# what are the relativistic/cosmological implications on a long rigid body? [duplicate]

This is my first question. Hope it's in respect of quality standards.

Let's suppose to have a "long" rigid almost unbreakable bar of fixed negligible diameter . (we can imagine it as a rigid wire) Lets suppose that the "bar" goes from Earth to Sun (8 light minute distance) but not consider the masses/gravity of Sun and Earth.

1. If I pull the bar 1 meter , what's the relativistic analisys ? Since the info that "I pull the bar" travels at light speed , in the 8 minutes the info reach the Sun is the Bar one meter longer ?

2.The cosmological question: If the bar goes from one galaxy to another , how the universe expansion reflects on it?

• Concerning 1. I would even say: it travels with the speed of sound in your material, probably much slower than $c$. – mikuszefski Jun 12 '15 at 11:54
• Concerning 2: 8 light minutes is not long enough for any significant effects of expansion to manifest in it; the structural strength would overpower expansion by many orders of magnitude. – Jim Jun 12 '15 at 14:46