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Physicists saw a black hole for the first time, debated the expansion rate of the universe, pondered the origin of time and modeled the end of clouds.

Researchers explored the zone between life and death, charted the mind’s system for arranging ideas and memories and learned how life’s complexity emerged.

Mathematicians and computer scientists made big progress in number theory, graph theory, machine learning and quantum computing, even as they reexamined our fundamental understanding of mathematics and neural networks.

Celebrate a year’s worth of scientific and mathematical insights by solving this brain-teasing cryptic crossword from our puzzle columnist.

Several mathematicians under the age of 30 left their marks all over the field, and amateur problem-solvers of all ages made significant contributions to long-dormant puzzles.

Biologists gained new insights into life’s genomically tumultuous past, viruses as crucial components of life, the hidden talents of complex cells and basic aspects of cognition and memory.

The field of fundamental physics is experiencing both a period of confusion and an openness to new ideas.