Sean M. Carroll Quotes

What we can’t do is demand that the universe scratch our explanatory itches. Curiosity is a virtue, and it’s good to look for answers to “Why?” questions whenever we might be able to find them, or when we think that asking such questions might help us to understand things better. But we should be at peace with the possibility that, for some questions, the answer doesn’t go any deeper than “That’s what it is.” We’re not used to that—our intuition assures us that every event can be explained in terms of some reason why. To understand why we have that impression, we need to dig more deeply into how our actual universe has evolved.

... I just want to understand the large-scale story that string gas cosmology is trying to sell us. We have nine dimensions of space — they are all very small — and in three dimensions they start unwinding and getting bigger. Is that the basic idea?

Meaning in life can’t be reduced to simplistic mottos. In some number of years I will be dead; some memory of my time here on Earth may linger, but I won’t be around to savor it.

The “reasons” and “causes” why things happen, in other words, aren’t fundamental; they are emergent. We need to dig in to the actual history of the universe to see why these concepts have emerged.

The momentary or Laplacian nature of physical evolution doesn’t have much relevance for the choices we face in our everyday lives. For poetic naturalism, the situation is clear. There is one way of talking about the universe that describes it as elementary particles or quantum states, in which Laplace holds sway and what happens next depends only on the state of the system right now.

Inflation is a simple idea: imagine that the universe begins in a tiny patch of space dominated by the potential energy of some scalar field, a kind of super-dense dark energy. This causes that patch to expand at a terrifically accelerated rate, smoothing out the density and diluting away any unwanted relics. Eventually the scalar field decays into ordinary matter and radiation, reheating the universe into a conventional Big Bang state, after which things proceed as normal.

There probably are more forces than we know about, but they’re only going to be of direct interest to physicists, I’m afraid. No tractor beams.

People don't like to read papers — they like to read titles.

When exactly does an observation occur? ... What were the laws of physics doing before there was anyone measuring things? And what do you mean by a measurement, anyway? Does it have to be a consciousness human being? ... Can a rock or a virus or an earthworm do an observation?

The mystery of the arrow of time comes down to this: Why were the conditions in the early universe set up in a particular way, in a configuration of low entropy that enabled all of the interesting and irreversible processes to come?

Poetic naturalism is a philosophy of freedom and responsibility. The raw materials of life are given to us by the natural world, and we must work to understand them and accept the consequences. The move from description to prescription, from saying what happens to passing judgment on what should happen, is a creative one, a fundamentally human act. The world is just the world, unfolding according to the patterns of nature, free of any judgmental attributes. The world exists; beauty and goodness are things that we bring to it.

It can't be stressed enough that the multiverse is utterly hypothetical—but that doesn't mean it isn't real.

But sometimes reality chooses not to conform to our preferences.

What we’re seeing is a manifestation of the layered nature of our descriptions of reality. At the deepest level we currently know about, the basic notions are things like “spacetime,” “quantum fields,” “equations of motion,” and “interactions.” No causes, whether material, formal, efficient, or final. But there are levels on top of that, where the vocabulary changes.

But the very fact that matter in the cosmos is still moving, rather than at rest, is the single most surprising thing about the universe.