Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?

The closer the bird is to the surface of the water, the firmer and more inelastic is the uplift of the rising air. The bird appears to almost feel the surface with the tip of its weather wing.

I have been connected with the Niels Bohr Institute since the completion of my university studies, first as a research fellow and, from 1956, as a professor of physics at the University of Copenhagen....

I like physics. I think it is the best science out of all three of them, because generally it's more useful. You learn about speed and velocity and time, and that's all clever stuff.

Rocket scientists agree that we have about reached the limit of our ability to travel in space using chemical rockets. To achieve anything near the speed of light we will need a new energy source and...

From this time on, the universe is built up into an aggregate of permanent objects connected by causal relations that are independent of the subject and are placed in objective space and time.

According to String Theory, what appears to be empty space is actually a tumultuous ocean of strings vibrating at the precise frequencies that create the 4 dimensions you and I call height, width,...

A black hole really is an object with very rich structure, just like Earth has a rich structure of mountains, valleys, oceans, and so forth. Its warped space whirls around the central singularity like...

First of all, time travel per se does not exist. 'Travel' implies that you choose both your destination and when you come back. It's more a 'time shot,' a 'time through.' But it's definitely not time...

Planck... and Bohr... have invented systems containing electrons of which the motion produces no effect upon external charges... Not only is this inconsistent with the accepted laws of...

Infinity... is used in physics simply as a shorthand for a very big number.

Primary causes are unknown to us; but are subject to simple and constant laws, which may be discovered by observation, the study of them being the object of natural philosophy. Heat, like gravity,...

It will all stop someday, but not for billions of years. Many billions. Even the stars run down, you know. Entropy must increase.

You are exporting disorder {in the form of heat into the Universe} now as you read this book. You are hastening the demise of everything that exists, bringing forward by your very existence the...

The universe is full of energy, but much of it is at equilibrium. At equilibrium no energy can flow, and therefore it cannot be used for work, any more than the level waters of a pond can be used to...

Hinton spent most of his adult years trying to visualize higher spatial dimensions. He had no interest in finding a physical interpretation for the fourth dimension. Einstein saw, however, that the...

So many of the properties of matter, especially when in the gaseous form, can be deduced from the hypothesis that their minute parts are in rapid motion, the velocity increasing with the temperature,...

Noether's theorem fused together symmetries and conservation laws - these two giant pillars of physics are actually nothing but different facets of the same fundamental property.

In the beginning, there was physics.

The infinite zero of a black hole - mass crammed into zero space, curving space infinitely - punches a hole in the smooth rubber sheet. The equations of general relativity cannot deal with the...

There are two approaches to the study of macroscopic physics. Historically the oldest approach, developed mainly in the first half of the 19th century by such men as Carnot, Clausius, William Thomson...

The question is, of course, is it going to be possible to amalgamate everything, and merely discover that this world represents different aspects of one thing?

It baffled me how people could resist math's gorgeousness, but people did, and people do. The fine of its purity drives them away, the purity of the fine, unmixed with the heaviness of unnecessitated...

Three quarks for Muster Mark!

I'll be looking for you, Will, every moment, every single moment. And when we do find each other again, we'll cling together so tight that nothing and no one'll ever tear us apart. Every atom of me...

But in the dynamic space of the living Rocket , the double integral has a different meaning. To integrate here is to operate on a rate of change so that time falls away: change is stilled...'Meters...