Question

Volcanoes on two mountain tops, Mt. Helen and Mt. Wagner, which are 300km apart, suddenly erupt in a burst of light at the same time in the reference frame of a seismologist at rest in a laboratory midway between the volcanoes. The seismologist’s assistant is at rest in a lab near Helen when it erupts. Also, a fast spacecraft, flying directly from Helen toward Wagner at v = 0.8c relative to the ground, is above Helen when it erupts.

1. Draw a spacetime diagram that includes the worldlines of Helen, Wagner, the seismologist, the seismologist’s assistant, and the spacecraft.

2. Does Helen erupt before, after, or at the same time as Wagner in the reference frame of the seismologist’s assistant?

3. Does Helen erupt before, after, or at the same time as Wagner in the reference frame of the spacecraft?

4. Is the distance between the eruptions in the spacecraft frame greater than, less than, or equal to the distance from Helen to Wagner in the seismologist’s frame?

Answer 1

seismologist 1. Any would line diagram fer photon NI Helen Tact Wagner 300km For spacecraft o=0.8c fonda sponunft IT w х 0.80 20.821 b for Beismologist, his maistant an two mountains tama = 0, d=0 so, world line to spauwaff 729 world line of these I b. & such that toma=0.8 2. → T obviously & < 45° 2-07 2