The Big Bang Theory

2. the lightest, simplest, and most abundant chemical element in the universe
4. the scientific study of everything in the universe outside Earth's atmosphere, including stars, planets, comets, and galaxies.
5. pioneering American astronomer who revolutionized 20th-century astronomy by proving that other galaxies exist outside the Milky Way.
10. influential American avant-garde stage director, playwright, and designer known for pioneering experimental theater through immersive, slow-motion imagery.
13. the faint, nearly uniform, remnant heat left over from the Big Bang, filling all space in the observable universe.
16. a massive, gravitationally bound system consisting of stars, stellar remnants, gas, dust, and dark matter.
17. a colorless, odorless, tasteless, and non-toxic inert gas.
18. German-born theoretical physicist widely regarded as the most influential scientist of the 20th century.

1. German-American radio astronomer and physicist who co-discovered cosmic microwave background radiation.
3. rominent British astrophysicist and cosmologist known for developing the theory of stellar nucleosynthesis.
6. the entire range of all types of electromagnetic radiation, organized by frequency, wavelength, and photon energy.
7. everything that exists, encompassing all space, time, matter, and energy.
8. he narrow band of electromagnetic radiation that the human eye can detect, typically spanning wavelengths from about 380 to 750 nanometers.
9. the prevailing scientific model explaining that the universe expanded from an extremely hot, dense singularity approximately 13.8 billion years ago.
11. an instrument that breaks up a wave into a frequency spectrum.
12. the ability to do work, cause change, or power movement.
14. an astronomical phenomenon where light from an object moving away from an observer is stretched, increasing its wavelength.
15. an astronomical phenomenon where the light from an object, such as a star or galaxy, is compressed into shorter wavelengths.