invention of X-ray (1895)

invention of compass (1300)

invention of telephone (1896)

invention of the numbers/numerals (30000 BC)

the date the theory of relativity was published (general theory was published in 1916)

landing man on the moon (July 20, 1969)

invention of seismograph (1880)

the date the periodic table was published (1869)

Isaac Newton (January 4, 1643)

WW2 – 1939 – Nazi invasion of Poland to August 1945 atomic bombings in Japan

x-ray – google “Roentgen” – I forget the year but I’m thinking 1920’s

compass – pre-medieval. I can’t pin down the century.

telephone – very late 1800’s Elisha Gray and Alexander Graham Bell. Bell got to the patent clerk 10 minutes faster.

Numerals – Persians, Etruscans, who knows. B.C. times….

theory of relativity I think was published somewhere between 1913 and 1917 by Einstein

landing on the moon……first time was July 20, 1969

seismographs…..chinese had a primitive one from like the year 600.

Dmitri Mendeleev published the first P.T. in 1800’s, like 1870ish. Mosely’s modern table came in the early 1900’s, like 1915ish.

Newton was doing his thing in the mid and late 1700’s. Don’t know if he lived into the 1800’s offhand.

Good luck!

(2) 5th century BC–Zero 1st used in Sanskrit

(3) 4th century BC–Olmecs of Mexico 1st to use “true” zero (a shell glyph)

(4)3400 BC–Mesopotamia uses a Base 60 number system.

(5) 3100 BC –Base 10 counting system used in Egypt.

(6) 221-206 BC—-magnetic compass invented in China

(7)130 AD–Ptolemy used a zero with long bar over it within a sexigesimal system of numbers. Greeks later changed it to become their omicron letter (or 70).

(8) 132 AD———-1st seimoscope invented in China and

was called a “dragon jar”. It could register the

presence of earthquakes.

(9)525 AD–Zero used with Roman numerals but as a WORD only (“nulla”=nothing. When division of numbers produced a zero remainder, the word “nihil” was used).

(10) 628–Brahmagupta of India was first to treat zero as a number and used it in division.

(11)7th century–Idea of zero moved to Cambodia, then China and then to Islamic world.

(12) 1642-1727: Lifetime of Sir Isaac Newton. Invented the

reflecting telescope in 1668. He explained the workings

of the universe with /through math.

(13)1864–Dmitri Mendeleev published the 1st Periodic Table. Over 700 versions of the periodic table have been published since then.

(14)1876–Though 2 men discovered and/or invented the telephone at the same time, ALEXANDER GRAHAM BELL applied for and got the first patent for it.

(15)1880–John Milne invented the horizontal pendulum seizmograph.

(16) 1895—Wilhelm Roentgen discovers the x-ray.

(17) 1915–Einstein’s Theory of Special Relativity published after 10 years of developing it. “Field Equations” is what the theory was published in.

(18) 1935–Charles F. Richter invents a scale to predict earthquakes.

(19) 1939–Hitler’s invasion of Poland on Sept. 2 starts World War 2 (he’d been in power in Germany, however, since 1933). USA enters the war, after Pear Harbor attack, in Dec. 1941. War in Europe ends in May 1945, and in Pacific in August 1945 (peace treaty signed in September)

(20) 1969–USA first to land a man on the moon,Neil Armstrong in Apollo 11, on July 20. Famous words: “One small step for man, one giant leap for mankind.” Second man on moon was fellow astronaut Edwin “Buzz” Aldrin.