The Cosmological Constant

(This page was started on 2007 May 21, and will be added to from time to time.)

Since mass/energy is conserved (because of the time-translational symmetry of the universe),
the right hand side of our equation is constant (its derivative is zero).

So, the derivative of the left-hand side must also be zero. The left-hand side is geometry!

That is, if the Cosmological Constant Λ is geometrical.

Einstein did not know of the Bianchi identities, so it took him years to find the second term in parentheses.

The derivative of the sum in parentheses is zero — mission accomplished!

This brings out clearly why you can add a CONSTANT term (to either side of the equation!)

Why would you want to do so? Because such a term, it is easy to show, creates "anti-gravity."

Hey, no levity, please!

But is it levity?       "The whole thing is a vicious circle. The law of gravitation is⎯a put-up job."
Eddington, "The Nature of the Physical World"

What next? Feb 2007 Physics Today, I think...

updated 2007 May 22     by our Webmaster