Expert: Steve Nelson - 1/28/2008

Question
A star that suddenly explodes is called a supernova. Looking at the events of supernovas in the past in different parts of the universe, do you think we can learn about what the laws of physics were at different times in the past?

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Kindly please help solve my question.  

Answer
It's possible, supernovae that we see from very far away are transmitting light billions of years old.  What we know so far is that the laws of physics from the past appear to be as they are now.  Many interesting experiments have been devised on Earth to test this theory.

For an example of a space telescope due to launch at the end of May that I have some experience with (part of the main instrument was assembled in my branch of the space science division at the naval research lab), see here:  http://glast.gsfc.nasa.gov/  By timing the different wavelengths, the Gamma-ray Large Area Space Telescope hopes to uncover whether or not very short-wavelength gamma rays actually have to detour through extra distance if spacetime has some kind of non-regular structure.  

So every time we launch a new space telescope or build a new one on the ground scientists are hoping to discover something new.  And by the fact that they're looking at light that was emitted very long ago we should notice if there was any difference in the past.  Especially any difference in the physics that would change the frequencies light was emitted at by typical atoms or other affect other quantities which we can measure with ridiculous precision.