What is Space, and What is it Like? (More Than You Think!)
- Mar 20
- 9 min read
Updated: Mar 21
Space, or outer space, is the name given to the area that contains planets, galaxies, stars, and other celestial bodies; an area thought to be infinite, although its exact extent remains undetermined. This area, composed of matter and energy, has its own unique laws of physics.
In classical physics, physical space is generally considered to be three linear dimensions. Modern physicists often view space, along with time, as part of an unlimited four-dimensional continuum known as spacetime. What do the concepts of the universe and space mean? I'm here to give you some interesting facts about space. Let's dive into the void!
Contents
What is space like?
Space is an extremely cold place with a temperature of -270.45°C . This is actually the fundamental temperature of space, that is, the temperature of its own fabric. Because some nebulae or stars heat their surroundings due to the energy they emit, not all of space is at the same temperature.
Furthermore, space operates quite differently from Earth because it has its own unique rules. Space is a "solid vacuum," meaning there are very few atoms or molecules in the environment, and therefore the pressure is very low . For space to be a "perfect vacuum," it needs to be a state of complete nothingness, containing nothing at all. So, if someone asks you, "Do you know what space is like?", you can reply, "It's cold and almost nothing, a miraculous place filled with celestial bodies."
What's in Space?
We've answered the question "What is space?" and described what space is like. So, what's in space? Of course, there's a lot in this vastness, and ironically, we've explored more of space than our oceans. Here's a short list of what's in space:
Planets | Stars |
Galaxies | Nebulae |
Black Holes | Supernova Explosions |
Asteroids | Meteors |
Natural Satellites | Artificial Satellites |
Supernova Remnants | Potential Extraterrestrial Life |
Radiation | Ultraviolet Rays |
39 Elements | Space Stations |
Dark Matter | Dark Energy |
How did the universe form?
Most scientists believe that the formation of the universe... It is explained by the Big Bang theory . According to the Big Bang theory, the universe formed and began to expand 13.8 billion years ago as a result of the explosion of a dense and hot point (singularity).
What are the elements that make up space?
Space consists of 68.3% dark energy , 24% dark matter, and 4.6% hydrogen, helium, plasma, neutrinos, radiation, and gases.
What is the Universe and Space, and What Isn't? Things You Need to Know.
Now that we've quickly answered the questions "How did the universe form?" and "What is space?", it's time to answer your questions about space and what it is about.
How Big is the Universe?
The observable universe is 94 billion light-years in size . Scientists have found that the most distant objects in the universe are 47 billion light-years away . This suggests that the radius of the observable universe is 47 billion light-years.
How long would it take to travel to the observable universe?
The observable universe is 46.5 billion light-years , or 28.5 gigaparsecs, from Earth. Even if you were to leave Earth at the speed of light, it would take you approximately 93 billion years to reach the observable universe .
Is the universe infinite?
So, does space have an end? The idea that the universe is infinite is a matter of debate . Some scientists say it could be infinite if they consider space to be perfectly flat. On the other hand, it is also thought that space is simply very large, since it is not certain what lies beyond observable space.
We currently know that the observable universe is 94 billion light-years long, but whether there is anything beyond that is a question mark.
Is there evidence that the universe is expanding?
Yes, in 1923, Edwin Hubble discovered that the farther a galaxy is from us, the faster it appears to be pulled outwards into space. This means the universe is expanding equally in all directions.
What is the rate of expansion of the universe?
While there is no definitive answer to the question of the universe's expansion rate , it is thought to be expanding uniformly throughout the universe at a rate of 67.5 km per second .
Where is the center of the universe?
The universe is theoretically considered infinite because it is constantly expanding. Therefore, it has no center. If we narrow the scope a bit, we could consider Earth as the "center" of the observable universe, the part of the universe where light reaches us. However, assuming this wouldn't be entirely accurate. It would be like trying to map a constantly expanding area!
The Shape of the Universe
It is argued that the shape of the universe is flat . To understand this, scientists studied the temperature fluctuations of the Cosmic Microwave Background (CMB). As a result, they found that the positive and negative energy in the universe are equal , meaning there is no curvature due to one being higher or lower than the other. If there were inequality, the "fabric" of the universe would be warped. In support of this, some scientists argue that the universe is isotropic , meaning it looks the same no matter where you look from . You can think of it like looking at a sheet of A4 paper.
Separately, according to general relativity, spacetime is a four-dimensional object that must obey an equation called the Einstein equation, which describes how matter bends spacetime.
Does sound travel through space?
No, sound cannot travel through space. Sound is a mechanical wave and requires a medium to propagate. Since space is a vacuum, meaning there is no air, and sounds travel by vibrating molecules in the air, they cannot travel through space.
What would happen if we went into space without a spacesuit?
You would faint within 10-15 seconds and die from lack of oxygen within 90 seconds . Because space is a vacuum, all the air in your lungs would be sucked out first. The oxygen in your body would expand, and you would begin to swell, but because your skin is elastic enough, you wouldn't burst.
At this point, because you are at near-zero pressure, the boiling point of liquids drops, and your body fluids begin to boil. The surface of your eyes and tongue will start to burn. Then you will begin to freeze, and after 12-26 hours you will be completely rigid. Unless a star burns you up or you collide with something, you can float in the vacuum of space for millions of years.
Is humanity the only intelligent species in the universe?
The answer to this remains a great mystery to us all. There are various theories on the subject, but none have been proven. One of the most popular is that humankind is the first and only life form with consciousness in the universe.
Furthermore, "mushrooms" on Mars, fossil worms on the ALH84001 meteorite, the Mars Viking robot experiment, the "Wow!" signal, and Tabby Star do not provide sufficient evidence to definitively determine whether we are alone in space.
Theories of Life in Space
Whether there are extraterrestrial beings in the universe is, for now, an undeniably ongoing dilemma . The most famous question on the subject came from the Italian-American physicist Enrico Fermi in 1950: “Where is everyone?”. These questions are collectively known as the Fermi paradox or the “Great Silence”. Countless theories have been put forward to answer this question, and they all still hang in the “void”.
All theories about extraterrestrial intelligent life you need to know:
The Existence of Countless Galaxies | Given the countless planets and stars in the universe, it's not unreasonable to think that none of them contain intelligent life. However, since no signs have been observed so far, it remains an unproven theory. |
The Great Filter Theory | He suggests that there may be some insurmountable challenges or "filters" that prevent intelligent civilizations from emerging and surviving. The paradox arises if these filters are widespread and thus prevent most civilizations from reaching the point of interstellar communication. |
Zoo Hypothesis | He argues that extraterrestrial beings are aware of humans, but prefer to observe them rather than communicate. |
Rare Earth Hypothesis | He argues that Earth-like planets with conditions suitable for complex life are extremely rare in the universe. |
Self-Destruction Hypothesis | It suggests that advanced civilizations tend to self-destruct before they can establish interstellar communication. |
Challenges of Interstellar Travel | If traveling between stars is extremely difficult or expensive, it could explain why we haven't seen any evidence of extraterrestrial civilizations. |
Timing Hypothesis | Other intelligent civilizations may have existed in the galaxy, but their existence did not intersect with ours. They may have emerged and disappeared long before or after our existence. |
Technological "Silent Zones" | Some advanced civilizations deliberately avoid emitting detectable signals into space to avoid attracting the attention of potentially hostile entities or to protect their own safety. |
Galactic Habitable Zone | It refers to the region in a galaxy where conditions are suitable for the emergence and sustenance of life. Some variations of the Big Quiet theory suggest that Earth may be located in a region where intelligent civilizations are rare or nonexistent. |
Technological Transcendence | It suggests that some advanced civilizations could transition to a state beyond the biological or physical realm, rendering traditional forms of communication and perception obsolete. |
In short, various theories about the universe have been put forward by humans, but none have been proven because we have no evidence of extraterrestrial life. If our technological advancements continue at such a rapid pace, perhaps one day we will be able to answer the question of whether aliens exist.
How will the universe end?
The fate of the universe can be measured by its density. As space continues to expand, its density is gradually decreasing, and consequently, its temperature is also decreasing over time. Theories about how the universe will end are based on speculation, and the astronomical community is making new discoveries every day. Therefore, it is certain that the hypotheses presented will one day be revised.
Theories about how the universe will end:
The Great Freezing (Heat Death) | This is the widely accepted theory. It proposes that the universe will continue to expand at an accelerating rate due to dark energy. As it expands, galaxies will move further apart, and the universe will become colder and darker. Eventually, the universe will reach a state of maximum entropy where all matter is evenly distributed and there is no more energy available for work. |
The Great Collapse | He proposes that the expansion of the universe will eventually reverse, causing it to collapse in on itself. This would result in a terrifying event where all matter and energy are reduced to a hot, dense state. |
Great Tear | It suggests that dark energy will continue to increase in power over time. As a result, it will eventually become so powerful that it will shatter not only galaxies and stars, but even atoms and subatomic particles. |
The Big Leap | It proposes that the universe is in an endless cycle of expansion and contraction. After the universe reaches its maximum size and begins to contract, a new Big Bang will occur, and the cycle will begin again. |
Vacuum Decay | It proposes that the universe exists in a false vacuum state and that at some point it could transition to a lower-energy, true vacuum state. This transition would propagate at the speed of light and effectively destroy the universe as we know it. |
Cosmic Pessimism | This suggests that because our observations are limited by the boundaries of the universe, we may never fully understand its ultimate fate. According to this view, the true destiny of the universe is forever beyond our reach. |
How do we explore the universe?
The earliest recorded astronomical studies were conducted in Assyria and Babylon around 1000 BC, and research has continued relentlessly to this day (we cannot say the same for medieval Europe). So how did humankind begin to explore the universe? Here's what has been done throughout history to explore space and the universe:
Primitive Observations | Spectroscopy |
Telescopes | Computer Simulations |
Satellites | Laboratory Experiments |
Space Missions | Space Stations |
Spacecraft | Spacecraft |
Countries that Conduct Research on Space
Of the more than 70 space agencies in the world, only 16 are capable of launching a mission, and only 7 have the ability to send probes to deep space, such as the Moon or Mars. Furthermore, only 3 agencies are known to be capable of conducting manned missions. Here are the countries that have made advanced progress in space research:
Agency | Launch Capability | Space Probe | Manned Flight |
NASA / USSF (America) | X | X | X |
ROSCOSMOS (Russia) | X | X | X |
CNSA / CMSA (China) | X | X | X |
ESA (22 European Countries) | X | X | X |
ASI (Italy) | X | X | |
ISRO (India) | X | X | |
JAXA (Japan) | X | X | |
CNES (France) | X | | |
ASA / NSPA (Australia) | X | | |
AEB (Brazil) | X | | |
ISA (Iran) | X | | |
ISA (Israel) | X | | |
KENSA (Kenya) | X | | |
WIFE / MUSCLE (South Korea) | X | | |
NADA (North Korea) | X | | |
SSAU (Ukraine) | X | | |
Although Russia was the first country to land on the Moon's surface with the Luna 2 spacecraft on September 13, 1959, Neil A. Armstrong, Michael Collins, and Edwin E. Aldrin Jr. made history as the first people to set foot on the Moon with the Apollo 11 mission on July 20, 1969.
"If I, as the Galaxy Explorer, have been able to answer your questions such as 'What is space, what is space like, what is in space, is there life in space, can we live in space, does space have a beginning and an end?' then I am very happy. Our journey into this vast emptiness is just beginning! Next, we will escape Earth's atmosphere to see planets, stars, nebulae, supernova explosions, black holes, and try to reach the speed of light! If you want to continue learning interesting facts about space, my articles below are waiting for you!"
