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 CONTENTS Introduction Fermi's Piano Tuner Problem How Old is Old? If the Terrestrial Poles were to Melt... Sunlight Exerts Pressure Falling Eastward What if an Asteroid Hit the Earth Using a Jeep to Estimate the Energy in Gasoline How do Police Radars really work? How "Fast" is the Speed of Light? How Long is a Light Year? How Big is a Trillion? "Seeing" the Earth, Moon, and Sun to Scale Of Stars and Drops of Water If I Were to Build a Model of the Cosmos... A Number Trick Designing a High Altitude Balloon Pressure in the Vicinity of a Lunar Astronaut Space Suit due to Outgassing of Coolant Water Calendar Calculations Telling Time by the Stars - Sidereal Time Fields, an Heuristic Approach The Irrationality of The Irrationality of The Number (i)i Estimating the Temperature of a Flat Plate in Low Earth Orbit Proving that (p)1/n is Irrational when p is a Prime and n>1 The Transcendentality of Ideal Gases under Constant Volume, Constant Pressure, Constant Temperature and Adiabatic Conditions Maxwell's Equations: The Vector and Scalar Potentials A Possible Scalar Term Describing Energy Density in the Gravitational Field A Proposed Relativistic, Thermodynamic Four-Vector Motivational Argument for the Expression-eix=cosx+isinx Another Motivational Argument for the Expression-eix=cosx+isinx Calculating the Energy from Sunlight over a 12 hour period Calculating the Energy from Sunlight over actual full day Perfect Numbers-A Case Study Gravitation Inside a Uniform Hollow Sphere Further note on Gravitation Inside a Uniform Hollow Sphere Pythagorean Triples Black Holes and Point Set Topology Additional Notes on Black Holes and Point Set Topology Field Equations and Equations of Motion (General Relativity) The observer in modern physics A Note on the Centrifugal and Coriolis Accelerations as Pseudo Accelerations - PDF File On Expansion of the Universe - PDF File

## If I Were to Build a Model of the Cosmos...

Let's try to build a scale model of the universe. The visible sun has a diameter of 864,000 miles (more than 3/4 million miles). Let us build a model universe in which the sun is reduced in size to a sphere one millimeter in diameter (about the size of a salt grain). On this scale, Earth would be as large as a single grain of talcum powder (10 microns), and would be 4.3 inches from the sun. On the same scale, Proxima Centauri would still be 17 miles away. If a sphere, with a radius of 17 miles, were constructed around our scale model sun, there would be one star on the sphere's surface, Proxima Centauri. All the remaining stars of the galaxy would be located outside the sphere. The Milky Way galaxy would have a scale diameter of 425,000 miles, i.e., almost twice the actual distance from the earth to the moon. M31 would be slightly larger than the Milky Way (500,000 miles or so in diameter), and would be located 7,000,000 miles away, more than 1/10 the distance from the earth to Mars at opposition (Mars' point of closest approach to the earth)!

And so on, outward ...

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