Question about relativity and mass.

Question

Let's say we accelerate a proton to close the speed of light. According to Einstein, at this speed this particle will have much more mass.

From the Proton's perspective, could it see itself as standing still while the entire universe is racing past it at close to the speed of light?

Would that mean from the proton's perspective, the mass of the Universe just got exponentially larger?

Answer 1

The "proper length" and "proper time" of the aforementioned proton, or anything for that matter, within its own inertial reference frame, (if you are assuming that it stops accelerating and begins to move at constant velocity) experiences no length contraction, time dilation, or mass increase. Each "object" sees his own self as "normal" but observes the other as moving slowly.  

Answer 2

Yes.

Yes.

(But remember, the proton can calculate -- if protons could calculate -- that these big things moving by it are moving very fast, and could calculate their rest mass. It just knows that, in its reference frame, it would be much harder to move them by a factor of gamma.)