Quotes from Brian Greene

if you know the quantum wavefunction right now for every particle in the universe, Schrödinger's equation tells you how the wavefunction was or will be at any other moment you specify. This

If free will is an illusion, and if time travel to the past is possible, then your inability to prevent your parents from meeting poses no puzzle. Although you feel as if you have control over your actions, the laws of physics are really pulling the strings.

In the Inflationary Multiverse, our universe could well be an island oasis in a gigantic but largely inhospitable cosmic archipelago.

Physicists traced the failure to the jitters of quantum uncertainty. Mathematical techniques had been developed for analyzing the jitters of the strong, weak, and electromagnetic fields, but when the same methods were applied to the gravitational field-a field that governs the curvature of spacetime itself-they proved ineffective. This left the mathematics saturated with inconsistencies such as infinite probabilities.

Remember from Chapter 7 that in the Many Worlds framework, every potential outcome embodied in a quantum wavefunction—a particle's spinning this way or that, another particle's being here or there—is realized in its own separate, parallel universe. The universe we're aware of at any given moment is but one of an infinite number in which every possible evolution allowed by quantum physics is separately realized.

The studies concluded that the graviton must be massless and chargeless, and must have the quantum mechanical property known as spin-2. (Very roughly, the graviton should spin like a top, twice as fast as the spin of a photon.)

undulations do

When the brain's penchant for simplified schematic representations is applied to itself, to its own attention, the resulting description ignores the very physical processes responsible for that attention. That is why thoughts and sensations seem ethereal, as if they come from nowhere, as if they hover in our heads. If your schematic representation of your body were to leave out your arms, the motion of your hands would seem ethereal too.

Special relativity declares a similar law for all motion: the combined speed of any object's motion through space and its motion through time is always precisely equal to the speed of light.

We need a means for measuring the sizes of different infinite collections of universes. It is this information that we need in order to work out how likely it is that we reside in one type of universe rather than another. Until we find a fundamental dictum for how we should compare infinite collections of universes, we won't be able to foretell mathematically what typical multiverse dwellers-us-should see in experiments and observations. Solving the measure problem is imperative.

The uncertainty principle establishes that regardless of what equipment you use or what techniques you employ, if you increase the resolution of your measurement of one property, there is an unavoidable cost: you necessarily reduce how accurately you can measure a complementary property. As a prime example, the uncertainty principle shows that the more accurately you measure an object's position, the less accurately you can measure its speed, and vice versa.

Now, from special relativity we know that energy and mass are two sides of the same coin: Greater energy means greater mass, and vice versa. Thus, according to string theory, the mass of an elementary particle is determined by the energy of the vibrational pattern of its internal string. Heavier particles have internal strings that vibrate more energetically, while lighter particles have internal strings that vibrate less energetically.

Eternity is always presented to us as an idea that we can't grasp, as something enormous, enormous! Why does it have to be enormous? All of a sudden, instead of all that, imagine there'll be a little room, something like a country bathhouse, sooty, with spiders in all the corners, and that's the whole of eternity. You know, I sometimes imagine it like that.

The overarching lesson that has emerged from scientific inquiry over the last century is that human experience is often a misleading guide to the true nature of reality.

No deviations from the predictions of general relativity have been found in experiments performed with our present level of technology.

Then, just as two trees are the same age if they have the same number of tree rings, and just as two samples of glacial sediment are the same age if they have the same percentage of radioactive carbon, two locations in space are passing through the same moment in time when they have the same value of the inflaton field. That's how we set and synchronize clocks in our bubble universe.

so, with only finitely many different particle arrangements, the arrangements of particles within patches must be duplicated an infinite number of times. That's the result we've been after.

Deeply. As we have seen, humans prevailed in no small part because our species has the capacity to pool brain and brawn, to live and work in groups, to divvy up responsibilities and effectively meet the needs of the collective. The greater social cohesion of those in a religiously bound group would have made them a more formidable force in the ancestral world, and according to this line of argument, securing an adaptive role for religious affiliation.

each of the bubble universes appears to have finite spatial extent when examined from the outside, but infinite spatial extent when examined from the inside.

Solving problems, learning how the universe is put together-that's what had always captivated me.

By shaping our intuition and developing our cognitive skills, evolution initiated our education in physics but our more comprehensive understanding has emerged from the force of human curiosity expressed through the language of mathematics.

as if my own identity hardly matters because it has been subsumed by what I can only describe as a feeling of gratitude for the gift of experience.

The entropy of a system is related to the number of indistinguishable rearrangements of its constituents, but properly speaking is not equal to the number itself. The relationship is expressed by a mathematical operation called a logarithm; don't be put off if this brings back bad memories of high school math class. In our coin example, it simply means that you pick out the exponent in the number of rearrangements-that is, the entropy is defined as 1,000 rather than 2^1000.

Note too that while professional philosophers are paid to scrutinize belief - to reveal hidden assumptions and bring attention to faulty inferences - that's not how most of us now, or our ancestors then, go about it. Many beliefs in most lives go unexamined.