The general theory of relativity 100 years The Finnish Society for Natural Philosophy, The House of Sciences, Helsinki November 10, :15Prof. Tapio Markkanen, What do the stars tell us? The status of astronomy and the knowledge about the universe at the time the theory of relativity was born. Through centuries, astronomy has aimed to explain the motions of celestial bodies. In the early 1900s, the increased knowledge of matter and its interaction with radiation made it possible to raise the question of the buildup of the universe and the celestial structures. 17:10Dr. Hannu Kurki-Suonio, The birth and the essence of the general theory of relativity I aim to describe in an understandable manner what the general theory of relativity is (and what it is not). The general theory of relativity is a creation of Albert Einstein, but not all of his ideas were realized in the final theory. The underlying principle behind general relativity is that the essence of gravity is geometrical in nature. Gravity is not a real force but an apparent force actually explained by the curvature of space-time. I will also describe some classical and modern tests of the theory of relativity. 18:00Coffee break 18:20Dr Tuomo Suntola, What could have been done differently if todays instruments, observations and knowledge had been available to Einstein? The theories of relativity were based on the relativity and equivalence principles to make the laws of nature look the same for observers in any frame of reference. The laws of nature studied, included the laws of motion by Isaac Newton, Maxwells equations of electromagnetism, and the phase velocity of light in an interferometric test setup. At Einsteins time, following the Newtonian world picture, distant space was assumed to be static, and the structure of atoms as well as atomic clocks were unknown. What kind of new perspectives on a restructuring of the theory bases can be derived from todays knowledge and observations? Is the geometry of space the cause of the effect of gravitation? Do motion and gravitation modify time or affect the characteristic frequency of atomic clocks? 19:15-Discussion on the theory of relativity and its role as the basis of our picture of reality. 20:00 The General Theory of Relativity 100 years 18:20Dr Tuomo Suntola What could have been done differently if todays instruments, observations and knowledge had been available to Einstein? The theories of relativity were based on relativity and equivalence principles to make the laws of nature look the same for observers in any frame of reference. The laws of nature tested included the laws of motion by Isaac Newton, Maxwells equations of electromagnetism and the phase velocity of light in an interferometric test setup. At Einsteins time, following the Newtonian world picture, distant space was assumed to be static, the structure of atoms as well as atomic clocks were unknown. What kind of new perspectives on a restructuring of the theory bases can be derived from todays knowledge and observations? Is the geometry of space the cause of the effect of gravitation? Do motion and gravitation modify time or do they affect the characteristic frequency of atomic clocks? The Finnish Society for Natural Philosophy, The House of Sciences, Helsinki November 10, 20152 What could have been done differently if todays instruments, observations and knowledge had been available to Einstein? 1.The principle of relativity and the laws of nature. 2.What has been observed regarding the behavior of clocks during the last 100 years? 3.What does quantum mechanics tell us about the characteristic frequency of atomic clocks? 4.From motion to gravitation or from gravitation to motion? 5.The equivalence principle or the conservation of energy? Cosmological predictions. Tuomo Suntola The Finnish Society for Natural Philosophy, The House of Sciences, Helsinki November 10, 20153 Special relativity1905 Henri Poincar: Electromagnetic mass E=mc 2 Walter Kaufmann 1902 Maxwells equations and the constancy of the velocity of light are established by time dilation and length contraction (1899/1904) Hendrik Lorentz: Olinto De Pretto E=mc 2 The principle of relativity, the constancy of the velocity of light The Finnish Society for Natural Philosophy, The House of Sciences, Helsinki November 10, 20154 How does the principle of relativity re-establish the Newtonian law of motion, F=ma ? v c t Observations, Kaufmann 1902 v c t Newton: v = a t SR: v c t The principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference. The Finnish Society for Natural Philosophy, The House of Sciences, Helsinki November 10, 20155 The general theory of relativity 100 years Do we modify our observational reality in such a way that the laws of nature which we regard as real appear unchanged or should we identify the laws of nature that apply in our natural observational reality where time and location have unequivocal meanings? The Finnish Society for Natural Philosophy, The House of Sciences, Helsinki November 10, 20156 The fourth dimension the concept of space-time What is the distance travelled in a space-time frame of reference, which has velocity v 0,1,2 relative to an observer? Herman Minkowski Minkowski space (1908) ds 2 = dx 2 +dy 2 +dz 2 (icdt) 2 Henri Poincar: Lorentz-transformation can be described as a rotation of the coordinate system (1905) v 0 =00