When it comes to the force of gravity, we usually think of things being pulled towards the ground. But what about light? Is light attracted by gravity?
Let’s find out the answer to this question in this short article.
Is light attracted by gravity?
It turns out that the answer is both yes and no. Let’s take a closer look.
First, let’s consider what we mean by “light”. For our purposes, let’s think of light as electromagnetic radiation. This includes everything from radio waves to gamma rays.
Now, what we know about gravity is that it is a force that attracts objects with mass. The more mass an object has, the more gravity it has.
Does that mean that light has no gravity?
No, actually. Even though light doesn’t have mass, it does have energy. And according to Einstein’s famous equation, E=mc2, energy has mass. So, even though light doesn’t have “physical” mass, it does have what we call “gravitational mass”.
Does that mean that light is attracted to other objects with gravity?
Yes, but the force is very weak. In fact, it’s so weak that we don’t usually notice it.
The reason the force is so weak is that the amount of gravitational mass that light has is very small. Remember, the gravitational force is proportional to the mass of the objects. So, if one object has twice the mass of another object, the force of gravity between them will be twice as strong.
But since light has such a small amount of mass, the force of gravity between two objects is usually much, much weaker than the other forces that act on them.
Why do we even care if light has gravity?
Well, it turns out that the force of gravity is the only force that can bend light. This is because the force of gravity is the only force that acts on objects with mass and energy.
So, if you want to bend light, you need to have a very strong source of gravity. This is why we can use things like lenses and mirrors to focus light. The stronger the source of gravity, the more we can bend the light.
In fact, the force of gravity is so strong that it can even bend spacetime itself! This is how we get things like black holes