Space is a vast and unexplored realm that continues to raise many questions for mankind. Despite huge progress in science and technology, many mysteries of the Universe remain unsolved.

1. What is dark matter?

Dark matter is one of the biggest mysteries of modern astrophysics. According to current models, dark matter accounts for about 27% of the mass and energy of the Universe, but its nature remains unknown. It does not emit, absorb or reflect light, making it invisible to modern telescopes.

Scientists know dark matter exists because of its gravitational effects on visible objects such as galaxies and stars. For example, the rotational speed of the outer regions of galaxies is too high to be explained by visible matter alone. This points to the presence of ‘invisible’ matter that creates additional gravity.

Despite numerous experiments and theories, no dark matter particles have yet been directly detected. The main candidates for dark matter particles are the hypothetical weakly interacting massive particles (WIMPs) and axions, but their existence remains unproven.

2. What is dark energy?

While dark matter makes up about 27% of the universe, the even more mysterious dark energy takes up about 68%. This phenomenon was discovered in the late 1990s when astronomers discovered that the expansion of the Universe was accelerating. This behavior cannot be explained by gravity and ordinary matter alone.

Dark energy is a hypothetical form of energy that acts as ‘anti-gravity’, causing the universe to expand ever faster. However, its nature remains a complete mystery. Some scientists link dark energy to the cosmological constant - a concept proposed by Albert Einstein - but its exact mechanism is unknown.

3 What happened before the Big Bang?

The Big Bang is a theory that describes the beginning of our universe about 13.8 billion years ago. According to this model, the Universe emerged from an extremely dense and hot state, after which it began to expand and cool.

However, the question of what happened before the Big Bang remains open. Many scientists believe that the concept of ‘before’ is meaningless in the context of the Big Bang, since time itself could have started at that point. Other theories suggest the existence of a cyclic universe, where the Big Bang was just one of a series of ‘contraction and expansion’ events.

There are also hypotheses of a multiverse - the idea that our cosmos is just one of an infinite number of universes with different physical laws. For now, these theories remain speculative, as we have no tools to test such ideas.

4. Is there life beyond Earth?

The question of the existence of extraterrestrial life has preoccupied mankind for centuries. At the moment, Earth remains the only known place in the universe where life exists. However, the scale of the cosmos is so large that the probability of the existence of other life forms seems high.

There are many projects searching for extraterrestrial life. For example, the SETI programme is searching for radio signals from intelligent civilizations. In addition, astronomers are investigating exoplanets (planets outside the solar system) that are in the so-called ‘habitable zone,’ a region around a star where conditions may be suitable for the existence of liquid water.

Particular attention has been paid to satellites in our solar system, such as Europa (a satellite of Jupiter) and Enceladus (a satellite of Saturn), where oceans of water may lurk beneath an icy crust. So far, however, no evidence of life beyond Earth has been found.

5. Why is there an asymmetry of matter and antimatter?

According to modern physical theories, matter and antimatter should have formed in equal amounts at the moment of the Big Bang. Today, however, we observe a universe made up almost entirely of matter, while antimatter is extremely rare.

Antimatter is a form of matter whose particles have an opposite charge to ordinary particles (e.g., the positron is the antiparticle of the electron). When matter and antimatter collide, they annihilate, turning into energy.

So why is there only matter left in the Universe? Scientists suggest that in the early Universe there may have been processes that broke the symmetry between matter and antimatter. However, the exact mechanism of this violation is still unknown.

6. What happens inside black holes?

Black holes are regions of space-time with gravity so strong that even light cannot escape. The central region of a black hole is called a singularity - a point with infinite density and zero volume.

According to Einstein's general theory of relativity, the laws of physics stop working in a singularity. This makes black holes some of the most mysterious objects in the universe. What happens inside them? Where does the absorbed matter disappear to? And is there a connection between black holes and hypothetical ‘white holes’ that eject matter outward?

Some theories suggest that black holes may be ‘portals’ to other universes or dimensions. However it is impossible to check these hypotheses because of impossibility to observe processes inside the event horizon of a black hole.

7. What is the fate of the universe?

How will the existence of our Universe end? This is one of the most fundamental questions of cosmology. The fate of the Universe depends on its density and expansion rate.

There are several scenarios:

- Big Rip (Big Rip): If dark energy continues to accelerate the expansion of the Universe, eventually galaxies, stars, and even atoms will be ripped apart.

- Big Crunch (Big Crunch): If gravity proves stronger than dark energy, expansion will stop and the universe will begin to shrink.

- Heat Death: If expansion continues indefinitely without acceleration or deceleration, the temperature of the universe will gradually drop to absolute zero.

At this point, the evidence points to an accelerating expansion of the Universe, making the Big Bang scenario the most likely. However, much depends on the nature of dark energy, which remains a mystery.