Professor Sean Carroll – Life Specializing in Cosmology and Quantum Physics

 

Who is Professor Sean Carroll?🧑‍🔬

 

Professor Sean Carroll is a physicist that specializes in quantum mechanics, gravitation, cosmology, statistical mechanics, and foundations of physics. He gives mind-expanding insights into big scientific subjects such as the multiverse and the nature of nature of time.

He is the Homewood Professor of Natural Philosophy at Johns Hopkins University in Baltimore. He has been a contributor to the physics blog Cosmic Variance, and has published in scientific journals such as Nature as well as other publications, including The New York Times, Sky & Telescope and New Scientist. He is known for atheism, critique of theism and defence of naturalism.

Also, a New York Times best-selling author, his highly accredited books include ‘Spacetime and Geometry‘ (a graduate textbook in general relativity), ‘From Eternity to Here‘ (about the arrow of time), ‘The Particle at the End of the Universe‘ (about the Higgs boson, sometimes called the Higgs particle, which is an elementary particle in the Standard Model of particle physics produced by the quantum excitation of the Higgs field, one of the fields in particle physics theory), ‘The Big Picture: On the Origins of Life, Meaning, and the Universe Itself‘ (about ontology), and ‘Something Deeply Hidden‘ (about the foundations of quantum mechanics).

 

Sean Carroll Videos 🎥

 

Here are some videos of Professor Sean Carroll’s findings and insights, including time, time travel, the multiverse, spacetime, consciousness, the universe, life, and meaning.

Carroll’s insights on time include two major views on its nature:

1. Presentism: Only the present moment is real. The past no longer exists and the future doesn’t yet exist.
2. Eternalism: All moments in time (past, present, and future) exist equally (like different locations in space). From this perspective, time is more like another dimension than a flowing “now.”

He argues that modern physics (especially relativity), supports eternalism because the equations don’t single out a unique “present” moment.

Time in physics is often represented mathematically as part of spacetime. Einstein’s theory of relativity treats time as a dimension joining the three spatial ones, meaning observers can disagree on what “now” is, yet the physical laws remain consistent. Understanding time affects how we think about causality, the universe’s history, and even human experience.

With regards to time-travel, Carroll discusses paradoxes, especially in relation to relativity and the fundamental laws of physics:

• Paradoxes Are Logical More Than Physical – Paradoxes like the classic “grandfather paradox” (a logical, theoretical thought experiment where a time traveler goes to the past and kills their biological grandfather before their parent is conceived) are issues of logic or consistency, not necessarily something forbidden by the fundamental equations of physics.
• Physics Doesn’t Automatically Forbid Time Travel – In relativity, the equations can allow solutions with closed timelike curves (paths that loop back through time) in certain exotic spacetime geometries.
• Multiverse or Branching Histories – Paradoxes might be resolved by branching timelines or multiverse ideas, where changes in the past don’t change our timeline, but create a different branch instead
• Relativity and the Nature of Time – Einstein’s relativity treats time as part of spacetime, where the notion of a universal “now” breaks down, meaning that time travel paradoxes interact deeply with how physics models time itself.

This leads onto his views on the multiverse, which include:

1. The Many-Worlds Interpretation (MWI) of Quantum Mechanics – According to MWI, every quantum event that can happen does happen, but in different, branching parallel universes. This means there isn’t just one outcome, but a constantly branching multiverse of all possible outcomes.
2. The Multiverse as a Natural Consequence of Physics – The multiverse isn’t some speculative add-on, but a natural outcome of quantum mechanics. The wave function of the universe evolves deterministically without collapse, leading to many coexisting realities.
3. No Collapse, No Hidden Variables – Carroll rejects the idea that quantum states “collapse” when measured (which is the standard Copenhagen interpretation). Instead, all outcomes happen in parallel, eliminating the need for hidden variables or special observer roles.
4. Multiverse Types Beyond MWI – Carroll also acknowledges other kinds of multiverse ideas from cosmology like eternal inflation leading to “bubble universes”, but sees the MWI quantum multiverse as more fundamental. The cosmological multiverse is more speculative and separate from the quantum multiverse, but both might be part of a bigger picture.
5. Multiverse and Scientific Reality – The multiverse idea is scientific and testable in principle, not just philosophy or science fiction. It’s the simplest explanation for quantum phenomena without adding unnecessary postulates.
6. Philosophical Implications – The multiverse challenges classical intuitions about reality, identity, and probability. We should rethink what “reality” means if many versions of ourselves exist simultaneously.

Continuing more on his views on reality, as well as spacetime, Carroll touches on the following:

• Emergence & Fundamental Physics – Carroll sees spacetime not as fundamental, but as an emergent phenomenon that arises from deeper structures. For example, from a quantum state evolving in Hilbert space (the fundamental mathematical description in quantum mechanics). In quantum theory, he advocates a version of the Many-Worlds Interpretation, where the universal wave function describes reality and observed “classical” spacetime and particles appear as emergent from it.
• Arrow of Time & Entropy – Time’s flow (the familiar sense of past to future) comes from entropy increase. A universe with no entropy gradient would lack change and memory. He’s written extensively (e.g. ‘From Eternity to Here‘) on how the arrow of time arises from very low initial entropy conditions.

With regards to consciousness, Carroll is a naturalist/physicalist. He believes there is one natural world governed by physical law and no separate metaphysical or spiritual realm. He accepts consciousness as real, but thinks it doesn’t require new physics beyond neural processes. Thoughts and feelings are patterns in complex physical systems (brains). “Consciousness exists, it’s part of an algorithmically compressed description of the world.”

His insights into the universe include concepts like dark energy, cosmological expansion, and how spacetime symmetries govern universe evolution. Some of his research suggests that our universe’s Big Bang may be just one inflationary event in a larger (possibly infinite) picture, with entropy always increasing.

With regards to life and meaning, Carroll believes that life is not something mysterious beyond physics; it’s a complex, emergent process enabled by non-equilibrium conditions. For example, energy from the Sun allowing complex, low-entropy structures. He explains life in terms of thermodynamics and complexity; life harnesses energy flows to build and maintain far-from-equilibrium structures.

According to Carroll, the universe does not have built-in purpose, morality, or cosmic direction. It doesn’t intervene or care about human goals. Concepts like right, wrong, and meaning don’t exist in physics itself; they are human-scale descriptions of how we want to live. In ‘The Big Picture: On the Origins of Life, Meaning, and the Universe Itself‘, Carroll defends poetic naturalism; all phenomena are part of one natural world, but we can use different “stories” or layers of description (e.g. physics, biology, ethics) that are each real and useful at their level.

Carroll believes that we create meaning. Without supernatural grounding, meaning becomes something humans create, based on what matters to us (our relationships, experiences, and values), not something encoded in the laws of physics.

You can read more on Sean Carroll here, quantum physics here, the multiverse here, and the nature of time here. Also, here is a link to Sean Carroll’s website.