You are scientifically illiterate if you are asking questions that have easily discoverable answers (as in this example, centuries of confirmed results)

The burn from the thrusters doesn't push against space, it pushes against the rocket.

For more easily discoverable answers to basic physics questions, perhaps take a physics 101 course. Or just Google your question.

Or do it the way you just did it... Cunningham's law and all that. But be aware that people will consider you scientifically illiterate if you do it the way you just did it.