Big Bangs and Boltzmann Brains

This past week, I watched a fascinating TED Talk from cosmologist Sean Carroll. The question he poses is one that has puzzled scientists, philosophers, and theologians for millennia: Why does our orderly universe exist at all? The second law of thermodynamics states that entropy (disorder) tends to increase over time. This is intuitive to most of us; it’s easy to break an egg, but difficult to put a broken egg back together, because there are far more arrangements in which the pieces of the egg can be shattered than unbroken. As a result, things tend toward more chaos and disorder. But why was the universe ever orderly to begin with?

Carroll does a great job demolishing the explanation which I’ve always favored, that our universe is just a fluke. Even though individual atoms move in hard-to-predict ways we can nevertheless predict the behavior of macroscopic objects. For example, the molecules in the air and ground are constantly jostling one another, moving in every possible direction. But we don’t expect them to spontaneously arrange themselves into a car, because the probability of the molecules simultaneously moving into the correct position is extremely unlikely. But over a long enough period of time (vastly longer than the age of the universe) it will eventually happen by pure chance.

This same argument could be scaled up to the universe itself. Quantum mechanics indicates that particles are constantly popping in and out of existence at random. If you wait for an unimaginably long time, all of the particles that make up our universe will spontaneously pop into existence out of the nothingness and assemble themselves in an orderly way, in a random quantum fluctuation. Many have speculated that such a fluctuation caused the Big Bang. The length of time we would have to wait for such an event to occur is called the Poincarre Recurrence Time, and is estimated to be on the order of 10^10^10^10^10^1.1 years. I’ve always been fond of this idea, and it seems easy to invoke the Anthropic Principle here: Conscious observers will only be able to marvel over their own existence during those rare periods of time when the universe is in a low-entropy state by pure chance. But as Carroll points out (using an argument originally made by Ludwig Boltzmann over a hundred years ago), that isn’t necessarily the case. It would be far easier for an individual brain to form from a quantum fluctuation, than an entire universe with hundreds of billions of galaxies. If our existence was a fluke of an infinitesimally unlikely quantum fluctuation, we would predict that we should be lonely Boltzmann Brains floating through empty space, rather than inhabitants of an enormously complex universe. Since we do indeed live in a complex universe, Carroll therefore concludes that our universe is not merely a random quantum fluctuation.

But if the Big Bang wasn’t merely a freak random occurrence, what caused it? Unfortunately, neither physicists nor philosophers have a solid answer for this question. Carroll suspects that there must be a multiverse, in which unknown laws of nature occasionally give rise to low-entropy universes such as our own. He cites the work of Lee Smolin, who proposed the idea of the fecund universe, in which a Big Bang occurs at the singularity of a black hole and a new universe is created. This would solve the Boltzmann Brain paradox, because universes would constantly be spawning new universes through the laws of nature, but randomly-occurring Boltzmann Brains would still be unfathomably rare.

Another possibility is that our understanding of entropy is incomplete; perhaps our universe is indeed a random quantum fluctuation, but for reasons we don’t understand it’s easier for entire universes which can eventually produce conscious observers to randomly fluctuate into existence, than it is for Boltzmann Brains to do so. Perhaps the laws that govern the creation of universes tend to give rise to things like our own universe rather than Boltzmann Brains. Perhaps our universe is merely a holographic representation of a two-dimensional universe with different laws of physics than those we observe, and therefore entropy doesn’t apply at all. Perhaps our world is a simulated reality, and the simulators find complex worlds more interesting than lone Boltzmann Brains. Or perhaps we are indeed Boltzmann Brains, and for some reason don’t realize it.

Whatever the reason we live in an orderly universe, our understanding of physics is slowly making it possible to weigh the different theories to see which are the most likely. As our understanding of cosmology continues to improve, perhaps we will one day be able to understand what (if anything) caused the Big Bang. If Carroll’s multiverse theory turns out to be correct, perhaps it will vindicate the Hindu concept of cyclical creation and destruction: Universes are born, die, and are eventually reborn in different forms.

Watch the short version of Sean Carroll’s talk here. If you’re interested in the full hour-long lecture, watch it here.

Book Review - "Disrupting Class" by Clayton Christensen

Clayton Christensen’s book, Disrupting Class, is a fascinating look at how disruptive new technologies will soon transform the dismal state of the American education system. By far, the most intriguing aspect is the potential for online education to completely upend traditional schools and dramatically improve education.

Some of the biggest problems with schools are often lost in the contentious political debates over teachers’ unions, vouchers, and merit pay. Often, the underlying problems are completely ignored because they seem intractable. The traditional classroom model – where one teacher instructs 25 students – is antiquated and ineffective at addressing students’ needs. As Disrupting Class illustrates, each student has unique learning styles and abilities, which are completely ignored in traditional schools.

In brick-and-mortar schools, where there are vastly more students than teachers, education cannot be customized to individual students. The instructor tries his or her best to teach according to the learning style that reaches the most students, but those who march to the beat of a different drum inevitably fall through the cracks. Classes invariably move at the same pace despite the fact that students do not learn at the same pace. An instructor teaches a unit, the students are tested on the material, and the entire class moves on to the next unit, regardless of the performance of individual students. As a result, the advanced students are bored in school and want to move faster, while the struggling students fall farther and farther behind as their knowledge deficiencies accumulate.

Disrupting Class envisions a future where these things are no longer problems, due to interactive online education that is far better than today’s education software, which far too often is nothing more than glorified flash cards. In the online classes of the future, each student will be able to learn at his or her own pace, and won’t advance to the next unit until he or she has mastered the material from the current one. The concept of awarding letter grades for classes might be replaced by measuring how long it takes a student to earn an A.

Additionally, online education will allow for classes to be customized to the student’s particular learning style. The debates over whether one particular teaching style is better than another, or whether charter schools are better than traditional schools, will vanish. When each student can learn the material in a manner tailored to his or her own needs, we will finally recognize that no single teaching style or type of school is best for all students.

Although the book primarily focuses on the American education system, the international implications of disruptive education technology are possibly even more profound. Salman Khan, the founder of the Khan Academy, stressed this point in his recent TED Talk. Online education offers the possibility to turbo-charge the human development of countries where access to education is still a problem. Far too many children in the slums of developing countries have little access to education of any kind. The proliferation of online education – which should roughly coincide with the proliferation of smartphones and tablets in much of the developing world – will open up vast new worlds of information to students in the most remote parts of the planet, where local teachers are unavailable, unknowledgeable, or expensive.

Disrupting Class gets its name because, in Christensen’s view, these educational innovations will largely take place outside of traditional classrooms, and eventually supplant them entirely. In the infancy of online education, teachers will use online education to supplement their in-class curriculum, or use it to allow students to take classes that are not offered at the school. Over time, education software will play a larger and larger role in classrooms until the schools themselves are no longer necessary. Students might continue to gather with their local friends in a building called a “school” to learn, but classes will be determined by learning style, ability, and personal interests rather than by school district. Teachers will instruct students entirely via computer.

How long will it take until online education is widely adopted? Not long, by Christensen’s estimate. He notes that online education is following the same adoption pattern of many other disruptive technologies, such as digital photography, which start off very slowly but suddenly become dominant once they reach critical mass. According to Christensen, in the United States in 2000 there were 1,000 students in classrooms for every 1 online learner. By 2007, this ratio had dropped to 100 to 1. If this trend continues, online learning will command a sizable chunk of the market (10%) by 2014, and gain a majority by 2019. Shortly thereafter, our 170-year-old model of classroom-based learning will come to an end.

Projections from "Disrupting Class" by Clayton Christensen

My sole criticism of the book is that it is a bit too broad. Christensen primarily focuses on online education, but devotes short sections to other innovations like new methods of evaluating teaching styles, and teaching highschoolers the necessary parenting skills they will need to one day raise successful children of their own. Although these are certainly interesting ideas worth exploring, they felt a bit out of place in a book primarily about the disruptive nature of education technology. I would have liked to see these chapters replaced with more information about online education, which is, after all, the main focus of the book.

Disrupting Class is thought-provoking and charts a very plausible course for would-be developers of online education tools. The future of education will inevitably be online. The advantages are just too numerous to ignore.

4/5 stars