Some scientists have proposed adding the category of a Type IV civilization that controls space-time well enough to affect the entire universe.

Why stop at one universe?

—CHRIS IMPEY

There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.

—MARK TWAIN

13     ADVANCED CIVILIZATIONS

The tabloid headlines blared:

“Giant Alien Megastructure Found in Space!”

“Astronomers Baffled by Alien Machine in Space!”

Even the Washington Post, not used to running lurid stories on UFOs and aliens, ran the headline, “The Weirdest Star in the Sky Is Acting Up Again.”

Suddenly, astronomers, who normally analyze boring reams of data from satellites and radio telescopes, were flooded with calls from anxious journalists, asking if it was true that they had finally found an alien structure in space.

This caught them by surprise. The astronomical community was at a loss for words. Yes, something strange had been discovered in space. Yes, it defied explanation, but it was too soon to say what it meant. This might just be a wild goose chase.

The controversy began when astronomers were looking at exoplanets transiting distant stars. Usually, a giant Jupiter-sized exoplanet, moving in front of its mother star, will dim its starlight by 1 percent or so. But one day they were analyzing the data from the Kepler spacecraft concerning the star KIC 8462852, which is about 1,400 light-years from Earth. They found an astonishing anomaly: something had dimmed the starlight by a massive 15 percent in 2011. These anomalies can usually be dismissed. Perhaps there was something wrong with the instruments, a spike in power, a transient surge in electrical output, or perhaps it was nothing but dust on the telescope mirrors.

But then it was observed a second time in 2013, this time dimming the star’s light by 22 percent. Nothing known to science can dim starlight regularly by that amount.

“We’d never seen anything like this star. It was really weird,” said Tabetha Boyajian, a postdoctoral fellow at Yale.

The situation became even more bizarre when Bradley Schaefer of Louisiana State University searched old photographic plates and found that the star’s light has been dimming periodically since 1890. Astronomy Now magazine wrote that this “has triggered a frenzy of observations as astronomers hurry to try to get to the bottom of what is rapidly becoming one of the biggest mysteries in astronomy.”

So astronomers made long lists of possible explanations. But one by one, doubt was cast on the usual scientific suspects.

What could possibly cause this massive dip in starlight? Could it really be something twenty-two times larger than Jupiter? One possibility was that it was caused by a planet plunging into the star. But that was ruled out because the anomaly kept reappearing. Another possibility was the dust from the disk of the solar system. As a solar system condenses in space, the original disk of gas and dust can be many times larger than the sun itself. So maybe the dimming of starlight occurred because the disk passed in front of the star. But this was ruled out when analyzing the star itself, which was found to be mature. The dust should have long since condensed or been swept into space by the solar winds.

After discarding a number of possible solutions, there was still one option that could not be easily dismissed. No one wanted to believe it, but it could not be ruled out: maybe it was a colossal megastructure built by an alien intelligence.

“Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build,” says Jason Wright, an astronomer from Penn State University.

Since the time elapsed between dips in starlight in 2011 and 2013 was 750 days, astronomers predicted that it would recur again in May 2017. Right on schedule, the star began to dim. This time, practically every telescope on Earth capable of measuring starlight was tracking the star. Astronomers from around the world witnessed the star dimming by 3 percent and then brightening again.

But what could it be? Some thought it might be a Dyson sphere, first proposed by Olaf Stapledon in 1937 but later analyzed by physicist Freeman Dyson. A Dyson sphere is a gigantic sphere around a star, designed to harvest the energy from its massive amounts of starlight. Or it could be a huge sphere orbiting a star that periodically passes in front of the star, causing starlight to dim. Perhaps this was something created in order to power the machines of an advanced Type II civilization. This last supposition tweaked the imagination of amateurs and journalists alike. They asked, What is a Type II civilization?

KARDASHEV SCALE OF CIVILIZATIONS

This classification of advanced civilizations was first proposed by Russian astronomer Nikolai Kardashev in 1964. He was not satisfied looking for alien civilizations without any idea of what he might be searching for. Scientists like to quantify the unknown, so he introduced a scale that ranked civilizations on the basis of energy consumption. Different ones might have different cultures, politics, and history, but all of them would require energy. His ranking was as follows:

1. A Type I civilization utilizes all the energy of the sunlight that falls on that planet.

2. A Type II civilization utilizes all the energy its sun produces.

3. A Type III civilization utilizes the energy of an entire galaxy.

In this way, Kardashev conveniently gave a simple method for computing and ranking the possible civilizations within the galaxy, based on energy use.

Each civilization, in turn, has an energy consumption that can be computed. It is easy to calculate how much sunlight falls on a square foot of land on Earth. Multiplying this by the surface area of the Earth illuminated by the sun and one immediately calculates the approximate energy of an average Type I civilization. (We find that a Type I civilization harnesses the power of 7 x 10¹⁷ watts, which is about one hundred thousand times the energy output of the Earth today.)

Since we know the fraction of the sun’s energy that falls on the Earth, we can then multiply to include the surface area of the entire sun, and we get its total energy output (which is roughly 4 x 10²⁶ watts). This tells us roughly how much energy is utilized in a Type II civilization.

We also know how many stars there are in the Milky Way galaxy, so we can multiply by this number and find the energy output of an entire galaxy, giving us the energy consumption of a Type III civilization in our galaxy, which is roughly 4 x 10³⁷ watts.

The results were intriguing. Kardeshev found that each civilization was greater than the previous one by a factor of between ten billion and one hundred billion.

One can then mathematically compute when we might rise up this scale. Using the total energy consumption of the planet Earth, we find that we are currently a Type 0.7 civilization.

Assuming a 2 percent to 3 percent annual increase in energy output, which roughly corresponds to the current average growth rate or annual growth in GDP for the planet, we are about a century or two away from becoming a Type I civilization. Rising to the level of a Type II civilization could take a few thousand years, according to this calculation. When we would become a Type III civilization is more difficult to compute, since it involves advances in interstellar travel that are difficult to predict. By one estimate, we will probably not become a Type III civilization for one hundred thousand years and possibly not for a million years.

TRANSITION FROM TYPE 0 TO TYPE I

Of all the transitions, perhaps the most difficult is the transition from Type 0 to Type I, which we are undergoing at present. This is because a Type 0 civilization is the most uncivilized, both technologically and socially. It has risen only recently from the swamp of sectarianism, dictatorship, and religious strife, et cetera. It still has all the scars from its brutal past, which was full of inquisitions, persecutions, pogroms, and wars. Our own history books are full of horrid tales of massacres and genocide, much of it driven by superstition, ignorance, hysteria, and hatred.

But we are witnessing the birth pangs of a new Type I civilization, based on science and prosperity. We see the seeds of this momentous transition germinating every day before our eyes. Already, a planetary language is being born. The internet itself is nothing but a Type I phone system. So the internet is the first Type I technology to develop.

We are also witnessing the emergence of a planetary culture. In sports, we see the rise of soccer and the Olympics. In music, we see the rise of global stars. In fashion, we see the same high-end stores and brands at all the elite malls.

Some fear that this process will threaten local cultures and customs. But in most third-world countries today, the elites are bilingual, fluent in the local language and also a global European language or Mandarin as well. In the future, people will likely be bicultural, fluent in all the customs of the local culture but also at ease with the emerging planetary culture. So the richness and diversity of Earth will survive even as this new planetary culture arises.

Now that we have classified civilizations in space, we can use this to help calculate the number of advanced civilizations in the galaxy. For example, if we apply the Drake equation to a Type I civilization to estimate how plentiful they might be in the galaxy, it would appear they should be quite common. Yet we see no obvious evidence of them. Why? There are several possibilities. Elon Musk has speculated that, as civilizations master advanced technology, they develop the power to destroy themselves and that the biggest threat facing a Type I civilization may be a self-inflicted one.

For us, there are several challenges as we make the transition from Type 0 to Type I: global warming, bioterrorism, and nuclear proliferation, to name a few.

The first and most immediate is nuclear proliferation. The bomb is spreading into some of the most unstable regions of the world, such as the Middle East, the Indian subcontinent, and the Korean peninsula. Even small countries may one day have the ability to develop nuclear weapons. In the past, it took a large nation-state to refine uranium ore into weapons-grade materials. Gigantic gaseous diffusion plants and banks of ultracentrifuges were required. These enrichment facilities were so large they could easily be seen by satellite. This was beyond the reach of small nations.

But blueprints for nuclear weapons have been stolen and then sold to unstable regimes. The cost of ultracentrifuges and purifying uranium into weapons-grade material has fallen. As a result, even nations like North Korea, which is perpetually teetering on the brink of collapse, can amass a small but deadly nuclear arsenal today.

Now the danger is that a regional war, between India and Pakistan, say, could escalate to a major war, drawing in the major nuclear powers. Since the United States and Russia each possess about seven thousand nuclear weapons, this threat is significant. There is even a concern that nonstate actors or terrorist groups could procure a nuclear bomb.

The Pentagon commissioned a report from the Global Business Network think tank that analyzed what might happen if global warming destroys the economies of many poor nations such as Bangladesh. It concluded that, in a worst-case scenario, nations may use nuclear weapons to protect their borders from being overrun by a flood of millions of desperate, starving refugees. And even if it does not cause a nuclear war, global warming is an existential threat to humanity.

GLOBAL WARMING AND BIOTERRORISM

Since the end of the last glacial period about ten thousand years ago, the Earth has been gradually warming up. However, over the past half century, the Earth has been heating at an alarming and accelerating rate. We see evidence of this on numerous fronts:

· Every major glacier on the Earth is receding

· The northern polar ice has thinned by an average of 50 percent over the past fifty years

· Large parts of Greenland, which is covered by the world’s second-largest ice sheet, are thawing out

· A section of Antarctica the size of Delaware, the Larsen Ice Shelf C, broke off in 2017, and the stability of the ice sheets and ice shelves is now in question

· The last few years have been the hottest ever recorded in human history

· The Earth’s average temperature has increased by about 1.3 degrees Celsius in the past century

· On average, summer is about one week longer than it was in the past

· We are seeing more and more “one-hundred-year events,” such as forest fires, floods, droughts, and hurricanes

There is the danger that, if this global warming accelerates unabated into the coming decades, it could destabilize the nations of the world, create mass starvation, generate mass migration from the coastal areas, and threaten the world economy and prevent the transition to a Type I civilization.

There is also the threat of weaponized biogerms that could potentially wipe out 98 percent of the human population.

Throughout world history, the greatest killers have not been wars but plagues and epidemics. Unfortunately, it is possible that nations have kept secret stockpiles of deadly diseases, such as smallpox, which could be weaponized using biotechnology to create havoc. There is also the danger that someone could create a doomsday weapon by bioengineering some existing disease—Ebola, HIV, avian flu—and making it more lethal or causing it to spread more quickly and easily.

Perhaps in the future, if we ever venture to other planets, we may find the ashes of dead civilizations: planets whose atmospheres are highly radioactive; planets that are too hot, because of a runaway greenhouse effect; or planets with empty cities because they used advanced biotech weaponry on themselves. So the transition from Type 0 to Type I is not guaranteed and in fact represents the greatest challenge facing an emerging civilization.

ENERGY FOR TYPE I CIVILIZATION

A key question is whether a Type I civilization can make the transition to energy sources other than fossil fuels.

One possibility is to harness uranium nuclear power. But uranium fuel for a conventional nuclear reactor creates large amounts of nuclear waste products, which are radioactive for millions of years. Even today, fifty years into the nuclear age, we still do not have a safe way to store high-level nuclear waste. This material is also quite hot and can create a meltdown, as we have seen in the Chernobyl and Fukushima disasters.

An alternative to uranium fission power is fusion power, which, as we saw in chapter 8, is not ready yet for commercial use, but a Type I civilization a century more advanced than ours may have perfected the technology and could use it as an indispensable source of nearly unlimited energy.

One advantage of fusion power is that its fuel is hydrogen, which can be extracted from seawater. A fusion plant also cannot suffer a catastrophic meltdown like the ones we saw at Chernobyl and Fukushima. If there is a malfunction in the fusion plant (such as the superhot gas touching the lining of the reactor) the fusion process automatically shuts itself off. (This is because the fusion process has to attain the Lawson criterion: it must maintain the proper density and temperature to fuse the hydrogen over a certain period of time. But if the fusion process gets out of control, the Lawson criterion is no longer satisfied, and it stops by itself.)

Also, a fusion reactor only produces modest amounts of nuclear waste. Because neutrons are created in the process of fusing hydrogen, these neutrons can irradiate the steel of the reactor, making it slightly radioactive. But the amount of waste created in this fashion is only a tiny fraction of that generated by uranium reactors.

In addition to fusion power, there are other possible renewable energy sources. One attractive possibility for a Type I civilization is to exploit space-based solar energy. Since 60 percent of the energy of the sun is lost passing through the atmosphere, satellites could harness much more solar energy than collectors on the surface of the Earth.

A space-based solar energy system might consist of many huge mirrors orbiting the Earth collecting sunlight. They would be geostationary (orbiting the Earth at the same rate at which the Earth rotates, so they appear to be in a fixed location in the sky). This energy can then be beamed down to a receiving station on the Earth in the form of microwave radiation, and it would then be distributed through a traditional electrical grid.

There are many advantages to space solar energy. It is clean and without waste products. It can generate power twenty-four hours a day, rather than just during daylight hours. (These satellites are almost never in the shadow of the Earth, since their path takes them considerably away from the Earth’s orbit.) The solar panels have no moving parts, which vastly reduces breakdowns and repair costs. And best of all, space solar power taps into a limitless supply of free energy from the sun.

Every scientific panel that has looked into the question of space solar has concluded that the goal is achievable with off-the-shelf technology. But the main problem, like all endeavors involving space travel, is cost. Simple estimates show that this is currently many times more expensive than simply putting solar panels out in your backyard.

Space solar energy is beyond the means of a Type 0 civilization like ours, but it may become a natural source of energy for a Type I civilization for several reasons:

1. The cost of space travel is dropping, especially because of the introduction of private rocket companies and the invention of reusable rockets.

2. The space elevator may be possible late in this century.

3. Space solar panels can be made of lightweight nanomaterials, keeping weight and costs down.

4. The solar satellites can be assembled in space by robots, eliminating the need for astronauts.

It also is generally considered safe because while microwaves can be harmful, calculations show that most of the energy is confined within the beam, and the energy that escapes outside the beam should fall within accepted environmental standards.

TRANSITION TO TYPE II

Eventually, a Type I civilization may exhaust the power available on its home planet and look to exploit the enormous energy found in the sun itself.

A Type II civilization should be easy to find, because they are likely immortal. Nothing known to science can destroy their culture. Meteor or asteroid collisions can be avoided using rocketry. The greenhouse effect can be avoided using hydrogen-based or solar technologies (fuel cells, fusion plants, space solar satellites, et cetera). If there are any planetary threats, they can even leave their home in large space armadas. They might even be able to move their planet if necessary. Since they have enough energy to deflect asteroids, they can whip them around their planet, causing a small shift in its trajectory. With successive “slingshot” maneuvers, they could move the orbit of their planet farther from the sun if their star is late in its life cycle and beginning to expand.

To supply energy for their civilization, they might, as we mentioned earlier, build a Dyson sphere to harvest most of the energy from the sun itself. (One problem with building such gigantic megastructures is there might not be enough building material on the rocky planets to construct them. Since our sun is 109 times bigger than the Earth in diameter, it would require an immense amount of material to build one of these structures. Perhaps the solution to this practical problem is to use nanotechnology. If these megastructures are made of nanomaterials, they might only be a few molecules in thickness, which would vastly decrease the amount of building materials required.)

The number of space missions needed to create such megastructures is truly monumental. But the key to building them may be to utilize space-based robots and self-organizing materials. For example, if a nanofactory could be built on the moon to make panels for the Dyson sphere, they could be assembled in outer space. Because these robots are self-replicating, an almost unlimited number of them could be built to create this structure.

But even if a Type II civilization is virtually immortal, it still faces a long-term threat: the second law of thermodynamics, the fact that all their machines will create enough infrared heat radiation to make life impossible on their planet. The second law says that entropy (disorder, chaos, or waste) always increases in a closed system. In this case every machine, every appliance, every apparatus generates waste, in the form of heat. Naïvely, we can assume that the solution is to build gigantic refrigerators to cool down the planet. These refrigerators do in fact lower the temperature inside them, but if we add everything up, including heat from the motors used by the refrigerators, the average heat of the whole system still increases.

(For example, on a very hot day, we fan our faces for relief, thinking that this cools us down. Fanning ourselves does cool down our face, giving us temporary relief, but the heat generated by the motion of our muscles, bones, and so on actually produces more net heat. So fanning ourselves gives us immediate psychological relief, but our total body temperature and the temperature of the air around us actually go up.)

COOLING DOWN A TYPE II CIVILIZATION

A Type II civilization, in order to survive the second law, may necessarily have to disperse its machinery or overheat. As we discussed earlier, one solution would be to move most of the machinery to outer space, so that the mother planet becomes a park. This means that a Type II civilization might build all its heat-generating equipment off the planet. Although it consumes the energy output of a star, the waste heat generated is in outer space and hence dissipates harmlessly.

Eventually the Dyson sphere itself begins to heat up. This means that a Dyson sphere must necessarily emit infrared radiation. (Even if we assume that the civilization creates machines to try to conceal this infrared radiation, eventually these machines themselves become hot and radiate in the infrared.)

Scientists have scanned the heavens looking for the telltale signs of infrared radiation from a Type II civilization, and they have failed to find it. Scientists at Fermilab outside Chicago scanned 250,000 stars looking for signatures of a Type II civilization but only found four that were “amusing but still questionable,” so their results were inconclusive. It is possible that the James Webb Space Telescope, which will go into service late in 2018 and will look specifically for infrared radiation, may have the sensitivity to find the heat signature of all Type II civilizations in our sector of the galaxy.

So this is a mystery. If Type II civilizations are virtually immortal, and they necessarily emit waste infrared radiation, then why haven’t we detected them? Perhaps looking for infrared emissions is too narrow.

Astronomer Chris Impey of the University of Arizona, commenting on finding a Type II civilization, has written, “The premise is that any highly advanced civilization will leave a much larger footprint than we will. Type II or later civilizations may employ technologies that we’re tinkering with or can barely imagine. They might orchestrate stellar cataclysms or use propulsion by anti-matter. They might manipulate space-time to create wormholes or baby universes and communicate by gravity waves.”

Or, as David Grinspoon has written, “Logic tells me that it is reasonable to look for godlike signs of advanced aliens in the sky. And yet the idea seems ridiculous. It is both logical and absurd. Go figure.”

One possible way out of this dilemma is to realize that there are two ways to rank a civilization: by its energy consumption, but also by its information consumption.

Modern society has expanded in the direction of miniaturization and energy efficiency as it consumes an exploding amount of information. In fact, Carl Sagan proposed a way to rank civilizations by information.

In this scenario a Type A civilization consumes a million bits of information. A Type B civilization would consume ten times that number, or ten million bits of information, and so on, until we hit Type Z, which can consume an astounding 10³¹ bits of information. By this calculation, we are a Type H civilization. The point here is that civilizations may advance on the scale of information consumption while consuming the same amount of energy. Thus they may not produce a significant amount of infrared radiation.

We see an example of this when we visit a science museum. We are amazed at the size of the machines of the industrial revolution, with gigantic locomotives and huge steamboats. But we also notice how inefficient they were, generating a large amount of waste heat. Similarly, the gigantic computer banks of the 1950s can be surpassed by an ordinary cell phone today. Modern technology became much more sophisticated, intelligent, and less wasteful of energy.

So a Type II civilization can consume a vast amount of energy without burning up by distributing their machines in Dyson spheres, on asteroids and nearby planets, or by creating superefficient miniaturized computer systems. Instead of being consumed by the heat generated by their huge energy usage, their technology may also be superefficient, consuming vast amounts of information and producing relatively little waste heat.

WILL HUMANITY SPLIT APART?

There are limitations, however, to how far each civilization will advance in terms of space travel. For example, a Type I civilization, as we have seen, is limited by its planetary energy. At best, it will master the art of terraforming a planet like Mars and begin to explore the nearest stars. Robotic probes will begin exploring nearby solar systems and perhaps the first astronauts will be sent to the nearest star, like Proxima Centauri. But its technology and its economy are not sufficiently advanced to begin the systematic colonization of scores of nearby star systems.

For a Type II civilization, which is centuries to millennia more advanced, colonization of a sector of the Milky Way becomes a real possibility. But even for a Type II civilization, eventually they are constrained by the light barrier. If we assume that faster-than-light propulsion is not available to them, it may take many centuries to colonize their sector of the galaxy.

But if it takes centuries to go from one star system to another, then eventually the ties to the home world become extremely tenuous. Planets will eventually lose contact with other worlds, and new branches of humanity may emerge that can adapt to radically different environments. Colonists may also genetically and cybernetically modify themselves to adapt to strange environments. Eventually, they may not feel any connection to the home planet.

This seems to contradict the vision of Asimov in his Foundation series, with a Galactic Empire emerging fifty thousand years from now that has colonized most of the galaxy. Can we reconcile these two very different visions of the future?

Is the ultimate fate of human civilization to splinter into smaller entities, with only the sketchiest knowledge of one another? This raises the ultimate question: Will we gain the stars but lose our humanity in the process? And what does it mean to be human anyway if there are so many distinct branches of humanity?

This divergence seems to be universal in nature, a common thread that runs through all of evolution, not just humanity. Darwin was the first to see how this occurs through the animal and plant kingdoms when he sketched a prophetic diagram in his notebook. He drew a picture of the branches of a tree, with different arms diverging into smaller branches. In one simple diagram, he drew the tree of life, with all the diversity of nature evolving from a single species.

Perhaps this diagram applies not only to life on Earth but to humanity itself thousands of years from now, when we become a Type II civilization capable of colonizing the nearby stars.

GREAT DIASPORA IN THE GALAXY

To gain some concrete insight into this problem, we have to reanalyze our own evolution. Looking at the sweep of human history, we can see that roughly seventy-five thousand years ago, a Great Diaspora took place, with small bands of humans moving away from Africa through the Middle East, creating settlements along the way. Perhaps driven by ecological disasters, such as the Toba eruption and a glaciation period, one of the main branches went through the Middle East and journeyed on to Central Asia. Then this migration split further into several smaller branches about forty thousand years ago. One branch kept on going east and eventually settled in Asia, forming the core of the modern Asian people. The other branch turned around and went into northern Europe, eventually becoming Caucasians. Yet another branch went southeast and eventually passed through India and into Southeast Asia and then Australia.

Today, we see the consequences of this Great Diaspora.

We see a variety of humans of different colors, sizes, shapes, and cultures who have no ancestral memory of their true origins. One can even calculate roughly how divergent the human race is. If we assume that one generation is 20 years long, then at most about 3,500 generations separate any two humans on the planet.

But today, tens of thousands of years later, with modern technology, we can begin to re-create all the migration routes of the past and build an ancestral family tree of human migrations over the past seventy-five thousand years.

I had a vivid demonstration of this while hosting a BBC TV science special about the nature of time. BBC took some of my DNA and sequenced it. Four of my genes were then carefully compared with the genes of thousands of other individuals around the world, looking for a match. Then the locations of the people who matched these four genes were identified on a map. The result was rather interesting. It showed a concentration of people scattered through Japan and China who had a match, but then there was a thin trail of dots that tapered off into the distance near the Gobi Desert, through Tibet. So, using DNA analysis, it was possible to retrace the route that my ancestors took about twenty thousand years ago.

HOW FAR WILL WE DIVERGE?

How far will humanity diverge over thousands of years? Will humanity be recognizable after tens of thousands of years of genetic separation?

This question can actually be answered using DNA as a “clock.” Biologists have noticed that DNA mutates at roughly the same rate across the ages. For example, our closest evolutionary neighbor is the chimpanzee. Analysis of the chimpanzee shows that we differ by approximately 4 percent of our DNA. Studies of chimpanzee and human fossils indicate that we separated from them about 6 million years ago.

This means that our DNA mutated at the rate of 1 percent over a period of 1.5 million years. This is only an approximate number, but let us see if it can allow us to understand the ancient history of our own DNA.

Assume, for the moment, that this rate of change (1 percent change every 1.5 million years) is roughly constant.

Now let us analyze the Neanderthal, our closest humanlike kin. DNA and fossil analysis of the Neanderthal show that their DNA differs from our DNA by about 0.5 percent and that we separated from them roughly five hundred thousand to a million years ago. So this is in rough agreement with the DNA clock.

If we now analyze the human race, we find that any two humans chosen at random can differ in their DNA by 0.1 percent. Our clock then says that different branches began to diverge about 150,000 years ago, which is in rough agreement with the actual origins of humanity.

So given this DNA clock, we can calculate roughly when we diverged from the chimpanzees, the Neanderthals, and also our fellow human beings.

The point is that we can use this clock to estimate how far humanity will change in the future if we disperse throughout the galaxy and don’t drastically tinker with our DNA. Assume for the moment that we remain a Type II civilization with only sub-light-speed rockets for 100,000 years.

Even if different human settlements lose all contact with other branches of humanity, this means humans will probably only diverge by about 0.1 percent in our DNA, which is the amount of divergence that we already see today among humans.

The conclusion here is that, as humanity spreads throughout the galaxy at sub-light speed and different branches lose all contact with other branches, we will still be basically human. Even after 100,000 years, when we might reasonably be expected to attain light speed, different human settlements will differ no more than any two humans on the Earth today.

This phenomenon also applies to the very language that we speak. Archeologists and linguists have noticed that a startling pattern emerges when they try to trace the origin of language. They find that languages constantly branch out into other smaller dialects due to migrations; over time, these new dialects become full-fledged languages themselves.

If we create a vast tree of all known languages and how they branched off one another and compare it with the ancestral tree detailing ancient migration routes, we find an identical pattern.

For example, Iceland, which has been largely isolated from Europe since 874 AD, when the first Norwegian settlements began, can be used as a laboratory to test linguistic and genetic theories. The Icelandic language is closely related to the Norwegian language of the ninth century, with a little bit of Scottish and Irish thrown in the mix. (This is probably due to the Vikings taking slaves from Scotland and Ireland.) It is then possible to create a DNA clock and a linguistic clock to roughly calculate how much divergence there is over a thousand years. Even after a thousand years, one can easily find evidence of ancient migration patterns imprinted in their language.

But even if our DNA and language still resemble themselves after thousands of years of separation, what about our culture and our beliefs? Will we be able to understand and identify with these divergent cultures?

COMMON CORE VALUES

When we look at the Great Diaspora and the civilizations that it created, we see not only a variety of physical differences in skin color, size, hair, et cetera, but also a certain core set of characteristics that are remarkably the same across all cultures, even when they lost all contact with one another for thousands of years.

We see evidence of this today when we go to the movies. People of different races and cultures, who might have diverged from us seventy-five thousand years ago, still laugh, cry, and thrill at the same moment in the film. Translators of foreign films notice the commonality of the jokes and humor in the movies, although the languages themselves diverged long ago.

This also applies to our sense of aesthetics. If we visit an art museum that has exhibits from ancient civilizations, we see common themes. Regardless of the culture, we find artwork depicting landscape scenes, portraits of the rich and powerful, and images of myths and gods. Although the sense of beauty is difficult to quantify, what is considered beautiful in one culture is often considered beautiful by another totally unrelated culture. For example, no matter which culture we examine, we see similar flowers and floral patterns.

Another theme that cuts across the barriers of space and time is our common social values. One core concern is for the welfare of others. This means kindness, generosity, friendship, thoughtfulness. Various forms of the Golden Rule are found in numerous civilizations. Many of the religions of the world, at the most fundamental level, stress the same concepts, such as charity and sympathy for the poor and unfortunate.

The other core characteristic is focused not inward, but outward. This includes curiosity, innovation, creativity, and the urge to explore and discover. All the cultures of the world have myths and legends about great explorers and pathfinders.

Thus, the caveman principle recognizes that our core personalities have not changed much in two hundred thousand years, so even as we spread out among the stars, we will most likely retain our values and personal characteristics.

Furthermore, psychologists have noted that there might be an image of what is attractive that is encoded in our brain. If we take photographs of hundreds of different people at random and then, using computers, superimpose these pictures on top of one another, we see a composite, average image that emerges. Surprisingly, this image is considered by many to be attractive. If true, this implies that there is an average image that might be hardwired in our brains that determines what we consider to be attractive. What we consider to be beautiful in a person’s face is actually the norm, not the exception.

But what happens when we finally attain Type III status and have the capability of faster-than-light travel? Will we spread the values and aesthetics of our world across the galaxy?

TRANSITION TO TYPE III

Eventually, a Type II civilization may exhaust the power of not just its home star but all the nearby stars and gradually start the journey to become a Type III civilization, which is galactic. Not only can a Type III civilization harvest the energy from billions of stars, it can also harness the energy of black holes, like the supermassive one located at the center of the Milky Way galaxy, which weighs as much as two million suns. If a starship travels in the direction of our galactic nuclei, we find a vast collection of dense stars and dust clouds that would be an ideal source of energy for a Type III civilization. To communicate across the galaxy, such an advanced civilization may use gravity waves, which were first predicted by Einstein in 1916 but finally detected by physicists in 2016. Unlike laser beams, which might be absorbed, scattered, and diffused as they travel, gravity waves would be able to spread across the stars and galaxy and therefore may be more reliable over great distances.

It is unclear at this point whether faster-than-light travel is feasible, so we need to consider for the moment the possibility that it is not.

If only sub-light spacecraft are possible, then a Type III civilization may decide to explore the billions of worlds in their galactic backyard by sending self-replicating probes that travel at sub-light speeds to the stars. The idea is to place these robotics on a distant moon. Moons make an ideal choice because their environments are more stable, without erosion, and they are easy to land on and leave from, because of their low gravity. With solar collectors to supply energy, a lunar probe can scan the solar system and radio back useful information indefinitely.

Once it has landed, the probe will create a factory from the lunar material in order to manufacture a thousand copies of itself. Each clone in the second generation then blasts off to colonize other distant moons. So, starting with one robot, we then have a thousand. If each of them creates another thousand robots, then we have a million. Then a billion. Then a trillion. In just a few generations, we can have an expanding sphere containing quadrillions of these devices, which scientists call von Neumann machines.

This in fact is the plot of the movie 2001, which even today portrays perhaps the most realistic encounter with an alien intelligence. In that movie, aliens put a von Neumann machine, the monolith, on the moon, which sends signals to a relay station based on Jupiter in order to monitor and even influence the evolution of humanity.

So our first encounter may not be with a bug-eyed monster but with a small self-replicating probe. This could be quite small, miniaturized by nanotechnology, perhaps so small that you would not even notice it. Conceivably, in your backyard or on the moon, there is evidence of a past visitation that is nearly invisible.

In fact, Professor Paul Davies has made a proposal. He wrote an article advocating going back to the moon in order to search for anomalous energy signatures or radio transmissions. If a von Neumann probe landed on the moon millions of years ago, it would likely use sunlight for its power, so it could continually broadcast radio emissions. And since the moon has no erosion, chances are it will be in near-perfect working condition and may still be in operation.

Since there is renewed interest in going back to the moon and then on to Mars, this would give scientists an excellent opportunity to see if any evidence exists for the presence of previous visitations.

(Some people, like Erich von Däniken, have claimed that alien ships already landed centuries ago and that these alien astronauts are depicted in the artwork of ancient civilizations. They claim that the elaborate headdresses and costumes often found in ancient paintings and monuments are actually depictions of ancient astronauts, with their helmets, fuel tanks, pressure suits, et cetera. While this idea cannot be dismissed, it is very difficult to prove. Ancient paintings are not enough. We need positive, tangible proof of previous visitations. For example, if there were alien spaceports, there must be debris and waste left over, in the form of wires, chips, tools, electronics, garbage, and machinery. One alien chip would settle this entire debate. So if one of your acquaintances claims to have been abducted by aliens from space, tell him or her to steal something from the ship the next time it happens.)

So even if light speed cannot be broken, a Type III civilization could have trillions upon trillions of probes spread across the entire galaxy within a few hundred thousand years, all sending back useful information.

Von Neumann machines may be the most efficient way for a Type III civilization to obtain information concerning the state of the galaxy. But there is yet another way to explore the galaxy more directly, and this is through something I call “laser porting.”

LASER PORTING TO THE STARS

One of the dreams of science fiction writers is to be able to explore the universe as pure-energy beings. Perhaps one day, far in the future, we might be able to shed our material existence and roam the cosmos, riding on a beam of light. We would be able to travel to distant stars at the fastest possible velocity. When we are free of material constraints, we would be able to ride alongside comets, skim the surface of erupting volcanoes, fly past the rings of Saturn, and visit destinations on the other side of the galaxy.

Instead of being a flight of fantasy, this dream may actually be rooted in solid science. In chapter 10, we analyzed the Human Connectome Project, the ambitious effort to map the entire brain. Perhaps late in this century or early in the next, we will have the complete map, which in principle will contain all our memories, sensations, feelings, even our personality. Then the connectome might be placed on a laser beam and sent into outer space. All the information necessary to create a digital copy of your mind can travel across the heavens.

In one second, your connectome could be sent to the moon. Within minutes it could reach Mars. Within hours, it could reach the gas giants. And within four years, you could visit Proxima Centauri. Within a hundred thousand years, you could reach the ends of the Milky Way galaxy.

Once it arrives on a distant planet, the information on the laser beam would be downloaded into a mainframe computer. Then your connectome could control a robotic avatar. Its body is so sturdy that it can survive even if the atmosphere is poisonous, the temperature is freezing or hellish, or the gravity strong or weak. So although all your neural patterns are contained inside the mainframe computer, you have all the sensations coming from the avatar. For all intents and purposes, you are inhabiting it.

The advantage of this approach is that there is no need for messy, expensive booster rockets or space stations. You never face the problem of weightlessness, asteroid collisions, radiation, accidents, and boredom because you are transmitted as pure information. And at the speed of light, you have taken the fastest possible journey to the stars. From your point of view, the trip is instantaneous. All you remember is entering the laboratory and then instantly arriving at your destination. (This is because time effectively stops while riding on the light beam. Your consciousness is frozen as you move at the speed of light, so you travel across the cosmos without any time delay. This is quite different from suspended animation, since when traveling at the speed of light, as I mentioned, time effectively stops. And while you would not see the sights while you were in transit, you could stop at any relay station and observe your surroundings.)

I call this “laser porting,” and it is perhaps the most convenient and rapid way to reach the stars. A Type I civilization a century from now may be able to conduct the first laser porting experiments. But for Type II and III civilizations, laser porting may be the preferred method of transportation across the galaxy because they will most likely have already colonized distant planets with self-replicating robots. Perhaps a Type III civilization would have a vast laser porting superhighway connecting the stars in the Milky Way galaxy with trillions of souls in transit at any one time.

Although this idea seems to provide the most convenient way to explore the galaxy, to actually create the laser port requires solving several practical problems.

Placing your connectome on a laser beam is not a problem, since lasers can in principle transport unlimited amounts of information. The main problem is to create a network of relay stations along the way that receive your connectome, amplify it, and send it along to the next station. As we mentioned, the Oort Cloud extends several light-years from a star, so the Oort Clouds from different stars can overlap. Thus, stationary comets in the Oort Cloud may provide ideal sites for these relay stations. (Creating relay stations on Oort Cloud comets would be preferable to placing them on a distant moon, since moons orbit around planets and are often obscured by them, while these comets are stationary.)

As we’ve seen, these relay stations can only be set up at slower-than-light-speed velocities. One way to solve this problem is to use a system of laser sails, which travel at a significant fraction of the speed of light. Once these laser sails land on an Oort Cloud comet, they could use nanotechnology to make copies of themselves and assemble a relay station using the raw materials found on the comet.

So although the original relay stations would have to be made at sub-light speeds, after that our connectomes could be free to roam at light speed.

Laser porting could be used not only for scientific purposes but also for recreation. We might take a vacation among the stars. We would first map out a sequence of planets, moons, or comets we wish to visit, no matter how hostile or dangerous the environment may be. We might make a checklist of the types of avatars that we wish to inhabit. (These avatars do not exist in virtual reality but are actual robots endowed with superhuman powers.) So on each planet, there is an avatar waiting for us with all the traits and superpowers we desire. When we reach that planet, we assume the identity of that avatar, travel across the planet, and enjoy all the incredible sights. Afterward, we return the robot for the next customer to use. Then we laser-port to the next destination. In a single vacation, we may be able to explore several moons, comets, and exoplanets. We never have to worry about accidents or illnesses, since it is just our connectome roaming across the galaxy.

So when we gaze into the heavens at night wondering if anyone is out there, although it may appear to be cold, still, and empty, perhaps the night sky is teeming with trillions of travelers being sent at the speed of light across the heavens.

WORMHOLES AND THE PLANCK ENERGY

This, however, leaves open the second possibility, that faster-than-light travel might be possible for a Type III civilization. A new law of physics enters into this picture. This is the realm of the Planck energy, the scale at which bizarre new phenomena occur that violate the usual laws of gravity.

To understand why the Planck energy is so important, it is essential to realize that at present all known physical phenomena, from the Big Bang to the motion of subatomic particles, can be explained by two theories: Einstein’s general theory of relativity and the quantum theory. Together, they represent the bedrock physical laws governing all matter and energy. The first, general relativity, is the theory of the very big: relativity explains the Big Bang, the properties of black holes, and the evolution of the expanding universe. The second is the theory of the very small: the quantum theory describes the properties and motion of atomic and subatomic particles that make possible all the electronic miracles in our living room.

The problem is that these two theories cannot be united into a single comprehensive one. They are quite dissimilar, based on different assumptions, different mathematics, and different physical pictures.

If a unified field theory were possible, the energy at which unification would take place is the Planck energy. This is the point at which Einstein’s theory of gravity breaks down completely. It is the energy of the Big Bang and the energy at the center of a black hole.

The Planck energy is 10¹⁹ billion electron volts, which is a quadrillion times the energy produced by the Large Hadron Collider at CERN, the most powerful particle accelerator on Earth.

At first, it would seem hopeless to probe the Planck energy, since it is so enormous. But a Type III civilization, which has more than 10²⁰ times more energy than a Type I civilization, has enough power to do so. So a Type III civilization may be able to play with the fabric of space-time and bend it at will.

They may reach this incredible energy scale by creating a particle accelerator much bigger than the Large Hadron Collider. The LHC is a circular tube in the shape of a doughnut seventeen miles in circumference, surrounded by huge magnetic fields.

When a stream of protons is injected into the LHC, the magnetic fields bend their path into a circle. Then pulses of energy are periodically sent into the doughnut, causing them to accelerate. There are two beams of protons traveling inside the tube in opposite directions. When they reach maximum velocity, they collide head-on, unleashing the energy of fourteen trillion electron volts, the largest burst of energy ever created artificially. (This collision is so powerful that some people have worried that perhaps it might open up a black hole that could consume the Earth. This is not a valid concern. In fact, there are naturally occurring subatomic particles that hit the Earth all the time with energies much larger than fourteen trillion electron volts. Mother Nature can hit us with cosmic rays far more powerful than the puny ones created in our labs.)

BEYOND THE LHC

The LHC has made many headlines, including the discovery of the elusive Higgs boson, which won the Nobel Prize for two physicists, Peter Higgs and Francois Englert. One of the main purposes of the LHC was to complete the last piece of the puzzle, called the Standard Model of particles, which is the most advanced version of the quantum theory and gives us a complete description of the universe at low energies.

The Standard Model is sometimes called “the theory of almost everything” because it accurately describes the low-energy universe that we see around us. But it cannot be the final theory, for several reasons:

1. It makes no mention of gravity. Worse, when we combine the Standard Model with Einstein’s theory of gravity, the hybrid theory blows up, giving us nonsense (calculations become infinite, meaning that the theory is useless).

2. It has a strange collection of particles that seem quite contrived. It has thirty-six quarks and anti-quarks, a series of Yang-Mills gluons, leptons (electrons and muons), and Higgs bosons.

3. It has nineteen or so free parameters (masses and couplings of particles) that have to be put in by hand. These masses and couplings are not determined by the theory; no one knows why they have these numerical values.

It’s hard to believe that the Standard Model, with its motley collection of subatomic particles, is nature’s final theory. It’s like taking Scotch tape and wrapping up a platypus, aardvark, and whale and calling it Mother Nature’s finest creation, the end product of millions of years of evolution.

The next big particle accelerator currently in the planning stage is the International Linear Collider (ILC), consisting of a straight tube approximately thirty miles long in which beams of electrons and anti-electrons will collide. The current plan is that it will be based in the Kitakami Mountains of Japan and is expected to cost roughly $20 billion, of which half will be supplied by the Japanese government.

Although the maximum energy of the ILC will be only one trillion electron volts, in many ways it will be superior to the LHC. When smashing protons into each other, the collision is extremely difficult to analyze because the proton has a complicated structure. It contains three quarks, held together by particles called “gluons.” The electron, however, has no known structure. It looks like a point particle. Therefore, when an electron collides with an anti-electron, it is a clean, simple interaction.

Even with these advances in physics, our Type 0 civilization cannot directly probe the Planck energy. But this is within the realm of a Type III civilization. Building accelerators like the ILC may be a crucial step in being able to one day test how stable space-time is and determine whether we might be able to take shortcuts through it.

ACCELERATOR IN THE ASTEROID BELT

Eventually, an advanced civilization might build a particle accelerator the size of the asteroid belt. A circular beam of protons would be sent around the belt, guided by gigantic magnets. On Earth, particles are sent inside a large circular tube containing a vacuum. But since the vacuum of outer space is better than any vacuum on the Earth, this accelerator does not need a tube at all.

All it needs is a series of gigantic magnetic stations placed strategically around the belt, making a circular path for the proton beam. It is somewhat like a relay race. Each time the protons go past a station, a surge of electrical energy powers the magnets, which kick the proton beam so that it moves to the next station at the correct angle. Each time the proton beam passes by a magnetic station, more energy is pumped into the beam in the form of laser power, until it gradually reaches the Planck energy.

Once the accelerator attains this energy, it can focus that energy onto a single point. A wormhole should open up there. It would then be injected with enough negative energy to stabilize it so it doesn’t collapse.

What might a trip through the wormhole look like? No one knows, but an educated guess was made by the physicist Kip Thorne of Caltech when he helped to advise the directors of the film Interstellar. Thorne used a computer program to trace the paths of light beams as they went past one, so that you could get a visual feeling for what this trip might look like. Unlike the usual cinematic representations, this was the most rigorous attempt yet to visualize this journey on film.

(In the movie, as you approach a black hole, you see a gigantic black sphere, called the event horizon. As you go through the event horizon, you pass the point of no return. Inside the black sphere lies the black hole itself, a tiny point of incredible density and gravity.)

In addition to building gigantic particle accelerators, there are a few other ways that physicists have considered exploiting wormholes. One possibility is that the Big Bang was so explosive that it might have inflated tiny wormholes that existed in the infant universe 13.8 billion years ago. When the universe began to expand exponentially, these wormholes may have expanded with it. This means that, although at present no one has ever seen one, they might be a naturally occurring phenomenon. Some physicists have speculated about how to go about finding one in space. (To find a naturally occurring wormhole, which is the subject of several Star Trek episodes, one would look for an object that distorts the passage of starlight in a particular way, perhaps so it resembles a sphere or a ring.)

As a starship enters a wormhole, it must withstand intense radiation due to quantum fluctuations. In principle, only string theory has the ability to calculate the fluctuations, so you can determine if you will survive. Credit 9

Another possibility, also explored by Kip Thorne and his collaborators, is to find a tiny one in the vacuum and then expand it. Our latest understanding of space is that it may be frothing with tiny wormholes as universes spring into existence and then vanish again. So if you had enough energy, you might be able to manipulate a preexisting wormhole and inflate it.

There is one problem, however, with all these proposals. The wormhole is surrounded by particles of gravity, called gravitons. As you are about to pass through it you will encounter quantum corrections in the form of gravitational radiation. Normally, quantum corrections are small and can be ignored. But calculations show that these corrections are infinite as you pass through a wormhole, so the radiation would likely be lethal. Also the radiation levels are so strong that the wormhole may close, making a passage impossible. There is a debate among physicists today about how dangerous it might be to travel through a wormhole.

Einstein’s relativity is no longer of any use as we enter the wormhole. Quantum effects are so large that we need a higher theory to take us through. Currently the only one capable of doing this is string theory, which is one of the strangest ever proposed in physics.

QUANTUM FUZZINESS

What theory can unify general relativity and the quantum theory at the Planck energy? Einstein spent the last thirty years of his life chasing after a “theory of everything” that could allow him to “read the mind of God,” but he failed. This remains one of the biggest questions facing modern physics. The solution will reveal some of the most important secrets of the universe, and, using it, we may be able to explore time travel, wormholes, higher dimensions, parallel universes, even what happened before the Big Bang. Furthermore, the answer will determine whether or not humanity can travel the universe at faster-than-light velocities.

To understand this, we have to understand the basis of the quantum theory, the Heisenberg uncertainty principle. This innocent sounding principle states that no matter how sensitive your instruments, you can never know both the velocity and position of any subatomic particle, say an electron. There is always a quantum “fuzziness.” Thus, a startling picture emerges. An electron is actually a collection of different states, with each state describing an electron in a different position with a different velocity. (Einstein hated this principle. He believed in “objective reality,” which is the commonsense notion that objects exist in definite, well-defined states and that you can determine the exact position and velocity of any particle.)

But quantum theory states otherwise. When you look in a mirror, you are not seeing yourself as you really are. You are made up of a vast collection of waves. So the image you see in the mirror is actually an average, a composite of all these waves. There is even a small probability that some of these waves can spread out all over your room and into space. In fact, some of your waves can even spread out to Mars or beyond. (One problem we give our Ph.D. students is to calculate the probability that some of your waves spread out to Mars and that one day you will get out of bed and wake up on the Red Planet.)

These waves are called “quantum corrections” or “quantum fluctuations.” Normally, these corrections are small, so the commonsense notion is perfectly fine, since we are a collection of atoms and can only see averages. But at the subatomic level, these quantum corrections can be large, so that electrons can be several places at the same time and exist in parallel states. (Newton would be shocked if you explained to him how the electrons in transistors can exist in parallel states. These corrections make modern electronics possible. So if we could somehow turn off this quantum fuzziness, all of these marvels of technology would stop functioning and society would be thrown almost a hundred years into the past, before the electric age.)

Fortunately, physicists can calculate these quantum corrections for subatomic particles and make predictions for them, some of which are valid to incredible accuracy, to one part in ten trillion. In fact, the quantum theory is so accurate that it is perhaps the most successful theory of all time. Nothing else can match its accuracy when applied to ordinary matter. It may be the most bizarre theory ever proposed in history (Einstein once said that the more successful the quantum theory becomes, the stranger it becomes), but it has one small thing going for it: it is undeniably correct.

So the Heisenberg uncertainty principle forces us to reevaluate what we know about reality. One result is that black holes cannot really be black. Quantum theory says that there must be quantum corrections to pure blackness, so black holes are actually gray. (And they emit a faint radiation called Hawking radiation.) Many textbooks say that at the center of a black hole, or at the beginning of time, there is a “singularity,” a point of infinite gravity. But infinite gravity violates the uncertainty principle. (In other words, there is no such thing as a “singularity”; it is simply a word we invent to disguise our ignorance about what occurs when the equations don’t work out. In the quantum theory, there are no singularities because there is a fuzziness that prevents knowing the precise location of the black hole.) Similarly, it is often stated that a pure vacuum is a state of pure nothingness. The concept of “zero” violates the uncertainty principle, so there is no such thing as pure nothingness. (Instead, the vacuum is a cauldron of virtual matter and antimatter particles constantly springing in and out of existence.) And there is no such thing as absolute zero, the temperature at which all motion stops. (Even as we approach it, atoms continue to move slightly, which is called the zero-point energy.)

When we try to formulate a quantum theory of gravity, a problem occurs, however. The quantum corrections to Einstein’s theory are described by particles we call “gravitons.” Just like a photon is a particle of light, a graviton is a particle of gravity. Gravitons are so elusive that they have never been seen in the laboratory. But physicists are confident that they do exist, since they are essential to any quantum theory of gravity. When we try to calculate with these gravitons, however, we find that quantum corrections are infinite. Quantum gravity is riddled with corrections that blow up the equations. Some of the greatest minds in physics have tried to solve this problem, but all have failed.

So this is one goal of modern physics: to create a quantum theory of gravity where the quantum corrections are finite and calculable. In other words, Einstein’s theory of gravity allows for the formation of wormholes, which may one day give us shortcuts through the galaxy. But Einstein’s theory cannot tell us if these wormholes are stable or not. To calculate these quantum corrections, we need a theory that combines relativity with the quantum theory.

STRING THEORY

So far, the leading (and only) candidate to solve this problem is something called string theory, which says that all matter and energy in the universe is composed of tiny strings. Each vibration of the string corresponds to a different subatomic particle. So the electron is not really a point particle. If you had a supermicroscope, you would see that it is not a particle at all but a vibrating string. The electron appears to be a point particle only because the string is so tiny.

If the string vibrates at a different frequency, it corresponds to a different particle, such as a quark, mu meson, neutrino, photon, and so on. That is why physicists have discovered such a ridiculous number of subatomic particles. There are literally hundreds, all because they are just different vibrations of a tiny string. In this way, string theory can explain the quantum theory of subatomic particles. According to string theory, as the string moves, it forces space-time to curl up exactly as Einstein predicted, and hence it unifies Einstein’s theory and the quantum theory in a very pleasing fashion.

This means that subatomic particles are just like musical notes. The universe is a symphony of strings, physics represents the harmonies of these notes, and the “mind of God” that Einstein chased after for so many decades is cosmic music resonating through hyperspace.

So how does string theory banish the quantum corrections that have bedeviled physicists for decades? String theory possesses something called “supersymmetry.” For every particle, there is a partner: a superparticle or “sparticle.” For example, the partner of the electron is the “selectron.” The partner of the quark is the “squark.” So we have two types of quantum corrections, those coming from ordinary particles and those from the sparticles. The beauty of string theory is that the quantum corrections coming from these two sets of particles exactly cancel each other out.

Thus, string theory gives us a simple but elegant way to eliminate these infinite quantum corrections. They vanish because the theory reveals a new symmetry that gives the theory its mathematical power and its beauty.

To artists, beauty may be an ethereal quantity that they aspire to capture in their works. But to a theoretical physicist, beauty is symmetry. It is also an absolute necessity when probing the ultimate nature of space and time. For example, if I have a snowflake and rotate it by 60 degrees, the snowflake remains the same. In the same way, a kaleidoscope creates beautiful patterns because it uses mirrors to repeatedly duplicate an image so it fills up 360 degrees. We say that the snowflake and kaleidoscope both possess radial symmetry; that is, they remain the same after a certain radial rotation.

Let’s say I have an equation containing many subatomic particles and then I shuffle or rearrange them among one another. If the equation remains the same after interchanging these particles, I would then say that the equation has a symmetry.

THE POWER OF SYMMETRY

Symmetry is not just a matter of aesthetics. It is a powerful way to eliminate imperfections and anomalies in your equations. If you rotate the snowflake, you can rapidly spot any defects by comparing the rotated version with the original. If they are not the same, then you have a problem that needs correcting.

In the same way, when constructing a quantum equation, we often find that a theory is infested with tiny anomalies and divergences. But if the equation has a symmetry, then these defects are eliminated. In the same way, supersymmetry takes care of the infinities and imperfections often found in a quantum theory.

As a bonus, it turns out that supersymmetry is the largest symmetry ever found in physics. Supersymmetry can take all known subatomic particles and mix them together or rearrange them while preserving the original equation. In fact, supersymmetry is so powerful that it can take Einstein’s theory, including the graviton and the subatomic particles of the Standard Model, and rotate them or interchange them. This gives us a pleasing and natural way to unify Einstein’s theory of gravity and subatomic particles.

String theory is like a gigantic cosmic snowflake, except that each prong of the snowflake represents the entire set of Einstein’s equations and the Standard Model of subatomic particles. So each prong of the snowflake represents all the particles of the universe. As we rotate the snowflake, all the particles of the universe are interchanged. Some physicists have noted that even if Einstein had never been born, and billions of dollars were never spent on smashing atoms to create the Standard Model, then all of twentieth-century physics might have been discovered if you simply possessed string theory.

Most important, supersymmetry cancels the quantum corrections of particles with those of sparticles, leaving us with a finite theory of gravity. That is the miracle of string theory. This also explains the answer to the question most often heard about string theory: Why does it exist in ten dimensions? Why not thirteen, or twenty?

This is because the number of particles in string theory can vary with the dimensionality of space-time. In higher dimensions, we have more particles, since there are more ways in which particles can vibrate. When we try to cancel the quantum corrections from the particles against the corrections from the sparticles, we find that this cancellation can happen only in ten dimensions.

Usually, mathematicians create new, imaginative structures that physicists later incorporate into their theories. For example, the theory of curved surfaces was worked out by mathematicians in the nineteenth century and was later incorporated into Einstein’s theory of gravity in 1915. But this time, the reverse happened. String theory has opened up so many new branches of mathematics that the mathematicians were startled. Young, aspiring mathematicians, who usually scorn applications of their discipline, have to learn string theory if they want to be on the cutting edge.

Although Einstein’s theory allows for the possibility of wormholes and faster-than-light travel, you need string theory to calculate how stable these wormholes are in the presence of quantum corrections.

In summary, these quantum corrections are infinite, so removing these infinities is one of the fundamental problems in physics. String theory eliminates these quantum corrections, because it has two types of quantum corrections that precisely cancel each other. This precise cancellation between particles and sparticles is due to supersymmetry.

However, as elegant and powerful as string theory is, it is not enough; it must ultimately face the final challenge, which is experiment.

CRITICISMS OF STRING THEORY

Although this picture is compelling and persuasive, there are valid criticisms one can make of the theory. First, since the energy at which string theory (or any theory of everything for that matter) unifies all of physics is the Planck energy, no machine on Earth is powerful enough to rigorously test it. A direct test would involve creating a baby universe in the laboratory, which is obviously out of the question given current technology.

Second, like any physical theory, it has more than one solution. For example, Maxwell’s equations, which govern light, have an infinite number of solutions. This is not a problem because, at the very beginning of any experiment, we specify what we are studying, whether it’s a light bulb, laser, or a TV. Then later, given these initial conditions, we solve the equations of Maxwell. But if we have a theory of the universe, then what are its initial conditions? Physicists believe that a “theory of everything” should dictate its own initial state, that is, they would prefer that the initial conditions of the Big Bang somehow emerge from the theory itself. String theory, however, does not tell you which of its many solutions is the correct one for our universe. And, without initial conditions, string theory contains an infinite number of parallel universes, called the multiverse, each one as valid as the next. So we have an embarrassment of riches, with string theory predicting not only our own familiar universe but perhaps an infinite number of other equally valid alien universes as well.

Third, perhaps the most startling prediction of string theory is that the universe is not four-dimensional at all but exists in ten dimensions. In all of physics, nowhere have we seen a prediction this bizarre, a theory of space-time that selects out its own dimensionality. This was so strange that many physicists at first dismissed it as science fiction. (When string theory was first proposed, the fact that it could only exist in ten dimensions was a source of ridicule. Nobel laureate Richard Feynman, for example, would tease John Schwarz, one of the founders of string theory, by asking him, “So John, how many dimensions are we in today?”)

LIVING IN HYPERSPACE

We know that any object in our universe can be described by three numbers: length, width, and height. If we add time, then four numbers can describe any event in the universe. For example, if I want to meet someone in New York City, I might say that we should meet at Forty-Second Street and Fifth Avenue, on the tenth floor, at noon. But to a mathematician the need for only three or four coordinates might seem arbitrary, since there is nothing special about three or four dimensions. Why should the most fundamental feature of the physical universe be described by such ordinary numbers?

So mathematicians have no problem with string theory. But to visualize these higher dimensions, physicists often use analogies. When I was a child, I used to spend many hours gazing at the Japanese Tea Garden in San Francisco. Watching the fish swim in the shallow pond, I asked myself a question that only a child would ask: “What would it be like to be a fish?” What a strange world they would see, I thought. They would think the universe was only two-dimensional. They could only swim in this limited space by moving sideways, but never up or down. Any fish who dared mention a third dimension beyond the pond would be considered a crackpot. I then imagined there was a fish living in the pond who would scoff anytime someone mentioned hyperspace, since the universe was just what you could touch and feel, nothing more. Then I imagined grabbing that fish and lifting him into the world of “up.” What would he see? He would see beings moving without fins. A new law of physics. Beings breathing without water. A new law of biology. Then I imagined putting the scientist fish back into the pond and he would have to explain to the other fish the incredible creatures that live in the world of “up.”

Similarly, perhaps we are the fish. If string theory is proven correct, it means that there are unseen dimensions beyond our familiar four-dimensional world. But where are these higher dimensions? One possibility is that six of the ten original dimensions have “curled up” so they cannot be seen anymore. Think of taking a sheet of paper and rolling it up into a tight tube. The original sheet was two-dimensional, but the rolling-up process has created a one-dimensional tube. From a distance, you only see the one-dimensional tube, but in reality it is still two-dimensional.

In the same way, string theory says that the universe was originally ten-dimensional, but for some reason six of these dimensions curled up, leaving us with the illusion that our world has only four. Although this feature of string theory seems fantastic, efforts are under way to actually measure these higher dimensions.

But how do higher dimensions help string theory unify relativity and quantum mechanics? If you try to unify the gravitational, nuclear, and electromagnetic forces into a single theory, you find that there is not enough “room” in four dimensions to do this. They are like pieces of a jigsaw puzzle that don’t fit together. But once you start to add more and more dimensions, you find enough room to assemble these lower theories, like matching jigsaw pieces together to make the whole.

For example, think of a two-dimensional world of Flatlanders, who, like cookie men, can only move left or right, but never “up.” Imagine that there was once a beautiful three-dimensional crystal that exploded, showering fragments onto Flatland. Over the years, the Flatlanders have reassembled this crystal into two large fragments. But as hard as they try, they are unable to fit these last two fragments together. Then one day, a Flatlander makes the outrageous proposal that if they move one fragment “up,” into the unseen third dimension, then the two fragments would fit together and form a beautiful three-dimensional crystal. So the key to re-creating the crystal was moving the fragments through the third dimension. By analogy, these two fragments are relativity theory and the quantum theory, the crystal is string theory, and the explosion was the Big Bang.

Even though string theory fits the data neatly, we still need to test it. Although as discussed a direct test is not possible, most physics is done indirectly. For example, we know that the sun is made mainly of hydrogen and helium, yet no one has ever visited the sun. We know the sun’s composition because we analyze it indirectly, looking at sunlight through a prism, which breaks it up into bands of colors. By studying these bands within the rainbow, we can identify the fingerprint of hydrogen and helium. (In fact, helium was not found on Earth first. In 1868, scientists discovered evidence of a strange new element when analyzing sunlight during an eclipse, which was christened “helium,” meaning “metal from the sun.” It wasn’t until 1895 that direct evidence of helium was discovered on the Earth, when scientists realized it was a gas and not a metal.)

DARK MATTER AND STRINGS

In the same way, string theory might be proven via a variety of indirect tests. Since each vibration of the string corresponds to a particle, we can in our particle accelerators search for entirely new particles that represent higher “octaves” of the string. The hope is that by smashing protons together at trillions of volts, you briefly create a new particle among the debris that is predicted by string theory. This, in turn, may help explain one of the great unsolved problems in astronomy.

In the 1960s, when astronomers examined the rotation of the Milky Way galaxy, they found something strange. It was rotating so fast that, by Newton’s laws, it should fly apart, yet the galaxy has been stable for about ten billion years. In fact, the galaxy rotated about ten times faster than it should according to traditional Newtonian mechanics.

This posed a tremendous problem. Either Newton’s equations were wrong (which was almost unthinkable) or there was an invisible halo of unknown matter surrounding the galaxies, increasing their mass sufficiently for gravity to hold them together. This meant that perhaps the pictures we see of gorgeous galaxies with their beautiful spiral arms are incomplete, that they are actually surrounded by a gigantic invisible halo that is ten times more massive than the visible galaxy. Since photographs of galaxies only show the beautiful swirling mass of stars, whatever is holding the mass together must not interact with light—it must be invisible.

Astrophysicists dubbed this missing mass “dark matter.” Its existence forced them to revise their theories, which said that the universe is made mainly of atoms. We now have maps of dark matter throughout the universe. Although it is invisible, it bends starlight just as anything with mass should. Therefore, by analyzing the distortion of starlight surrounding galaxies, we can use computers to calculate the presence of dark matter and map its distribution across the universe. Sure enough, this map shows that most of the total mass of a galaxy exists in this form.

In addition to being invisible, dark matter has gravity, but you can’t hold it in your hand. Since it does not interact with atoms at all (because it is electrically neutral) it will pass through your hand, the floor, and through the crust of the Earth. It would oscillate between New York and Australia as if the Earth did not exist at all, except that it would be bound by Earth’s gravity. So although dark matter is invisible, it still interacts via gravity with other particles.

One theory is that dark matter is a higher vibration of the superstring. The leading candidate is the superpartner of the photon, which is called the “photino,” or “little photon.” It has all the right properties to be dark matter: it is invisible because it does not interact with light, and yet it has weight and is stable.

There are several ways to prove this conjecture. The first is to create dark matter directly with the Large Hadron Collider by smashing protons into each other. For a brief instant of time, a particle of dark matter would be formed inside the accelerator. If this is possible, it would have enormous repercussions for science. It would represent the first time in history that a new form of matter has been found that is not based on atoms. If the LHC is not powerful enough to produce dark matter, then perhaps the ILC can.

There also is another way to prove this conjecture. The Earth is moving in a wind of this invisible dark matter. The hope is that a dark matter particle may smash into a proton inside a particle detector, creating a shower of subatomic particles that might be photographed. At present, there are physicists around the world patiently waiting to find the signature of a collision between matter and dark matter in their detectors. There is a Nobel Prize waiting for the first physicist to do so.

If dark matter is found, either with particle accelerators or with ground-based sensors, we will be able to compare its properties with those predicted by string theory. In this way, we will have evidence to evaluate the validity of the theory.

Although finding dark matter would be a great step toward proving string theory, other proofs are possible. For example, Newton’s law of gravity governs the motion of large objects like stars and planets, but little is known about the force of gravity acting over small distances, like a few inches or feet. Since string theory postulates higher dimensions, this means that Newton’s famous inverse square law (that gravity diminishes in proportion with the square of the distance) should be violated at small distances because Newton’s law is predicated on three dimensions. (If space were four-dimensional, for instance, then gravity should diminish in proportion to the inverse cube of the distance. So far, tests of Newton’s law of gravity have not shown any evidence of a higher dimension, but physicists aren’t giving up.)

Another possible avenue is to send gravity wave detectors into space. The Laser Interferometer Gravitational-Wave Observatory (LIGO) based in Louisiana and Washington State was successful in picking up gravity waves from colliding black holes in 2016 and colliding neutron stars in 2017. A modified version of the space-based Laser Interferometer Space Antenna (LISA) may be able to detect gravity waves from the instant of the Big Bang. The hope is that one might be able to “run the videotape backward” and make conjectures about the nature of the pre–Big Bang era. This would allow a crude test of some of the predictions of string theory concerning the pre–Big Bang universe.

STRING THEORY AND WORMHOLES

Still other tests of string theory may involve finding other exotic particles predicted by the theory, such as micro black holes, which resemble subatomic particles.

We have seen how physics allows us to speculate about civilizations far into the future, making reasonable conjectures based on their energy consumption. Civilizations can be expected to evolve from a Type I planetary civilization to a Type II stellar civilization and finally to a Type III galactic civilization. A galactic civilization, in turn, is likely to explore the galaxy via von Neumann probes or by laser porting their consciousness across the galaxy. The key point is that a Type III civilization may be able to access the Planck energy, the point where space-time becomes unstable and faster-than-light travel might be possible. But to calculate the physics of faster-than-light travel, we need a theory that goes beyond Einstein’s theory, which might well be string theory.

The hope is that using string theory, we will be able to calculate the quantum corrections necessary to analyze exotic phenomena such as time travel, interdimensional travel, wormholes, and what happened before the Big Bang. For example, assume that a Type III civilization is capable of manipulating black holes and thereby creating a gateway to a parallel universe through a wormhole. Without string theory, it is impossible to calculate what happens when you enter. Will it explode? Will gravitational radiation close it just as you enter it? Will you be able to pass through it and live to tell about it?

String theory should be capable of calculating how much gravitational radiation you would encounter when you pass through the wormhole and answer these questions.

Another hotly debated question among physicists is what happens if you enter a wormhole and go backward in time. If you then kill your grandfather before you are born, then you have a paradox. How can you exist at all if you just killed your ancestor? Einstein’s theory actually allows for time travel (if negative energy exists) but says nothing about how to resolve these paradoxes. String theory, because it is a finite theory in which everything can be calculated, should be able to resolve all these mind-twisting paradoxes. (My own strictly personal opinion is that the river of time forks into two rivers when you enter a time machine—in other words, the timeline splits. This means that you have killed someone else’s grandfather who looks just like your own grandfather but exists in another timeline in an alternate universe. So the multiverse resolves all time paradoxes.)

At present, however, because of the complexity of the mathematics of string theory, physicists have not been able to apply it to these questions. This is a mathematical problem, not an experimental one, so perhaps one day an enterprising physicist will be able to definitively calculate the properties of wormholes and hyperspace. Instead of idly speculating about faster-than-light travel, a physicist using string theory has the ability to determine whether this might be possible. But we will have to wait until the theory is sufficiently understood to make this determination.

END OF THE DIASPORA?

So there is a possibility that a Type III civilization may be able to use a quantum theory of gravity to achieve faster-than-light-speed spaceships.

But what are the implications of this for humanity?

Earlier, we noted that a Type II civilization, bound by the speed of light, may establish space colonies that eventually branch off, creating many distinct genetic lineages which may eventually lose all contact with the mother planet.

The question remains, What happens when a Type III civilization masters the Planck energy and begins to make contact with these branches of humanity?

History may repeat itself. For example, the Great Diaspora ended with the coming of the airplane and modern technology, giving us a rapid international transportation network. Today, we can take a short plane trip over continents that once took our ancestors tens of thousands of years to cross.

In the same way, when we make the transition from a Type II civilization to a Type III civilization, we will, by definition, have enough power to explore the Planck energy, the point at which space-time becomes unstable.

If we assume that this makes faster-than-light travel possible, it means that a Type III civilization might be able to unify the various Type II colonies that have spread out across the galaxy. Given our common human heritage, it may make possible the creation of a new galactic civilization, as envisioned by Asimov.

As we have seen earlier, the amount of genetic divergence that humanity may experience over several tens of thousands of years in the future is roughly the same as the divergence that has already occurred since the Great Diaspora. The key point is that we have maintained our humanity throughout. A young child, born in one culture, can easily grow up and mature in another totally different culture, even if the two cultures may be separated by a vast cultural chasm.

This also means that Type III archeologists, curious about ancient human migrations, may try to retrace the ancient migration routes of various branches of Type II civilizations across the galaxy. Galactic archeologists may look for signs of various ancient Type II civilizations.

In the Foundation saga, our heroes are in search of the ancestral planet that gave birth to the Galactic Empire, whose name and location were lost in the chaos of galactic prehistory. Given that the human population numbers in the trillions, with millions of inhabited planets, this seems like a hopeless task. But by exploring the most ancient planets in the galaxy, they find ruins of the earliest planetary colonies. They see how planets were abandoned because of wars, disease, and other calamities.

Likewise, a Type III civilization may emerge from a Type II civilization and try to retrace the various branches that were explored centuries earlier by sub-light-speed spaceships. In the same way that our current civilization is enriched by the presence of so many different types of cultures, each with a different history and perspective, a Type III civilization may be enriched by interacting with the many divergent civilizations that emerged during a Type II civilization.

So the creation of faster-than-light spaceships may make the dream of Asimov come true, unifying humanity into one galactic civilization.

As Sir Martin Rees has said, “If humans avoid self-destruction, the post-human era beckons. Life from Earth could spread through the entire galaxy, evolving into a teeming complexity far beyond what we can even conceive. If so, our tiny planet—this pale blue dot floating in space—could be the most important place in the entire Galaxy. The first interstellar voyagers from Earth would have a mission that would resonate through the entire Galaxy and beyond.”

But eventually any advanced civilization will have to face the ultimate challenge to their existence, which is the end of the universe itself. We have to ask the question, Can an advanced civilization, with all its vast technology, evade the death of everything there is? Perhaps the only hope for intelligent life is to evolve into a Type IV civilization.