On this day in physics: 29 January 1926, we say Happy Birthday to Abdus Salem, one of three physicists to share the Nobel Prize in 1979 for unifying the electromagnetic and weak force to the electroweak force. [Source].
Word of the Day: Mass- First, let's take a look at a couple of definitions. From wikipedia: "It is generally the amount of matter of an object. It is determined by the strength of its mutual gravitational attraction to other bodies, its resistance to being accelerated by a force, and in the theory of relativity gives the mass–energy content of a system. The SI unit of mass is the kilogram (kg)." [Source] From Hyperphysics: "The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else." [Source] Isn't that the truth. Unofficially, Mass is "how much stuff there is". It can be quantified in a couple of ways. First, as mentioned in both of the definitions, it is a way to quantify inertia. If you have two objects of the same volume, but one is more massive, it will be harder to move, a lot harder to slow down, do more damage if it collides (i.e. more momentum), etc. Next, it is a cause for gravitational attraction. Mass attracts more mass. Next, we have Newton's Second Law: F = ma. If you have an object, which will have constant mass, the more force you give, the more acceleration you will get. So mass defines how much force you need to generate acceleration. Lastly, mass is a quantifiable measure of energy, think about Einstein's E = mc^2. c^2 is the speed of light squared it will always be the same, so mass, by this equation is the same as energy, or energy waiting to be released.
One thing that most people confuse is that mass is the same thing as weight. This makes sense since we're on earth, and the earth is a monster constant mass next to us, so gravity is constant. So, the more massive something is, the more weight it has on Earth. However, the same mass on the moon will have 1/6 of the weight. Weight is equal to mass times gravity, so on Earth, they are totally linearly related. However, mass and weight are separate quantities, so be careful, you cannot use those words interchangably!
Killer Resource: The way that various atoms are created: This periodic table is color coded to show how different elements are created, either via the Big Bang, Supernova, Man-Made, Large Star, Small Star, and/or Cosmic Rays.
Keywords: Mass, Inertia, Momentum, Einstein, Elements, Stars, Astronomy, Supernova, Small Star, Large Star, Cosmic Rays, Big Bang.
