Dr. John's Science World

Dr. John's Science World

Dr. John Videos you may find useful
You can find the rest of them on www.youtube.com/jas2754

Introduction to my class - this is for my students



Why are Objects Round?



Stars - Why do they Twinkle?



Light Years - dealing with large dimensions



Physics - the Goal is to Simplify and Unify




The Asteroid Threat - We are surrounded by Comets and Asteroids, if left unmanaged will eventually pose a serious threat to human civilization.



The Branches of Astronomy



Evolution of Stars



About Stars



The Lifecycle of the Sun




Black Holes, White Dwarfs, and other Stellar Corpses



Extreme Physics of Black Holes

Physical Constants

Physical Constants represent a quantity believed to be the same throughout the Universe in both space and time. The behavior of the Universe is governed by these physical constants.

An example of a physical constant is the speed of light c.

C = 2.99792458 x 10^8 meters / sec * note that 10^8 means 10 to the power of 8 or 100,000,000 (100 million)

Physical Constants have dimensions ( e.g. meters per second) unless they represent ratios and they typically represent some universal property of the universe. For example, the speed of light represents the speed of propagation of an electromagnetic wave in vacuum, independent of your frame of reference. C also represents an upper limit of the speed on anything. The speed of light finds it's way into many different aspects of physics.

Below is a list of some of the major physical constants.



Summary of important physical constants

Fundamental Physical Constants
Speed of Light in a Vacuum c 2.99792458 x 10^8 meters / sec
Gravitational Constant G 6.67428 x 10^-11 meters^3 / (Kg Sec^2)
Plancks constant h 6.626068 x 10^-34 Joule sec
Elementary Charge e 1.602176 x 10^-19 C ( Coulombs)
Electron Mass me 9.109382 x 10^-31 Kg
Proton Mass mp 1.672 621 637 × 10^−27 Kg
Magnetic Permeability u0

Fundamental Physical Chemistry Constants
Atomic Mass Unit mu 1.660 538 86 × 10^−27 kg
Avogadro's Number Na 6.022 1415 × 10^23 mol^−1 ( Mole)
Boltzmann Constant k 1.380 650 × 10^−23 Joule·K^−1
Gas Constant R 8.314 472(15) Joule·K^−1·mol^−1

Questions and Answers ( ask anything and someone including me will try to get you an answer)

• Basics
• Perspectives on time, space, motion, size, mass, charge, energy and other basic measures

What is time and space ? Anybody care to provide a definition?

Categories for Discussion

This is a broad subject and my attempt goal is to integrate across different disciplines. I recommend you address your posts along the following lines. I am open to suggestions on how to better organize.

• Questions and Answers (Ask anything related to Science)
  http://drjohnscience.blogspot.com/2008/11/questions-and-answers-ask-anything-and.html
  
  
• Basics
• Perspectives on time, space, motion, size, mass, charge and other basic measures http://drjohnscience.blogspot.com/2008/11/basics.html
• Physical Constants http://drjohnscience.blogspot.com/2008/11/physical-constants.html
• Scientific Notation
• Problems / Solutions to Solve
• Science vs Belief Systems

• Classical Physics
• History
• Mechanics
• Problems / Solutions to Solve
• Thermodynamics
• Problems / Solutions to Solve
• Electricity and Magnetism
• Problems to Solve / Solutions

• Quantum Physics
• History / Great Scientists
• Classical vs Quantum Regimes
• Basic concepts of particle vs wave
• Heisenberg's Uncertainty Principle
• Famous discoveries and experiments that led to the classical model
• Problems to Solve / Solutions

• Statistical Physics
• General Definition
• Problems to Solve / Solutions

• Special and General Relativity
• History / Einstein and Others
• Thought Experiments
• Special Theory
• Problems to Solve / Solutions
• General Theory

• Astronomy - What you can see from Earth
• Celestial Sphere
• The Ecliptic
• Viewing the night sky
• Observing the Moon
• Observing the Planets
• Use of Telescopes
• Shooting Stars / Meteor Showers
• Comets
• Auroras
• Lunar and Solar Eclipses

• Sun and Stars
• Interesting Facts
• Measuring Distnace to Stars
• Structure of Stars
• Energy Generation in stars
• Comparing stars - HR diagrams
• Binary Star Systems
• Stellar Evolution

• Stellar Remnants
• White Dwarfs
• Neutron Stars
• Black Holes

• Planets and Exo Planets
• Solar System Planets
• Nebular Theory of planetary formation

• Cosmology
• Galaxies
• Big Bang Theory
• Dark Matter Hypothesis
• Expansion of the Universe
• Age of the Universe

• Search for Extraterrestrial Intelligence
• Drakes Equation / other basic concepts
• Why haven't we been contacted yet and the implications of the Silence

• Gravity
• What the heck is it
• Classical View
• Relativistic View
• Gravitons

• String Theory / Particle Physics
• Basics

• Earth Science
• Plate Tectonics
• Volcanism
• Earth Quakes / Tsunamis
• Atmosphere
• Weather
• Climate Change
• Earth's History
• Earth's Future

• Extraterrestrial Threats to Earth
• Asteroids and Comets
• Cosmic Bursts / Supernovae
• Other Threats

• Limits to Human Growth on Earth
• Is the Earth anywhere near the limits of how many humans it can comfortabley support

• Global Warming

• Alternative Energy Technology and Policy

• Space Technology and Policy

Dr.John's Blog

Organization Top Level
http://drjohnscience.blogspot.com/2008/11/categories-for-discussion.html