Sunday, October 30, 2005

Six Degrees of Separation

Six degrees of separation is the theory that anyone on the planet can be connected to any other person on the planet through a chain of acquaintances that has no more than five intermediaries. The theory was first proposed in 1929 by the Hungarian writer Frigyes Karinthy in a short story called Chains. (Wikipedia)

In 2001, Columbia University professor Duncan Watts sent e-mails to 48,000 people who were each instructed to forward the email to a person they knew who they thought was most likely to know a target individual personally. That person would do the same, and so on, until the email wes finally transmitted to its target recipient. The original emails contained the target individual’s name, occupation, and general location. The data collected by 48,000 senders and 19 targets (in 157 countries), showed that the average number of intermediaries was indeed, five.

Yesterday I met Peter Hansen at Starbucks. Peter is a scientist at Aerospace Corporation who has a keen interest in “discordant redshifts.” Some stellar objects such as quasars that are emitted by galaxies have spectral redshift values that are dramatically different from the host galaxy that emitted them. The big differences are not explained by the standard Big Bang model of the universe and thus are a big pain in the rear to the Astrophysics establishment.

I wrote a paper (“Optical Redshifts Due to Correlations in Quasar Plasmas”) in 2003 describing a theory that could potentially (maybe, perhaps, somehow, … several other mealy-mouthed disclaimers) explain the discordant redshift cases.

Peter was bothered by the fact that if quasars are ejected isotropically from galaxies as Halton Arp suggested decades ago, then why are there no observable blueshifts (since some must be coming toward us)? Like my work, Peter’s theory uses a framework developed by my former professor Emil Wolf at U. Rochester.

Peter sent Wolf his draft paper for comments and Wolf mentioned that he had a former student living in California who was working on the problem.

Just two steps were required: Pete – Emil – me. We beat the magic six.

After exchanging a few emails, Pete and I decided to meet at Starbucks. Pete sent me the picture from his Aerospace Badge so that I might recognize him. Here is what he wrote:

I'm attaching my picture. It's one of the biggest smiles I ever made - you should spot me easily, especially in my California home-boy weekend uniform (swim trunks and tank top).

Peter Hansen, smiling

I remember going to work each and every day. Discordant was just the right word to describe my mood.

But Peter surprised me with his wit, his charm and good cheer. It must have been Saturday.


Anonymous Anonymous said...

Hi dad,

I loved your blog about Peter smiling. Too funny. He must have a wonderful sense of humor!!

Love you,


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