text: This value is the slope of a double cone which separates space-like and time-like intervals in Minkowski space.
full_question: This value is the slope of a double cone which separates space-like and time-like intervals in Minkowski space. When converting the energy-momentum relation to natural units, this constant is set to one. The Lorentz factor is defined using velocity, and this quantity, whose ratio with velocity is sometimes symbolized beta. One of the assumptions of special relativity is that this value appears the same in every reference frame. The Michelson-Morley experiment could not find evidence of the ether causing this value to change and exceeding this value violates causality. For 10 points, what universal speed limit is roughly three hundred million meters per second?
first_sentence: This value is the slope of a double cone which separates space-like and time-like intervals in Minkowski space.
raw_answer: speed of light [prompt on "c"]