A Hundred Billion Galaxies, and We're Still a Type 0.7 Civilization

Lex Fridman opens with Kaku's public bet that this century we may hear from aliens, or at least pick up their traffic. Kaku flags it as speculation at once, then reaches for a census rather than a feeling. Astronomers have already identified about 4,000 exoplanets. For the first time, he says, we have a census of the Milky Way: on average every star has a planet, and about one fifth of those planets are Earth-sized.

Do the math, he tells Fridman. A hundred billion stars in the galaxy times those fractions yields billions of potential Earth-sized worlds. Hubble's field of view holds about a hundred billion galaxies. Multiply again — a hundred billion galaxies times a hundred billion stars — and the total sits beyond what a human brain can picture. Against that background, the claim that we are the only ones is, in his word, ridiculous.

If contact comes, Kaku expects we will first intercept ordinary broadcasts — their *I Love Lucy*, their *Leave It to Beaver* — and then try to place the senders on the Kardashev scale. He is a physicist, so he ranks civilizations the way he ranks black holes and stars: by energy and information. Type One harnesses the power of a planet, steering weather, earthquakes, volcanoes, the plot of *Flash Gordon*. Type Two plays with entire stars, the energy budget of *Star Trek*'s Federation. Type Three roams galactic space lanes, the picture of *Star Wars*.

The ladder was supposed to stop there. After a talk at the London Planetarium, a boy walked up and told him he was wrong. There is a Type Four, the child said: the power of the continuum. Kaku's first reflex was to correct him — planets, stars, galaxies, that's it — but the boy would not drop it. Back home, Kaku asked whether *Star Trek*'s continuum pointed at a real extra-galactic energy source. The answer, he decided, is dark energy.

Seventy-three percent of the universe's energy is dark energy; dark matter is about 23 percent; ordinary matter, the stuff of people and planets, is 4 percent. We are the oddballs. Dark energy is the leftover shove of the Big Bang, the reason galaxies recede. The more empty space you have, the more repulsive energy you have, so the expansion accelerates — an exponential, de Sitter curve, the present state of the cosmos. Type Four would plug into that. Type Five would look for energy outside our universe altogether, in the multiverse.

Type Five is the multiverse because Kaku, as a quantum physicist, does not believe the Big Bang happened only once. A unique bang, he says, would violate the Heisenberg uncertainty principle. Inflation is itself a quantum theory, so there is a finite chance that universes are being born all the time, including as we speak. The picture is aesthetically pleasing to him for a private reason. He was raised Presbyterian; his parents were Buddhists. The two stories of the cosmos do not agree.

In Buddhism there is only nirvana: no beginning, no end, only timelessness. In Christianity there is an instant when God said, let there be light. He has carried those mutually exclusive pictures for decades and now thinks they can be fused. Our universe had a beginning. Other bubble universes sit in the same bath, expanding into a dimension beyond three-dimensional comprehension — eleven-dimensional hyperspace. Nirvana, in this telling, is that timeless hyperspace, where bangs keep happening.

He uses the same picture against a late argument of Stephen Hawking's. Hawking wrote that there is no God because the bang was instantaneous, leaving no time in which a creator could work. The multiverse restores a time before time: each bubble has its own clock. When two bubbles collide, or one buds a baby universe, that event is what we call the Big Bang. Creation becomes a collision, or a split, not a one-off miracle in a void.

The picture is not a hobby. String theory is Kaku's day job; the City of New York pays him to work on it, and string theory is already a multiverse theory. Every particle we see — electron, proton, quark — is a vibration on a tiny string. In the 1950s, atom smashers kept vomiting new particles until Robert Oppenheimer announced that the Nobel Prize should go to the physicist who did *not* discover one that year. Those particles, Kaku says now, were musical notes.

He pushes the metaphor as far as it will go. Physics is the harmonies you can write on vibrating strings. Chemistry is the melodies you can play on them. The universe is a symphony of strings. And the mind of God that Einstein spent his last thirty years writing about would be cosmic music resonating through eleven-dimensional hyperspace. Fridman asks what that mind is, and why we are here. Kaku quotes Steven Weinberg's line that the more we learn, the more pointless it looks, then declines to pretend he holds the secret.

What he will report is how the giants split God in two. Einstein rejected the personal God of the Bible — the one who answers prayers, walks on water, smites the Philistines — and believed in Spinoza's God: order, simplicity, harmony, beauty. The universe could have been ugly and random. Instead the known laws fit on a single sheet of paper. Einstein's equation is an inch long; string theory and the Standard Model run longer, but they still fit. Einstein imagined himself as a boy walking into a vast library, stunned by its elegance, able to read only the first page of the first volume.

Galileo, asked the same family of questions, drew a different line. The purpose of science is to determine how the heavens go; the purpose of religion is to determine how to go to heaven. Natural law on one side, ethics on the other. Trouble starts, Kaku says, when scientists pontificate about ethics and religious voices pontificate about natural law. Morality is not mandated by a law of physics. If you try to discuss right and wrong with a squirrel, there is no shared frame of reference.

That squirrel is also Kaku's model of first contact. Aliens who visit would try to talk to us the way we talk to squirrels in a forest, then lose interest because we do not talk back and have nothing to offer. Fridman still wants a friend-or-foe answer. Kaku's first reply is that they will mostly ignore us. If you are a deer, who should you fear more: the hunter with a 16-gauge shotgun, or the man with a briefcase and glasses? Instinct says the hunter. The developer is the one who flattens the forest.

H. G. Wells already wrote that version. In *The War of the Worlds* the invaders do not hate *Homo sapiens*. Humans are simply in the way. Kaku's personal belief — he says he cannot prove any of it — is that a truly advanced civilization would be peaceful, because Earth has so little worth taking. Gold is a mostly useless metal that happens to look pretty to us; squirrels do not care. Rare earths and platinum-group metals might matter for electronics. Beyond that, the cupboard is bare.

Culture travels even worse. People love Shakespeare, art, and poetry; off Earth those mean nothing. When Kaku writes down a string-theory equation, he hopes that on the other side of the galaxy an alien is writing the same equation in different notation. That alien would feel nothing in front of Shakespeare, Hemingway, or a poem. The only cargo that might survive an interstellar trip is an equation.

What would they even look like? Kaku does not start with science fiction. He asks how we became intelligent, and he counts three ingredients. First, stereo vision, the eyes of a hunter set on the front of the face, locking onto a target. Predators, he argues, are smarter than prey because ambush, camouflage, stealth, and deceit are cognitively expensive; rabbits, eyes on the sides of their heads, only have to run. Second, an opposable thumb, or a claw or tentacle — some organ that lets a creature manipulate the environment. Third, language. Mama bear never tells baby bear to avoid the human hunter. Each generation of bears starts over.

How many animals have all three? Just us. Primates have a language, capped at maybe twenty words. A human baby learns several words a day; a typical adult knows almost five thousand. Teach a gorilla any language, including its own, and the ceiling is still about twenty. Functionally, then, aliens will likely be descended from predators, able to work on the world, and able to hand knowledge to the next generation. Recognition is not guaranteed, because even *Homo sapiens* is about to change the template.

Robots already have the intelligence of a cockroach. In the coming years they may reach a mouse, then a rabbit, then a cat or dog. By the end of the century they will probably be as smart as a monkey. That is the dangerous rung. Monkeys are self-aware; they know they are monkeys and may have a different agenda. Dogs are confused: they think we are dogs, the top dog, which is why they whimper and lick. A monkey has no such illusion. Kaku's near-term fix is a chip that shuts a robot down when it has murderous thoughts. That window lasts about a hundred years. In two hundred, the machines will be smart enough to pull the chip. Rather than compete, he says, we should merge and become part cybernetic.

The first step of that merge is already in the lab. Scientists can record simple memories in mice and send them over the internet. Primates are next, at Wake Forest and in Los Angeles. After that comes a memory chip for Alzheimer's patients, who wander and lose the map of their own lives. Push a button, Kaku says, and memories flood back into the hippocampus: where they live, who they are. He thinks the chip is definitely in the cards. The longer arc is BrainNet, an internet that carries emotions, feelings, and sensations, so people communicate telepathically.

Entertainment is the canary. Charlie Chaplin was a giant of silent film; when the talkies arrived, audiences no longer wanted an actor who never spoke, and a generation of performers lost their jobs. The next replacement, Kaku argues, is BrainNet itself. Future audiences will ask who still wants a screen with images. Sound plus picture is the entire premise of a multi-billion-dollar industry. When memory and feeling can move on the same pipes, that premise collapses. Human relations change with it: empathy stops being an act of imagination and becomes an input.

Some people fear the connection will make relationships shallower. Kaku sees the opposite, a continuation of a curve that has been running for the whole species. For more than 90 percent of human history a person knew fifty to a hundred others — the tribe, the entire universe. Towns raised that to a few thousand. The telephone did the same at a distance. The internet reaches the population of the planet. BrainNet is the next segment, not a break.

He parts company with colleagues who call technology a neutral double-edged sword. The internet, in his telling, has a moral direction: it spreads knowledge, knowledge empowers, and people who learn they need not live under a dictatorship start to act. That spreads democracy, and democracies do not war with other democracies. He invites a sheet of paper and a list of every war from elementary school: kings, queens, emperors, dictators. Never two major democracies. Wars will not vanish — they are politics by other means — but he expects them to become less intense and less frequent. Existential risk from AI, he adds, is real, just not this century's homework. Grandchildren will face it as robots climb from dog to monkey.

The merge has a second half: we digitize ourselves. Medieval dualism split soul from body; when the body died, the soul went to heaven. Twentieth-century neuroscience scoffed — look at the brain and you see neurons, period. Now dualism is returning in another costume, because memories, feelings, and sensations can be copied. That effort is the Connectome Project, a bid to map every connection in a human brain, funded at billions of dollars alongside the genome. Silicon Valley is already ahead of the science in one grim sense: companies will digitize relatives so the living can finish a conversation with the dead.

We leave a digital trail our ancestors never did. They were lucky to get one line in a church book, a baptism and a death, a whole life squeezed into a few letters. We upload a sneeze. Kaku's proposal is to send the copy into space. Encode a digitized brain on a laser, fire it at the Moon, and you arrive in one second; Mars in twenty minutes; Pluto in eight hours. Breakfast in New York, a morning snack on the Moon, Mars by noon, the asteroid belt in the afternoon, dinner back in New York, all at the speed of light. No booster, no weightlessness, no meteorites. A lunar mainframe downloads the beam into an avatar — Superman, Superwoman, anything you like.

Up to that point, he stresses, everything sits inside the laws of physics. Then he sticks his neck out. He thinks the highway already exists: a laser superhighway outside Earth, billions of alien souls zapping across the galaxy. Are we smart enough to know? No. It could sit just outside Earth's orbit, and our instruments could neither prove nor disprove it unless the travelers sent a human-readable signal. They need not look like little green men. They can wear any avatar, including ours. Zookeepers already plant dummy animals so the real ones will not be afraid; those walnut-sized brains accept the fake. An alien civilization, looking at our tiny brains, would say the same.

Digital copies are one path. Biology is the other, and Kaku thinks artificial intelligence will hand us the key. In the coming decades everyone will have their genome sequenced. Billions of genomes, many from young people, will run through pattern-recognition systems — he analogizes to an MRI — hunting for age genes. The fountain of youth that emperors lusted after will, in this telling, be found by a machine. Aging, he says, is no longer a mystery. It is the buildup of errors. Cells slow, go into senescence, and die because mistakes accumulate in the genome and in cellular activity. CRISPR-type tools might fix those genes. Forever, perhaps.

Where does a car age? In the engine, where the moving parts are and where combustion happens. In a cell, combustion lives in the mitochondria. Repair the errors that pile up there, and immortality becomes a biological project rather than a metaphor. Fridman asks whether Kaku himself would take the deal. The answer is not a simple yes. Quality of life is the constraint, and Greek myth already filed the warning. Aurora, goddess of the dawn, loved the mortal Tithonus and begged Zeus to make him immortal. She forgot to ask for eternal youth. Tithonus grew older and more decrepit, a bag of bones who could never die.

Immortality is a fine idea, Kaku says, if youth comes with it. He believes — again, he cannot prove it — that grandchildren may reach thirty and stop, keeping the wisdom of age inside a healthy body for centuries. Fridman asks whether meaning itself depends on dying. Kaku's reply is that we already live inside that knowledge. Every waking moment we are aware of death, even when we do not name it. College is a corridor toward middle age, a career, retirement, and then the end. You graduate high school and college because a clock is running without your permission. That clock is what supplies urgency. He tries not to meditate on his own date. Once you do, you start altering your behavior to match the deadline you expect.

When Kaku interviews scientists on the radio, he asks what changed them, and how old they were. Nobel winners and laboratory directors give almost the same answer: ten. For Steven Weinberg it was a telescope. For Heinz Pagels a chemistry kit. For Isidor Rabi a planetarium. For Einstein a compass. Before ten, the universe is mommy and daddy. Around ten, a child wonders what lies beyond, and the epiphany lands: there is a universe out there, and it can be explored. That shock, he says, stays for life.

Then comes the trap. The greatest destroyer of scientists known to science is junior high school. Classmates say you like that nerdy stuff; friends shun you; you become the weirdo; science is made boring. Richard Feynman's father used to walk him through the forest and teach him everything about birds — shape, wings, color, beak — except the name. A bully asked the future Nobel winner what that bird was called. Feynman did not know. The bully asked if he was stupid. In that instant Feynman understood that for most people, science is giving names to birds.

Naming dinosaurs and plants is not science. Science is principles, concepts, physical pictures. Kaku's favorite Einstein line is that unless you can explain a theory to a child, the theory is probably worthless. Relativity is clocks, meter sticks, rockets, and locomotives. Newton's gravity is balls and spinning wheels. The distinguished scientists he meets in old age still remember the flush of that first telescope. The picture, not the vocabulary, is what survived junior high.

His own shock arrived at eight. Every newspaper carried the death of a great scientist and, on the front page, a photograph of a desk with an open book: the unfinished manuscript of the greatest scientist of the age. The boy could not understand why the man had not finished it. If you are a great scientist, isn't it homework? You go home, you solve it, or you ask your mom. The mystery outranked any adventure story. Years later he learned the name, Albert Einstein, and the book's title, the theory of everything. Today he can read the dead ends. Einstein lost his way on the third try because he had no physical picture. The first try, clocks and lightning, gave special relativity and the atomic bomb. The second, balls on curved surfaces, gave the Big Bang and black holes. On the third he kept saying he was still looking for the picture. He never found it. The picture, Kaku says, is string theory.

Why strings? Because nature has two hands that do not speak. The left hand is the theory of the small, quantum mechanics, atoms and quarks. The right hand is the theory of the large, relativity, black holes and bangs. One is built on discrete particles, the other on smooth surfaces, and they hate each other. The greatest minds of the era tried to force a handshake and failed. The only theory that has survived every challenge so far is string theory. That does not mean it is correct. It could be wrong. Right now it is the only game in town. People tell Kaku they do not believe it and demand an alternative. He tells them there is none. Get used to it.

Strings tempt people to treat the universe as a computer, and therefore as a simulation. Kaku does not. He does not think we are puppets on a screen after someone hit play. Even Newtonian mechanics says the weather, with its billions of atoms, cannot be simulated in a finite time. The smallest object that can describe the weather is the weather. The smallest object that can simulate a human is a human. Add quantum mechanics — all possible universes, a multiverse — and the calculation spirals out of control on any conventional machine.

There is one remaining argument, still debated, and it comes from black holes. Throw an encyclopedia into a black hole and the information is not lost; it ends up on the surface. That surface is finite, so the maximum information a black hole can store is a calculable number. If universes come out of black holes, each universe holds finite information, and all possible universes collapse to a number you could write on a sheet of paper — huge, Planck-length huge, but finite. If a computer could ever simulate that number, the universe would be a simulation. His intuition still says no: no computer can build a universe capable of simulating the entire universe except the universe itself. We are efficient. There are no shortcuts.

The second objection is blunter. Why would a super-intelligence simulate humans? Most of us, he says, are kind of stupid. We do crazy things and call them art, humor, civilization. Why go to all that effort to simulate *Saturday Night Live*? Fridman offers a softer version: set the initial conditions and the laws, walk away, and watch. Kaku notes that this is roughly how life started. In the 1950s Stanley Miller put hydrogen, methane, toxic gases, water, and a spark in a beaker, left for a few weeks, and found amino acids. Leave it years and you might get proteins; leave it millions of years and DNA might form. The universe is about 13.8 billion years old. That is plenty of time for accidents, including us. We are not, he is glad to add, the point of the exercise. Look to your left and right.

Closer to home, Fridman asks when a human steps on Mars. Kaku gives it a good chance in twenty or thirty years. There is no physics obstacle, only a difficult and dangerous engineering problem. By the end of the century he expects the first starships, and they will not look like the *Enterprise*. They will be tiny chips fired by lasers, with parachutes, in the spirit of the Breakthrough Starshot program Stephen Hawking backed: 20 percent of light speed, Alpha Centauri in about twenty years. Beyond that sits fusion, in some sense the ultimate energy source, still unstable, still not here.

Stars form almost for free. A large enough cloud of gas collapses, and you have a star. On Earth the same reaction is hard because a star is a monopole, spherically symmetric, easy to compress. Magnetism is bipolar — north pole, south pole — so squeezing plasma with magnets is like squeezing a long balloon: pinch one end and the other bulges. Anomalies appear because the squeeze is not uniform. Kaku still thinks fusion is inevitable, and that it will give unlimited energy from seawater: extract hydrogen, burn it, no meltdown, no nuclear waste. Fission produces about thirty tons of hot waste per reactor per year, dangerous for thousands or millions of years. Fusion's waste is helium, which you can sell.

Master fusion and you brush Type One. We are Type Zero, Kaku says, still living on dead plants — oil and coal. Carl Sagan put us at about 0.7, and Kaku thinks we are perhaps a hundred years from 1.0. The first Type One technology is already here: the internet, the first truly planetary tool. Type One languages on that network are already English and Mandarin. Type One sport is soccer and the Olympics. Type One youth music is rock and rap. Type One fashion is Gucci and Chanel. Type One economy is the European Union, NAFTA, the rest of the transnational stacking. Culture, language, and markets are knitting together on a planetary scale; the energy source will follow, and then the pattern will spill off the planet.

Why bother with Mars at all? Because the dinosaurs did not have a space program, and that is why they are not in the room. We do, which means we have an insurance policy. He immediately adds a brake: do not bankrupt or hollow out Earth to get there. What is needed is a settlement, a backup if something happens at home, which means terraforming. Raise Mars's average temperature by six degrees and the polar ice caps begin to melt, releasing water vapor, a greenhouse gas, which melts more ice. The loop is autocatalytic. Once it runs, liquid water can fill the old rivers and an ocean astronomers think was about the size of the United States. Elon Musk has floated hydrogen warheads on the caps. Kaku is not sure: the side effects are poorly understood, and who wants to read the newspaper by that glow. He prefers solar satellites that beam sunlight onto the ice. Mars has plenty of water. It is just frozen.