“Tourism × Astrophysics”: The Meaning of Travel

Whenever I hear the word “journey,” there is something that always comes to mind: the man-made object that has traveled farther from Earth than any other in human history and continues on a journey from which it will never return. It is Voyager 1, the interplanetary probe launched by NASA 48 years ago, in 1977.Voyager is an interplanetary probe that set out into the distant reaches of space—places we cannot reach directly—serving as the eyes and ears of humanity on Earth. As of January 2025, it is located approximately 24.8 billion kilometers from Earth—a vast distance that would take 23 hours and 8 minutes to reach even at the speed of light. To intuitively grasp this immense distance, imagine the Sun as a 1-meter-diameter balance ball; Earth would be a 1-centimeter-diameter marble located 100 meters away from it. Neptune, the planet orbiting at the very edge of the solar system, is a cherry located 3 kilometers away. And Voyager 1 is one-tenth the size of an influenza virus, situated 17 kilometers away. On its journey so far, Voyager 1 has made numerous discoveries that humanity could never have foreseen, and it continues to fly at the staggering speed of 60,000 kilometers per hour. As seen from Earth, it is heading toward the constellation Ophiuchus. Moreover, it remains connected to Earth via radio waves. Although its camera has failed and it can no longer see, its “ears” are still functioning. Even at this very moment, as it travels through the pitch-black expanse of space, it continues to send the sounds of stellar winds from its surroundings back to Earth.

And, as is well known, it carries the Golden Record—a disc containing information about Earth—on its side. This record is a copper disc exactly the same size as an LP record, with a gold-plated surface. It features a message from Jimmy Carter, the 39th President of the United States at the time of launch: “This is a small gift from a distant star. It represents our sounds, science, images, music, thoughts, and feelings... (omitted)... Once we have solved the problems we face today, we hope to join you as fellow citizens of the galaxy. ”In addition, there are greetings in 55 languages from Earth; the 23rd of these is a Japanese greeting saying, “Hello, how are you?” Furthermore, there are 32 pieces of world music, including folk music, three of which are works by Bach. This was included based on the idea that the mathematical nature inherent in Bach’s music might function as a universal language should we encounter extraterrestrial intelligent life (i.e., ETs) within the galaxy; part of this was my own suggestion.

Furthermore, the surface of the record cover features mathematical diagrams illustrating how to play the record, along with a diagram engraved to indicate Earth’s position within the Milky Way. In addition to these elements, the cover’s surface is coated with uranium-238, which has a half-life of approximately 4.5 billion years; this is designed so that whoever finds the record can estimate its date of creation based on the residual radiation levels. In other words, this Golden Record is a testament to Earth’s civilization—a time capsule sent out with the next 4.5 billion years in mind. By that time, Earth will likely have been swallowed up by the expanding Sun, and all traces of our planet will have vanished without a trace from the galaxy. If, by then, this record is found by some extraterrestrial intelligent civilization, Earth and we ourselves will be brought back to life in their imagination. It feels as though this endless journey is, in fact, the ultimate journey.

What Is Travel in Our Daily Lives?

Now, what is travel in our daily lives? In fact, if we trace the history of our biological evolution, we see that we are designed in such a way that we cannot survive if we remain in one place. This is likely because life itself could not have emerged without interaction with the environment, including the intake of air and food. Life is an entity that cannot continue to survive on its own. Moreover, since the environment in which living things inhabit is constantly changing, organisms must adapt themselves to that environment in order to survive.

On the other hand, for creatures like us that possess a “mind,” becoming too accustomed to our environment can lead to a decline in our ability to detect environmental changes, which can sometimes hinder our evolution as a species. In other words, most sentient organisms are designed to perceive the state of the outside world as a series of changes. However, as we often experience in daily life, if we are constantly surrounded by the same scent, we eventually stop noticing it. This is because, in order to survive, we must adapt to our environment. On the other hand, if a different scent is present, we can detect it.

This is because if that scent is emitted by something dangerous to our survival, we must avoid it immediately. Speaking of snakes in reference to this year’s zodiac sign, the reason snakes flick their tongues is to detect changes in infrared radiation. Prey with body heat constantly emits infrared radiation, but when the prey moves, the intensity of the infrared radiation changes, and snakes use these changes to pinpoint the prey’s location. Therefore, it is said that when encountering a venomous snake, it is essential to remain still and not move.

In this way, for organisms to grow and survive, their ability to adapt to their environment and respond sensitively to new environments—thereby acquiring new wisdom and transforming themselves—strengthens their capacity for survival. Changing the subject, the Japanese eel is a fish famous for its long journey. Although they are caught in waters near Japan, their spawning grounds are reportedly in the Western Mariana Islands, more than 3,000 kilometers away from Japan. It seems that their distinct flavor, different from that of farmed eels, stems from this journey.

Incidentally, for us humans as well, the ability to refresh both body and mind by occasionally changing our environment is likely a trait shaped by the long process of biological evolution. Why not consider that this is the origin of travel? Just as our mood can change simply by rearranging the furniture in a room—without even stepping outside—humans are sensitive to their environment. In other words, human emotions and sensibilities—such as our feelings and perspectives—are greatly influenced by our surroundings. This is why traveling can lead to a rediscovery of oneself, and by learning about things previously unknown, one’s horizons are greatly expanded. While reading can also broaden one’s horizons, the encounters we have while traveling are accompanied by physical sensations. It is an experience gained by placing one’s body in that environment, seeing with one’s own eyes, hearing with one’s own ears, and savoring it with one’s entire being. That said, it is not only grand journeys like traveling abroad that hold meaning. Even on your usual commute, which you usually pass by on the bus, if you walk it occasionally, you might come across a small flower peeking out from a crack in the concrete by the roadside, or an interesting sign you’d normally overlook. Or perhaps you’ll take a short train ride and find renewed energy from a cup of tea enjoyed at a small café overlooking the sea. These are also the benefits of a small journey.

What Is a Journey Inward?

By the way, travel isn’t just about going out into the world. We also need to take a journey inward. This is a journey of the heart that we experience when we take time to engage with the things we love. Amid the hustle and bustle of daily life, taking just a moment to embark on this inner journey can lead to an encounter with a new version of yourself and give you a fresh burst of energy. Setting out on journeys both outward and inward is the first step toward a rich and fulfilling life. It would not be an exaggeration to say that setting out on a journey and looking into the distance is a way of getting to know the self that is closest to you.

Now, as I conclude this article, I would like to touch upon Matsuo Basho, a haiku poet from the early Edo period. As is well known, at the beginning of his masterpiece *The Narrow Road to the Deep North*, Basho wrote: “The days and months are travelers of a hundred generations, and the years that come and go are also travelers.” In other words, he composed the verse: “The days and months are travelers who never remain forever, and the years that come and pass are also travelers. ”He likens the finite existence of human life to a journey when compared to the vast and boundless universe, attempting to superimpose his own existence upon the eternal time and space of the cosmos. If “travel” is a limited period with a starting point and an endpoint, “the journey” seems to contain a longing for the endless, the eternal. There is a verse said to have been composed by Basho at the very end of his life. It is said to have been composed on October 8, 1694—four days before his death—and has long been regarded as Basho’s death poem.

“Sick on my journey, my dreams roam the withered fields”

The circumstances surrounding the composition of this haiku are detailed in *The Diary of the Memorial Service for Old Man Basho*, written by his disciple Shiko. However, I am intrigued by the preface attached to this haiku, which reads “Composed While Ill.” Since I am not a literary scholar, I hesitate to delve into a detailed analysis here, but if this were truly a death poem, would such a preface have been included? That said, even if we assume that one of his disciples added it later, it still feels unnatural when we consider the final circumstances implied by the aforementioned document—namely, the recorded scene of Basho and his disciples refining the poem together. This suggests that Basho himself was still fully conscious. Therefore, I wonder: Although it was indeed composed while he lay on his deathbed, I am beginning to feel that Basho himself did not consider it a death poem. Did Basho not strongly hope that one day his illness would be cured and he would be able to set out on a journey again? To live is to compile one’s own travel chronicle, and perhaps that is the lamp of hope that burns quietly yet eternally within one’s heart.