How does a spaceship move in space if space is void of everything?

It carries its own stuff (propellant) against which to push against. It is no different than if you were sitting on a boat with a pile of rocks aboard, and you were to throw rock-by-rock backward. Eventually, there would be significant recoil for you and the boat and the unthrown rocks to gain a desired speed. "And if you think its pushing up against the gas from the ship itself your wrong because where is that gas going?" Why does it matter where the gas is going? The gas is being thrusted backward at very high speeds. The gas eventually just diffuses in to the background vacuum and makes it slightly less of a vacuum. Unless of course there is a large celestial body in the way, in which case that gas pushes on that celestial body. Which is indeed what happens to the propellant used to launch rockets from Earth or the Moon. All the propellant slams directly in to the launch site, and ultimately pushes the celestial body in the opposite direction.

It is because for every action there is an equal but opposite reaction. It doesn't need to (push against) anything.

It carries its own stuff (propellant) against which to push against. It is no different than if you were sitting on a boat with a pile of rocks aboard, and you were to throw rock-by-rock backward. Eventually, there would be significant recoil for you and the boat and the unthrown rocks to gain a desired speed. "And if you think its pushing up against the gas from the ship itself your wrong because where is that gas going?" Why does it matter where the gas is going? The gas is being thrusted backward at very high speeds. The gas eventually just diffuses in to the background vacuum and makes it slightly less of a vacuum. Unless of course there is a large celestial body in the way, in which case that gas pushes on that celestial body. Which is indeed what happens to the propellant used to launch rockets from Earth or the Moon. All the propellant slams directly in to the launch site, and ultimately pushes the celestial body in the opposite direction.

It is because for every action there is an equal but opposite reaction. It doesn't need to (push against) anything.

It makes perfect sense. Newton's third law states that forces always come in pairs, equal in magnitude and opposite in direction. The ship pushes against the exhaust gas, giving it momentum in one direction. This is clearly true because if no forces acted on the gas, it would not suddenly accelerate out the back of the rocket. However, it does accelerate out the back of the rocket, therefore we know the rocket is exerting a force on the gas. Newton's third law tells us that the gas must also therefore exert a force on the rocket in the other (forward) direction. That's what makes a rocket accelerate forward. Let me remind you that you came here for information. It is not my problem if you also brought along a bunch of wrong assumptions.

It makes perfect sense. Newton's third law states that forces always come in pairs, equal in magnitude and opposite in direction. The ship pushes against the exhaust gas, giving it momentum in one direction. This is clearly true because if no forces acted on the gas, it would not suddenly accelerate out the back of the rocket. However, it does accelerate out the back of the rocket, therefore we know the rocket is exerting a force on the gas. Newton's third law tells us that the gas must also therefore exert a force on the rocket in the other (forward) direction. That's what makes a rocket accelerate forward. Let me remind you that you came here for information. It is not my problem if you also brought along a bunch of wrong assumptions.

say you were floating around in space, and you happened to have a big rock handy and you threw it out in front of you, the rock has mass and would impart momentum on you. you would be pushed however slightly in the opposite direction. a rocket works the same way.

say you were floating around in space, and you happened to have a big rock handy and you threw it out in front of you, the rock has mass and would impart momentum on you. you would be pushed however slightly in the opposite direction. a rocket works the same way.

>>How would a spaceship even move if there was nothing to push up against? Airplanes push up against the air to move.<< No they don't. They require the air to generate lift but not to move forward. Only aircraft driven by propellers push against the air to move forward. >>This makes NO sense at all. And if you think its pushing up against the gas from the ship itself your wrong because where is that gas going?<< Sorry, but it is well established that rocket engines work by the reaction between the exhaust gases and the mass of the spacecraft. Think how an explosion pushes in all directions, then imagine channelling that force in one direction. That is basically how a rocket engine works. In keeping with Newton's third law, blasting out exhaust gases at high speed in one direction causes the rocket to move in the other. Your reasoning is backwards. It makes no sense to you, but evidently works, so perhaps it is your understanding that is wrong, not the principle as described.