Quotes About Physics

The first variation is called the delayed-choice experiment and was suggested in 1980 by the eminent physicist John Wheeler. The experiment brushes up against an eerily odd-sounding question: Does the past depend on the future?

The mathematical analyses pinned down the quantity of information a given black hole contains, without providing insight into the information itself.

it's as though the photons have a "premonition" of the experimental situation they will encounter farther downstream, and act accordingly. It's as if a consistent and definite history becomes manifest only after the future to which it leads has been fully settled.4

A calculation—not an assumption, not a hypothesis, not an inspired guess—determines the number of space dimensions according to string theory, and the surprising thing is that the calculated number is not three, but nine. String theory leads us, inevitably, to a universe with six extra space dimensions

Based on the composition of the sun—the quantities of various heavy elements it now contains, determined by spectroscopic measurements—solar physicists believe the sun is a grandchild of the universe's first stars, a third-generation arrival.

For instance, a black hole as light as a small asteroid would emit about as much radiation as a million-megaton hydrogen bomb, with radiation concentrated in the gamma-ray part of the electromagnetic spectrum.

Entropy can decrease. It's just ridiculously unlikely.

If superstring theory is proven correct, we will be forced to accept that the reality we have known is but a delicate chiffon draped over a thick and richly textured cosmic fabric.

If entropy has been steadily increasing since the big bang, then the entropy back at the bang must have been much lower than it is today.

According to special relativity, no longer can space and time be thought of as universal concepts set in stone, experienced identically by everyone. Rather, space and time emerged from Einstein's reworking as malleable constructs whose form and appearance depend on one's state of motion.

The principle of relativity rests on a simple fact: Whenever we discuss speed or velocity (an object's speed and its direction of motion), we must specify precisely who or what is doing the measuring.

The big bang is a theory, partly described in the last two chapters, that delineates cosmic evolution from a split second after whatever happened to bring the universe into existence, but it says nothing at all about time zero itself.

the Nobel Prize–winning particle physicist Isidor Isaac Rabi greeted the discovery of the muon with a less than enthusiastic Who ordered that? Nevertheless, there it was. And more was to follow.

a) The probability wave for a macroscopic object is generally narrowly peaked. (b) The probability wave for a microscopic object, say, a single particle, is typically widely spread.

Since gravity and acceleration are equivalent, if you feel gravity's influence, you must be accelerating. Einstein argued that only those observers who feel no force at all—including the force of gravity—are justified in declaring that they are not accelerating.

These frozen moments are grouped into nows—into events that happen at the same time—in different ways by observers in different states of motion.

Many find it fatuous and downright repugnant to claim that the wonders of life and the universe are mere reflections of microscopic particles engaged in a pointless dance fully choreographed by the laws of physics.

Each moment—each event or happening—exists, just as each point in space exists. Moments don't momentarily come to life when illuminated by the "spotlight" of an observer's present; that image aligns well with our intuition but fails to stand up to logical analysis. Instead, once illuminated, always illuminated. Moments don't change. Moments are. Being illuminated is simply one of the many unchanging features that constitute a moment.

physicists abandoned their belief in a Newtonian, material universe because they had come to realize that the universe is not made of matter suspended in empty space but energy.

There is no quantum world. There is only an abstract quantum description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.

Figure 3.3 Newton's drawing of a cannon on a mountain In Newton's famous cannon-on-a-mountain sketch, the dropped cannonball falls straight downward, while those fired with larger

In 1875, when young Max Planck announced his interest in physics, the chairman of his physics department suggested he study something more exciting. Physics, he said, was just about complete: "All the important discoveries have already been made.

Twentieth-century physics, going full circle back to Heracleitus, postulates that all matter is in motion. In other words, there is no thing, only energy.

Atoms are mainly empty space. Matter is composed chiefly of nothing.