Friday, October 26, 2012

Speculation - Hot Jupiters as Expended Batteries

Hot Jupiters are large planets – about the size of Jupiter or larger - that orbit very close to their star.  They comprise the upper left corner of this plot.   A year on one of these planets is only a few days, or even less. These planets are relatively easy to discover because of their large and short-period effect on their star's motion and a much higher probability of transit, so the statistics we have on extrasolar planets are skewed a bit toward this type of planet.  Nevertheless, they appear to be fairly common, though are no longer in the majority of the 843 2030 exoplanets catalogued to date.

Exoplanet Orbital period vs. age of host star
Hot Jupiters were a surprise to astronomers when first discovered, although Otto Struve had speculated on their existence in 1952, arguing that they were the only planets detectable by ground based telescopes. Hot Jupiters were not a real paradigm-buster, but were unexpected, because they can't form that close to the star -  it's like trying to get steam to condense on a hot soldering iron. Hot Jupiters have to form much further out from their star, and then migrate inward. There are plausible models for how this could happen fairly quickly as a result of complex tidal interaction with a disk of dust still surrounding the star shortly after it forms.  Such a natural migration may take only a few million years, but it has to happen early or there won't be enough of a disk to interact with.  What astronomers would really like to do is catch one of these planets in the act of migrating, but that will require a bit of luck and probably better telescopes.

Tuesday, October 23, 2012

Homework from Professor Shostak

Seth Shostak may be right about UFOs,or he could be wildly wrong, but it is difficult to ignore his critiques of the the notion that UFOs are spacecraft from other planets. The SETI astronomer and podcast host recently appeared on Martin Willis' Podcast UFO to explain his views, which are also laid out in Chapter 4 of his book, Confessions of an Alien Hunter.

Friday, October 19, 2012

Did the Hitchhiker's Guide to the Galaxy Get It Right?

The late, great DNA
More than 30 years ago, Douglas Adams wrote his famous Hitchhiker's Guide novels around the idea that the Earth was a giant, purpose built computer simulation intended to answer a question (actually, to question an answer) of staggering difficulty.  Of course, this was all in good fun, but the idea is actually very interesting.

Maybe Adams just didn’t think big enough.  There has been much discussion in the last few years about whether our entire universe is in fact a computer simulation (by hyper intelligent, pan-dimensional mice, if you like).  This was first seriously proposed in a 2003 paper by Nick Bostrom,  We don’t know how to build or program such a computer ourselves, but we can imagine that it could be built, and if our universe is a simulation, there is no way to know what actual constraints might exist.  

Tuesday, October 2, 2012

Doubt is a Core Value

It is our responsibility as scientists, knowing the great progress and great value of a satisfactory philosophy of ignorance, the great progress that is the the fruit of freedom of thought, to proclaim the value of this freedom, to teach how doubt is not to be feared but welcomed and discussed, and to demand this freedom as our duty to all coming generations.
- - - Richard Feynman

Here is how things go wrong: beliefs hold the believer. The believer acts, thinks and perceives the world through his beliefs and in order to support them, and is cognitively and morally blinded and enslaved; unable to inquire outside a narrow, nonthreatening sphere, and willing to use any means whatever to propagate the One Truth.  Then belief exists for it's own sake, and it can escape all moral restraints, with terrible consequences that are only too well known.The problem is not so much the belief systems themselves, but with the banishment of the one great value: doubt.