Vocab

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Across
  1. 1. The exact average density of matter needed for the universe to be flat (neither expanding forever nor collapsing).
  2. 6. A period in the universe when matter dominated over radiation in determining its behavior.
  3. 7. A space-based telescope that observes distant objects without atmospheric distortion.
  4. 10. Faint microwave radiation left over from the early universe, evidence of the Big Bang.
  5. 11. The extremely hot and dense early state of the universe shortly after the Big Bang.
  6. 13. The four basic forces in nature: gravity, electromagnetism, strong nuclear force, and weak nuclear force.
  7. 14. A type of variable star whose brightness changes predictably, used to measure cosmic distances.
  8. 16. The compression of light to shorter (bluer) wavelengths, indicating an object is moving closer.
  9. 19. A point where density becomes infinite, such as at the center of a black hole or the universe at its beginning.
  10. 21. The scientific model stating the universe began as a hot, dense state and has been expanding ever since.
  11. 22. A large system of stars, gas, dust, and dark matter bound together by gravity.
  12. 23. A measure of how hot or cold something is, related to the average kinetic energy of particles.
  13. 28. A fundamental force involving electric and magnetic fields that affects charged particles.
  14. 29. The distance light travels in one year (about 9.46 trillion kilometers or 5.88 trillion miles).
  15. 30. A region of space where gravity is so strong that not even light can escape.
  16. 32. The change in wavelength of waves due to motion between the source and observer.
Down
  1. 2. Dark or bright lines in a spectrum caused by absorption or emission of specific wavelengths.
  2. 3. Energy cannot be created or destroyed, only transferred or transformed.
  3. 4. The study of the origin, structure, evolution, and eventual fate of the universe.
  4. 5. A pair of equal and opposite charges or magnetic poles separated by a distance.
  5. 8. The overall geometry of the universe (flat, open, or closed).
  6. 9. The process where small atomic nuclei combine to form a larger nucleus, releasing energy (powers stars).
  7. 12. Faint microwave radiation left over from the Big Bang that fills the universe.
  8. 15. An instrument used to measure the intensity of light.
  9. 17. Invisible matter that does not emit light but exerts gravitational effects on visible matter.
  10. 18. Large, nearly empty regions of space between galaxy clusters.
  11. 20. Matter made of particles with opposite charge to normal matter (e.g., positrons vs electrons).
  12. 24. The stretching of light to longer (redder) wavelengths, usually indicating an object is moving away.
  13. 25. The SI unit of temperature, starting at absolute zero (0 K).
  14. 26. A dimension in which events occur in sequence, allowing measurement of duration and change.
  15. 27. The apparent shift in position of an object when viewed from different locations, used to measure distance.
  16. 31. A brief period of extremely rapid expansion of the universe right after the Big Bang.