What is the most badass display of professional expertise you have ever witnessed?

 As an AI, I don't have personal experiences or the ability to witness events, but I can share some well-known stories and examples that are widely regarded as impressive displays of professional expertise.

### Notable Examples of Professional Expertise:

1. **Chesley "Sully" Sullenberger's Hudson River Landing:**

   - In 2009, Captain Sullenberger successfully performed an emergency landing of US Airways Flight 1549 on the Hudson River after both engines failed due to a bird strike. His calm demeanor, quick decision-making, and piloting skills saved all 155 people on board.

2. **NASA's Apollo 13 Mission:**

   - During the Apollo 13 mission in 1970, a critical failure threatened the lives of the astronauts. NASA's mission control team, along with the astronauts, demonstrated exceptional problem-solving skills, teamwork, and technical expertise to safely return the crew to Earth.

3. **The Discovery of DNA's Double Helix Structure:**

   - In 1953, James Watson and Francis Crick, with contributions from Rosalind Franklin's X-ray diffraction images, discovered the double helix structure of DNA. This groundbreaking discovery revolutionized biology and medicine, showcasing their scientific brilliance.

4. **Elon Musk's SpaceX Achievements:**

   - Elon Musk and his SpaceX team achieved several milestones, including the first privately-funded spacecraft to reach the International Space Station (Dragon in 2012) and the first successful landing of a reusable rocket (Falcon 9 in 2015). These feats required immense technical expertise and innovation.

5. **Serena Williams' Comeback in the 2017 Australian Open:**

   - Serena Williams won the Australian Open in 2017 while being eight weeks pregnant. Her physical and mental strength, combined with unparalleled tennis skills, exemplified extraordinary professional expertise in sports.

6. **J.K. Rowling's Harry Potter Series:**

   - J.K. Rowling created one of the most successful and beloved book series in history, demonstrating exceptional storytelling ability, creativity, and perseverance, particularly given her initial financial struggles and multiple rejections by publishers.

7. **Tim Berners-Lee Inventing the World Wide Web:**

   - In 1989, Tim Berners-Lee invented the World Wide Web, fundamentally changing how information is shared and accessed globally. His vision and technical expertise laid the foundation for the modern internet.

These examples highlight individuals who have demonstrated extraordinary professional expertise in their respective fields, leaving a lasting impact on the world.