ASTR 1020 1st Edition Lecture 4 Outline of Last Lecture I. Atoms & LightA. Atomic TerminologyB. LightOutline of Current Lecture I. RelativityA. Laws & TheoriesB. TestsCurrent LectureI. RelativityA. Laws & Theories- Einstein’s Theories of Relativity- Special Theory of Relativity (1905) Usual notions of space and time must be revised for speed approaching light speed (c), E= mc2- General Theory of Relativity (1915) Expands special theory to include "curved space-time”- Absolutes of Relativity1. Laws of nature are the same for everyone2. The speed of light is the same for everyone- Reference Frames- Einstein: Light speed is c in all reference frames- Time Dilation- Time moves slower in moving objects by an amount depending on its speed- Time almost halts for objects moving near the speed of light- A Journey to Vega- The distance is about 25 light years- If you could travel to Vega at 0.999c, the trip would seem to take only 2 years.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Key Ideas of General Relativity- Gravity arises from distortions of space-time by the distribution of mass- Time runs slowly in gravitational fields- Black holes can exist in space-time- Rapid changes in the motion of large masses can cause gravitational waves- Tests:Mercury’s orbit, lensing, time dilation- Curvature near the Sun- Sun’s mass curves space-time near its surface- If we could shrink the Sun without changing its mass, curvature of space-time would become greater near its surface, as would strength of gravity- Curvature near Black Hole - Continued shrinkage of Sun would eventually make curvature so greatthat it would be like a bottomless pit in space-time: a black holeB. Tests- Tests of Relativity- First test of speed of light comes from the Michelson-Morley Experiment- Time dilation happens routinely to subatomic particles the approach the speed of light in accelerators- Time dilation has also been verified through precision measurements in airplanes moving at much slower speeds- Prediction that E= mc2 is verified daily in nuclear reactors and in the core of the