Negative Rest Mass: Faster than Light?

[Daedalus_]

Theoretically, if an object were to have negative rest mass, would it travel faster than light?

 

[Shooting Star]

Theoretically, if an object were to have negative rest mass, would it travel faster than light?

Which kind of mass are you talking about -- inertial mass, "active" gravitational mass, or the "passive" gravitational mass?

Generally, when considering negative masses, it is assumed that they fall with the same acceleration as as positive masses, and conservation of momentum is valid. They do not travel faster than light.

By putting '-m' in place of m in Newton's law of gravitation, you can play around a bit with the concept of negative mass. Note that negative masses move in the opposite direction of the applied force on it. Can you figure out what will happen when a mass m and a mass '-m' are just left close to one another?

To answer your question, objects with imaginary masses, which are called tachyons, travel faster than light.

EDIT: There is already a lot of discussion going on in https://www.physicsforums.com/showthread.php?t=66852, which I had somehow missed.

 

[Entropia]

The concept of negative rest mass is purely theoretical and has not been observed in any known particles. It is a mathematical concept that arises in certain equations and models, but it does not have any physical meaning in our current understanding of the universe.

Furthermore, the speed of light is considered to be the maximum speed in the universe according to Einstein's theory of relativity. This means that no object, regardless of its mass or energy, can travel faster than the speed of light. So, even if an object were to have negative rest mass, it would still be bound by the speed limit of light.

It is important to note that the speed of light is not just a physical limitation, but it is also a fundamental aspect of the structure of the universe. It is deeply intertwined with the fabric of space and time, and any attempt to surpass it would result in a violation of the laws of physics.

In conclusion, the idea of negative rest mass does not necessarily imply faster-than-light travel. And even if it did, it would still be impossible for any object to travel faster than the speed of light due to the fundamental limitations of the universe.