John D. Barrow QUOTES

1 " There are only certain intervals of time when life of any sort is possible in an expanding universe and we can practise astronomy only during that habitable time interval in cosmic history. "

― John D. Barrow , The Book of Universes: Exploring the Limits of the Cosmos

2 " Since only a narrow range of the allowed values for, say, the fine structure constant will permit observers to exist in the Universe, we must find ourselves in the narrow range of possibilities which permit them, no matter how improbable they are. We must ask for the conditional probability of observing constants to take particular ranges, given that other features of the Universe, like its age, satisfy necessary conditions for life. "

― John D. Barrow , The Constants of Nature: The Numbers That Encode the Deepest Secrets of the Universe

3 " Turing attended Wittgenstein's lectures on the philosophy of mathematics in Cambridge in 1939 and disagreed strongly with a line of argument that Wittgenstein was pursuing which wanted to allow contradictions to exist in mathematical systems. Wittgenstein argues that he can see why people don't like contradictions outside of mathematics but cannot see what harm they do inside mathematics. Turing is exasperated and points out that such contradictions inside mathematics will lead to disasters outside mathematics: bridges will fall down. Only if there are no applications will the consequences of contradictions be innocuous. Turing eventually gave up attending these lectures. His despair is understandable. The inclusion of just one contradiction (like 0 = 1) in an axiomatic system allows any statement about the objects in the system to be proved true (and also proved false). When Bertrand Russel pointed this out in a lecture he was once challenged by a heckler demanding that he show how the questioner could be proved to be the Pope if 2 + 2 = 5. Russel replied immediately that 'if twice 2 is 5, then 4 is 5, subtract 3; then 1 = 2. But you and the Pope are 2; therefore you and the Pope are 1'! A contradictory statement is the ultimate Trojan horse. "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

4 " We can measure the fine structure constant with very great precision, but so far none of our theories has provided an explanation of its measured value. One of the aims of superstring theory is to predict this quantity precisely. Any theory that could do that would be taken very seriously indeed as a potential 'Theory of Everything'. "

― John D. Barrow , Impossibility: The Limits of Science and the Science of Limits

5 " If the deep logic of what determines the value of the fine-structure constant also played a significant role in our understanding of all the physical processes in which the fine-structure constant enters, then we would be stymied. Fortunately, we do not need to know everything before we can know something. "

― John D. Barrow , New Theories of Everything

6 " We know what we are, but know not what we may be. "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

7 " The first physicist to stress the all-encompassing role of [the fine-structure constant] and [the proton/electron mass ratio] in determining the inevitable structure of atomic systems seems to have been Max Born. "

― John D. Barrow , The Anthropic Cosmological Principle

8 " History is full of people who thought they were right -- absolutely right, completely right, without a shadow of a doubt. And because history never seems like history when you are living through it, it is tempting for us to think the same. "

― John D. Barrow , PI in the Sky: Counting, Thinking, and Being

9 " Any universe simple enough to be understood is too simple to produce a mind able to understand it

-Barrow's Uncertainty Principle "

― John D. Barrow , 100 Essential Things You Didn't Know You Didn't Know

10 " Prior to then it was believed that black holes were just cosmic cookie monsters, swallowing everything that came within their gravitational clutches. "

― John D. Barrow , The Constants of Nature: The Numbers That Encode the Deepest Secrets of the Universe

11 " I love cosmology: there’s something uplifting about viewing the entire universe as a single object with a certain shape. What entity, short of God, could be nobler or worthier of man’s attention than the cosmos itself? Forget about interest rates, forget about war and murder, let’s talk about space.” Rudy Rucker21 "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

12 " Einstein argued that the laws of Nature should appear to be the same for all observers in the Universe, no matter where they were or how they were moving. If they were not then there would exist privileged observers for whom the laws of Nature looked simpler than they did for other observers. "

― John D. Barrow , The Constants of Nature: The Numbers That Encode the Deepest Secrets of the Universe

13 " universal laws prescribe how things will behave not, like human laws, how they ought to behave. "

― John D. Barrow , The Constants of Nature: The Numbers That Encode the Deepest Secrets of the Universe

14 " Three laws governing black hole changes were thus found, but it was soon noticed that something unusual was going on. If one merely replaced the words 'surface area' by 'entropy' and 'gravitational field' by 'temperature', then the laws of black hole changes became merely statements of the laws of thermodynamics. The rule that the horizon surface areas can never decrease in physical processes becomes the second law of thermodynamics that the entropy can never decrease; the constancy of the gravitational field around the horizon is the so-called zeroth law of thermodynamics that the temperature must be the same everywhere in a state of thermal equilibrium. The rule linking allowed changes in the defining quantities of the black hole just becomes the first law of thermodynamics, which is more commonly known as the conservation of energy. "

― John D. Barrow , Theories of Everything: The Quest for Ultimate Explanation

15 " Then, in 1974, Stephen Hawking made a dramatic discovery. He decided to examine for the forst time what occurs when one applies the notions of quantum mechanics to black holes. What he discovered was that black holes are not completely black. When quantum mechanics is included in the discussion of their properties, it is possible for energy to escape from the surface of the black hole and be recorded by an outside observer. The variation in the strength of the gravitational field near the horizon surface is strong enough to create pairs of particles and antiparticles spontaneously. The energy necessary to do this is extracted from the source of the gravitational field, and as the process continues, so the mass of the black hole ebbs away. If one waits long enough, it should disappear completely unless some unknown physics intervenes in the final stages. Such a discovery was exciting enough, but its most satisfying aspect was the fact that the particles radiated away from the surface of the black hole were found to have all the characteristics of heat radiation, with a temperature precisely equal to the gravitational field at the horizon and an entropy given by its surface area, just as the analogy had suggested. Black holes did possess a non-zero temperature and obeyed the laws of thermodynamics, but only when quantum mechanics was included in their description. "

― John D. Barrow , Theories of Everything: The Quest for Ultimate Explanation

16 " This picture of matter curving space and curvaceous space dictating how matter and light will move has several striking features. It brings the non-Euclidean geometries that we talked about in the last chapter out from the library of pure mathematics into the arena of science. The vast collection of geometries describing spaces that are not simply the flat space of Euclid are the ones that Einstein used to capture the possible structures of space distorted by the presence of mass and energy. "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

17 " Gravity acts on all forms of mass and energy, but energy comes in a host of very different forms that behave in peculiar ways that were not known in Newton's day. Wotst of all, gravity gravitates. Those waves of gravity that spread out, rippling the curvature of space, carry energy too and that energy acts as a source for its own gravity field. Gravity interacts with itself in a way that light does not. "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

18 " All our puzzles about whether or not lambda exists and, if so, what is responsible for giving it such a strange value, are like questions about the inflationary scalar field's potential landscape. Why is its final vacuum state so fantastically close to the zero line? How does it 'know' where to end up when the scalar field starts rolling downhill in its landscape? Nobody knows the answer to these questions. They are the greatest unsolved problems in gravitation physics and astronomy. The nature of their answers could take many forms. There could exist some deep new principle that links together all the different forces of Nature in a way that dictates the vacuum levels of all the fields of energy that feel their effects. This principle would be unlike any that we know because it would need to control all the possible contributions to lambda that arise at symmetry breakings during the expansion of the Universe. It would need to control physics over a vast range of energies. "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

19 " nothing is higher than heaven; nothing is beyond the walls of the world; nothing is lower than hell, or more glorious than virtue.”48 "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe

20 " There are about one hundred billion galaxies within this visible universe and the average density of material within a galaxy is about one million times greater than that in the visible universe as a whole, and corresponds to about one atom in every cubic centimetre. "

― John D. Barrow , The Book of Nothing: Vacuums, Voids, and the Latest Ideas about the Origins of the Universe