It’s Friday! And my promised bloggy content-providing hasn’t really materialized. Someone has to write those letters of recommendation, and my students weren’t impressed by my pleas that there was blogging to be done.

But I gave a colloquium yesterday at Caltech, and afterwards one of the folks who came to dinner was Lloyd Knox, an old friend and a cosmologist at UC Davis. Talk naturally turned to his most well-known work: the Dark Energy Song, sung to his class and (inevitably) captured to video and posted to YouTube by a quick-thinking student. But to my surprise, it only has about 1,000 views! Surely we can help bring this masterpiece to a wider audience.

Note that musical/lyrical critiques by people who have not demonstrated bravery by putting their own performances on YouTube will be derided as acts of base cowardice.

Sean, off topic but since you are an expert on gravity I am really curious if you also observed the following parallel? Maybe you could do a future blog on it.

There is an interesting parallel between the electric field and the gravity field, a duality if you will. It leads to a 5th Maxwell equation.

In the electric field we have Coulomb’s Law F = q1q2/4πεR^2. The analogous entity in gravity is Newton’s Law of Gravitation F = Gm1m2/R^2. In the electric field the energy stored in the electric field of a spherical single plate capacitor with radius R and charge q is given by U = q^2/8πεR. The gravity analogue for the energy stored in the gravity field by a spherical mass m is U = Gm^2/2R.

The analogue of the electric field vector in gravity is a gravity field vector that I have named Newton Height or NH for short:

NH = Gm/R^2 (direction unit vector R)

The gravity analogue to Gauss’s Law for the Electric Field, Maxwell’s fifth equation, the Law for the Gravity Field:

∫ NH • dA (closed surface) = 4πGm

For the electric field we figured out the field strength and direction using Gauss’ Law and integrated the electric field energy density μ = ½ εE^2 over all of space from the surface of the charge to infinity in all directions to get the energy stored in the field. The energy density of a gravitational field is given by μ = (1/8πG) NH^2.

Then for Newton’s law of gravity we have F = mNH analogous to F = qE and F = − del U(gravity field) analogous to F = − del U(electric field).

Matt

OK, any song at all based on a neutral milk hotel track is genius is my book. Could be about the damn flat earth and it would still rule. Neutral Milk Hotel + cosmology = greatest thing ever.

Sili

Sorry, can’t make sense of what he’s saying.

So, is this also why you’re too busy posing for the SkepDude calendar to make money for Donors Choose?

http://www.caseyrentz.com casey rentz

Is this set to the tune of one of Jeff Mangum’s songs…I believe it is! Which song?’In The Aeroplane Over The Sea’? Fantastic. Great adaptation! I love science set to music.

The fact that it’s set to the tune of one of my all-time favorite songs certainly clenches this one for me. Hooray!

Brian

Please adopt a strict one post per day policy on this blog. Seriously, there are like seven of you. Give each person a day of the week if you have to. Tired of coming here and being disappointed.

polymath

To David Degner: This analogy is well-known, but what you have only works for *classical* gravitation. If you do relativistic gravitation, there is even more that can be done. In particular, there is an analog to the magnetic field (with a VxB term in the ‘Lorenz force law’). The main difference is that ‘mass’ has only one sign, instead of the ‘charge’ which can be either sign (positive or negative). This comes about because gravity is a tensor interaction (spin 2) rather than a vector interaction (spin 1).

Alison

I like the song, though the mention of a “He” is somewhat puzzling, if the song is trying to teach students about a scientific concept. In any case, Professor Knox is a talented musician. I wish one of my professors would do something like this… I seem to only catch such moments on YouTube! (I am a UCD student, who loves Cosmic Variance.)

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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson.
Here are some of his favorite blog posts, home page, and email: carroll [at] cosmicvariance.com .

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