The concept of negative mass, including that of hypothetical particles called tachyons, is a topic that has been explored in theoretical physics. However, it's important to note that negative mass has not been observed or confirmed in experiments, and its existence remains purely speculative at this point.
Negative mass is often considered as a hypothetical concept that arises from certain mathematical equations and models. It is not a straightforward extension of the concept of positive mass that we observe in everyday objects. Negative mass would have some unusual properties, such as accelerating in the opposite direction of an applied force, rather than in the same direction as the force, as positive mass does.
Tachyons, on the other hand, are hypothetical particles that are often discussed in the context of special relativity. According to special relativity, the speed of light is an upper limit, and particles with mass cannot reach or exceed this speed. Tachyons are proposed as particles that always travel faster than the speed of light, and as a consequence, they are associated with imaginary (complex) mass values. However, it's important to note that tachyons are still hypothetical and their existence has not been confirmed.
It's worth emphasizing that the concept of negative mass, as well as tachyons, are mainly explored within theoretical frameworks and mathematical models to understand the implications they would have on various physical phenomena. However, their actual existence and behavior in the physical world are still open questions that require further experimental evidence or theoretical development to be resolved.