Firecrackers A and B are 600 m apart. You are standing exactly halfway between them. Your lab partner is 300 m on the other side of firecracker A. You see two flashes of light, from the two explosions, at exactly the same instant of time. Define event 1 to be “firecracker A explodes” and event 2 to be “firecracker B explodes.” According to your lab partner, based on measurements he or she makes, does event 1 occur before, after, or at the same time as event 2? Explain.