When considering extraterrestrial intelligence, most science fiction tends to think of intelligent beings inhabiting protoplasmic bodies. Those protoplasmic bodies may look very odd, with all kinds of weird appendages and strange facial features. But the basic model of consciousness is not radically different from mind as we know it: a single consciousness inhabiting a single protoplasmic body. But there are many other very different possibilities.
The universe is believed to be about three times the age of our planet. Intelligent life may have evolved on other planets many millions or billions of years before it appeared on our planet. Having had vast eons to develop, intelligence may have evolved into strange forms vastly different from the “single brain in a single body” that we are used to considering. Let us consider some of the possibilities.
Group minds. On some planets, the minds of individual organisms may be united into some kind of group mind or planetary consciousness. Such a group mind could be a permanent linking, as imagined by the Star Trek series, with its depiction of the Borg. Or such a group mind may be only a temporary linking, something to be achieved on only particular occasions. We can imagine a planet in which people are individuals 90% of the time, but become linked into a group mind 10% of the time.
Planetary electronic minds. On some planets, there may be no individual bodies with minds. There may be a single electronic planetary mind. Such a planetary mind may have an army of robots at its command to fulfill its wishes. Such robots may have no consciousness of their own, but may be merely agents of the planetary electronic mind. If you were to connect ten robots to a human mind, the human would not be able to productively do the multitasking needed to operate those ten robots at the same time. But an electronic planetary supermind might have no such problem, and might be able to control thousands or millions of robots at the same time.
Body-switching minds. Once some alien civilization has learned the secrets of consciousness, it may find a way to do things with consciousness we could never dream of. The inhabitants of such a civilization may be able to switch their minds from one body to another, whether robotic or protoplasmic. We can imagine a society where someone might put his body into hibernation for the weekend, and have his mind inhabit a robot body for the same weekend, switching back to his original body at the end of the weekend. Or particular individuals might switch bodies for a particular length of time. Such a switch might be as easy as connecting two individuals to some fancy electronic device that connects with their brains.
Disembodied minds. Since we do not understand the secrets of consciousness, we have no way of knowing whether consciousness is irreducibly dependent on solid matter. It is possible that consciousness can exist when you have only an energy state or a vaporous material state. If so, then highly advanced extraterrestrials may have evolved into a disembodied state. They may have deliberately chosen such an evolution in order to make themselves immortal. Such a possibility was imagined by Arthur C. Clarke in the novel 2001: A Space Odyssey. He imagined a sequence of evolution in which aliens first evolved into robotic bodies and then ages later evolved into a pure energy state to make themselves “beyond the reaches of time.”
Disembodied shape-shifters. In the X Men comic books and movies, a character named Mystique is depicted as a genetic mutant who can shift shape to resemble any human. It is ridiculous to imagine that any genetic mutation would give humans such a power. But if some superadvanced alien race were millions of years older than ours, and had evolved into a disembodied state, the members of such a race might have the ability to temporarily materialize themselves into a tangible form. A disembodied intelligence might be a cloud of atoms or subatomic particles; and if such particles were a conscious mind, such a mind might be able to temporarily reorganize itself into a variety of physical forms. Even if a disembodied intelligence were pure energy, energy can be converted to matter, and matter converted to energy. So if you were a member of a superadvanced race on another planet, you might start your day not by asking yourself “what should I wear today?” but instead “what should I be today?” with the possible answers including a male, a female, some other type of organism, a fish, a plant, a car, or who knows how many other possibilities. Even if your disembodied cloud didn't have all the types of particles you needed, you could probably grab some of the needed particle types from the air, the soil, or miscellaneous objects lying about.
Conscious starships. When we think of interstellar spaceships, we always to tend to think of beings traveling in a spaceship. But many civilizations may have discarded such an idea, in favor of making starships themselves intelligent. When a starship arrives on our planet, the only intelligence in it may be a conscious intelligence housed in the electronics of the starship itself. Such an intelligence may launch robots to explore a planet, and such robots may be merely mobile eyes and ears for the electronic intelligence within the spaceship. Such conscious starships may be more practical for interstellar voyages that might require thousands of years. I offer this idea to any sci-fi novelist who may wish to write an epic novel told in the first person, one entitled I, Starship.
Migrating mind-clouds. If a superadvanced extraterrestrial civilization were to evolve into a disembodied state, it might not be content to hang around its original solar system. Being freed from the needs of food, water, and oxygen, a disembodied mind might launch itself across the interstellar void in search of adventure. Such migrating mind clouds may now be hanging around our planet. One does not rebut such a possibility by saying that there is no evidence that such mind clouds are communicating with us. A disembodied superintelligence may regard us as we regard insects at our feet – something too stupid to be worthy of communication, but merely something to be studied.
Planetary nebula or migrating mind cloud?
Galactic superminds. Civilizations millions of years older than ours may have discovered some way to achieve instantaneous communication with other civilizations. So rather than just considering the idea of a planetary supermind uniting all the minds on a single planet, we can also consider the possibility of a galactic supermind uniting the minds on a million far-flung planets. If you were to encounter such a supermind, it might be easy to mistake it for a deity.