In the absence of any external forces or obstacles, such as gravity or atmospheric drag, a bullet shot in space would continue to travel in a straight line at a constant velocity indefinitely. This is due to the principle of inertia, which states that an object in motion will remain in motion unless acted upon by an external force.
In space, there is no significant atmosphere to slow down the bullet, and there is no gravitational force to pull it back. Therefore, the bullet would not experience any significant deceleration or come to a stop on its own. It would continue moving in a straight line until it encounters an external force or object that alters its path.
It's important to note that space is not completely empty, and there are extremely low-density particles and debris present. While these particles are widely dispersed, collisions with them over extremely long periods of time could eventually slow down the bullet. However, the likelihood of such collisions is extremely low, and the bullet would essentially travel very far before encountering any significant resistance.
So, in theory, a bullet shot in space could travel indefinitely until it interacts with another object or force that affects its trajectory.