Quotes About Physics

entropy, as Boltzmann fully understood, is nothing other than the number of microscopic states that our blurred vision of the world fails to distinguish.

Carlo Rovelli

Only where there is heat is there a distinction between past and future. Thoughts, for instance, unfold from the past to the future, not vice versa—and, in fact, thinking produces heat in our heads. . . .

Planets circle around the sun, and things fall, because space around them is curved.

The origin of time may be similar to that of heat: it comes from averages of many microscopic variables. Let's see this in detail.

A novel image of the world is taking shape: a world without space and without time. The space where the world "inhabits" and the time "along which" things evolve might soon disappear from our fundamental description of the physical world, in the same manner in which notions such as "the centre of the universe" have disappeared in the past.

When we say that the volume of a room is, for example, one hundred cubic meters, we are in effect counting the grains of space-the "quanta of the gravitational field"-that it contains. In a room, this number has more than one hundred digits. When we say that the area of this page is forty-five square inches, we are actually counting the number of links in the web, or loops, that traverse the page. Across the page of this book, there is a number of quanta with more or less seventy digits.

It is always heat and only heat that distinguishes the past from the future.

Time is an effect of our overlooking the physical microstates of things. Time is information we don't have. Time is our ignorance.

Where time passes uniformly, in interplanetary space, things do not fall.

The difference between past and future only exists when there is heat.

The "quantum leaps" from one orbit to another constitute their way of being real: an electron is a combination of leaps from one interaction to another.

Despite certain obscurities,

Newton asserts explicitly in his book that we can't ever measure the true time t, but if we assume that it exists, we can set up an efficient framework to describe nature.

Solen böjer rummet runt omkring sig och jorden kretsar inte kring den för att den vore dragen av en gåtfull kraft, utan för att den rör sig rakt fram i ett rum som böjs.

Whenever you consider a phenomenon certifying the passage of time , it is through the production of heat that it does so. There is no preferred direction of time without heat.

It is hardly surprising that there are more things in heaven and earth, dear reader, than have been dreamed of in our philosophy—or in our physics.

Einstein predicted that time passes more quickly high up than below, nearer to Earth. This was measured and turned out to be the case. If a person who has lived at sea level meets up with his twin who has lived in the mountains, he will find that his sibling is slightly older than he. And this is just the beginning.

the "singularity" that classic general relativity anticipated disappears as soon as we take quantum gravity into account.

The world of quantum mechanics is not a world of objects: it is a world of events.

Einstein wrote an equation that says that R is equivalent to the energy of matter. That is to say: space curves where there is matter. That is it. The equation fits into half a line, and there is nothing more. A vision—that space curves—became an equation.

Einstein's equation shows that space cannot stand still; it must be expanding. In 1930 the expansion of the universe was actually observed.

If Planck is the father of the theory, Einstein is the parent who nurtured it.

Por mi parte, quería ahora ver cómo era el mundo donde la razón y las leyes de la física obligaban a un orden riguroso e inevitable, donde fabular no era una necesidad sino un oficio de pocos, abocados a examinar con pausa el rigor de los afectos y del mundo.