Warning: This discussion deals with the ending of Persona 5. As such, there will be spoilers.
When I pitched The Well of Images to one of my writing buddies, he mentioned that using the collective unconscious as a fantasy world sounded a lot like the Persona video games. Knowing nothing about the series, I thought I would try the newly-released Persona 5. It was lots of fun. You play as Akira, a high school student on parole from juvenile prison, serving time on a false charge. On your first day of school, you discover that you and your new friends have the ability to enter the “cognitive realm,” a world that reflects reality as people perceive it to be. When someone has a selfish and distorted view of reality, it creates a “palace” of theirs in the cognitive realm, which their “shadow” rules over. When their shadows are defeated, their real-life counterparts see the evil in what they have done, and publicly confess their crimes in tears.
The wide variety of characters were extremely well-written, showing multiple dimensions of both the heroes and villains. It was cathartic to confront the twisted minds of a crime ringleader, an abusive mentor, a CEO who treated his employees like slaves, and others. All the while, threads of mystery piled up. Akira’s false conviction, the police’s tendency to look the other way, the mysterious deaths in the subway, all began pointing toward one man, Masayoshi Shido, the favored candidate for Prime Minister.
Finally, after many play hours of vigilante action, you take on Shido’s palace. The stakes: the entire country, and vengeance for a life ruined by a false conviction. Tension builds as you fight your way through the palace, defeating progressively harder mini-bosses and wrapping up side-plots, until the final battle is at hand. And then . . . it is just like any other boss battle. Shido’s shadow has a few forms, and then he is defeated. You steal his treasure and escape the palace.
Now at this point, you’re expecting a twist. You know Shido knows about the cognitive realm, and it has been foreshadowed that he has techniques to keep his heart from changing even if his shadow is defeated. However, back in the real world, Shido appears on public TV and starts confessing his crimes and schemes, before the news people cut him off. And then, well, that’s it. All that buildup for him to go out like a whimper.
But the game is not over. There is another palace, the palace of the people. Its ruling shadow is Yaldabaoth, not a reflection of a human like the other shadow rulers, but a god born of humanity’s desire to give up their free will and responsibility . . . which would have been cool, except it has nothing to do with the 90-hour-long story you have been playing up to this point. You defeat him because it is what the game wants you to do, not because you have any investment in what is going on anymore. The moment that was supposed to be the climax has already happened, and by now, you have played the game for so long that you just want it to end.
So what went wrong? What could the writers have done differently to deliver that epic, satisfying ending that the players have been excited for the whole time? The answer is to integrate Yaldabaoth and Shido into the same plot. My version of Persona 5’s ending goes like this:
When Shido appears on TV after his shadow has been defeated, he confesses nothing. Instead of being full of sorrow at the atrocities he has committed, he is even more confident than before, boasting that he has the country in his fist. Yet still, the people flock to support him. It appears that the main characters have failed. However, just like in the actual ending, they discover the final palace, the palace of the people, where the shadows of the people huddle in their voluntary prisons moping about there being no hope and giving up their decisions to a ruler. In the actual ending, Shido is among them. In my version, he is not.
When they meet Yaldabaoth in my ending, a distorted version of Shido’s face is stuck to his body. The characters learn that Yaldabaoth has existed for years, plotting to subdue humanity, and has been using Shido as his vessel. The collapse of Shido’s palace allowed Yaldabaoth to take control of Shido’s body, and increase his influence over humanity. Shido’s face cries, “freeeee meeeeee!” suggesting that his heart was indeed changed when his shadow was defeated, but he now has no control over his actions.
When the main characters defeat Yaldabaoth, Shido is freed to confess his crimes. After that, my version ends the same way the actual story does. Shido is put in prison, Akira is acquitted, and all the other threads are tied up. The players are left satisfied with a good twist and a properly-built climax.
I liked most of Persona 5. It was very well-written, and had amazing graphics and music. I know the writers had the skill to make the ending worthy of the rest of the game, but we are left with what we got. So the least I can do is to learn from their mistake, and avoid it in my own stories.
In-depth weekly discussions about science, philosophy, and occasionally sci-fi and fantasy.
Friday, May 25, 2018
Friday, May 18, 2018
What is God?
I grew up in a Christian home in rural United States, believing, as most people in that culture do, in the existence of God the person. This person called God had his own subjective conscious viewpoint. He had the ability to cause anything to happen merely by willing it to be so, including both temporary suspension of the laws of physics, and the creation of the entire Universe. This God was thought to be real and literal. In other words, I believed in a physical God, also known as a “personal God” or “literal God.”
Back then, if you had asked me if I thought God was physical, I would have said no, God is spiritual. If you had asked me what I meant by that, I would have said physical reality is made of one type of substance, and spiritual reality is made of another type of substance. However, that is a false dichotomy. After all, the part of physical reality my present and past selves agree about is made of multiple types of substances. There are particles, fields, and space-time, and maybe a few things we do not know about yet. However, the reason we group them under the umbrella term, “physical” is because the way in which they exist is the same. The God I believed in was not made of space-time, particles, or fields, but he was thought to exist in the same way. That is why I call this kind of God a physical God.
I viewed God as the answer to questions like, “why does the Universe exist?” and, “why do we exist?” The Earth was the way it was because God made it that way, with human beings in mind. Everything that happened, everything I did, was measured against what God wanted, and how it fit into his grand plan. However, after about 20 years of living like this, I started seeing things that did not add up with this view. I learned how ideas of God and gods appeared in cultures and developed over time, and I saw how my God was the same as any other in this regard. I saw sick people get prayed over. Some of them were healed, and some were not. I had ideas pop into my head about the future. Some of them came true, and some did not. Eventually I came to realize that things can happen by chance, that if there are a million opportunities for things with a one-in-a-million probability to happen in a day, we should expect to see one-in-a-million things happen every day.
As we learn and grow, our mental pictures expand, filling in more of the jigsaw puzzle of knowledge. Sometimes we replace ideas with new ones, which may or may not be more correct, but other times we come to see a larger view of the picture, one which encompasses the views we had before. We come to see those views more clearly, why we held them, and how they fit or don’t fit with the rest of reality.
One fateful day, I was hit with the realization that the Universe and everything in it behaves as it would without a physical God. I looked up evidence for the existence of God, which came in two forms. The first was from science, but these were all either conspiracy theories, or of the form, “this seems like too much of a coincidence, therefore God is responsible.” For instance, I have heard the argument that since the conditions in the Universe make life extremely unlikely, God must have created the Earth for us. These arguments don't stand up to probability, nor do they meet their burden of proof. The second form of evidence for God was in philosophical arguments, like the Ontological Argument, the Teleological Argument, the Cosmological Argument, and the Argument from Morality. However, all of these either have extraordinary claims in their premises without justification, such as “it is possible for a Maximally Great Being to exist,” or their conclusions do not follow from the premises. Ultimately, I had to admit that I could find no evidence that the physical God I had believed in for my entire life actually existed.
For a while, I felt bitter toward the culture I had been raised in and the people who had taught me what I perceived to be nothing but lies. I faced existential and epistemological crises. This period did not last long, but it was rough. It is no wonder people get defensive and afraid whenever someone says something that even hints at a conflict with their worldview.
This was a turning point in my life. From then on, I started studying all different fields of science and philosophy. I wanted to understand the world and humanity as broadly and in depth as possible. In my quest, I have come across many public intellectuals with deep and important things to say. Among them was the psychology professor Jordan Peterson, who introduced me to the concept of Jungian archetypes, the models of behavior built into the human unconscious that manifest in fictional characters.
With perfect timing, in one of those one-in-a-million events that I mentioned earlier, Jordan Peterson started a series of public lectures, which he posted to YouTube, about the significance of the Biblical stories from the perspective of evolutionary psychology. Instead of taking them as literal historical events, like I had for my entire life, he treated them as a window into the depths of the human mind, as stories passed down for hundreds of generations, undergoing a kind of natural selection so that only the most meaningful and resonant parts remained, the rest lost to memory. Freed from the blinders of literalism, the Biblical stories exploded with meaning like I never imagined.
My thoughts turned back to consider once again the idea of God. Of course, a physical God was out of the question; the more I learned of science and philosophy, the more solidly that coffin was nailed shut. However, things I had heard believers say before, but had made no sense to me, started to come back. The idea that morality could not exist without a god. The idea that everyone worships something, whether they profess to or not. And for the first time in my life, it all started to make sense. God is not a person, not in the physical sense. God is an archetype.
Archetypes are the embodiments of human behavior patters. We see ourselves in fictional and mythological characters, and in forces of nature. This is where the gods of Ancient Greece and other pantheons come from. Capital-G God is the archetypal embodiment of all of the best qualities of human nature. This is why religious people take “God is good” as a truism, and why they say that without God, morality does not exist.
Atheists sometimes point to the things God does in the Bible which are obviously evil, and say, “God is not good.” But those instances are a product of the limitations of human knowledge at the time they were written. Archetypes are not made-up, they are discovered and studied. Since Biblical times, humanity has gone through revolutions of moral philosophy, so our understanding of the best of human nature, God, has matured. It is only natural that parts of the ancient views of God will appear barbaric to us. They were trying to understand, and, not having the philosophical knowledge of millennia to draw upon, got some of it wrong.
So why do most people insist on believing, and requiring others to believe, in a physical God rather than an archetypal God? Or from another perspective, what could drive me to speak such heresy? The answer lies in our psychology. We have a natural instinct to search for the meaning in facts, and to take that which is meaningful as factual. Only in the past few hundred years, since the dawn of science, have we begun to learn the difference.
Some would call me an atheist, because I believe there is no physical God. Others would call me a Christian, because I actively try to learn about and model my life around the best and fullest aspects of human nature, which God represents, and because I find value in the philosophy and culture that has come from the Christian tradition. I don’t care about the labels myself. It’s the honest search for truth that matters; after all, that’s in accordance with the nature of God.
Friday, May 11, 2018
Miscommunication and Mental Dictionaries
When you speak the same language as someone, it is assumed that you understand each other. After all, that is the point of language in the first place. However, the process is not nearly as smooth as we might believe. To understand this, let’s look at the mechanisms behind how language works. First, the person who wants to speak has a thought, and they want to produce the same thought in the other person’s mind. They translate the thought into words, and then speak those words. The person on the receiving end hears the words, and translates them into their own thoughts. If all goes well, the thoughts the second person ends up with are the same thoughts the first person started with.
Many of us naively assume everyone who speaks the same language has common definitions of the words in that language. After all, words mean what they mean, right? Well, let’s look at how dictionaries work. If you want to know the definition of a word, you look it up and the dictionary tells you. However, it tells you using other words, all of which can be found in the same dictionary. It is entirely self-referencing; it does not relate any word to any kind of objective meaning. When translating between thoughts and words, we use our own mental dictionaries, which are constructed by what we think words mean. Our beliefs about the meanings of words are not built around any kind of objective meaning, but are shaped by our own experiences. Thus, since everybody’s personal experiences are different, everybody’s mental dictionary ends up slightly different from everybody else’s.
Because of this, people can use the same words, but speak different languages in a sense. This is what happens when people “talk past each other,” or try to have a conversation, but feel like the other person does not understand a word they say. In order to solve this problem, we need to remember that the purpose of a conversation is to communicate a message, not to convince the other person that their definition is wrong. We might try using different words, but sometimes there aren’t enough words held in common to do so. If we want to be the most effective, we should concede to temporarily use the other person’s definition. The skill of being able to jump between definitions depending on who you are talking with can make it much easier to get along with lots of different people.
Let’s consider some examples of people using the same words with different meanings. First, “reality.” When a physicist talks about reality, they mean the objective aspects of the world that exist and have properties independently of anyone’s beliefs, knowledge, or perception. However, when a psychologist or philosopher talks about reality, they might mean that which affects one’s behavior and conscious experience. These people would say the pulled muscle in my hip is more real to me than the extreme poverty of a child in Nigeria, whereas a physicist would say they are equally real.
Another word that is used differently by different people, and which is the cause of much animosity among people these days, is “racism.” When most people talk about racism, they mean judging a person by their skin color instead of their individual characteristics. This, of course, can be done by anyone toward anyone. But when people in social justice circles talk about racism, they are referring to the extra hardships of life that are put on some groups of people and not others. To these people, being racist means participating, knowingly or not, in the features of the social system that allow these unfair hardships to happen. This kind of racism only flows in the direction of the underprivileged groups. If someone says, “it’s impossible to be racist against white people,” and the person they are talking to says, “that statement is racist,” they are talking about two different things, and must realize this quickly or their friendship will be in jeopardy.
There is little point arguing over whose definitions are correct. After all, it is not the words themselves that have meaning, but rather the meaning is produced when the words are translated by people into thoughts. If this idea seems strange, imagine speaking English to someone who only knows French. Before your words have any meaning to them, they must be taught to understand them. The same is true for someone who speaks the same language, but uses words differently.
In order to get along with people, you will want to practice listening for signs that you are using words differently. The most obvious is when the other person seems to make no sense at all. If an otherwise intelligent person says something that is ridiculously stupid, chances are that what they mean to say actually makes sense, and they used words that you use differently. A less obvious sign is if they say something that seems hurtful or prejudiced, especially if it is unprovoked. If you can’t tell by their words, check their mannerisms, because it is easier to tell someone’s intentions that way. Always remember that it’s not the words that are important, it’s the communication of one person’s thoughts to another.
Many of us naively assume everyone who speaks the same language has common definitions of the words in that language. After all, words mean what they mean, right? Well, let’s look at how dictionaries work. If you want to know the definition of a word, you look it up and the dictionary tells you. However, it tells you using other words, all of which can be found in the same dictionary. It is entirely self-referencing; it does not relate any word to any kind of objective meaning. When translating between thoughts and words, we use our own mental dictionaries, which are constructed by what we think words mean. Our beliefs about the meanings of words are not built around any kind of objective meaning, but are shaped by our own experiences. Thus, since everybody’s personal experiences are different, everybody’s mental dictionary ends up slightly different from everybody else’s.
Because of this, people can use the same words, but speak different languages in a sense. This is what happens when people “talk past each other,” or try to have a conversation, but feel like the other person does not understand a word they say. In order to solve this problem, we need to remember that the purpose of a conversation is to communicate a message, not to convince the other person that their definition is wrong. We might try using different words, but sometimes there aren’t enough words held in common to do so. If we want to be the most effective, we should concede to temporarily use the other person’s definition. The skill of being able to jump between definitions depending on who you are talking with can make it much easier to get along with lots of different people.
Let’s consider some examples of people using the same words with different meanings. First, “reality.” When a physicist talks about reality, they mean the objective aspects of the world that exist and have properties independently of anyone’s beliefs, knowledge, or perception. However, when a psychologist or philosopher talks about reality, they might mean that which affects one’s behavior and conscious experience. These people would say the pulled muscle in my hip is more real to me than the extreme poverty of a child in Nigeria, whereas a physicist would say they are equally real.
Another word that is used differently by different people, and which is the cause of much animosity among people these days, is “racism.” When most people talk about racism, they mean judging a person by their skin color instead of their individual characteristics. This, of course, can be done by anyone toward anyone. But when people in social justice circles talk about racism, they are referring to the extra hardships of life that are put on some groups of people and not others. To these people, being racist means participating, knowingly or not, in the features of the social system that allow these unfair hardships to happen. This kind of racism only flows in the direction of the underprivileged groups. If someone says, “it’s impossible to be racist against white people,” and the person they are talking to says, “that statement is racist,” they are talking about two different things, and must realize this quickly or their friendship will be in jeopardy.
There is little point arguing over whose definitions are correct. After all, it is not the words themselves that have meaning, but rather the meaning is produced when the words are translated by people into thoughts. If this idea seems strange, imagine speaking English to someone who only knows French. Before your words have any meaning to them, they must be taught to understand them. The same is true for someone who speaks the same language, but uses words differently.
In order to get along with people, you will want to practice listening for signs that you are using words differently. The most obvious is when the other person seems to make no sense at all. If an otherwise intelligent person says something that is ridiculously stupid, chances are that what they mean to say actually makes sense, and they used words that you use differently. A less obvious sign is if they say something that seems hurtful or prejudiced, especially if it is unprovoked. If you can’t tell by their words, check their mannerisms, because it is easier to tell someone’s intentions that way. Always remember that it’s not the words that are important, it’s the communication of one person’s thoughts to another.
Friday, May 4, 2018
Types of Planets in the Universe
Our world is a planet. This place, where we live our lives and strive for meaning and love, is one large stone among many flying around the sun. But our sun is not alone; there are an uncountable number of stars, and breakthroughs in the past few years have shown us that most if not all stars have their own planets. As of May 5, 2018, over 3700 planets have been found, and the number is growing exponentially. As we learn more about these extrasolar planets, we find that there are many different kinds of planets, some of which are not found in our solar system. So let’s take a look at all of the different and interesting types of planets that can be found around the universe.
For this discussion, I am not going to make any distinction between planets, dwarf planets, and moons. What counts as a moon or dwarf planet in our solar system could easily count as a planet if it were in the right orbit around the right kind of star. In our own solar system, Jupiter’s moon Ganymede and Saturn’s moon Titan are bigger than the planet Mercury, and they would have been planets themselves if they had not been caught by their parents.
Rocky
Starting off with the kind of planet everyone knows about, rocky planets have solid surfaces. Earth is one, as are Mercury, Venus, and Mars. Because Earth is the only planet we know of that has life, we make a guess that the best place to look for life elsewhere in the galaxy is on rocky planets. We have just recently achieved the technology to find them in their host stars’ habitable zones, but we do not yet have powerful enough telescopes to look for life’s signatures in their atmospheres.
Gas giant
These planets are thought to have no surface. They are so big that the pressure from their gravity causes a smooth transition between their gaseous atmospheres and liquid cores. Jupiter and Saturn are our solar system’s representatives of this group. Because they are so massive, they are the easiest type of planet to observe around other stars.
Ice giant
When a planet that would be a gas giant is formed far enough away from its host star, it is formed from the water ice that collects in the outer parts of the stellar system, rather than the hydrogen and metals that collect in the inner regions. Like gas giants, they have no surface, but smoothly transition between gaseous atmosphere and liquid core. In our solar system, Uranus and Neptune are ice giants.
Ice ball
Like ice giants, planets that are small enough to be rocky but are formed in the outer regions of the solar system where water ice is abundant have a high concentration of ice. Such planets are like Antarctica all the time. Ceres in the asteroid belt, and Pluto and its friends in the Kuiper belt are our neighborhood ice ball planets.
Icy Ocean
There is a special world type that, as far as we know, only exists as moons around gas or ice giants. These moons are far enough from their parent star that their surfaces are covered in thick ice, but the gravity difference across them from the giant planet they orbit causes internal friction, which heats them up inside. These worlds have vast oceans beneath their icy shells, like the Earth’s molten mantle beneath its rocky crust. It is thought that the conditions at the bottom of these oceans might be right for organic molecules to form life, and so they are of interest to exobiologists. Jupiter’s moon Europa and Saturn’s Enceladus are icy ocean worlds.
Tidally locked
These are technically not a different kind of planet, but they are interesting enough to have their own mention. When rocky planets are too close to their host stars, the same side always faces the star. They are close enough that the difference between the star’s gravity on one side of the planet and the other is great enough that the heavier density clumps of the planet get stuck pointing toward the star. It is kind of like how balloons float with the tie pointing downward. Our own Moon is tidally locked with Earth, which is why the same face always points toward us. Around stars that are small and dim, like red dwarfs, there can be Earth-sized tidally locked planets in the habitable zone. In fact, the closest star to the sun, Proxima Centauri, has just such a planet. Tidally locked habitable planets have been a hot topic of the astrobiology community, with debates about whether the climate and weather of such places could allow life to exist.
Our sun is not the only star to have planets. In fact, from our various methods of detecting exoplanets in our stellar neighborhood, we have learned that it is extremely rare for a star not to have a few. As with all endeavors to peer into the unknown, the exoplanet search has been a treasure trove of new, exciting knowledge, and we have discovered several exotic planet types that are not found in our solar system.
Hot Jupiter
The first planets we discovered around other stars were larger than Jupiter and had closer orbits than Mercury. This makes sense, because the bigger and closer a planet is to its host star, the more it pulls on that star, and the easier it is to see the signs that it’s there. We used to think gas giants had to be far from their stars, like our solar system’s outer planets, but now we know that inner gas giants are just as common.
Magma
Solar systems are made from collapsing clouds of gas and dust called protoplanetary disks. When this happens, all of the gravitational energy turns into heat, so small enough planets that are close enough to their suns are formed as magma balls. As eons pass, their outsides cool into rocky crusts, becoming the rocky planets with molten cores we are familiar with. Some planets around other stars, however, orbit so close that the heat from the sun keeps their surfaces molten after the formation phase. Magma planets can also be created when gas giants migrate too close to their host stars, and enough of their atmospheres get blown off that the remaining matter forms a molten rock ball.
Ocean
Our solar system jumps from Earth’s mass to Uranus’s, a 15-fold increase. But there is no reason planets couldn’t form in this mass gap. Indeed, we have found plenty of planets around other stars with multiples of Earth’s mass in the single digits, sometimes called super-Earths. Based on solar system models, we suspect such planets to attract and hold onto more water than Earth, covering their entire surfaces. It is suspected that ocean planets might be far more common than Earth-like worlds with both ocean and land. If this is true, it offers an optimistic solution to the Fermi Paradox: that life is common in the universe, but it almost exclusively arises on ocean planets, where space programs and radio broadcasting are extremely difficult to invent.
Brown dwarf
There is no limit to how big a planet can be; or rather, if it is big enough, it is a star instead of a planet. Because of this, there is a gray area a few times heavier than Jupiter where we are not sure whether to call it a star or a planet. It may have a tiny bit of nuclear fusion in its core, but it is not hot enough to shine. These are called brown dwarfs, following the trend in stars from yellow dwarf, orange dwarf, and red dwarf.
Diamond
55 Cancri e is a strange planet. Made almost entirely of carbon, it is eight times the mass of the Earth, but only twice as wide. And what is another name for super-dense carbon? Diamond! That’s right, though extremely rare, there are planets in the universe that are made of diamond, though unfortunately their surfaces are probably covered in graphite. So I guess we could call them pencil planets? Still, 55 Cancri e is a creative spark for writers and artists envisioning a romantic future of humanity in space.
These exotic planets break open the possibility of many more rare planet types waiting to be discovered. Doubtless, this list will be much longer in the future. Heck, our descendants may advance enough someday that they will be able to create custom planets of their own. They might have planets with multiple surfaces, the matter in between carved out like matryoshka dolls. They might have planets covered in computronium, where life has advanced beyond biology and covered the surface with network circuitry, running their own virtual reality universe. For a galactic civilization, such feats of engineering would be child’s play. The universe is strange and wonderful and full of mystery waiting to be uncovered, and possibility waiting to be realized.
For this discussion, I am not going to make any distinction between planets, dwarf planets, and moons. What counts as a moon or dwarf planet in our solar system could easily count as a planet if it were in the right orbit around the right kind of star. In our own solar system, Jupiter’s moon Ganymede and Saturn’s moon Titan are bigger than the planet Mercury, and they would have been planets themselves if they had not been caught by their parents.
Rocky
Starting off with the kind of planet everyone knows about, rocky planets have solid surfaces. Earth is one, as are Mercury, Venus, and Mars. Because Earth is the only planet we know of that has life, we make a guess that the best place to look for life elsewhere in the galaxy is on rocky planets. We have just recently achieved the technology to find them in their host stars’ habitable zones, but we do not yet have powerful enough telescopes to look for life’s signatures in their atmospheres.
Gas giant
These planets are thought to have no surface. They are so big that the pressure from their gravity causes a smooth transition between their gaseous atmospheres and liquid cores. Jupiter and Saturn are our solar system’s representatives of this group. Because they are so massive, they are the easiest type of planet to observe around other stars.
Ice giant
When a planet that would be a gas giant is formed far enough away from its host star, it is formed from the water ice that collects in the outer parts of the stellar system, rather than the hydrogen and metals that collect in the inner regions. Like gas giants, they have no surface, but smoothly transition between gaseous atmosphere and liquid core. In our solar system, Uranus and Neptune are ice giants.
Ice ball
Everyone's favorite. |
Like ice giants, planets that are small enough to be rocky but are formed in the outer regions of the solar system where water ice is abundant have a high concentration of ice. Such planets are like Antarctica all the time. Ceres in the asteroid belt, and Pluto and its friends in the Kuiper belt are our neighborhood ice ball planets.
Icy Ocean
There is a special world type that, as far as we know, only exists as moons around gas or ice giants. These moons are far enough from their parent star that their surfaces are covered in thick ice, but the gravity difference across them from the giant planet they orbit causes internal friction, which heats them up inside. These worlds have vast oceans beneath their icy shells, like the Earth’s molten mantle beneath its rocky crust. It is thought that the conditions at the bottom of these oceans might be right for organic molecules to form life, and so they are of interest to exobiologists. Jupiter’s moon Europa and Saturn’s Enceladus are icy ocean worlds.
Tidally locked
Full, half, or crescent, we always see the Man in the Moon. |
These are technically not a different kind of planet, but they are interesting enough to have their own mention. When rocky planets are too close to their host stars, the same side always faces the star. They are close enough that the difference between the star’s gravity on one side of the planet and the other is great enough that the heavier density clumps of the planet get stuck pointing toward the star. It is kind of like how balloons float with the tie pointing downward. Our own Moon is tidally locked with Earth, which is why the same face always points toward us. Around stars that are small and dim, like red dwarfs, there can be Earth-sized tidally locked planets in the habitable zone. In fact, the closest star to the sun, Proxima Centauri, has just such a planet. Tidally locked habitable planets have been a hot topic of the astrobiology community, with debates about whether the climate and weather of such places could allow life to exist.
Our sun is not the only star to have planets. In fact, from our various methods of detecting exoplanets in our stellar neighborhood, we have learned that it is extremely rare for a star not to have a few. As with all endeavors to peer into the unknown, the exoplanet search has been a treasure trove of new, exciting knowledge, and we have discovered several exotic planet types that are not found in our solar system.
Hot Jupiter
The first planets we discovered around other stars were larger than Jupiter and had closer orbits than Mercury. This makes sense, because the bigger and closer a planet is to its host star, the more it pulls on that star, and the easier it is to see the signs that it’s there. We used to think gas giants had to be far from their stars, like our solar system’s outer planets, but now we know that inner gas giants are just as common.
Magma
Solar systems are made from collapsing clouds of gas and dust called protoplanetary disks. When this happens, all of the gravitational energy turns into heat, so small enough planets that are close enough to their suns are formed as magma balls. As eons pass, their outsides cool into rocky crusts, becoming the rocky planets with molten cores we are familiar with. Some planets around other stars, however, orbit so close that the heat from the sun keeps their surfaces molten after the formation phase. Magma planets can also be created when gas giants migrate too close to their host stars, and enough of their atmospheres get blown off that the remaining matter forms a molten rock ball.
Ocean
No land. |
Our solar system jumps from Earth’s mass to Uranus’s, a 15-fold increase. But there is no reason planets couldn’t form in this mass gap. Indeed, we have found plenty of planets around other stars with multiples of Earth’s mass in the single digits, sometimes called super-Earths. Based on solar system models, we suspect such planets to attract and hold onto more water than Earth, covering their entire surfaces. It is suspected that ocean planets might be far more common than Earth-like worlds with both ocean and land. If this is true, it offers an optimistic solution to the Fermi Paradox: that life is common in the universe, but it almost exclusively arises on ocean planets, where space programs and radio broadcasting are extremely difficult to invent.
Brown dwarf
There is no limit to how big a planet can be; or rather, if it is big enough, it is a star instead of a planet. Because of this, there is a gray area a few times heavier than Jupiter where we are not sure whether to call it a star or a planet. It may have a tiny bit of nuclear fusion in its core, but it is not hot enough to shine. These are called brown dwarfs, following the trend in stars from yellow dwarf, orange dwarf, and red dwarf.
Diamond
Not actually what it looks like. |
55 Cancri e is a strange planet. Made almost entirely of carbon, it is eight times the mass of the Earth, but only twice as wide. And what is another name for super-dense carbon? Diamond! That’s right, though extremely rare, there are planets in the universe that are made of diamond, though unfortunately their surfaces are probably covered in graphite. So I guess we could call them pencil planets? Still, 55 Cancri e is a creative spark for writers and artists envisioning a romantic future of humanity in space.
These exotic planets break open the possibility of many more rare planet types waiting to be discovered. Doubtless, this list will be much longer in the future. Heck, our descendants may advance enough someday that they will be able to create custom planets of their own. They might have planets with multiple surfaces, the matter in between carved out like matryoshka dolls. They might have planets covered in computronium, where life has advanced beyond biology and covered the surface with network circuitry, running their own virtual reality universe. For a galactic civilization, such feats of engineering would be child’s play. The universe is strange and wonderful and full of mystery waiting to be uncovered, and possibility waiting to be realized.
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