Papa ... its interesting that if 2 people read the same text, they understand 2 different things...
But your picture that you provided about principle of jet engine lead to wrong conclusions.
I don't know the credibility of those sources and BTW EU projects are not good example of "well used money", because usually materials create people that are interested in "earning the money" and not interested in the field that project is about (usually people that understand the topic and people working on the topic for "EU project", are 2 different groups
).
but lets look on jet engine from physical point
Air that goes THRU engine (actually sucked from front of engine) is pushed behind the engine and that push produces force in oposit direction.
The article you provide is not well written and it tries to say that when you take an air from front of engine and put that air behind that engine, you will have lower pressure in front of engine and high pressure behind that engine (you take air from front and added it to air behind engine)... that difference of pressures will have some pushing effect on objects between that low pressure location and high pressure location (sucking effect from front and pushing effect from behind) ... for low velocity that force may be somehow important, but it is too ineffective, because the sucking and pushing efect is in all direction, not just in direction you wanna to use (this force is applied not just against engine but in all directions from "locations"). "pressure push" is there, thats true, but I think is not significant, and more importantly is too uneffective way to move an airplane (actually if you use this principle in enclosed environment with huge pressure difference, like in a gun barrel + bullet, this difference in pressure have huge "pushing effect", but this is not the case for open environment).
So push against atmosphere behind engine is not significant effective way that will enable you to fly.
What is important for jet engine is that you speedup huge amount of air in closed system (inside engine) and then trow that air behind engine (and according to 3th Newton law of motion, it will "produce" the same amount of force in opposite direction).
Speaking about rocket engine in the space, the situation is little different.
Bit negative effect in the atmosphere:
3th Newton law motion applied in the atmosphere will tell you, that air that is in front of your airplane take airplanes movement energy (because airplane is hitting steady air molecules and impart move energy to them (actually another part of movement energy is transformed to heat that is produced by this "impact").... that's reason why airplane must be aerodynamic, to minimize imparted energy).... so in atmosphere your jet engines must produce enough energy to "speedup the plane" and more importantly to equilibrate the lost movement energy that airplane imparted to air around that airplane.
This effect is not in vacuum -> you need engine just to speedup the craft or to stop it... not to "continue moving". Engine don't need so much medium to work with (medium = air/gas/whatever you decide to throw from closed system to outside).
Negative effect in the space
In atmosphere you had something that you were able to take from outside, speedup it in closed system and throw behind the airplane (you had air)... in vacuum you must have all "throw-able things" already in the closed system (there is nothing around you to take and throw. Space ships must throw just things they already have. To work effectively, you must have
A) huge mass of throw-able things (this is not good, because you need energy to transport that throw-able things from Earth into space).
B) throw things very fast... One way to do so is to take some liquid, heat it so it expands (you produce pressure) and throw it from closed system as fast as is manageable in opposite direction needed force to be applied
.
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The article states: backward push produced the equivalent in forward thrust.
Information about "pushing the atmosphere" is nice, but irrelevant to jet engine principle... (and I agree that it may be misleading, that it somehow have something to do with jet engine principle.)
The article doesn't tell anything like "atmosphere push engine forward".
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The EU project... well you already know my opinion about EU projects (I worked as an scientist on university I saw many results of "EU projects" from different countries... but if ask them "how you dare to present this as an result of project" they respond with "well we did best we can,we produced XXX pages of materials, we buy XXX pencils aso... so required and monitored parameters were fulfilled.". If you continue to ask about quality of that materials, they will tell you "Quality of that materials is not part of monitoring, its a matter of "responsible person""). So yes... EU project result is much less trustful even compared to wikipedia where people at least may change a mistake in text.
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PS: sorry for my English... I hope that is it understandable.