Steven Weinberg Quotes

One of the great achievements of science has been, if not to make it impossible for intelligent people to be religious, then at least to make it possible for them not to be religious. We should not retreat from this accomplishment.

As a special case of Newton's Second Law, a body... when acted on by zero force, will experience zero acceleration—that is, it will move with constant velocity. Newton listed this... as the First Law... The Third Law... action equals reaction: If one body exerts a force on another... the second... exerts an equal force in the opposite direction on the first.

In 1709 Hauksbee observed that when air inside a glass vessel was evacuated... [to] 1/60 normal air pressure and the vessel was attached to... frictional electricity, a strange light would be seen... Flashes... similar... had... been noticed in the partial vacuum above... mercury in barometers. ...[T]oday we know ...[w]hen an electric current flows through a gas, the electrons knock into the gas atoms and give up some... energy... reemitted as as light. Today's fluorescent lights and neon signs are based on the same principle... but even at 1/60 atmospheric pressure the air interfered too much with the flow of electrons to allow their nature to be discovered. Real progress became possible only when the gas... could be removed...

Perhaps the most important immediate consequence of Planck’s work was to provide long-sought values for atomic constants.

It is... convenient to state Coulomb's law in modern terms, first used... by James Clerk Maxwell. The electric force... is always proportional to the electric charge... We call the factor of proportionality the electric field so...Electric force... = Electric charge... x Electric field

Hertz showed... the... rays were not appreciably deflected by electrified metal plates. This seemed to rule out... electrically charged particles... Hertz concluded the rays were some sort of wave... the nature of light was... not well understood, and a magnetic deflection did not seem impossible. In 1891 Hertz made a further observation... to support the wave theory... The rays could penetrate thin foils of gold and other metals, much as light penetrates glass. ...We know now that... the... particles were traveling so fast, and the electric forces were so weak... the deflection was too small to observe.

The years since the mid-1970s have been the most frustrating in the history of particle physics. We are paying the price of our own success: theory has advanced so far that further progress will require the study of processes at energies far beyond the reach of existing facilities. In order to break out of this impasse, physicists began in 1982 to develop plans for a scientific project of unprecedented size and cost, known as the Superconducting Super Collider.

Finally, learn something about the history of science, or at a minimum the history of your own branch of science. The least important reason for this is that the history may actually be of some use to you in your own scientific work.

It doesn't work to build half an accelerator. The particles need to go all the way around.

The development of quantum mechanics in the 1920s was the greatest advance in physical science since the work of Isaac Newton. It was not easy; the ideas of quantum mechanics present a profound departure from ordinary human intuition. Quantum mechanics has won acceptance through its success. It is essential to modern atomic, molecular, nuclear, and elementary particle physics, and to a great deal of chemistry and condensed matter physics as well.

Thomson used Newton's Second Law to obtain a general formula... to interpret measurements of the cathode-ray deflection... produced by... electric or magnetic forces... In his cathode ray tube, the ray particles pass through... the deflection region... subjected to electric and magnetic forces... at right angles to their original direction... then through a much longer force-free... drift region... in which they drift freely until they hit the end of the tube... [a] glowing spot... The forces exerted on the cathode ray particles give them an acceleration at right angles to the axis of the tube, so... the particles have a small component of velocity at right angles to their original motion... equal to the product of the acceleration and the time... in the [very short] deflection region... [T]he downward displacement of the ray when it hits the end of the tube is the downward velocity produced in the deflection region times the length of time... in the drift region... [T]he electric force... on a particle is proportional to the [particle's] electric charge... [U]nlike the electric force, the magnetic force... on a particle is proportional to the particle's velocity as well as its charge. By measuring... deflections due to... [both] forces, Thomson... could determine both the ray-particle velocities and the ratio of their charge and mass.

[T]he property of being a geodesic is invariant under coordinate transformations... so the path of the photon or particle will... be a geodesic in any spatial coordinate system...

I decided to exclude material that was highly speculative... cosmological theory in higher dimensions... anthropic reasoning... holographic cosmology... conjectures about the details of inflation, or many other new ideas. ...The present book is largely concerned with ...mainstream cosmology: ...inflation driven by one or more scalar fields ...followed by a big bang dominated by radiation, , baryonic matter, and .

Perrin... showed in 1895 that the rays deposit negative electrical charge on a charge collector... inside... the tube.

When several forces act... the total force is the sum... each component of the total force is the sum of the corresponding components of the individual forces.