Lorentz Contraction
Hello, I have to do a presentation next week. My topic is Special Relativity: Time Dilation & Lorentz Contraction. I think I understood time dilation well enough, but I have trouble understanding Lorentz Contraction.
So I got this example on my slides where an astronaut on a rocket travels at 0.9c for 10 years. Using the time dilation equation, the time passes for an observer on Earth is 22.9 years. I will then go to Lorentz Contraction from here. For the astronaut in the rocket, the distance is 0.9c * 10 = 9 light-years, but for the observer on Earth, the distance is 0.9c * 22.9 = 20.6 light-years. So, I understand that the space is compressed for the astronaut. But according to Lorentz Contraction, the object itself - here the rocket - must be compressed according to the observer on Earth. Why and how? I don't think I understood well enough, and I'm scared of how I'm going to explain it to the audience. I would appreciate all help. Thank you!