Last night, I headed to the beautiful Bell House, in the Gowanus section of Brooklyn, for this month's Secret Science Club lecture, featuring physicist Dr Sean Carroll of Caltech, the proprietor of the Preposterous Universe blog.
Dr Carroll began his lecture by noting the indignant questions he sometimes receives: How dare you contemplate the meaning of the universe or the origins of life? Who do you think you are? He noted that inquiring about the nature of the universe is an invitation to discussion, and an affirmation of the scientific project of deeper thinking. He noted that humans have a need for reasons, and cited the occasional danger of this, using the example of Lucia de Brek, a nurse in the Netherlands who received a life sentence for the deaths of her patients, though there was no concrete evidence of the crimes... as Dr Carroll put it, 'bad math convicted her'. The argument in favor of her conviction was based on statistics, the number of deaths of patients under her care seemed unlikely. When a statistician reviewed the numbers, it was revealed that the patient mortality rate actually went down during de Berk's tenure as a nurse. Dr Carroll observed that people don't want to accept patient deaths, we need reasons for them. Ms de Berk was exonerated and is now a free woman.
Dr Carroll noted that the philosophers Aristotle, Spinoza, and Leibnitz all averred that everything has a cause, a concept known as the Principle of Sufficient Reason- nothing occurs without a reason, things don't just randomly occur. To counter the PSR, Dr Carroll quoted the work of greeting card designer Emily McDowall: “Please let me be the first to punch the next person who tells you everything happens for a reason”
Teleology is the philosophical exercise of attempting to find causes and goals- if something moves, is something moving it? Teleology works with everyday things, it's a sensible thing to think that, if your coffee cup is moving, that something is moving it. It took centuries to discover that teleology doesn't always work on the deepest level- physics demands a different way of thinking that everyday life does. Bertrand Russell had a harsh view of teleology: “The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm.” In our everyday lives, the concepts of cause and effect are useful, but they aren't always useful to physicists.
The topic of the talk then shifted to the Conservation of Momentum... momentum (mass times velocity) keeps an object in a closed system moving with the same velocity. This contradicts the Aristotelian model, in which an object will sit still unless something is pushing it. The Persian polymath Ibn Sina was the first individual to propose the conservation of momentum, and proposed that, in a frictionless environment, a projectile would continue to move indefinitely. Galileo devised experiments to test this theory and Huygens devised the mathematical formula to describe it. There is no need to account for motion- momentum is natural, things just move, no reason for movement, no mover, is needed. Laplace was instrumental in the effort of building the science of physics from the observed 'laws of nature'. In a simple Newtonian model of the universe, there is a conservation of information. In the model known as Laplace's demon, if an intelligence understands the position and momentum of everything in the universe, that intelligence could calculate the position of everything throughout the past and the future. Dr Carroll noted that Laplace's demon is just a pattern- 6 precedes 7, but doesn't cause it.
Dr Carroll then brought up Frank Wilczek's Core Theory. The Core Theory involves quantum mechanics, spacetime and gravity, and matter interacting with the Higgs field. If one knows the Core Theory, one knows Pascal's demon- there is no meaning, no goal, and no judgment involved. Dr Carroll joked that there is one criterion for the acceptance of a physics model- does it fit on a T-shirt. He then displayed a diagram of the Core Theory, involving up quarks, down quarks, leptons, the strong force, the weak force, and the Higgs field. He then noted that there is no room for new laws of physics in everyday life, but that there is room for new laws of physics on other scales.
The next subject of the talk was Quantum Field Theory, which has changed the way physicists think- particles aren't important, fields are important. After noting that, at Caltech, he had inherited Richard Feynman's desk, Dr Carroll touched on crossing symmetry with regard to Feynman diagrams- imagine how a new particle interacts with known particles, drawing a Feynman diagram- once the particle interaction is mapped out, other interactions can be predicted by rotating the diagram ninety degrees. If the new particle can influence the known particles, then the particles can be 'smashed' to produce more. The only particles that have been seen are all part of the Core Theory, any new particles won't effect everyday life- for example, dark matter particles don't interact with 'normal' matter. The new physics is needed to model big things- dark matter, dark energy, and quantum gravity. For the everyday world, the Core Theory of quarks, leptons, and forces is sufficient- we are done. How do we get big concepts out of the core? A different vocabulary is needed for the macroscopic 'big picture' level.
Dr Carroll then brought up the concept of the Arrow of Time- the past and the future look different. As time passes, systems move from the orderly to the disorderly, a phenomenon known as entropy... the world was more orderly yesterday, and even more orderly the day before, all the way back to the Big Bang. If 'up' means always away from the Earth, 'future' means always away from the Big Bang. One second after the Big Bang, the result was a hot, smooth plasma- everything was exactly the same everywhere. Observation of the Cosmic Background Radiation revealed that, 380,000 years after the Big Bang, the universe could be characterized as ripples throughout a smooth background- the universe was clear and smooth, but there were differences in temperature and tiny tiny differences in density. Gravity started pulling matter together into clumps. 10 10 years after the Big Bang, stars and galaxies started to form. The Hubble Deep Field reveals hundreds of billions of galaxies, forming a 'lumpy' universe. At 1015, the universe will be dark and cold and static, mainly composed of black holes and rocks... then the rocks will fall into the black holes and the black holes will evaporate. 10100 years from now, there will be only empty space.
We live in a universe where entropy increases but there is interesting stuff- whether entropy is high or low has no bearing on complexity- while entropy increases, complexity comes and goes. Dr Carroll assured us, 'You are living in the middle of an exciting, fun part of the universe, not in spite of, but because of entropy. The 2nd Law of Thermodynamics causes complexity. Dr Carroll quoted geochemist Michael Russell on the purpose of life: "The purpose of life is to hydrogenate carbon dioxide." Though entropy increases, an extra carbon molecule added to carbon dioxide produces methane, a 'reaching toward metabolism' was a necessary precursor to life. Erwin Schrödinger noted that life is a process sustained by entropy- the earth's organisms give back the same amount of energy as they receive from the sun, but with higher entropy as we photosynthesize carbohydrates, chew cud, or write books. Along the way, complexity comes to be.
The topic then shifted closer to home, as Dr Carroll decided to turn to the topic of ourselves. He introduced us to Elisabeth of Bohemia, who would have been a philosopher if it weren't for her gender. She was courted by René Descartes, with whom she engaged in a long correspondence. When posed the question of how the soul interacts with the body, Elisabeth rejected body/mind dualism. If the soul were immaterial, how would it interact with the body? Decartes concluded that the pineal gland was the seat of the soul, an idea that never gained traction. Thought can be explained by the Core Theory- the brain is made of particles. Charged particles leap from neuron to neuron, creating magnetic fields. Dr Carroll related a funny story about undergoing an MRI, after which the radiologist informed him, "You definitely have a brain." Regarding the evolution of intelligence, Dr Carroll cited cognitive scientist Malcolm MacIver, who contrasted the cognitive needs of marine organisms with those of land-living organisms. Fish cannot see more than a few meters underwater, where land-lubbers can potentially see at a range of many kilometers. Fish have an evolutionary pressure to act immediately, while terrestrials can 'think on it' before having to act. While we don't know where consciousness came from, we can guess a lot about its origins. With the emergence of intelligence, humans have choice and purpose- Dr Carroll contrasted this with the determinism promulgated by B.F. Skinner, joking that Skinner believed that it's wrong to anthropomorphize human beings. He outlined an approach he calls 'Poetic Naturalism'... there is one world, but we can choose what we tell about it. He cited poet Muriel Rukeyser, who wrote, “The universe is made of stories, not atoms.” As human beings, we create stories, but we'll be dead someday. Dr Carroll showed pictures taken of Paris' catacombs, making note of bones arranged into fanciful patterns. He reminded us that life is not a thing which fills us, but a process. While we are ephemeral patterns of matter in the lifespan of the universe, we are in the middle of interesting things. He then showed us a diagram of the lifespans of various mammals, noting that we all have approximately the same number of heartbeats- about three billion heartbeats, the mouse having a fast rate, the horse having a slow rate. Dr Carroll mused that there is a last time for everything, a last book, a last Secret Science Club lecture- he then advised us that this is the best possible reason to value life, and urged us to make it all count, but also to contemplate the vastness of the universe, to sometimes 'stand in silence'.
He noted that we are small, and showed us the famous Pale Blue Dot photograph taken by Voyager One... we are small, but we stopped to take a picture of ourselves, which Dr Carroll characterized as 'awesome'. We are tiny, but we are self aware- we can learn about and care about the universe. We're small, but we're kind of a big deal.
During the Q&A, some bastard in the audience, perhaps inspired by this article asked Dr Carroll about the future use of the LHC to tie together the quantum scale and the cosmic scale. He answered that the LHC was conceived with an overwhelming project- the discovery of the Higgs boson, but that no other ideas for its use were a 'home run'. There is buzz about the possible discovery a new particle with about 700 times the mass of the proton, but Dr Carroll did not dare to guess the next new discovery. He did note, though, that there is hope that the nature of dark matter may be elucidated. When asked about the implications of quantum theory for everyday life, Dr Carroll noted that, if things work on the 'high' level, there's no need to go to the quantum level for explanations. When asked if we can 'see' behind the Cosmic Microwave Background Radiation, Dr Carroll noted that it would be possible to peer further back by detecting gravitational waves, then urged, 'SEND MONEY.' LIGO, the Laser Interferometer Gravitational-Wave Observatory, is designed to peer back into this primordial state. One second past the Big Bang, the universe became a nuclear reactor, this has been confirmed through nucleosynthesis. The real question is, where did the smooth primordial plasma come from? He repeated the fact that more money is needed for this research.
Once again, the Secret Science Club has served up an excellent lecture, a sprawling mix of particle physics, cosmology, and philosophy, leavened with a helping portion of humor. Kudos go to Dr Carroll, Margaret and Dorian, and the staff of the beautiful Bell House.
Besides his Preposterous Universe blog, there are a lot of videos of Dr Carroll out there in the t00bz. Here's a video of Dr Carroll lecturing about 'particles, fields, and the future of physics'. Pour yourself a libation and get a taste of that Secret Science ambiance:
Who knew that physics could be so fun? Well, besides us Secret Science scenesters...