1. basic assumption of science is that physics is controlled by a fairly small number of general principles. We use scientific methods to determine what the general principles are and then we use the general principles to try to explain everything. For a principle to be considered general, i.e. a law, what properties does it need to have? Why do general principles have those properties?

2. "Truth being uniform, and always the same, it is admirable to observe how easily we are enabled to make out very abstruse and difficult matters, when once true and genuine Principles are obtained."1

Edmond Halley

One important property of general principles or physical laws is that they should be uniformly true. We assume that laws are the same for all physical objects, at all locations in the universe, at all times. Is this assumption justified? Can you imagine a universe in which the laws varied at different times or places? Why is this assumption important to science?