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How Does Light Travel? Does It Travel Forever?

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blue, green and red laser beams

Light is almost always around us, but it’s not something that most people think twice about.

If you do start thinking about it, you might wonder how light travels and for how far. The answer is that light moves as a wave, and it can go on forever. Let’s go over what that means and dive a little deeper into the topic.

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How Does Light Travel?

Since light travels like a wave, it can travel through a vacuum without interacting with anything. However, when light does go through something, that object can absorb some of it. Light travels through these objects, like glass and water, leaving heat behind.

Think of a flashlight. When you turn it on and face it toward a pool, the light can travel through the pool. However, if the flashlight isn’t bright enough, it won’t illuminate the bottom of the pool.

It’s also worth noting that light travels in all directions. If you have a lightbulb in the middle of the room with no lampshade, the light is going to travel in every direction. This is a basic principle of light, and it’s why when we create light to use, we must find ways to direct it.

Both flashlights and lamps do this, and it’s how we control where the light goes, by reflecting it off the surface of the object.

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Image Credit: donatas1205, Shutterstock

How Far Does Light Travel?

Light can travel for infinity. It doesn’t have a set range, and that’s why we can see light from billions of miles away.

It’s also why when we point the James Webb or the Hubble telescope out into deep space, we can see even farther, observing the light from galaxies from the very early universe.

However, when light hits objects like planets or other matter, this either reflects or absorbs the light. The most extreme example of this is a black hole. If light hits a black hole, the gravity is so strong that it can’t escape, thus ending the distance that the light travels.

Other Things That Affect the Movement of Light

Sometimes, gravity can pull on light without completely absorbing it or reflecting it.

This is common with black holes, neutron stars, and even large stars. As light passes by these objects, their respective gravities can pull on the light. If the light is far enough away, it will continue to move away from the object, but it will have a new trajectory.

If you look at a ray of light from above, what it will look like when this is happening is that the light will bend. So, while light travels in a straight line in all directions from an object, the gravitational pull of different objects can shift where that light ends up.

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Final Thoughts

When you’re trying to figure out the science in the world, it can all seem a bit complicated. Hopefully, now that you know more about how light moves, you can move on to new questions and contemplate the ways that different things work.

That’s what science is all about, and if you’re asking questions like how light moves, an interest in science might just be in your future!

Featured Image Credit: nepool, Shutterstock

About the Author Robert Sparks

Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.

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