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The new version of physics, incorporating certain kinds of randomness, is called quantum physics (for reasons that will become clear later). It represented such a dramatic break with the previous, deterministic tradition that everything that came before is considered “classical,” even the theory of relativity. The remainder of this book is a basic introduction to quantum physics. 1 Randomness Isn’t Random Einstein's distaste for randomness, and his association of determinism with divinity, goes back to the Enlightenment conception of the universe as a gigantic piece of clockwork that only had to be set in motion initially by the Builder.

C) This equation can be applied more generally, to light for instance. Use it to find the momentum of a beam of light having energy E. (d) Convert your answer from the previous part into ordinary units. [answer: p=E/c] 7. 6, complete the proof of vcombined = (v1+v2)/(1+v1v2). 8 . A source of light with frequency f is moving toward an observer at velocity v (or away from the observer if v is negative). Find the relativistically correct equation for the Doppler shift of the light. [Hint: Write down an equation for the motion of one wavefront in the source’s frame, and then a second equation for the motion of the next wavefront in the source’s frame.

The average is not the only possible way to say what is a typical value for a quantity that can vary randomly; another possible definition is the median, defined as the value that is exceeded with 50% probability. When discussing incomes of people living in a certain town, the average could be very misleading, since it can be affected massively if a single resident of the town is Bill Gates. Nor is the FWHM the only possible way of stating the amount of random variation; another possible way of measuring it is the standard deviation (defined as the square root of the average squared deviation from the average value).