Say we built a cigar the mass of the sun out in deep space, with radius of 1 km, and length of a million miles. A spaceship flies by within a km at an immense speed. No problem, it will zoom down the length and never feel much of a gravitational pull (if it did, we could help it with a slippery trough to slide along).
But from the spaceship's perspective, the cigar is squished into just 2 km length by Lorentz contraction. That is, the alien sees an speherical object, mass of the sun, radius of 1 km. That's a non-spinning black hole in his reckoning. No way he can let it pass by him within 1 km, because he'd go through the event horizon and be trapped forever.
What's going on? Where's my mistake? Isn't the shape more dense than a black hole in his reference frame?
