# Can you create a black hole using kinetic energy?

Imagine you have a particle accelerator that you can crank up to arbitrarily high energies. Because of General Relativity, the particles get heavier and heavier as you dump more energy into them. Will these particles ever become a black hole from this relativistic mass? If so, what will an observer particle moving parallel to the black hole, just below that speed, see? What I'm getting at is, kinetic energy is relative. So therefore relativistic mass is as well. So would these particles be black holes to some observers but not others?

• Might get better quality answers in Physics.SE Commented Jul 8, 2019 at 19:52
• physics.stackexchange.com/questions/3436/… seems like a place where you might find an answer, although I didn't find any of the answers quite as clear as I'd like Commented Jul 8, 2019 at 20:09
• Relativistic mass is a deprecated concept because it can be misleading and confusing. This is one of those situations where it's misleading. ;) Please see physics.stackexchange.com/questions/133376/… Commented Jul 9, 2019 at 7:22
• However, if you collide a pair of objects with insanely high relative kinetic energy, then you could create a black hole. "All" you need to do is to make sure you have enough energy in a small enough radius. Commented Jul 9, 2019 at 7:37
• @Carl For example, a black hole of radius 1 fermi (about the size of a proton) has a mass a little over 673 million metric tons. So if you get all the energy obtained by annihilating 337 million tons of antimatter with an equal amount of normal matter and somehow convert that into the KE of a pair of protons in a head-on collision, then when the protons collide you'll have all that energy within the required Schwarzschild radius. I think. ;) The protons may radiate some of that energy away before they collide. Commented Jul 9, 2019 at 17:27