Are There Truly Empty Spaces in the Universe?
For all intents and purposes, statistically speaking, we can say that practically everywhere in the universe contains something. Our solar system, for example, with Neptune’s orbit stretching 4.5 billion kilometers in diameter, offers a remarkable perspective. As a sphere, it contains at least 47 billion billion billion cubic kilometers. However, the total volume of matter, including stars and other celestial bodies, within that sphere is less than 3 billion billion cubic kilometers, which is roughly twice the volume of the sun. This means that everything within the solar system occupies only one fifteen billionth of the volume of the space containing it. It would be exceedingly rare to find anything here without it already being illuminated or reflecting light. If you were to randomly pick a cubic kilometer of space, it might contain as few as 10 to 100 atoms of hydrogen per cubic meter.
The Solar System and Its Emptiness
Our solar system, with its planets and space debris, is not nearly as empty as one might expect. Most of its "objects" are arranged more-or-less on the "elliptical plane," meaning the vast majority of the "empty space" lies above and below that plane. Therefore, if one were seeking "emptiness," the space outside the plane would indeed be very empty. However, the arrangement of these celestial bodies skews the perception of space, making the solar system a relatively densely packed region in comparison.
Comparisons and Faraway Spaces
When we move beyond the solar system, the concept of emptiness becomes much more apparent. Just outside the reach of our local stars, the environment becomes vastly different. In these regions, the absence of light and stars is profound, and the dominant feature is the void of space itself. It is in such environments where the absence of matter becomes more prominent. For example, in the vast intergalactic space, if one were to enter a region without stars or planets, the darkness is more than just physical but also a reflection of the absence of solid matter.
Galactic Structures and Cosmic Voids
The combined gravitational forces of galaxies pull them into structures known as filaments. These filaments, in turn, leave vast regions stripped of stars, known as cosmic voids. If one were to enter one of these voids, equipped with advanced technology, one would likely detect a complete absence of stars in any direction. These voids are often considered the "sections" of the universe where no galaxies, matter, or mass exist, with dark energy being the primary component.
Cosmic voids are fascinating because they are some of the coldest regions in space, with a temperature of 2K, which is -456.07°F or -271.15°C. This extremely low temperature is the result of the vastness and sparsity of matter in these regions. The emptiness of these voids is a stark contrast to the bustling star systems and galaxies that populate the rest of the universe, making them a subject of intense scientific interest.
The vast majority of space, including these voids, is dominated by virtual particles, which are continuously appearing and disappearing due to the quantum fluctuations in the vacuum. While these virtual particles are an important aspect of the fabric of the universe, they are still a separate concept from the emptiness described in these regions. So, while there are regions of space that appear to be entirely empty, the vacuum itself is not devoid of quantum activity.
Conclusion
In conclusion, while the concept of empty space in the universe is intriguing, the space between galaxies and stars is more accurately described as vast and sparsely populated rather than entirely void. Despite its emptiness, the universe remains a mysterious and awe-inspiring place, with countless mysteries waiting to be uncovered.