John Barrow is a British cosmologist, mathematician and science writer who wrote New Theories of Everything.

Quotes by John Barrow in Time One

Euclid’s geometry was believed to be true – a precise description of reality … it provided important evidence that human thought could penetrate the nature of ultimate truth…

We’re talking about an overestimate by a factor of about 10 followed by 120 zeroes!

In more conventional quantum mechanical terms, we would say that the Universe is the result of a quantum mechanical tunneling process, where it must be interpreted as having tunnelled from nothing at all.

The existence of time is a mystery. There is no use for it.

If the forces of electricity and magnetism are to exist in our world today then monopoles must be formed in the early Universe.

Newton clung to the Stoic picture of a finite world surrounded by an infinite void space. He could imagine an empty space but not the absence of space itself.

If the expansion did have a beginning then we are faced with further questions: is this ‘beginning’ merely the start of the expansion of the Universe that we see today or is it the Beginning, in every sense, of the entire physical Universe?

Gradually, over the last twenty years, the vacuum has turned out to be more unusual, more fluid, less empty, and less intangible than ever Einstein could have imagined.

A major extension of physics will be necessary to delve into the first 10-43 second and follow the history of the universe in those first quantum moments when it was entirely shrouded in mystery.

We see that if there are three large dimensions of space because of some deep principle of nature, then we are very fortunate.

Unfortunately, the level of random fluctuations that would be expected to exist at any time in the universe was far too low to generate the structures we see today.

[If] the gravitational entropy … increases with time then the initial state of the universe was one of very low, or even zero, gravitational entropy.

The search then began for a natural process … which would insure that if the universe began with, say, nine space dimensions all expanding equally, six of those dimensions would remain trapped …. How this trapping might occur is still an unsolved problem.

Whereas most physicists regard the second law of thermodynamics as a reflection of the improbability of certain types of initial conditions, there are others who regard it as a far more fundamental idea that is prior to the laws of nature themselves.

[T]he entropy level at the beginning of the expansion of the Universe must have been staggeringly small, which implies that the initial conditions were very special indeed.

At present, physicists … search only for continuous pictures of fundamental physics. Maybe, one day, they will be motivated to look at possible structures of a fundamentally discrete world.

[T]he pure mathematical research literature is virtually impenetrable to outsiders.

Quantum tunneling processes, which are familiar to physicists and routinely observed, correspond to transitions which do not have a classical path.

There is one qualitative aspect of reality that sticks out from all others in both profundity and mystery. It is the consistent success of mathematics as a description of the workings of reality and the ability of the human mind to discover and invent mathematical truths.

The traditional view that initial conditions are for the theologians and evolution equations for the physicists seems to have been overthrown―at least temporarily.

The study of the Wave Function of the Universe is in its infancy. It will undoubtedly change in many ways before it is done.

What we really want is some principle that tells us why the organization of the Universe changes in the way that it does: why it now expands so uniformly and isotropically.

The question of why the Universe is as it is, is inextricably linked to that of why fundamental physics is the way that it is.

(E)lementary particles come in populations of universally identical particles.

The symbols are 0, ‘zero’, S, ‘successor of’, +, ×, and =.

Most fundamental pictures of the physical world assume that the basic notions – fields, space, and time – are continuous entities rather than discrete bits.

As we try to reconstruct the past history of these cosmologies, we encounter a striking feature. If matter and radiation continue to behave as they do today, and Einstein’s theory continues to hold, then there will be a past time when the expansion must have encountered a state of infinite density and temperature.

One of the most puzzling properties of our universe is that it is now expanding at a rate very close to the critical divide separating the ever-expanding universes from the recollapsing ones. It is a puzzle because as the universe expands it tends to deviate steadily from the critical divide because of the attractive force of gravity. In order that we be as close to the divide as is observed today, the universe must have begun expanding extraordinarily close to the divide originally.

The conventional Big Bang model held to a picture of the Universe in which it expanded from some initial state at a finite time in the past. This [conventional] expansion is forever decelerating after the start because of the retarding pull of gravity.

The nature of time is one of those baffling problems that physicists have debated for centuries, but have made depressingly meagre progress in unravelling.