Have you ever heard of Albert Einstein? He had some pretty crazy hair, but he also had some pretty great ideas.
One of those ideas was the theory of relativity, a scientific explanation about how space relates to time. The theory of relativity sounds very weird and strange when you first hear it. But it's very important for scientists studying outer space and how the universe works.
There are actually two theories of relativity, general relativity and special relativity. Let's take a closer look at each.
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Special relativity says that motion is always relative. Imagine a baseball floating alone in empty space. How do you know if it's moving or not? You can't. But if you put a basketball in space with the baseball, you could see whether the baseball was getting closer to the basketball or further away from it. Then you could see if the baseball was moving.
That's why it's called ''relativity.'' The motion of one thing is always relative to the motion of everything else.
Special relativity also says that light always travels at the same speed in empty space, 186,000 miles per second. So in one second, light could travel all the way around the planet Earth about seven and a half times!
Now here's the weird part. Special relativity also says that space and time are connected. Time can actually speed up if you're moving slowly through space, or slow down if you're moving quickly. Space and time together are called space-time. Space-time is like a giant trampoline that can 'bend' around big things like planets and stars.
Special relativity also says that mass, or the total amount of stuff in an object, can change depending on the speed of the object. If you started moving very fast, you would actually have more mass than you do right now.
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Now let's go on to general relativity. General relativity explains why things fall towards the ground when you drop them.
General relativity says that space-time is like a big trampoline. Imagine taking a big trampoline, and putting a heavy bowling ball on it. The bowling ball would make a dip in the trampoline and make the trampoline bend down.
General relativity says that planets do the same thing to space-time. They actually bend space and time around themselves. That's why things fall towards the ground. They're falling towards the middle of the Earth because Earth is pulling space-time towards itself.
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As you're walking around every day, you probably don't notice that the planet you live on is bending space and time. You don't notice that time can slow down as you move faster.
But if you're a scientist studying outer space, then the theory of relativity is very important. The theory of relativity helps us understand why things fall down instead of up. It can also help to explain why there are things like black holes or light, or how stars die. The theory of relativity can even be used to explain why GPS works or why gold is yellow and doesn't rust. And it's the logic behind Einstein's famous equation that E = mc2.
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Albert Einstein developed the theory of relativity, a scientific explanation about how space relates to time. Special relativity says that motion is always relative and that space and time exist in relation to each other. General relativity states that planets bend space and time the way a bowling ball bends a trampoline.
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This activity will help you assess your knowledge of the theory of relativity.
Determine whether the following statements are true or false. To do this, print or copy this page on a blank paper and write the letter of your answer on the table.
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A. The theory of relativity explains how space relates to speed.
B. Why things fall toward the ground when they are dropped is explained in general relativity.
C. Albert Einstein developed the general and special theory of relativity.
D. Time slows down as a person or object moves slowly in space.
E. In special relativity, you may see the movement of a single object in space.
F. Mass is affected by speed according to the special relativity theory.
G. As time and space are connected, time speeds up as you move quickly.
H. An object's motion is always relative to the motion of the objects around it.
J. Planets are able to bend space and time towards them thus allowing objects on Earth to fall towards the ground.
I. The speed of light is relative to the objects around it in space.
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