# Intro to Relativity Question

1. Jan 22, 2010

### doublemint

1. The star Alpha goes supernova. Then ten years later and 100 light years away, star beta goes supernova. Aliens passing by observes that the explosions occur 120 light years away. According to them, what is the time between the explosions?

2. So I think I am supposed to used the Lorentz Transformations.
x'=$$\gamma$$(x-vt) and x=$$\gamma$$(x'+vt')
Then I solved for v in both equations since we do not know the speed at which the aliens are traveling at. I equate them together to get t'
$$\gamma$$t'=[$$\gamma$$t(x-$$\gamma$$x')]/($$\gamma$$x-x')
I solved for it and got -24 years..
So does it mean that it took 24 years inbetween explosions according to the aliens reference frame?

Thank You

DoubleMint

2. Jan 22, 2010

### doublemint

Nvm i've got it! I had to use the spacetime interval..obviously XD

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