Hardest I can make

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Across
  1. 2. nonviolent independence leader
  2. 3. death pandemic that reshaped Europe
  3. 9. study of moral principles
  4. 12. major English playwright
  5. 14. rise of reason and science
  6. 18. revolution shift to machine production
  7. 19. chief Norse god
  8. 21. selection survival based evolution
  9. 23. secure communication
  10. 24. extreme devoted believer
  11. 25. war global tension without direct war
  12. 26. study of knowledge and existence
  13. 32. rebirth of art and science
  14. 36. horizon boundary beyond black hole escape
  15. 37. early civilization between rivers
  16. 38. study of language
  17. 39. vinci renaissance inventor artist
  18. 43. curie pioneer of radioactivity
  19. 44. study of signs and symbols
  20. 46. trench deepest ocean point
  21. 48. life has no meaning but you continue
  22. 51. study of knowledge
  23. 52. study of what exists
  24. 54. laws of motion and gravity
  25. 55. luther king jr civil rights leader
  26. 56. control what you can
  27. 60. renaissance sculptor painter
  28. 64. information used to influence opinion
  29. 68. method learning through questioning
  30. 69. manuscript unreadable illustrated book
  31. 70. private ownership economy
  32. 73. cat outcome unknown until observed
Down
  1. 1. project atomic bomb development program
  2. 4. map making
  3. 5. mandela anti apartheid president
  4. 6. meaning comes from individual choice
  5. 7. rule by administrative system
  6. 8. statement that seems self contradictory
  7. 10. paradox motion split into infinite steps
  8. 11. study of beauty
  9. 13. the great created vast ancient empire
  10. 15. stone key to translating ancient writing
  11. 16. helix structure of DNA
  12. 17. Egyptian sun god
  13. 20. French military emperor
  14. 22. single ruler system
  15. 27. valley early urban civilization
  16. 28. lovelace early programming thinker
  17. 29. khan built largest land empire
  18. 30. relativity and spacetime
  19. 31. barrier reef largest coral ecosystem
  20. 33. government by voting
  21. 34. evolution by natural selection
  22. 35. tectonics shifting of Earths crust
  23. 40. test machine judged by human conversation
  24. 41. king of Greek gods
  25. 42. Trojan war epic
  26. 45. sun centered solar system
  27. 47. turing father of computer science
  28. 49. river longest historically important river
  29. 50. increasing world interconnectedness
  30. 53. early telescopic astronomy
  31. 57. war mythic war between Greeks and Troy
  32. 58. study of reality beyond physics
  33. 59. boson particle linked to mass
  34. 61. classless ownership system
  35. 62. revolution monarchy collapses into republic
  36. 63. eleven first moon landing mission
  37. 65. i powerful English queen
  38. 66. journey home epic
  39. 67. desert largest hot desert
  40. 71. rainforest largest tropical forest
  41. 72. ancient epic poetry
  42. 74. detat sudden government overthrow