Stealth in space

[Human No More]

I was never actually saying transparent aluminium would be impossible.

As for propulsion, unless you had a system like the Normandy's, then any acceleration, deceleration or course change would create easily detectable emissions of heat, particles and radiation at the very least. Since there is no friction in space, a ship tracking could easily maintain a lock on the new projected course.

Also, with sensitive enough thermal sensors, it would be easy to detect any ship with life support from its heat, even with insulation. Another theoretical method of detection is that it would block background radiation, so could be noticed with a directional sensor.