of the South Pole.”

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Book:The Grand Design
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“Newton's laws of motion put an end to the idea of absolute position in space. The theory of relativity gets rid of absolute time. Consider a pair of twins. Suppose that one twin goes to live on the tip of a mountain while the other stays at sea level. The first twin would age faster than the second. Thus, if they met again, one would be older than the other. In this case, the difference in ages would be very small, but it would be much larger if one of the twins went for a long trip in a spaceship at nearly the speed of light. When he returned, he would be much younger than the one who stayed on Earth. This is known as the twins paradox, but it is a paradox only if one has the idea of absolute time at the back of one's mind. In the theory of relativity there is no unique absolute time, but instead each individual has his own personal measure of time that depends on where he is and how he is moving.”

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Book:A Brief History of Time: From the Big Bang to Black Holes
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“We now know that every particle has an antiparticle, with which it can annihilate. (In the case of the force-carrying particles, the antiparticles are the same as the particles themselves.) There could be whole antiworlds and antipeople made out of antiparticles. However, if you meet your antiself, don't shake hands! You would both vanish in a great flash of light.”

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Book:A Brief History of Time
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“Some would argue for the third possibility on the grounds that, if there were a complete set of laws, that would infringe God's freedom to change his mind and intervene in the world. It's a bit like the old paradox: Can God make a stone so heavy that he can't lift it? But the idea that God might want to change his mind is an example of the fallacy, pointed out by St. Augustine, of imagining God as a being existing in time: time is a property only of the universe that God created. Presumably, he knew what he intended when he set it up!”

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Book:A Brief History of Time
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“Boston and Chicago are two great seats of mathematical research located in major American cities. Until they won in 2004, if you asked a baseball fan in Boston what they most hoped to see in their lifetime, they would have answered a World Series win for the Boston Red Sox. Chicago Cubs fans are still waiting. Ask a mathematician in either of those cities or anywhere else in the world what they would most hope to see in their lifetime, and they would most likely answer: "A proof o the Riemann hypothesis!" Perhaps mathematicians, like Red Sox fans, will have their prayers answered in our lifetimes, or at least before the Cubs win the World Series.”

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Book:God Created the Integers: The Mathematical Breakthroughs That Changed History
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“La Tierra se nos va quedando demasiado pequeña. Los recursos físicos están siendo drenados a un ritmo alarmante. La humanidad ha hecho a nuestro planeta el obsequio desastroso del cambio climático, la contaminación, el aumento de las temperaturas, la reducción de los casquetes de hielo polar, la deforestación y el diezmamiento de especies animales. Nuestra población también está aumentando a un ritmo alarmante. Frente a esas cifras, está claro que ese crecimiento casi exponencial de la población no puede continuar el próximo milenio.”

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Book:Brief Answers to the Big Questions
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“Sin embargo, si descubrimos una teoría completa, debería en su momento ser comprensible en sus líneas generales por todos, no solo por unos pocos científicos. Entonces todos seremos capaces de tomar parte en la discusión de por qué el universo existe. Si encontramos la respuesta a ello, sería el triunfo definitivo de la razón humana, pues entonces conoceríamos la mente de Dios.”

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Book:The Theory of Everything: The Origin and Fate of the Universe
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“Il modello inflazionario ha mostrato come l'attuale stato dell'universo avrebbe potuto emergere da una serie piuttosto ampia di configurazioni iniziali fra loro differenti. Tuttavia, resta pur sempre vero che non sarebbe bastato prendere una qualsiasi configurazione iniziale per giungere all'universo che ci sta dinnanzi. Pertanto, anche il modello inflazionario non ci spiega perché la configurazione iniziale sia stata esattamente quella richiesta per produrre ciò che noi oggi osserviamo. Dobbiamo quindi cercare una spiegazione nel principio antropico? Tutto questo avvenne solamente grazie a un caso fortuito? Questa sembrerebbe una conclusione del tutto insoddisfacente, una rinuncia a tutte le nostre speranze di comprendere l'ordine sotteso all'universo.”

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Author:Stephen Hawking
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“Pendant des millions d'années, l'humanité a vécu comme les animaux. Par la suite, quelque chose est arrivé qui a libéré le pouvoir de notre imagination. Nous avons appris à parler et à écouter. La parole a permis la communication des idées, abilitant l'être humain à travailler ensemble afin de construire l'impossible. Les plus grandes réalisations de l'humanité se sont matérialisées en parlant, et ses plus grands échecs en ne parlant plus. Cela n'a pas lieu d'être. Nos plus grands espoirs pourraient devenir des réalités dans le futur. Avec la technologie à notre disposition, les possibilités sont illimitées. Tout ce que nous avons à faire est de s'assurer que nous continuions à parler.”

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Author:Stephen Hawking
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“.... attempts to combine these two forces with the strong nuclear force into what is called a grand unified theory (GUT). This title is rather an exaggeration: the resultant theories are not all that grand, nor are they fully unified, as they do not include gravity. Nor are they really complete theories, because they contain a number of parameters whose values cannot be predicted from a theory but have to be chosen to fit in with experiment. Nevertheless, they may be a step toward a complete, fully unified theory.”

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Book:A Briefer History of Time
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“Despite this, I have a bet with Kip Thorne of the California Institute of Technology that in fact Cygnus X-1 does not contain a black hole! This is a form of insurance policy for me. I have done a lot of work on black holes, and it would all be wasted if it turned out that black holes do not exist. But in that case, I would have the consolation of winning my bet, which would bring me four years of the magazine Private Eye. If black holes do exist, Kip will get one year of Penthouse. When we made the bet, in 1975, we were 80 per cent certain that Cygnus was a black hole. By now, I would say that we are about 95 per cent certain, but the bet has yet to be settled.”

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Book:A Briefer History of Time
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“The existence of radiation from black holes seems to imply that gravitational collapse is not as final and irreversible as we once thought. If an astronaut falls into a black hole, its mass will increase, but eventually the energy equivalent of that extra mass will be returned to the universe in the form of radiation. Thus, in a sense, the astronaut will be 'recycled'. It would be a poor sort of immortality, however, because any personal concept of time for the astronaut would almost certainly come to an end as he was torn apart inside the black hole! Even the types of particles that were eventually emitted by the black hole would in general be different from those that made up the astronaut: the only feature of the astronaut that would survive would be his mass or energy.”

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Book:A Brief History of Time
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“... might suggest that the so-called imaginary time is really the real time, and that what we call real time is just a figment of our imaginations. In real time, the universe has a beginning and an end at singularities that form a boundary to space-time and at which the laws of science break down. But in imaginary time, there are no singularities or boundaries. So maybe what we call imaginary time is really more basic, and what we call real is just an idea that we invent to help us describe what we think that universe is like. (....) a scientific theory is just a mathematical model we make to describe our observations: it exists only in our minds. So it is meaningless to ask: which is real, 'real' or 'imaginary' time? It is simply a matter of which is the more useful description.”

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Book:A Brief History of Time
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“For millions of years, mankind lived just like the animals. Then something happened which unleashed the power of our imagination. We learned to talk and we learned to listen. Speech has allowed the communication of ideas, enabling human beings to work together to build the impossible. Mankind's greatest achievements have come about by talking, and its greatest failures by not talking. It doesn't have to be like this. Our greatest hopes could become reality in the future. With the technology at our disposal, the possibilities are unbounded. All we need to do is make sure we keep talking.”

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Author:Stephen Hawking
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