Artist impression (generated with Midjourney AI) of a sunset on Proxima b.

EP. 13: FIVE REALISTIC WAYS TO REACH THE STARS.

Are there any realistic ways to reach the stars?

In the future, humans will explore the stars. This can happen in a few decades or centuries but is inevitable. The long period is due to the stars being incredibly distant, beyond what we can imagine. Our current technology is not advanced enough to travel through interstellar space. Yet, as we improve our understanding of physics and technology, we will create new propulsion techniques. We will find ways to overcome the barriers that separate us from distant planetary systems.

In this post, I describe five ways to reach Proxima Centauri b, now considered the closest (only about 4.2 ly) habitable planet to Earth. I start with something realistic and then move on to more fantastic possibilities.

Why should we travel to Proxima Centauri b?

Traveling to Proxima Centauri b is extremely important for science, the economy, and human understanding.

Venturing to Proxima Centauri b will help us learn about exoplanets and discover extraterrestrial life. It is located in a region where liquid water probably exists, making it a possible habitat for life. Studying this planet would offer valuable information about its atmosphere, geology, and signs of life. These findings would significantly advance our knowledge of the Universe. They would also enhance our understanding of our existence, helping us answer longstanding questions about life beyond Earth.

Journeying to Proxima Centauri b can lead to groundbreaking technologies, industries, and advancements. Developing efficient propulsion systems, life support technologies, and navigation techniques for interstellar travel can have wide-ranging impacts. These include benefits for transportation, energy generation, and resource management on Earth. Investing in these endeavors can bring economic growth, job opportunities, and technological progress.

Human nature is driven by a strong urge to explore and push boundaries. Traveling to another habitable planet signifies the ultimate achievement, reflecting our curiosity and thirst for knowledge. Interstellar travel symbolizes a future where humanity goes beyond our planet. It unites us and inspires future generations to pursue science and exploration. This effort would have a profound psychological and societal impact, fostering a sense of unity on a global scale.

In summary, traveling to Proxima Centauri b offers several benefits. We could gain new scientific knowledge. It might help us find alien life. The trip could lead to the creation of innovative technologies. Additionally, it would boost our economy and inspire us to explore beyond our limits. This journey would advance our understanding of the universe, unite humanity, and pave the way for interstellar travel.

What Kind of Planet is Proxima Centauri b?

Fig. 1: An imaginary landscape of Proxima Centauri b, made by the author with Midjourney AI.

With a minimum mass of at least 1.07 ME (Earth masses, ME = 5.9722 x 1024 kg) and a radius only slightly larger than that of Earth, Proxima b is deemed an Earth-like planet. This planet is situated within the habitable zone of Proxima Centauri. Nonetheless, it remains uncertain whether or not it possesses an atmosphere. Proxima Centauri is a flare star. It emits intense electromagnetic radiation. This radiation can strip away any atmospheric layer surrounding the planet. Furthermore, Proxima b is expected to be tidally locked with its host star. This means that one side of the world would always face Proxima Centauri. This occurs due to a 1:1 orbit where the rotation period matches the time taken to finish one orbit. The consequences of such tidal locking are still ambiguous, and it is unclear whether habitable conditions can arise. In such a scenario, the planet would experience an extreme climate, with only a part of it being habitable.

Proxima b is not tidally locked if:

  • Its eccentricity is higher than 0.1 – 0.06 (that is, the orbit is much flatter than a perfect circle); in this case, the planet would probably enter a Mercury-like 3:2 resonance (three rotations around the axis for every two revolutions around the primary star);
  • The planet isn’t symmetrical (e.g., triaxial). In this case, capture into a non-tidally locked orbit would be possible even with low eccentricity.

A non-tidally locked orbit has disadvantages. For example, the planet’s mantle would experience tidal heating, which leads to more volcanic activity and a possible loss of a magnetic field. Protecting the atmosphere from the stellar wind is challenging without a strong magnetic field.

Proxima Centauri b’s atmosphere has two possible scenarios. It either lost hydrogen and retained oxygen and carbon dioxide, or it formed farther away from its star and still had hydrogen. This distance would have helped preserve its water.

However, red dwarfs are not suitable for supporting life due to various challenges and uncertainties.

Among others:

  • The stellar wind from Proxima Centauri is more significant than the Sun’s and may remove parts of the planet’s atmosphere;
  • If a planet is tidally locked to its star, the atmosphere can collapse on its night side;
  • Proxima b may not always be in the habitable zone due to its eccentric orbit;
  • Proxima Centauri, a star unlike the Sun, had its habitable zone farther away in the past. If a planet like Proxima Centauri b formed in its current orbit, it could have been too close to the star. Water might not have existed there for up to 180 million years. This led to a runaway greenhouse effect, causing the planet’s water to evaporate into steam and escape into space, akin to Venus.

Still, red dwarfs like Proxima Centauri live for a very long time, much longer than the Sun. This gives life a lot of time to develop.

How to travel to Proxima b

Scientists have proposed five ways to travel to Proxima b. One method is the “generation ship.” This method was one of the first ways to reach the stars discussed in scientific literature. It is a potential choice with our current technology.

(a) Generation Ship:

Fig. 2: A generation ship allows humanity to travel to the nearest habitable planet at sub-light speed. Credits: Midjourney AI.

This idea involves creating a spacecraft that can support many generations of people during a long journey. The ship would travel at subluminal speeds, using nuclear power. It’s hard to know precisely how long it would take for the starship to reach its destination: tens of thousands of years or even more.

With our current technologies, a generation ship is technically possible. Still, it is essential to consider the drawbacks linked to such a venture.

Spending your entire life on a spaceship is challenging for your mental health. You never get to experience life on a planet. Being confined in a limited space can make you feel down. A boring routine contributes to this feeling. Moreover, not interacting with others much can also affect your mood. Also, being incapable of seeing different places can make you feel like you are missing out. Not trying new things makes you feel disconnected from the natural world.

Health concerns are also significant when planning a generation ship. Extended space travel can lead to problems like weakened bones and muscles, vision impairments, and increased radiation exposure. A lack of proper medical facilities and resources onboard makes keeping the crew’s overall health and well-being extremely difficult.

Additionally, the people living on the ship must create their society. They would need to make rules, govern themselves, and develop their way of life. It would be a big challenge to keep everyone happy and treat everyone fairly. There could be problems with people wanting too much power or causing trouble. Thinking about all these things is essential before embarking on a journey like this.

Finally, there are ethical concerns to consider. Is it fair to force future generations into space travel without their consent? Their descendants would have no choice in the matter. They would live and die on the spaceship, missing out on the joys of life on a planet. This raises questions about our responsibility to future generations.

(b) Ion Propulsion:

Fig. 3: A starship using ion propulsion to reach the stars. The author made the image using Midjourney AI.

Ion propulsion utilizes electrically charged particles (ions) to generate thrust. This technology is already used in spacecraft missions, like NASA’s Dawn mission. Ion thrusters offer low acceleration but can sustain continuous and efficient propulsion over a long period. With current capabilities, ion propulsion can reduce travel time to Proxima Centauri to a few thousand years. Still, significant advancements in this technology must occur for it to become a practical choice for interstellar travel.

(c) Anti-matter Propulsion:

Fig.4: An anti-matter-propelled starship approaching an exoplanet. The author made the image using Midjourney AI.

Anti-matter propulsion involves using anti-matter to generate thrust by converting mass into energy. This technology has great potential for faster space travel. Yet, producing, storing, and containing anti-matter is very challenging. At present, only small amounts of anti-matter can be made. If we overcome these challenges, we could reach speeds close to the speed of light. This would allow us to travel to Proxima Centauri in several decades or less.

(d) Travel Through a Wormhole:

Fig.5: A futuristic starship entering a wormhole. Wormholes, or Einstein-Rosen bridges, are hypothetical shortcuts through space-time. The author made the image using Midjourney AI.

Wormholes involve creating tunnels or shortcuts in spacetime that connect distant locations. There is ongoing research in theoretical physics about wormholes. Nonetheless, it is essential to note that there is no definitive consensus on the existence or feasibility of traversable wormholes.

According to conventional theories of general relativity, wormholes would need exotic matter with negative energy density. This type of matter would stabilize the wormholes. Exotic matter has properties contrary to ordinary matter. It has not been observed in nature and is purely speculative. Nevertheless, some theoretical physicists have proposed other models that avoid using exotic matter or colossal energies. One such approach is the concept of “traversable wormholes without exotic matter,” first put forth by Eric Davis in 1997. This model uses a form of matter called “phantom energy.” This is, again, negative energy. Still, it does not violate any physical energy conditions. Phantom energy is a hypothetical concept that arises from quantum field theory and has negative pressure. It remains an area of ongoing theoretical exploration and debate.

If wormholes are discovered and harnessed, they would allow almost instantaneous travel between Proxima Centauri and Earth.

(e) Solar Sail:

Fig.6: A spaceship driven by a solar sail is an intriguing possibility to reach the stars. The author made the image using Midjourney AI.

Solar sails are a fascinating spacecraft propulsion technology that harnesses the power of sunlight to propel a spacecraft through space. They work by utilizing the gentle pressure exerted by photons, or particles of light, emitted by the Sun. These photons can transfer momentum to the surface of large reflective sails, creating a slight but continuous acceleration.

One notable project exploring the potential of solar sails is the Breakthrough Starshot Project. This ambitious undertaking aims to send tiny, gram-scale spacecraft to the nearest star system, Alpha Centauri. The envisioned spacecraft would be equipped with ultra-lightweight sails and propelled by an array of powerful lasers from Earth. These tiny probes use the momentum from the laser beams. They could reach up to 20% of the speed of light. This ability significantly reduces the travel time to another star system.

As a final remark, we report an intriguing speculation by Harvard astrophysicist Avi Loeb. In 2018, he proposed that the peculiar interstellar object named Oumuamua is an alien spacecraft. Oumuamua means “scout” or “messenger” in Hawaiian. He suggested a solar sail propels it.

Nonetheless, this speculation remains highly controversial within the scientific community. The available data on Oumuamua is limited. Scientists have also proposed different natural explanations. These include cometary outgassing or a peculiar shape resulting from its formation. Further studies and observations are necessary to decide its true nature definitively.

EP. 8: WHAT WOULD BE A GREAT PLACE TO SEARCH FOR ET?

The Dyson sphere is a hypothetical megastructure physicist Freeman Dyson proposed in 1960.

According to his paper published in Science magazine, a technologically advanced alien civilization would use increasing energy as it grew. As the most significant source of energy in any solar system is the parent star, sooner or later, the civilization would build orbiting solar panels to try to capture it. Such structures would take up more and more space until they eventually covered the entire star like a sphere.

In a 2008 interview with Slate, Dyson also credited the concept to writer Olaf Stapledon, who introduced it in his novel Star Maker in 1937.

Dyson’s hypothesis turned out to be hard to verify because a complete Dyson sphere, absorbing all of the light from the star, would be invisible to an exo-planet hunting telescope (such as NASA’s Kepler). Only half-completed spheres would have a chance to be discovered.

Unfortunately, a Dyson sphere is unlikely to remain under construction for long. The time it takes to make a Dyson sphere is relatively short. A 2013 paper by Stuart Armstrong and Anders Sandberg (“Eternity in six hours: Intergalactic spreading of intelligent life and sharpening the Fermi paradox”) estimates that disassembling Mercury to make a partial Dyson shell could be done in 31 years.

An alternative would be to look for waste heat in the infrared. After being absorbed and used, the energy from a star needs to be reradiated, or else it would build up and eventually melt the Dyson sphere. This energy would be shifted to longer wavelengths so that a Dyson sphere might give off a peculiar energy signature in the infrared. In other words, Freeman Dyson saw a search for his namesake spheres as a complement in the infrared to what Frank Drake’s Search for extraterrestrial intelligence (SETI, see previous blog post) had begun to do with radiotelescopes.

Carl Sagan and Russell Walker first voiced an issue with Dyson’s SETI notion in their 1966 paper “The Infrared Detectability of Dyson’s Civilizations” for the Astrophysical Journal. The authors noted that:

discrimination of Dyson civilizations from naturally occurring low temperature objects is very difficult, unless Dyson civilizations have some further distinguishing feature, such as monocromatic radio-frequency emission.

In the following decades, the search for Dyson spheres expanded dramatically. Starting from the 1980’s researchers went to work using sources identified by the Infrared Astronomical Satellite (IRAS). These early searches produced little o no results, as most Dyson sphere candidates had either non-technological explanations or needed further study. Subsequent investigations using NASA’s space-based WISE (Wide Field Infrared Survey), with higher resolution than IRAS, have all concluded that the identification of a promising source would not in itself be proof of an extraterrestrial civilization unless the object could be followed up with more conventional methods, such as laser or radio search.

Among the latest developments concerning Dyson spheres are the following:

  • Dyson spheres could be built around black holes instead of stars.

Black holes can radiate incredible amounts of energy (105 more energy than the Sun) produced by the so-called “accretion disk” of gas and dust falling into the black hole’s maw. As a consequence of their spiraling and spinning motions, these materials heat up through friction to millions of degrees, emitting extremely energetic X-ray photons.

But why would an alien civilization decide to build a Dyson sphere around a distant black hole (if it weren’t “distant,” the civilization would have been “eaten” long before it managed to construct the sphere) rather than using their much closer parent star? Black holes concentrate an enormous mass into a space area that is orders of magnitude smaller than a star’s, and are therefore easier to encircle. On the downside, black holes often have bursts of activity followed by quiet periods as they consume varying lumps of matter in their disks. An alien species woulod have to protect their orbiting structures from the huge explosions that might destroy them.

  • Dyson spheres could be circling the husks of sunlike stars known as white dwarfs.

Every star has a finite lifetime. If a civilization arose around a typical sun-like star, then someday that star would turn into a red giant and leave behind a white dwarf. That process would roast its solar system’s inner planets and freeze the outer ones as the white dwarf cooled off. Consequently, the civilization would have to choose between moving to another system or building a series of habitats that harvest the radiation from the remaining white dwarf. It seems unlikely that a civilization, no matter how advanced, would go through the enormous effort of traveling to another star only to build a Dyson sphere.

This allows a direct connection between stellar lifetimes and the prevalence of Dyson spheres.

If enough aliens decided to build Dyson spheres around their white dwarf homes, then astronomers should find at least one Dyson sphere in white dwarf surveys. The presence of a megastructure like a Dyson sphere around a white dwarf would absorb part of its radiation and convert it into reusable energy. Since no conversion is 100% efficient, this process would leave behind waste heat that would escape as infrared light.

Astronomers have already found many white dwarfs with excess infrared emission, usually explained as dust in those systems, not megastructures. According to a paper by Ben Zuckerman and recently accepted for publication in the journal Monthly Notices of the Royal Astronomical Society, no more than 3% of habitable planets around sunlike stars give rise to a white dwarf sphere-building civilization. Still, there are so many planets orbiting sunlike stars that this calculation only provides an upper limit of 9 million potential alien civilizations in the Milky Way.

EP. 5: ARE ROGUE WORLDS THE ULTIMATE ABODE FOR LIFE?

The search for extraterrestrial life has captivated humanity for centuries. Countless questions arise in our quest to discover if we are alone in the vast universe. The Drake Equation, a mathematical formula introduced by astronomer Frank Drake in 1961, attempts to estimate the number of civilizations within our Milky Way Galaxy. However, recent scientific discoveries have unveiled a new intriguing possibility – rogue worlds. These wandering bodies, expelled from their original solar systems, may hold the potential for harboring life. In this blog post, we will explore the fascinating intersection of the Drake Equation and the enigmatic realm of rogue worlds, exploring the tantalizing notion of life beyond our home planet.

The original form of the equation is the following:

N = R* f(p) n(e) f(i) f(l) f (c) L

• N is the number of civilizations trying to communicate with us right now;

• R* is the rate of star formation in stars per year;

• f(p) is the fraction of those stars which have planetary systems;

• n(e) is the number of Goldilocks (i.e., Earth-type) planets in a planetary system);

• f(l) is the fraction of habitable planets that are inhabited;

 f(i) is the fraction of inhabited planets that possess intelligent technological civilizations;

• f (c) is the fraction of intelligent technological civilizations that choose to emit detectable signals;

• L is the length of time signals will be sent.

The first three factors are astronomical, the fourth and fifth are biological, and the last two factors are social. There are several issues with the equation. Among these:

(1) The uncertainties are large enough for the astronomical factors and increase as one progresses from the astronomical to the biological to the social.

(2) Most factors depend on theoretical insights of star and planet formation, new discoveries about exoplanets, and varying subjective opinions on the evolution of life and intelligence. The presumed longevity of civilization must also be taken into account.

(3) The equation has many hidden assumptions: a uniform star formation rate (SFR) over the Galaxy’s lifetime and a steady state of civilization birth and death. 

(4) No matter what value one chooses for R*, the assumption is always that a habitable planet must have a star. However, rogue worlds (bodies that have been thrown out of their own nascent solar system) wander around the Galaxy unattached to a star.

This last item has recently awakened great interest in the scientific community.

Theoretical calculations (Imagined Life, by James S. Trefil and Michael Summers, 2019) suggest that:

“[…] the number of rogues might be between twice and thousands of times the number of conventional planets. Interstellar space must be littered with them!”

Also, rogue planets need not be uninteresting ice balls with no life and energy. Lacking direct radiation from a star, a world can be heated by the residual power from its formation and the radioactive decay of elements in its interior. If provided with one or more moons, the planet can draw energy from a process known as tidal heating (which is responsible for the subsurface oceans on some of Jupiter and Saturn’s moons).

All in all, rogue planets can be compared to (Imagined Life by James S. Trefil and Michael Summers, 2019):

“[…] houses whose lights have been turned off but whose furnaces are still operating.”

Interestingly, rogue planets had been predicted as early as the 1930s by American horror and S.F. author Howard Phillips Lovecraft.

In his short story: The Haunter of the Dark, he wrote:

“[…] remember Yuggoth, and more distant Shaggai, and the ultimate void of the black planets… […].”

When the planet Pluto had just been discovered by Clyde Tombaugh (1906-97) at Lowell Observatory (Flagstaff, Arizona), he wrote another short story: The Whisperer in Darkness.

Here are a few quotes: 

“[…] Their main immediate abode is a still undiscovered and almost lightless planet at the very edge of our solar system – beyond Neptune and the ninth in distance from the [S]un. It is, as we have inferred, the object mystically hinted at as ‘Yuggoth’ in certain ancient and forbidden writings; […] I would not be surprised if astronomers become sufficiently sensitive to these thought-currents to discover Yuggoth when the Outer Ones wish them to do so. But Yuggoth, of course, is only the stepping-stone. The main body of the beings inhabits strangely organised abysses wholly beyond the utmost reach of any human imagination.”

And also:

“[…] Those wild hills are surely the outpost of a frightful cosmic race – as I doubt all the less since reading that a new ninth planet has been glimpsed beyond Neptune, just as those influences had said it would be glimpsed. Astronomers, with a hideous appropriateness they little suspect, have named this thing ‘Pluto.’ I feel, beyond question, that it is nothing less than nighted Yuggoth […].”

What would life be like on a rogue planet?

According to Imagined Life, by J.S. Trefil and M. Summers:

“It’s dark. Not midnight-on-a-side-street dark, but trapped-in-a-cave dark. And no wonder—there’s no sun in the sky, for this is a rogue world, one that circles no star. There is a moon up there somewhere, but without a source of light for it to reflect, it’s just a darker patch in the sky. Whatever life forms live on this planet had better be able to see in infrared because there’s simply no other light to be had. You’re wearing infrared sensors, fortunately, and you spot a few of these creatures scurrying back to the planet’s subterranean tunnels, where they can bask in the heat emanating from the planet’s interior. […]”

Life on a dark planet has been described by British author Arthur C. Clarke in his 1950 short story: A Walk in the Dark:

“[…] Here at the edge of the Galaxy, the stars were so few and scattered that their light was negligible. […]” 

“[…] Here at this outpost of the Universe, the sky held perhaps a hundred faintly gleaming points of light, as useless as the five ridiculous moons on which no one had ever bothered to land. […]” 

“[…] No one could deny that the tunnels out in the wasteland were rather puzzling, but everyone believed them to be volcanic vents. Though, of course, life often crept into such places. With a shudder, he remembered the giant polyps that had snared the first explorers of Vargon III […]

The Drake Equation is not meant to give a precise answer but to stimulate scientific discussion and exploration. It is based on several factors that affect the likelihood of finding intelligent life, such as the rate of star formation, the fraction of stars with planets, the fraction of planets suitable for life, and the fraction of civilizations that develop radio technology. Each factor is multiplied by the previous one, resulting in the number of detectable civilizations in our galaxy. However, many of these factors are uncertain, and different assumptions can lead to different outcomes. For example, some estimates suggest that there could be millions of civilizations in our Galaxy, while others suggest that we might be the only one.

According to a recent study, under the strictest set of assumptions, where life forms between 4.5 billion and 5.5 billion years after star formation, there are likely between four and 211 civilizations in the Milky Way today capable of communicating with others, with 36 the most likely figure. Another study yielded two main results: an optimistic one and a pessimistic one. In the optimistic situation, the researchers suggested the aforementioned 42,777 communicating extraterrestrial intelligent civilizations (CETIs) with an error margin of plus 267 and minus 369, and they would need to survive 2,000 years on average to communicate with us.

The Drake Equation is a fascinating way to explore the possibilities of extraterrestrial life and communication. It helps us understand what we know and don’t know about our place in the universe. It also inspires us to keep searching for signs of other civilizations and to wonder what they might be like.

Read more about this topic in this post and this other post.

EP. 2: IS THE UNIVERSE AN AWFUL WASTE OF SPACE?

“The universe is a pretty big place. If it’s just us, seems like an awful waste of space.” 

This quote is attributed to Carl Sagan from his novel Contact (1985). It is often interpreted as reflecting Sagan’s optimism and belief in the possibility of extraterrestrial life. He strongly advocated for the search for extraterrestrial intelligence (SETI) and believed that the discovery of intelligent life beyond Earth would have profound implications for humanity.

In other words, Sagan suggested that if the Universe is so vast and we are the only intelligent life in it, it would be a shame to waste all that space on just one civilization.

A recent estimate (Conselice C.J. et al. 2016) says the observable Universe contains two trillion – or two million million – galaxies. Of course, this is a huge number, which math buffs can probably better appreciate if I translate it into scientific notation:

two trillion = two million million = one thousand billion = 2 x 1012

Even if we neglect 99.9999% of the Universe and consider only the Milky Way, we are left with a staggering number of about 100 to 400 billion stars.

Of course, these hundreds of billion stars vastly differ in age, mass, and chemical composition.

According to the stellar luminosity function:

A small percentage of stars are massive, young, and very bright (the so-called O, B, and A spectral types, with colors ranging from ultraviolet/white to blue);

A relatively large number of stars are medium-sized (the F and G spectral types, yellow to orange in color). Our “dull” Sun is one of them;

The majority of stars are small, old, low-mass stars (the K, M spectral types, a.k.a. red dwarfs);

Many stars are brown dwarfs (dark, spherical lumps of stellar material that never reached the star stage).

In the last few decades, roughly from the early nineties, it has become known that most, if not all, stars possess planets. Our Sun has eight major ones (excluding the KBOs or Kuiper Belt Objects). The former planet Pluto, now demoted to “dwarf planet,” is one).

Just like stars, planets also show a vast range of types.

I found a helpful classification in Imagined Life: A Speculative Scientific Journey among the Exoplanets in Search of Intelligent Aliens, Ice Creatures, and Supergravity Animals by James S. Trefil and Michael Summers. We can envisage the following kinds of exoplanetary environments as the most promising for alien hunters:

(1) Goldilocks Planets: planets like Earth, located at a distance from their star that allows them to have oceans of liquid water on their surface for extended periods;

(2) Subsurface Ocean Worlds: planets on which oceans of liquid water are bounded below by solid rock and above by ice. Examples in our solar system: the planet Pluto and several moons of Jupiter, Saturn, Uranus, and Neptune);

(3) Rogue Worlds: planets without a parent star. Such planets have been ejected from their solar system of origin and now wander through space. An example is OTS 44, a free-floating planetary-mass object located at 550 light-years, with approximately the mass of Jupiter;

(4) Water Worlds: planets with no dry land at all. That’s what a post-apocalyptic Earth would look like. (See, e.g., Kevin Reynolds’ 1995 movie Waterworld);

(5) Tidally Locked Worlds: planets that always present the same face to their star, much as the Moon does with Earth. Their peculiarity is that one side is perennially hot, while the other is an eternal Antarctica;

(6) Super-Earths: planets whose size falls between Earth and Neptune. Given their mass, the main characteristic of these planets is their intense gravity. Creatures must live in oceans or evolve a strategy to deal with this crushing force. A nice fictionalization of this is Edmond Hamilton‘s Starwolf series (1967-68), where Morgan Chane, the son of a human missionary family, grows up in a heavier-than-Earth world.

If these worlds exist, and there’s a tiny chance some might be inhabited, well… I want to see them. I’ll probably never do it in person (sadly, I’m not an astronaut). However, I can still dream about them, hoping someone will get there someday.

I wish someone to be able to say, just like the replicant Roy Batty in Ridley Scott’s 1982 movie Blade Runner:

“I’ve seen things you people wouldn’t believe.
Attack ships on fire off the shoulder of Orion.
I watched C-beams glitter in the dark near the Tannhauser Gate.
All those moments will be lost in time, like tears in the rain.
Time to die.”

Read more about this topic in this post and this other post.