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 But as Carroll points out (using an argument originally made by Ludwig Boltzmann over a hundred years ago), that isn’t necessarily the case.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.

The Church of the Singularity

A new religion has taken hold of the digerati of the world. According to believers in the Singularity, technology is on an ever-accelerating trajectory, with new advances happening in shorter and shorter intervals of time. Within a few more decades, they claim, the world will be changing so quickly that society will not be able to keep up. According to this theory, as soon as we develop a machine that is more intelligent than we are, it will develop even smarter machines, which will develop even smarter machines, which will solve all of our problems and endow us all with godlike powers.

As strange as it sounds, this is an accurate description of the beliefs of Singularity enthusiasts. If this sounds goofy to you, you are certainly not alone. Virtual reality pioneer Jaron Lanier describes it as “the tech world’s new religion.” Mitch Kapor, the founder of Lotus Software (now a part of IBM), describes it as “intelligent design for the IQ 140 people.” I completely agree with them. The Singularity has all of the elements of a religious rapture: If we as a society behave ourselves, there will be one instant at some point in the next few decades that will transform the world and we will live forever in paradise. As Lanier notes, “books on the Singularity are at least as common in computer science departments as books on the rapture are in Christian bookstores.” The Singularity has many prominent adherents, including Microsoft founder Bill Gates, and Google's Sergey Brin and Larry Page.

If this religion has a high priest, it is futurist Ray Kurzweil. Its bible is Kurzweil’s 2005 tome, The Singularity Is Near. Kurzweil claims that the concept of the Singularity can be extrapolated from current technological trends. He completely rejects the idea that the ideas of the Singularity are motivated by any religious impulse, claiming that this is a veiled criticism to make it seem unscientific. He observes that computers have become much more powerful in recent decades, extrapolates that trend out a few more decades, and concludes that computers will soon leave us in the dust intellectually. He predicts the Singularity will occur around 2045.

Color me skeptical. While Kurzweil is quite right that merely labeling it a religion is insufficient to show that it’s inaccurate, I can see a number of very substantial problems with this belief. First of all, it is not reasonable to extrapolate current computing trends into the distant future. As Kurzweil himself notes, we are nearing the point in time (probably around 2019) when it will be impossible to shrink transistors anymore, and Moore’s Law will come to an end. Kurzweil then assumes (based on absolutely no evidence) that we will continue to double our computing power at approximately the same rate as before, by using three-dimensional computing chips. While this is possible, it is by no means guaranteed. The rapid increase in computing power that we’ve grown to expect could slow dramatically in the 2020s. If this happens, we almost certainly will not have truly intelligent artificial intelligence as soon as Kurzweil predicts.

Second, there is a very large difference between having the raw computing hardware to emulate a human brain, and actually having the software to create a program as complex as the human brain. This is not a minor problem. One rule of computer science is that as computer programs become more complex, it becomes evermore difficult to increase their complexity further. To make a program twice as smart requires drastically more than a twofold increase in the program’s complexity. It could be many, many decades (or longer) before we have any programs able to compete with humans intellectually.

Finally, Kurzweil makes a huge leap of faith by assuming to know the motives of beings more intelligent than we. If we create true artificial intelligence, what is to stop them from killing us all, or worse? Kurzweil claims that this will not happen because we will program them to respect us…but if they are more intelligent than we are, they could easily reprogram themselves if they wanted to. Or even if artificial intelligence is benign and wants nothing but to shower us with free goodies, there is absolutely no reason to think that they would want to create intelligence smarter than themselves, leading to a technological Singularity. Maybe their increased intelligence would allow them to see what Kurzweil apparently cannot: Creating entities smarter than themselves could pose a threat to their continued existence.

I think my previous entries have made clear that I am mostly a technological optimist. I share Ray Kurzweil’s belief that we will overcome many of the problems facing the world in the coming decades, including hunger, extreme poverty, naturally-occurring disease, environmental degradation, and aging. I will even grant that at some point in the future, we will probably create artificial intelligence that is smarter than we are and radically redefine our concept of what a human is. Despite all of this, the concept of a technological Singularity remains a completely irrational idea. It cloaks itself in the language of science and uses elegant graphs of past technological development to rationalize its predictions of future technological development, but ultimately it requires the same leaps of faith that are more characteristic of apocalyptic religious raptures than of science.

Book Review - "The Demon-Haunted World" by Carl Sagan

Astronomer Carl Sagan’s 1996 book, The Demon-Haunted World is the ultimate guide to critical thinking. Carl Sagan asks, “How can we make intelligent decisions about our increasingly technology-driven lives if we don’t understand the difference between the myths of pseudoscience, New Age thinking, and fundamentalist zealotry…and the testable hypotheses of science?”

Sagan offers a lengthy explanation of how the scientific method works, and how it is demonstrably more successful than any of its pseudoscientific imitators. He teaches the importance of having a skeptical worldview, especially of extraordinary claims. As he stated in Cosmos, “Extraordinary claims require extraordinary evidence.” Sagan explains the necessity of Ockham’s Razor – the rule of thumb that people should not assume anything that the evidence does not require them to assume – in critical thought. He systematically exposes the absurdity behind many of the most popular modern-day forms of pseudoscience, including astrology, homeopathy, psychics, alien abductions, Freudian psychoanalysis, doomsday predictions, graphology, and numerology.

While some have criticized the book as being anti-religious, Sagan himself disputed this characterization. He was clearly an agnostic, but had a deep appreciation for the sense of wonder that religion could inspire and recognized that it had much in common with his own appreciation for science. He does take certain religious views to task – such as the ideas of young-earth creationism, faith healing, and divine intervention. However, he notes that although “religions are often the state-protected nurseries of pseudoscience…there is no reason why religions have to play that role.” Sagan was a strong advocate of finding common ground between the religious and scientific communities: a central theme of his novel Contact.

14 years after its original publication, The Demon-Haunted World seems more topical than ever. The applications of critical thinking extend far beyond the realm of science. By being skeptical of unusual claims, we can better gauge the veracity of some of the odd statements we routinely hear from any authority, including our politicians, educators, corporate gurus, and religious leaders. In my opinion, there is no more important skill that our schools should teach students than the process of thinking critically. Unfortunately, most high schools and many universities don’t offer any classes in critical thought, even as electives. Carl Sagan’s The Demon-Haunted World can guide us where our schools do not.

The Demon-Haunted World was Sagan's last book before his death in 1996. Although it never reached the same level of popularity as some of his other works such as Cosmos and Contact, I think it is his most important work for the layperson. The Demon-Haunted World has shaped my view of the world more than any other book.

5/5 stars

Rebuttal to the Simulation Hypothesis

According to Nick Bostrom’s simulation hypothesis, every universe’s inhabitants would be equally likely to be living in a simulation, even if they were running simulations of their own. This leads to the uncomfortable conclusion that our universe is much more likely to be one of a huge number of simulations, rather than the one parent universe.

From a logical standpoint, this argument makes sense to me. But I’m always eager to poke holes in philosophical arguments, so here’s my best rebuttal as devil’s advocate. It doesn’t directly attack the logic of Bostrom’s philosophy; rather, it creates a probabilistic argument that we are NOT a simulation.

Let’s assume that simulations can be “turned off” by the parent universe at any time. Perhaps the inhabitants decide that the simulation is no longer needed for whatever reason, or perhaps the simulation is accidentally destroyed, or perhaps they are in a simulation themselves which is turned off by their parent universe. If this is the case, it would break the simulation chain. If Simulation A was the parent of Simulation B, which was the parent of the Simulation C, which was the parent of Simulation D, the inhabitants of Simulation A would be able to break this chain and destroy all of the simulations in this chain by turning off Simulation B.

The simulation hypothesis concludes that we are in a simulation in all probability, and that every universe is equally likely to be a simulation. This means that the universe that begat ours is also probably a simulation, as is the universe that begat our parent universe. If this is the case, it would be very likely that our own universe is merely one node in a huge chain of parent universes.

But this creates an interesting question. If any of those universes could break the chain at any time by turning off their simulation, the probability that not a single one of them would do so must be extraordinarily low. This strongly suggests that we are not in a simulation.

There are a couple of responses to this argument which I can foresee, so allow me to preemptively address them. Some might invoke the Anthropic Principle. It doesn’t make sense to marvel at the unlikelihood of our own existence, they will reason, because if our universe had been turned off we wouldn’t be here to speculate about it. In my opinion, this is a flawed application of the Anthropic Principle because there is another plausible explanation for our existence: Our simulated universe hasn’t been “turned off” by any of its parents because they don’t exist. We are the original universe.

So we have two possible explanations for our own universe. Either we are in a simulation, and are here due to the infinitesimally unlikely whims of an unimaginably vast chain of parent universes…or we are simply not a simulation. If these are the two possibilities, the latter seems much more likely from this probabilistic standpoint. It also has the advantage of surviving Ockham’s Razor.

What do you think? Is my probabilistic argument for our actual reality as strong as Bostrom’s argument for our simulated reality? What flaws do you see in my logic?

Are we living in a simulation?

Are we living in a simulated reality? Transhumanist philosopher Nick Bostrom thinks so. He puts forth the following argument. One of the following three statements must logically be true: 1) Advanced civilizations can never develop simulated realities; 2) No advanced civilization would ever choose to develop simulated realities; or 3) Our own reality is almost certainly simulated.

There are a few circumstances in which Statement #1 could theoretically be true. Perhaps there are no other advanced civilizations in the universe. Perhaps advanced civilizations exist, but simulations are simply impossible. Or perhaps they are possible, but beyond the technological capacity of any species. I think Statement #1 is the least plausible of the three. As I mentioned in a previous blog post, even extremely pessimistic interpretations of the Drake Equation should have yielded at least one other advanced civilization somewhere in our universe. The technological barriers to creating a simulation seem very small. We already have rudimentary virtual reality technology, and there is no fundamental reason why we shouldn’t be able to create all-encompassing simulations within a few decades. Since we’re nearly able to create them already, it seems unlikely that there are no other civilizations in the entire universe that are a few mere decades ahead of us.

Statement #2 involves speculation into the motives of other civilizations, of which we can’t possibly know anything. However, we do know about our own civilization and what motivates us. If humans develop this technology within a few decades, we will almost certainly make use of it, creating thousands upon thousands of simulations for entertainment or research. Therefore it seems very likely to me that Statement #2 is false.

This leaves Statement #3. If we have concluded that Statements #1 and #2 are false, Bostrom reasons that Statement #3 must be true. Why? Because there will be an enormous number of simulated realities. The probability that we find ourselves in the one parent universe, as opposed to one of the many simulations, must be vanishingly small.

The Simulation Hypothesis fascinates me, because it is one of the few rationales for the existence of some form of a god which I, an agnostic, do not think is easily refutable. Let’s examine the common rebuttals of the simulation hypothesis to see how much merit they hold.

Some have questioned the assumption that there is one parent universe and many simulations. If there are many parent universes and many simulated universes, critics reason, then the probability that we are in a simulation would not necessarily be quite so high. But I disagree. What are the implications of many parent universes capable of sustaining life and technology? Presumably EACH of them would be running many simulations, and thus it would not affect the probability of our being in a simulation much at all.

The most serious problem I see with the Simulation Hypothesis is that it has no empirical basis, and falls apart under the scrutiny of Ockham’s Razor. There is absolutely no conclusive evidence that we are living in a simulation. There may be a few teasing clues (e.g. the quantum world behaves suspiciously differently when we aren’t watching), but nothing substantive. However, I can see no obvious flaw in the logic of the Simulation Hypothesis. This leads back to an old philosophical debate between empiricists and rationalists: Can we determine reality through sound logic, without empirical evidence? I tentatively plant my flag on the side of the rationalists. Scientists frequently adopt a rationalist mindset when interpreting the Drake Equation or formulating string theory (despite absolutely no evidence for extraterrestrials or strings), but switch over to empiricist mode for topics like philosophy or theology. This seems to be a product of cultural bias. In my view, while we should always seek out evidence wherever possible, sound logic is often a sufficient (if inferior) substitute.

At the end of the day, I tend to lean toward the conclusion that Bostrom is correct: We are probably in a simulation. What do you think? Let me know if/where you think the logic of the Simulation Hypothesis is flawed, or any other examples of clues that would suggest a simulated reality.