In modern physics, vibrating strings are a concept used in certain theoretical models, such as string theory, to describe fundamental particles and their interactions. However, it's important to note that these models are still speculative and have not yet been experimentally confirmed.
In the context of string theory, which is one of the leading theoretical frameworks attempting to unify quantum mechanics and general relativity, the fundamental building blocks of the universe are hypothesized to be tiny, one-dimensional objects called strings. These strings can vibrate in different modes, and each mode corresponds to a different particle with specific properties, such as mass and charge.
Regarding what makes the strings vibrate, the exact mechanism is not yet fully understood within the framework of string theory. In the theory, the vibrations of strings are fundamental and not explained in terms of anything more fundamental. The different vibrational modes of the strings give rise to the diverse spectrum of particles observed in the universe.
However, it's important to note that our current understanding of string theory is still incomplete, and there are ongoing research efforts to better understand the nature of strings and their vibrations. Furthermore, it's worth mentioning that alternative theories and approaches exist that do not involve string-like objects as fundamental constituents of matter.
To summarize, according to string theory, the strings themselves are considered fundamental, and their vibrations give rise to different particles. However, the exact nature of what makes the strings vibrate and what the strings themselves are made of is not yet fully understood.