If light doesn't hit an object or travel through a new medium, it will continue to travel in a straight line at the speed of light. This is because light travels in waves, and in a vacuum, those waves have nothing to interfere with them.

Think of it like this: Imagine throwing a ball across a perfectly smooth, empty field. The ball will keep going in a straight line until it hits something or is affected by a force like wind or gravity. Light behaves similarly in a vacuum.

Here are a few key points:

* Vacuum: Light travels at its fastest in a vacuum, which is the absence of any matter.

* No obstacles: Without objects or changes in medium, there's nothing to bend or scatter the light.

* Straight path: The path of light is a straight line, known as a ray.

This concept is fundamental to understanding how light behaves and how we can use it to see the world around us.