December 3, 2009

Einstein Field Equations

Here in Germany I knew I would be probably yearning for some English, especially in my schooling.  As such, I signed up for a Nuclear Astrophysics class as some of you dear readers already know.  Also, this is a graduate level class.  I knew, or at least had heard, of the Einstein field equations and how they were supposed to equal 42 or some such thing...alright that last part is a lie.  I had heard of them before though.  So it turns out that this class seems to me to be more Cosmology than Nuclear Astrophys, especially since one of the first things mentioned in lecture was how we would develop the tools to solve the field equations in the first few weeks.  Here we are almost 2 months in and we recently got there.

I was amazed.  Why?  Because I was able to follow the steps.  These are 10-coupled equations.  You start with defining the metric which I think describes how the space-time you have should work.  On second thought I'm pretty sure that's wrong, but please roll with it for the purposes of this blog.  Anyway, you have to have this metric so that you can find the Christoffel symbols.  With the Christoffel symbols and the metric, you calculate the Riemann-Christoffel tensor and from that tensor, you use the metric to contract it to the second-rank Ricci tensor.  From the Ricci tensor, contracting with the metric again gets you the Ricci scalar.  And with all these pieces you solve the equations.  I was wowed.  I'm still not sure exactly what these equations tell us, but I'm pretty sure they describe the universe.  Holy cow.  

On a related note, I discovered today that I am definitely a theorist, not an experimentalist.  Sure, I like to think I have a little engineering in my blood, but that's just from watching too much MacGyver as a kid.  I definitely prefer math and the cosmos to experiments with circuits or particle accelerators and what not.  I'm happy sitting at a computer analyzing light from start thousands of light-years away or manually calculating Fourier transforms.  Is that wrong?  

No.  Cheers!

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