给出一个问题，需要从指定文本中找到答案。
提供一个问题和一段文本，在文本中找到问题的答案。
问题：文本中提到了什么？

文本：In the early 20th century, Albert Einstein published his theory of special relativity, which challenged the established laws of physics and introduced the concept of spacetime. This groundbreaking theory posited that time and space are not separate entities but are intertwined, and that the speed of light is a constant that cannot be exceeded.

答案：Albert Einstein的special relativity 理论，它质疑了已经确定的物理学定律，介绍了时空的概念。