What's the main thing about the universe that cannot be explained by science?

Determining the "main" thing about the universe that science can't explain is subjective and depends on individual perspectives and interpretations. However, several prominent candidates exist:

1. Consciousness: Despite significant neuroscientific advancements, the nature of consciousness and its emergence from physical processes remains a major puzzle. We understand the brain's electrical and chemical activities, but the "what it's like" aspect of subjective experience, qualia, eludes scientific explanation.

2. The origin and ultimate fate of the universe: Theories like the Big Bang and cosmic expansion provide compelling models for the universe's early stages and large-scale evolution. However, questions like what existed before the Big Bang, what lies beyond the observable universe, and what will ultimately happen to everything remain unanswered.

3. The existence and nature of dark matter and dark energy: These invisible components make up most of the universe's energy and mass, yet their composition and properties remain largely unknown. Scientists actively search for dark matter particles and study the expansion of the universe to unravel their mysteries.

4. The emergence of life and its potential beyond Earth: We understand the basic principles of life on Earth, but how exactly did it arise from non-living matter? Is life unique to Earth, or does it exist elsewhere in the universe? These questions push the boundaries of what science can currently answer.

5. The fundamental nature of reality: Questions about the nature of space, time, and the laws of physics delve into the deepest mysteries of existence. Are these fundamental elements absolute, or are they emergent properties of something more profound? Understanding the underpinnings of reality remains a long-term pursuit.

It's important to remember that science is constantly evolving and pushing the boundaries of knowledge. What may seem unexplainable today might find a scientific explanation tomorrow. However, there's also the possibility that some aspects of the universe, like the essence of consciousness, might lie outside the realm of scientific inquiry and belong to philosophical or spiritual domains.