If I have a mass that gets accelerated to a near the speed of light, before it gets I would think its relativistic mass would expand its Schwarzschild radius enough to turn it into a black hole. I have read on the internet that this is not actually the case and that relativistic mass shouldn't actually be interpreted as increasing mass.
the Wikipedia page mentions that relativistic mass is often misunderstood. what is typically misunderstood about this? (I think I am one of the ones that misunderstands it)
I also read that the Schwarzschild radius wont expand due to relativistic mass because if that were the case one observer may see the mass as a BH while a co-moving observer wont, and this cant be?
Why couldn't one observer see a BH while the other doesn't? I feel like that would make sense in relativity.