Department of Physics Seminar 4 KALUZA-KLEIN THEORY Author: Anˇ ze Zaloˇ znik Menthor: prof. dr. Norma Susana Mankoˇ c Borˇ stnik Ljubljana, April 2012 Abstract Physicists have tried to find the theory which would unify all the known interactions under a fundamental law for a long time. One of the first attempts was the Kaluza-Klein theory which uses the postu- lation of extra space dimensions as the basic idea. In this seminar the 5-dimensional Kaluza-Klein theory is described thoroughly and at the end the extension to higher dimensions is mentioned. The description of possibility of Kaluza-Klein theory to be the right unifying theory is also included.