Physics Phun!

You all failed the pop quiz. Thus, Labor Day is canceled for you all, and I expect you to be in class on that Monday instead. No excuses.

Instead of another quiz, I offer the following explanation of two of Einstein's greatest theories: E=Mc2, and the concept of Space-Time. Down the road I will get into relativity -- including the "special" kind.

Anyways, E=Mc2 is actually a straightforward concept once it's spelled out. The formula means:
E = Energy. That is, wavelengths of different frequencies.
M = Mass. The weight of a thing.
c2 = the speed of light (in a vacuum) squared.

The two big things to take away from this are, 1: Energy is mass, mass is energy. They are one and the same. You can consider matter to simply be highly concentrated energy (there are many concepts that open up with this idea - String Theory, for example). Thus, we are energy. Everything is. And 2: Given the "c2" part of the formula, this means for any amount of matter, there is an enormous amount of energy contained within. This is the force behind nuclear explosions. A teaspoon of uranium can blow up a city.

Moving on to "Space-Time". Space-Time was Einstein's way of explaining gravity -- interesting to note! Newton never attempted to explain gravity (God did it was the answer); rather, he was just describing the effects of gravity (also, just to be clear, Newton's theories of gravity, while very useful to our everyday world, have largely proven to be inaccurate - for example, our GPS system would not work using Newtonian rules for gravity). Space-Time, to wit, is our reality: Everything around us is space-time. We live within it like a bug on top of a lake. And everything with mass bends space-time, to the degree of that mass. You and I, right now, are bending space-time with our presence. It's minor to be sure. The sun bends space-time to enormous amounts, enough to actually bend light. But that in turn is nothing compared to far larger stars, Quasars, or the mother of all bends in Space-Time, black holes.

The bending of space-time is gravity -- things fall down these bends. Earth is falling down the bend in space-time created by the sun; the moon is falling down the bend in space-time created by the earth; and so on.

You can easily picture yourself in Space-Time when you consider what you must do when giving directions. For example, say you want to meet a friend for lunch in a cafe on the 5th floor of a building in mid-town Manhatten. To give good directions, you must give 4 co-ordinate points in Space-Time: Latitude (50th St), Longitude (7th Ave), Altitude (5th floor), and most cogently for this discussion, time (1PM). Common sense, right? Well, that's Space-Time!

Oh, and Space-Time is just a theory. One of the effects of Quantum Theory is to put the concept of Space-Time in doubt, since it does not speak to interactions at the quatum (i.e. sub-atomic) level.

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