Part a scientists estimate the probability of finding a habitable planet around the star alpha centauri a at roughly 85 %. your twin joanne is an adventurous astronaut, and decides to take a trip there to find out for sure. for the purposes of this question, we will assume that she travels at a constant speed until she arrives. she measures that the trip takes her a time ti, and determines the distance di that she travels using di ut,. you measure that the journey takes a time to, and that joanne travels a distance of d2 4.37 light years. d t (a) describe the two events that are associated with the distance and time measurements. (b) who measures the proper time between the events? who measures the shortest time? explain your answer. y b od nlo o d al (d) o (c) who measures the proper distance between the earth and alpha centauri a? who mea- sures the shortest distance? explain vour answer. d in (d) on arriving at alpha centauri a, joanne discovers that unfortunately all the rocky plan- ets are frozen-they are all beyond the "goldilocks" zone. disappointed, she immedi- ately returns to earth at the same speed v, and has a joyous reunion with her friends and ofamily. if v = 0.9c, what is the age difference between you and joanne on her return? make sure you specify who is older. m 08.0- lo d d d atd tailov noolo to stino a nolo od lo part b (advanced) (a) consider again the scenario of part a. halfway through her return journey, joanne decides to send you a written note outlining the details of the reunion party she wants to be organised for her arrival. she puts the message in a container, and shoots it towards earth at a speed relative to her of 0.5c. after you receive the message, how many days do you have to organise the party? (b) consider again the scenario of part a, but instead imagine that joanne travels at a different speed different in age from you when she returns? if your answer is yes, calculate the speed u if your answer is no, explain why not. u. is it possible for joanne to complete the same journey, but be 12 years