[joelthelion]

So it boils down to the angle of the blades being steeper on the compressor side than on the turbine side, doesn't it?

Another related question: what happens if you don't rotate the engine before you ignite it?

[exDM69]

There will be a fuel fire inside the engine. Just a regular fire at atmospheric pressure.

But jet engines can and do backfire spectacularly at times. You can find lots of cool footage from hobby turbine engine enthusiasts on the tubes.