[filipmilanko (OP)]

I know that objects stop because force or several forces that have an opposite directions than the direction of that object, but what happens when there aren't any opposite directional forces?

[RyanGuyardo]

When in vacuum, frictional force cause by air particles does not exist, but there is another factor, gravitational force.
It depends on where your vacuum column is.

[Peteuplink]

As far as I know, if an object in a vacuum is subjected to a force that moves it the object will carry on in that direction and speed until another force comes into effect. SO if you were in a vacuum, threw an object and there were no opposing forces such as gravity or friction to slow the object down, then it'll keep going in the same direction at the speed that it left your hand. But I could be wrong about this.

[JP]

Newton's first law of motion is often paraphrased as something like:

An object moving with a constant velocity (or at rest) will continue moving with a constant velocity (or remain at rest) unless acted upon by an outside force.

So something can't slow down unless there's some force coming in and making it slow down.  In a vacuum, far from other matter that might exert forces on it, the object will keep moving in a straight line without slowing down or changing direction.