Particle accelerators are considered the hallmark of human technological progress. By colliding subatomic particles at high energy, particle accelerators have brought a radical paradigm shift in our understanding of the universe. Accelerators typically collide energetic particles and look for the change in the energy of the system. This measurement of the energy of colliding particles plays a vital role in understanding the events that occur inside particle accelerators. Understanding the effect of particle accelerators in human society is incomplete without discussing the energies involved in the accelerators. Particle accelerators, as the name suggests, accelerate particles, and once these particles reach a certain amount of energy, they collide with them. The amount of energy required in the particles depends on the products desired by the physicists and the initial conditions of the experiment. If the accelerator is about to collide with two similarly charged particles (e.g. a pair of protons), then these particles must have enough kinetic energy to be able to overcome their electrostatic repulsive force and get close enough for the nuclear force to be effective (~1 fm). It is essential that all particles of similar charge cross this threshold of electrostatic potential energy, called the Coulomb barrier, to experience anything nuclear in nature. On the other hand, if a physicist wants to produce a pion (π0 or π+) by colliding two protons (p), it is essential that the protons have enough kinetic energy so that the energy of the collision is sufficient to create a particle with the desired rest mass, as given by the mass-energy equivalence relation. The threshold energy for protons to create a pion with a rest mass of 135M...... middle of paper...... collisions will not only elevate our lifestyle, but also define us in the process. Finding answers to mind-boggling questions simply by colliding particles together somehow shows how capable humans are. We must never tire of this study of the universe, it defines what we are. Works Cited Young, Hugh and Roger Freedman. University physics. 12. 2009. 917-925. PrintFowler, Michael. “Modern Physics”. University of Virginia. University of Virginia. Internet. November 13, 2013..CERN. CERN.2013. Internet. November 13, 2013 Quinn, Chris. “Discovery of the Top Quark.” . Fermi National Accelerator Laboratory. Internet. November 13, 2013. .Greene, Brian. Making sense of string theory. 2008. Video. TEDWeb. November 16 2013.