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 But as Carroll points out (using an argument originally made by Ludwig Boltzmann over a hundred years ago), that isn’t necessarily the case.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

In a party game dating back to the 1940s or earlier, a man and a woman were put in separate rooms and allowed to communicate with a judge through typed messages. One of the two would be trying to deceive the judge about his or her gender; the judge’s task was to determine the gender of the two participants through the typed conversations. In 1950, computer scientist Alan Turing modified the game to be used in the context of artificial intelligence. In the Turing Test, there is a human and computer participant, rather than a male and female participant. Both attempt to convince a judge that they are human via a text conversation. If the judge is unable to determine the human more often than chance would dictate, the computer is said to have passed the Turing Test. As of now, no computers have even come close to passing a Turing Test.

The Turing Test is commonly viewed as the holy grail of artificial intelligence. A computer that is capable of convincing humans of its humanity would have to be as richly programmed as a human brain. But would it truly be conscious, or would it merely be mimicking intelligence? Most computer scientists assert that the computer would actually be conscious in the same sense that we are. Since a brain, after all, is merely a pattern of information, it is no fundamentally different than a computer program. Both a brain and a computer program merely respond to external inputs and produce an output. There is no empirical test that we can conduct to determine if an entity is “conscious.” The only way to gauge that is by our interactions with the entity in question. When we interact with other humans, we typically take them at their word that they are conscious entities, because we are aware of our own consciousness and we observe that other humans generally behave like we do. Therefore, I think that any computer capable of passing the Turing Test would have just as much claim to consciousness as any human.

The mindset that computers, no matter how well-programmed, can only mimic consciousness will probably fall by the wayside in the 21^st century, as the distinction between natural and artificial becomes much less clear. For all of their merits, silicon computer chips have a lot of drawbacks, such as the amount of heat they emit and the amount of power they consume. In the coming decades, we will probably see more organic, carbon-based computers. At the same time, we will probably see a lot more “natural” humans with artificial additions to their brains. To some extent, brain implants already exist to help people cope with brain damage or to mitigate certain mental conditions. Eventually, they may be used in perfectly healthy individuals to enhance their mental capacity. These kinds of developments will likely blur the line between human and computer. When complex forms of intelligence can no longer be so neatly classified as “human” or “computer,” but instead represent a diverse spectrum ranging from 100% organic to 100% machine, will it still make any sense to assert that computers are able to mimic intelligence without being intelligent? I think not.

I think the reason that some people believe a computer would only be mimicking intelligence is because intelligent computers are not yet commonplace. While we have grown accustomed to computers that can crunch numbers and play chess much better than we can, we have not yet encountered any computers that can recognize patterns or respond with emotions as well as we can. As computers become more and more powerful, this day will come. Many decades from now, we may have computers that are truly capable of passing the Turing Test. They will probably lobby for basic rights under the law. When this happens, I think we will expand the definition of human rights to include non-human forms of intelligence, as there would be no moral basis for doing otherwise. And will we believe their claims that they are truly conscious beings? I think we will. They’ll get mad if we don’t.

Inception and the Ethics of Virtual Reality

***SPOILER ALERT***

I watched Inception last weekend - the first movie I've seen in the theater all year. It’s a great movie, and is a great illustration of the simulation hypothesis. Along with movies like The Matrix and Vanilla Sky, it explores the concept of whether our reality may be a simulation, and if there’s any way to tell the difference.

The reason I often blog about the simulation hypothesis is not merely because it’s an interesting philosophical question, although it certainly is. As Inception illustrates, there are some profound ethical dilemmas we will need to face in the future, when we have both the raw computing power and the understanding of our own neurology to escape to convincing, fictitious worlds.

In Inception, Cobb and Mal dream for decades (in dream-time) in a world of their own creation. Mal goes so far as to hide any evidence that she is dreaming, preferring to forget that their world is not real. When we have the technology to create simulated realities, there will almost certainly be people who want to do this. Even today, many people choose to spend a huge portion of their lives escaping into the crude virtual worlds that our technology allows, such as World of Warcraft. As long as this lifestyle is limited to computer geeks, most people will view it as an unhealthy activity. But when simulated worlds become truly convincing, it is probable that many others will want to join in.

How will society view people who want to spend years or decades in a simulation, living a better life than they have in this world? Will people scorn them like drug addicts? Will organized religions extol simulations as a way to have profound spiritual experiences, or will they be fearful of the threat that simulations pose to their monopoly on heaven? Might there be a mass exodus of people from this world, if nearly everyone prefers to live in a simulation? What would be the economic impact if a large portion of the population suddenly decided to stop working and live in a simulation? Will governments simply accept their choice and allow people to sleep the years away, or will they wake them up? Will those who remain behind envy those who have escaped to a better, simulated life? Perhaps we will empathize with them and respect their decision. (EDIT: I realized I used the pronouns “we” and “them” here to describe, respectively, those who remain behind and those who choose to live in a simulations…but honestly I have no idea which camp I would be in.) After all, how would we feel if we suddenly “woke up” to a higher plane of reality today, only to find that our “real” life was much worse than the one we experience in this world? I imagine that many of us would feel cheated out of our lives like Mal did, and be unable to accept the sudden decline in our standard of living. It seems very human to want to live the best life we possibly can. Since most of us wouldn’t want to wake up to a worse world, I think that eventually society will empathize with the dreamers and accept those who wish to remain lost in their subconscious.

This is but one of many new ethical questions we may have to confront by the middle of this century. Near the end of Inception Mal tells Cobb (who knows full well that he is dreaming), “You no longer believe in a single reality. So choose. Choose to be here with me.” Cobb rejects her offer, choosing to live in “actual reality” instead. While I’m pretty sure that the audience of 2010 is expected to applaud his decision, ultimately Mal is right. In a world where convincing simulations are possible, there is really no way to know if one is in a simulation or not. So why not just accept this and let people live in whatever world makes them happy? Could we really pass judgment on those who want to live permanently in a simulation, when we have no idea if we have chosen to do the same? Waking them up could be tantamount to destroying their lives. The audience of 2060 may react very differently to the ending of this movie.

What are your thoughts on the ethics of simulated reality? Do you think it would be more ethical (or practical) to let the dreamers dream, or to wake them up to "reality?"

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.