**RELATIVITY**

**Select the correct term to complete the sentences.**

**speed of light**

**reference frame**

**black hole**

**general relativity**

**big bang**

**special relativity**

**antimatter**

**time dilation**

**1. Every particle of matter has a(n) ____ twin.**

**2. ____ is equal to 3**

**×**

**108 meters per second.**

**3. ____ is a theory that describes what happens to matter, energy, time,**

**and space at speeds close to the speed of light.**

**4. An effect known as ____ causes time to move more slowly for an**

**object in motion than for one at rest.**

**5. According to ____ the force we call gravity is an effect created by the**

**curvature of space and time.**

**6. The perspective of an observer from which the position and motion of**

**a system can be described is called a(n) ____.**

**7. A(n) ____ is an object with such a strong gravity that its escape**

**velocity equals the speed of light.**

**8. According to the ____, the universe was once smaller than an atom**

**and began to expand after a huge explosion.**