by Leonard Susskind. Designed for "amateur" physicists who want to understand the actual foundations of the theory beyond just popular science descriptions.

~$15.99 at Barnes & Noble (Paperback) or ~$7.49 (eBook).

If you are looking for a "piece" to help you understand or dive deeper into this subject, here are some top-rated resources categorized by their approach:

These resources focus on concepts and historical context without requiring a deep background in math.

What is your current knowledge (e.g., beginner, high school, college student)?

by David J. Griffiths. Widely considered the "standard" undergraduate text, known for its friendly language and manageable pace.