Dark matter is believed to make up about 85% of the matter in the universe, but its nature remains a mystery.
Although we understand some of the biological processes that contribute to aging, the underlying mechanism remains a mystery.
Cosmic rays are high-energy particles that originate from beyond our solar system, but their exact source is still unknown.
Migraine are a common neurological condition that affects millions of people worldwide, but their underlying cause is still not fully understood.
Despite decades of research, scientists have not been able to conclusively determine how life began on Earth.
Despite the vastness of the universe and the billions of potentially habitable planets that likely exist, we have not yet found concrete evidence of extraterrestrial life.
While the Big Bang theory explains how the universe began, it does not explain why it began or what came before.
While scientists have made significant progress in understanding the brain, the question of how subjective experience arises from neural activity remains a mystery.
Although we can describe and measure gravity, the underlying mechanism by which massive objects attract each other is still not fully understood.
There are several theories about what will ultimately happen to the universe, but no one knows for sure.