"So when you ask me how string theory might be tested, I can tell you what's likely to happen at accelerators or some parts of the theory that are likely to be tested"

This quote by Edward Witten is describing the testing of string theory, a theory that tries to describe the essential nature of deep space. Witten is suggesting that string theory can be checked in 2 ways: through experiments conducted at particle accelerators, and by evaluating specific aspects of the theory. Particle accelerators permit researchers to study the habits of particles at extremely high speeds, which can assist them to understand the habits of matter and energy at the tiniest scales. Furthermore, by evaluating particular aspects of the theory, scientists can gain a much better understanding of how the universe works and how it is structured. By evaluating string theory in these 2 ways, scientists can get a much better understanding of the basic nature of deep space.