Books by Tegmark, Max

Tegmark, Max. Life 3.0. New York: Alfred A. Knopf, 2017. ISBN 978-1-101-94659-6.

The Earth formed from the protoplanetary disc surrounding the young Sun around 4.6 billion years ago. Around one hundred million years later, the nascent planet, beginning to solidify, was clobbered by a giant impactor which ejected the mass that made the Moon. This impact completely re-liquefied the Earth and Moon. Around 4.4 billion years ago, liquid water appeared on the Earth's surface (evidence for this comes from Hadean zircons which date from this era). And, some time thereafter, just about as soon as the Earth became environmentally hospitable to life (lack of disruption due to bombardment by comets and asteroids, and a temperature range in which the chemical reactions of life can proceed), life appeared. In speaking of the origin of life, the evidence is subtle and it's hard to be precise. There is completely unambiguous evidence of life on Earth 3.8 billion years ago, and more subtle clues that life may have existed as early as 4.28 billion years before the present. In any case, the Earth has been home to life for most of its existence as a planet.

This was what the author calls “Life 1.0”. Initially composed of single-celled organisms (which, nonetheless, dwarf in complexity of internal structure and chemistry anything produced by other natural processes or human technology to this day), life slowly diversified and organised into colonies of identical cells, evidence for which can be seen in rocks today.

About half a billion years ago, taking advantage of the far more efficient metabolism permitted by the oxygen-rich atmosphere produced by the simple organisms which preceded them, complex multi-cellular creatures sprang into existence in the “Cambrian explosion”. These critters manifested all the body forms found today, and every living being traces its lineage back to them. But they were still Life 1.0.

What is Life 1.0? Its key characteristics are that it can metabolise and reproduce, but that it can learn only through evolution. Life 1.0, from bacteria through insects, exhibits behaviour which can be quite complex, but that behaviour can be altered only by the random variation of mutations in the genetic code and natural selection of those variants which survive best in their environment. This process is necessarily slow, but given the vast expanses of geological time, has sufficed to produce myriad species, all exquisitely adapted to their ecological niches.

To put this in present-day computer jargon, Life 1.0 is “hard-wired”: its hardware (body plan and metabolic pathways) and software (behaviour in response to stimuli) are completely determined by its genetic code, and can be altered only through the process of evolution. Nothing an organism experiences or does can change its genetic programming: the programming of its descendants depends solely upon its success or lack thereof in producing viable offspring and the luck of mutation and recombination in altering the genome they inherit.

Much more recently, Life 2.0 developed. When? If you want to set a bunch of paleontologists squabbling, simply ask them when learned behaviour first appeared, but some time between the appearance of the first mammals and the ancestors of humans, beings developed the ability to learn from experience and alter their behaviour accordingly. Although some would argue simpler creatures (particularly birds) may do this, the fundamental hardware which seems to enable learning is the neocortex, which only mammalian brains possess. Modern humans are the quintessential exemplars of Life 2.0; they not only learn from experience, they've figured out how to pass what they've learned to other humans via speech, writing, and more recently, YouTube comments.

While Life 1.0 has hard-wired hardware and software, Life 2.0 is able to alter its own software. This is done by training the brain to respond in novel ways to stimuli. For example, you're born knowing no human language. In childhood, your brain automatically acquires the language(s) you hear from those around you. In adulthood you may, for example, choose to learn a new language by (tediously) training your brain to understand, speak, read, and write that language. You have deliberately altered your own software by reprogramming your brain, just as you can cause your mobile phone to behave in new ways by downloading a new application. But your ability to change yourself is limited to software. You have to work with the neurons and structure of your brain. You might wish to have more or better memory, the ability to see more colours (as some insects do), or run a sprint as fast as the current Olympic champion, but there is nothing you can do to alter those biological (hardware) constraints other than hope, over many generations, that your descendants might evolve those capabilities. Life 2.0 can design (within limits) its software, but not its hardware.

The emergence of a new major revision of life is a big thing. In 4.5 billion years, it has only happened twice, and each time it has remade the Earth. Many technologists believe that some time in the next century (and possibly within the lives of many reading this review) we may see the emergence of Life 3.0. Life 3.0, or Artificial General Intelligence (AGI), is machine intelligence, on whatever technological substrate, which can perform as well as or better than human beings, all of the intellectual tasks which they can do. A Life 3.0 AGI will be better at driving cars, doing scientific research, composing and performing music, painting pictures, writing fiction, persuading humans and other AGIs to adopt its opinions, and every other task including, most importantly, designing and building ever more capable AGIs. Life 1.0 was hard-wired; Life 2.0 could alter its software, but not its hardware; Life 3.0 can alter both its software and hardware. This may set off an “intelligence explosion” of recursive improvement, since each successive generation of AGIs will be even better at designing more capable successors, and this cycle of refinement will not be limited to the glacial timescale of random evolutionary change, but rather an engineering cycle which will run at electronic speed. Once the AGI train pulls out of the station, it may develop from the level of human intelligence to something as far beyond human cognition as humans are compared to ants in one human sleep cycle. Here is a summary of Life 1.0, 2.0, and 3.0.

The emergence of Life 3.0 is something about which we, exemplars of Life 2.0, should be concerned. After all, when we build a skyscraper or hydroelectric dam, we don't worry about, or rarely even consider, the multitude of Life 1.0 organisms, from bacteria through ants, which may perish as the result of our actions. Might mature Life 3.0, our descendants just as much as we are descended from Life 1.0, be similarly oblivious to our fate and concerns as it unfolds its incomprehensible plans? As artificial intelligence researcher Eliezer Yudkowsky puts it, “The AI does not hate you, nor does it love you, but you are made out of atoms which it can use for something else.” Or, as Max Tegmark observes here, “[t]he real worry isn't malevolence, but competence”. It's unlikely a super-intelligent AGI would care enough about humans to actively exterminate them, but if its goals don't align with those of humans, it may incidentally wipe them out as it, for example, disassembles the Earth to use its core for other purposes.

But isn't this all just science fiction—scary fairy tales by nerds ungrounded in reality? Well, maybe. What is beyond dispute is that for the last century the computing power available at constant cost has doubled about every two years, and this trend shows no evidence of abating in the near future. Well, that's interesting, because depending upon how you estimate the computational capacity of the human brain (a contentious question), most researchers expect digital computers to achieve that capacity within this century, with most estimates falling within the years from 2030 to 2070, assuming the exponential growth in computing power continues (and there is no physical law which appears to prevent it from doing so).

My own view of the development of machine intelligence is that of the author in this “intelligence landscape”.

Altitude on the map represents the difficulty of a cognitive task. Some tasks, for example management, may be relatively simple in and of themselves, but founded on prerequisites which are difficult. When I wrote my first computer program half a century ago, this map was almost entirely dry, with the water just beginning to lap into rote memorisation and arithmetic. Now many of the lowlands which people confidently said (often not long ago), “a computer will never…”, are submerged, and the ever-rising waters are reaching the foothills of cognitive tasks which employ many “knowledge workers” who considered themselves safe from the peril of “automation”. On the slope of Mount Science is the base camp of AI Design, which is shown in red since when the water surges into it, it's game over: machines will now be better than humans at improving themselves and designing their more intelligent and capable successors. Will this be game over for humans and, for that matter, biological life on Earth? That depends, and it depends upon decisions we may be making today.

Assuming we can create these super-intelligent machines, what will be their goals, and how can we ensure that our machines embody them? Will the machines discard our goals for their own as they become more intelligent and capable? How would bacteria have solved this problem contemplating their distant human descendants?

First of all, let's assume we can somehow design our future and constrain the AGIs to implement it. What kind of future will we choose? That's complicated. Here are the alternatives discussed by the author. I've deliberately given just the titles without summaries to stimulate your imagination about their consequences.

• Libertarian utopia
• Benevolent dictator
• Egalitarian utopia
• Gatekeeper
• Protector god
• Enslaved god
• Conquerors
• Descendants
• Zookeeper
• 1984
• Reversion
• Self-destruction

Choose wisely: whichever you choose may be the one your descendants (if any exist) may be stuck with for eternity. Interestingly, when these alternatives are discussed in chapter 5, none appears to be without serious downsides, and that's assuming we'll have the power to guide our future toward one of these outcomes. Or maybe we should just hope the AGIs come up with something better than we could think of. Hey, it worked for the bacteria and ants, both of which are prospering despite the occasional setback due to medical interventions or kids with magnifying glasses.

Let's assume progress toward AGI continues over the next few decades. I believe that what I've been calling the “Roaring Twenties” will be a phase transition in the structure of human societies and economies. Continued exponential growth in computing power will, without any fundamental breakthroughs in our understanding of problems and how to solve them, allow us to “brute force” previously intractable problems such as driving and flying in unprepared environments, understanding and speaking natural languages, language translation, much of general practice medical diagnosis and routine legal work, interaction with customers in retail environments, and many jobs in service industries, allowing them to be automated. The cost to replace a human worker will be comparable to a year's wages, and the automated replacement will work around the clock with only routine maintenance and never vote for a union.

This is nothing new: automation has been replacing manual labour since the 1950s, but as the intelligence landscape continues to flood, not just blue collar jobs, which have already been replaced by robots in automobile plants and electronics assembly lines, but white collar clerical and professional jobs people went into thinking them immune from automation. How will the economy cope with this? In societies with consensual government, those displaced vote; the computers who replace them don't (at least for the moment). Will there be a “robot tax” which funds a basic income for those made redundant? What are the consequences for a society where a majority of people have no job? Will voters at some point say “enough” and put an end to development of artificial intelligence (but note that this would have to be global and enforced by an intrusive and draconian regime; otherwise it would confer a huge first mover advantage on an actor who achieved AGI in a covert program)?

The following chart is presented to illustrate stagnation of income of lower-income households since around 1970.

I'm not sure this chart supports the argument that technology has been the principal cause for the stagnation of income among the bottom 90% of households since around 1970. There wasn't any major technological innovation which affected employment that occurred around that time: widespread use of microprocessors and personal computers did not happen until the 1980s when the flattening of the trend was already well underway. However, two public policy innovations in the United States which occurred in the years immediately before 1970 (1, 2) come to mind. You don't have to be an MIT cosmologist to figure out how they torpedoed the rising trend of prosperity for those aspiring to better themselves which had characterised the U.S. since 1940.

Nonetheless, what is coming down the track is something far more disruptive than the transition from an agricultural society to industrial production, and it may happen far more rapidly, allowing less time to adapt. We need to really get this right, because everything depends on it.

Observation and our understanding of the chemistry underlying the origin of life is compatible with Earth being the only host to life in our galaxy and, possibly, the visible universe. We have no idea whatsoever how our form of life emerged from non-living matter, and it's entirely possible it may have been an event so improbable we'll never understand it and which occurred only once. If this be the case, then what we do in the next few decades matters even more, because everything depends upon us, and what we choose. Will the universe remain dead, or will life burst forth from this most improbable seed to carry the spark born here to ignite life and intelligence throughout the universe? It could go either way. If we do nothing, life on Earth will surely be extinguished: the death of the Sun is certain, and long before that the Earth will be uninhabitable. We may be wiped out by an asteroid or comet strike, by a dictator with his fat finger on a button, or by accident (as Nathaniel Borenstein said, “The most likely way for the world to be destroyed, most experts agree, is by accident. That's where we come in; we're computer professionals. We cause accidents.”).

But if we survive these near-term risks, the future is essentially unbounded. Life will spread outward from this spark on Earth, from star to star, galaxy to galaxy, and eventually bring all the visible universe to life. It will be an explosion which dwarfs both its predecessors, the Cambrian and technological. Those who create it will not be like us, but they will be our descendants, and what they achieve will be our destiny. Perhaps they will remember us, and think kindly of those who imagined such things while confined to one little world. It doesn't matter; like the bacteria and ants, we will have done our part.

The author is co-founder of the Future of Life Institute which promotes and funds research into artificial intelligence safeguards. He guided the development of the Asilomar AI Principles, which have been endorsed to date by 1273 artificial intelligence and robotics researchers. In the last few years, discussion of the advent of AGI and the existential risks it may pose and potential ways to mitigate them has moved from a fringe topic into the mainstream of those engaged in developing the technologies moving toward that goal. This book is an excellent introduction to the risks and benefits of this possible future for a general audience, and encourages readers to ask themselves the difficult questions about what future they want and how to get there.

In the Kindle edition, everything is properly linked. Citations of documents on the Web are live links which may be clicked to display them. There is no index.

February 2018 

Tegmark, Max. Our Mathematical Universe. New York: Alfred A. Knopf, 2014. ISBN 978-0-307-59980-3.

In 1960, physicist Eugene Wigner wrote an essay titled “The Unreasonable Effectiveness of Mathematics in the Natural Sciences” in which he observed that “the enormous usefulness of mathematics in the natural sciences is something bordering on the mysterious and that there is no rational explanation for it”. Indeed, each time physics has expanded the horizon of its knowledge from the human scale, whether outward to the planets, stars, and galaxies; or inward to molecules, atoms, nucleons, and quarks it has been found that mathematical theories which precisely model these levels of structure can be found, and that these theories almost always predict new phenomena which are subsequently observed when experiments are performed to look for them. And yet it all seems very odd. The universe seems to obey laws written in the language of mathematics, but when we look at the universe we don't see anything which itself looks like mathematics. The mystery then, as posed by Stephen Hawking, is “What is it that breathes fire into the equations and makes a universe for them to describe?”

This book describes the author's personal journey to answer these deep questions. Max Tegmark, born in Stockholm, is a professor of physics at MIT who, by his own description, leads a double life. He has been a pioneer in developing techniques to tease out data about the early structure of the universe from maps of the cosmic background radiation obtained by satellite and balloon experiments and, in doing so, has been an important contributor to the emergence of precision cosmology: providing precise information on the age of the universe, its composition, and the seeding of large scale structure. This he calls his Dr. Jekyll work, and it is described in detail in the first part of the book. In the balance, his Mr. Hyde persona asserts itself and he delves deeply into the ultimate structure of reality.

He argues that just as science has in the past shown our universe to be far larger and more complicated than previously imagined, our contemporary theories suggest that everything we observe is part of an enormously greater four-level hierarchy of multiverses, arranged as follows.

The level I multiverse consists of all the regions of space outside our cosmic horizon from which light has not yet had time to reach us. If, as precision cosmology suggests, the universe is, if not infinite, so close as to be enormously larger than what we can observe, there will be a multitude of volumes of space as large as the one we can observe in which the laws of physics will be identical but the randomly specified initial conditions will vary. Because there is a finite number of possible quantum states within each observable radius and the number of such regions is likely to be much larger, there will be a multitude of observers just like you, and even more which will differ in various ways. This sounds completely crazy, but it is a straightforward prediction from our understanding of the Big Bang and the measurements of precision cosmology.

The level II multiverse follows directly from the theory of eternal inflation, which explains many otherwise mysterious aspects of the universe, such as why its curvature is so close to flat, why the cosmic background radiation has such a uniform temperature over the entire sky, and why the constants of physics appear to be exquisitely fine-tuned to permit the development of complex structures including life. Eternal (or chaotic) inflation argues that our level I multiverse (of which everything we can observe is a tiny bit) is a single “bubble” which nucleated when a pre-existing “false vacuum” phase decayed to a lower energy state. It is this decay which ultimately set off the enormous expansion after the Big Bang and provided the energy to create all of the content of the universe. But eternal inflation seems to require that there be an infinite series of bubbles created, all causally disconnected from one another. Because the process which causes a bubble to begin to inflate is affected by quantum fluctuations, although the fundamental physical laws in all of the bubbles will be the same, the initial conditions, including physical constants, will vary from bubble to bubble. Some bubbles will almost immediately recollapse into a black hole, others will expand so rapidly stars and galaxies never form, and in still others primordial nucleosynthesis may result in a universe filled only with helium. We find ourselves in a bubble which is hospitable to our form of life because we can only exist in such a bubble.

The level III multiverse is implied by the unitary evolution of the wave function in quantum mechanics and the multiple worlds interpretation which replaces collapse of the wave function with continually splitting universes in which every possible outcome occurs. In this view of quantum mechanics there is no randomness—the evolution of the wave function is completely deterministic. The results of our experiments appear to contain randomness because in the level III multiverse there are copies of each of us which experience every possible outcome of the experiment and we don't know which copy we are. In the author's words, “…causal physics will produce the illusion of randomness from your subjective viewpoint in any circumstance where you're being cloned. … So how does it feel when you get cloned? It feels random! And every time something fundamentally random appears to happen to you, which couldn't have been predicted even in principle, it's a sign that you've been cloned.”

In the level IV multiverse, not only do the initial conditions, physical constants, and the results of measuring an evolving quantum wave function vary, but the fundamental equations—the mathematical structure—of physics differ. There might be a different number of spatial dimensions, or two or more time dimensions, for example. The author argues that the ultimate ensemble theory is to assume that every mathematical structure exists as a physical structure in the level IV multiverse (perhaps with some constraints: for example, only computable structures may have physical representations). Most of these structures would not permit the existence of observers like ourselves, but once again we shouldn't be surprised to find ourselves living in a structure which allows us to exist. Thus, finally, the reason mathematics is so unreasonably effective in describing the laws of physics is just that mathematics and the laws of physics are one and the same thing. Any observer, regardless of how bizarre the universe it inhabits, will discover mathematical laws underlying the phenomena within that universe and conclude they make perfect sense.

Tegmark contends that when we try to discover the mathematical structure of the laws of physics, the outcome of quantum measurements, the physical constants which appear to be free parameters in our models, or the detailed properties of the visible part of our universe, we are simply trying to find our address in the respective levels of these multiverses. We will never find a reason from first principles for these things we measure: we observe what we do because that's the way they are where we happen to find ourselves. Observers elsewhere will see other things.

The principal opposition to multiverse arguments is that they are unscientific because they posit phenomena which are unobservable, perhaps even in principle, and hence cannot be falsified by experiment. Tegmark takes a different tack. He says that if you have a theory (for example, eternal inflation) which explains observations which otherwise do not make any sense and has made falsifiable predictions (the fine-scale structure of the cosmic background radiation) which have subsequently been confirmed by experiment, then if it predicts other inevitable consequences (the existence of a multitude of other Hubble volume universes outside our horizon and other bubbles with different physical constants) we should take these predictions seriously, even if we cannot think of any way at present to confirm them. Consider gravitational radiation: Einstein predicted it in 1916 as a consequence of general relativity. While general relativity has passed every experimental test in subsequent years, at the time of Einstein's prediction almost nobody thought a gravitational wave could be detected, and yet the consistency of the theory, validated by other tests, persuaded almost all physicists that gravitational waves must exist. It was not until the 1980s that indirect evidence for this phenomenon was detected, and to this date, despite the construction of elaborate apparatus and the efforts of hundreds of researchers over decades, no direct detection of gravitational radiation has been achieved.

There is a great deal more in this enlightening book. You will learn about the academic politics of doing highly speculative research, gaming the arXiv to get your paper listed as the first in the day's publications, the nature of consciousness and perception and its complex relation to consensus and external reality, the measure problem as an unappreciated deep mystery of cosmology, whether humans are alone in our observable universe, the continuum versus an underlying discrete structure, and the ultimate fate of our observable part of the multiverses.

In the Kindle edition, everything is properly linked, including the comprehensive index. Citations of documents on the Web are live links which may be clicked to display them.

March 2014