What are the most difficult college courses out there?

Just out of curiosity, what are some of the most difficult college courses you've heard of or experienced? I love a good challenge, and I'm interested to know what classes are likely to push me academically in college.

I've heard from many students that some of the most challenging college courses tend to be in the fields of mathematics, sciences, economics, and engineering. Here are a few examples of notoriously difficult courses across various disciplines:

1. Organic Chemistry: This course covers the structure, synthesis, and reactions of organic compounds, and is often required for students pursuing pre-med, chemistry, or biology degrees. It's known to be challenging due to the sheer volume of material covered and the need to understand complex concepts at a deeper level.

2. Quantum Mechanics: Typically offered to physics or engineering majors, this course delves into the principles governing the behavior of particles at the quantum level. It's considered difficult due to the abstract concepts and advanced mathematics involved.

3. Advanced Calculus (Real Analysis): This course provides a rigorous treatment of calculus, with a focus on mathematical proofs and the theoretical underpinnings of the subject. Students often find the abstract nature of proofs and the emphasis on formal logic particularly challenging.

4. Thermodynamics: A core course for engineering and physics majors, thermodynamics deals with the relationships between heat, work, and energy. Students may find it difficult due to the intricate and abstract principles, as well as the extensive problem-solving required.

5. Partial Differential Equations: Often taken by mathematics and engineering majors, this course entails the study of differential equations that involve partial derivatives. It is known to be challenging due to the complexity of the equations and the level of mathematical sophistication needed to tackle them.

6. Econometrics: This course, which combines economics, statistics, and mathematics, teaches students how to analyze economic data and build quantitative models. The mathematical rigor and the need to understand statistical concepts make this course quite demanding.

Of course, the difficulty of a course can vary depending on your prior experience, background, and natural aptitude in a certain topic. Additionally, the professor, their teaching style, and grading standards can also impact the overall difficulty of a class. Everyone's experience might be different, so don't be afraid to embrace challenges and explore subjects that genuinely interest you!