## Tuesday, April 8, 2014

### Time Dilation - Einstein’s Experiment of Thought or Gedanken

The special theory of relativity proposed by Einstein saw little special about it and not much interest was shown towards it. Eventually the theory revolutionized the 20th century physics and hundred years thereafter Einstein’s life and work became well known by the general public all over the world. His proposal was based on two elements; namely that the speed of light in a vacuum is constant irrespective of how they are moving and that the laws of physics are the same for all systems which move relative to one another at a steady speed.

Einstein use the experiment of thought or Gedanken, to develop his ideas and many findings are recorded about how he imagine what things would look like if the option of riding on a beam of light was provided. Besides his ideas, he also acknowledged and built on the works of others like Poincare, Maxwell, Lorentz to mention a few as well as other scientists.

This theory of relativity is expressed in terms of the mathematical equations which are not within the understanding of most people and it is a most challenging concept to students of the theory. According to Einstein, he is of the opinion that the thinking ability was most suitable to a child and states that `the normal adult never bothers about space time problems. Everything there is to be thought about is done in early childhood and he developed slowly beginning to wonder about space and time when he had already grown up’.

Gravitational Time Dilation

According to Einstein, the concept of the special theory of relativity, if not mathematics, should be accessible to students of all age group and this work inclusive of student activity takes into consideration the consequence of the special theory. In general relativity, clock in a gravitational field of lower potentials like the proximity to a planet would be running slower, the gravitational time dilation is not reciprocal. At the top of the tower, the observer will find that clocks at ground level move much slower and the observer on the ground will also agree to the same.

The gravitational time dilation thus is agreed by the observers with their own independent attitudes. Time dilation means that a process which takes certain time to take place in a moving system is observed to take more time by someone outside the system. Gravitational time dilation is the outcome of time passing at different rates in regions of various different gravitational potential. The higher the local distortion of space time because of gravity, slower would be the time that passes. Einstein had earlier predicted the effect of this theory of relativity and since then it has been confirmed by tests of general relativity.

To experimentally measure gravitational time dilation, atomic clocks on airplanes was used wherein the clocks that traveled abroad the airplanes, on returning were slightly fast with regards to clocks on the ground. This was significant that the Global Positioning System needs to be corrected for effects on clocks on artificial satellites with further experimental confirmation to the effect.