system
Given the following post, respond as if you're commenting on Reddit:
human
What's the point of rockets in space?

In many movies that deal with space travel you see ships that constantly have their main rockets engaged. Wouldn't this keep the ship at a constant rate of acceleration and not just propelling the ship at the same rate? Or is there a force, even in space, similar to friction that keeps ships from constantly accelerating? 

Edit: thanks for all the great responses. You guys have certainly answered my question but not only that you put it in terms I can easily understand lol I'm by no means a science expert just someone who has seen their fair share of space movies and a lot of free time on his hands.
gpt
Most movies don't care too much about being scientificly accurate vs apealing to look at. Let's ask it like this, if you want an impressive action shot, would you blast the rockets at full thrust or have it just sitting there doing nothing?

And yes you're right, the small resistance you get from space dust isn't a big factor as let's say  air resistance. You don't keep  your engines on because that would use up way too much fuel.