> Damien Broderick <d.broderick@english.unimelb.edu.au> wrote:
> >But Livio did find significant telltale evidence that some giant
> >stars once possessed giant planets that were then swallowed up.
> >The devouring stars release excessive amounts of infrared light,
> >spin rapidly, and are polluted with the element lithium.
> [...]
> >First, according to Livio's calculations, such a star is bigger
> >and brighter because it absorbs gravitational energy from the
> >orbiting companion. This heats the star so that it puffs off
> >expanding shells of dust, which radiate excessive amounts of
> >infrared light.
>
> Does this impact on one of Robert Bradbury's presumed anomalies?
>
Hmmmmph. I'm not "presuming" anything. Data is data. It is generally the astronomers themselves who consider it to be "anomalous" because it is inconsistent with common "expectations". All I do is try to bring consistency to the picture by expanding the frame of reference... :-)
It probably dosn't impact my perspective. At the Bioastronomy conference there was some discussion about the 18+ planets and a lot of work on ongoing projects to find more planets using various methods. I think there is pretty general agreement that there is a strong selection effect at work in the current results -- i.e. we see big planets with small orbits because that is what we can best detect currently. Livio's work may do a good job resolving the problem of why the stars with the massive planets have high metal concentrations -- they may have already consumed one or more of these planets.
My interpretation of some of the observations does postulate that excess infrared radiation is unaccounted for and could be coming from M-Brains. However, the Livio data is still focused on un-enclosed stars. These stars are still going to have atmospheres with a temperature of several thousand degrees K. They may generate excess infrared, but most of the radiation will still be in the visible range. My hypothesis suggests that for enclosed stars all of the visible radiation would be down-shifted into the infrared and that there would be many orders of magnitude less radiation in the visible (according to the black body emission curve). Presumably Livio is working with stars that he can "see", while my emphasis is on the stars that we cannot "see".
While I've devoted some thought to whether the observed "planets" could be supercomputers (like the old Jupiter Brians idea), I can't come up with a good reason why a civilization would waste most of the energy the star generates. At the Extro4 conference, Anders indicated that he has an updated version of his J-Brain paper that adds some additional classifications & structures for the supercomputers/SIs, but I don't think these help much. The only explanation I can imagine is that the system is *very* element poor. This could occur if you had a system that started out with several large planets. The smaller planets may have been cast out into space and most of the larger planets crashed into the star. The material remaining is only enough to build a J-Brain. This argument is stretched thin however in my opinion. For this ultimately to hold water, stellar mining would have to be impossible and I think Robert Freitas would disagree with that. [And I'm not foolish enough to want to directly disagree with Robert's educated opinions.]
It is good though, that people are "starting" to give some consideration to what happens to the planets in the long run. It means that the winds are blowing in the direction of not only how things begin, but how they end as well. The Bioastronomy conference was striking in the very strong emphasis on how life gets started. There was little or no discussion on what happens to atmospheres, continents, life, etc. on planets (such as ours) with billions of years of evolutionary potential. I.e. there was much discussion of our planet (or others like it at the 2-3 billion year stage), but none at the 6-7 billion year stage. It is interesting to note that planets around K & M stars should still be around with many much older than the Earth is (our sun is a G star and so burns hotter & faster than K & M stars).
For the record, less than 10 people out of 200+ at the conference stopped by to look at my poster. None to my knowledge were from either NASA Ames (the location of the Bioastronomy initiative) or the SETI Inst. One fellow from JPL was fairly interested and requested a copy of the paper. After Stuart Bowyer (president elect of IAU Commission 51) reported on the negative results from the Serendip III search, I pointed out that you could "use Nanotechnology to dismantle Mercury in 14 days to produce a solar collector enshrouding the star" and as a result, searches of nearby stars that could be "seen" were unlikely to yield signs of intelligent life. I also pointed out that the only way to proceed was to cross the HIPPARCOS data (showing nearby stars with high parallax motion) with the IRAS data (showing high IR regions) [current searches tend to use the HIPPARCOS data alone].
Stuart's response could be best summarized as "less than open minded".
During a coffee break, I overheard two young scientists from NASA Ames & The SETI Inst. discussing "I don't understand the comment about dismantling Mercury...". So I stopped and did a brief explanation about molecular disassembly, exponetial growth, etc. When I got through, they had no "scientific" objections as far as I could determine. At least one however seemed very concerned that the astrologers would never allow me to dismantle Mercury since it would cause a signficant amount of disruption to their frame of reference.
It is going to take a very big hammer and some very long nails....
Robert