by Paul Gilster | Feb 16, 2007 | Culture and Society |
When Vernor Vinge takes on the topic “What if the Singularity Does NOT Happen,” interesting things are bound to follow. Thus his talk for the Long Now Foundation-sponsored Seminars About Long-Term Thinking yesterday. Vinge, a computer scientist and science fiction author, is not giving up his belief that the Singularity will happen. That event, which he believes will take place in the next few decades, should happen suddenly and be transformative in its effect. Here’s how Vinge himself describes the Singularity in an online precis of the material he used in his presentation:
It seems plausible that with technology we can, in the fairly near future, create (or become) creatures who surpass humans in every intellectual and creative dimension. Events beyond this event — call it the Technological Singularity — are as unimaginable to us as opera is to a flatworm.
Vinge’s ideas on the Singularity date back to the 1980s; he refined his thoughts on it in a 1993 essay called “The Coming Technological Singularity.” But what if the Singularity doesn’t occur? Pressed to come up with alternatives, Vinge is able to construct scenarios where the Singularity fails, three of them in fact, ranging from a return to nuclear confrontation to a ‘golden age’ where a kind of enlightenment spreads tolerance and technology-enriched education throughout the globe.
A major concern: we are in need of self-sufficient settlements outside this planet, and need to direct our energies to developing cheaper ways of getting into space. To the objection that the stars are too far away to make reasonable targets, Vinge has this to say:
* Asteroid belt civilizations might have more wealth potential than terrestrial ones.
* In the Long Now, the stars are NOT too far, even at relatively low speeds. Furthermore, interstellar radio networks would be trivial to maintain (1980s level technology). Over time, there could be dozens, hundreds, thousands of distinct human histories exchanging their experience across the centuries….
Perhaps the most plausible scenario in the event of a non-Singularity future is the one Vinge calls ‘The Wheel of Time,’ in which mega-disasters occur and civilization moves through a cycle of destruction and recovery. That makes the archaeologists and dumpster divers of his novel A Deepness in the Sky hugely significant for the survival of civilization.
All fascinating notions — and any aspiring science fiction writer should pay attention — but Vinge’s conclusion is strong: “I still regard the Singularity as the most likely non-catastrophic outcome for our near future.”
by Paul Gilster | Feb 16, 2007 | Deep Sky Astronomy & Telescopes |
Understanding dark matter, a major goal for cosmology, comes down to figuring out how normal matter interacts with its mysterious counterpart. A vital part of this work may be the objects called dwarf spheroidal galaxies, surely among the most bizarre agglomerations every observed. For current thinking (based on mass-to-light ratios) is that a dwarf spheroidal may be a galaxy composed almost entirely of dark matter.
And if that’s hard to imagine, consider the problem of researchers trying to observe such objects. A dwarf spheroidal is all but devoid of gas and contains few stars, its normal (baryonic) matter having been stripped away by interactions with larger galaxies. In fact, these ghostly galaxies seem to need larger galaxies in their proximity to form, according to new work by Stelios Kazantzidis (Stanford Linear Accelerator Center), Lucio Mayer (Swiss Federal Institute of Technology) and collaborators.
Working with supercomputer simulations, the Kazantzidis team constructed a model for dark galaxy formation, one that begins as a relatively normal galaxy approaches the Milky Way some 10 billion years ago. In a complex sequence of events, gas within the smaller galaxy heats up as it experiences gravitational forces from the larger system. The consequence: gas and luminous stars are gradually stripped away, leaving behind the dark matter ‘shadow’ galaxy.
Image (click to enlarge): This supercomputer simulation shows as bright clumps the dark matter satellites that can be found around our Milky Way galaxy. The central region corresponds to that containing the luminous matter (gas and stars) of the Milky Way. Credit: Stelios Kazantzidis.
Which may explain why we see fewer satellite galaxies around the Milky Way than theory would predict — the ‘missing’ galaxies may be there but dominated by dark matter. “These galaxies could just be too dark to detect,” said Kazantzidis. “But their possible existence will substantially alleviate the missing satellites problem with profound implications for the predictive power of the [Lambda Cold Dark Matter] theory.”
That would be a satisfying outcome indeed, for the Lambda Cold Dark Matter theory is the attempt to fit dark matter into the broad cosmological framework, and working out a consistent place for the mysterious dark stuff that peppers the universe would unlock many doors. On that score, be aware that the Sloan Digital Sky Survey has revealed a number of extremely faint satellite galaxies near the Milky Way within recent months. Will these be the key to confirming Kazantzidis’ theories?
The paper is Mayer et al., “Early gas stripping as the origin of the darkest galaxies in the Universe,” Nature 445 (15 February 2007), pp. 738-740. The abstract is here.
by Paul Gilster | Feb 15, 2007 | Autonomy and Robotics |
Speaking at the Space Technology and Applications International Forum (STAIF 2007) in Albuquerque yesterday, space historian Roger Launius questioned whether the idea of a human future in interstellar space is still relevant. From a USA Today story:
“We may already be Cyborgs,” Launius pointed out, looking out into an audience filled with people wearing glasses, hearing aids and sporting hip and knee replacements—not to mention those clinging to their handheld mobile phones and other communication devices.
Projecting hundreds of years into the future, Launius said he believed that it is likely humans will evolve in ways that cannot be fathomed today, into a form of species perhaps tagged Homo sapiens Astro. “Will our movement to places like the Moon and Mars hasten this evolutionary process? … I don’t know the answer,” he said.
Neither does any of us. You can read the whole thing here.
by Paul Gilster | Feb 15, 2007 | Administrative
Due to my own clumsiness with some needed spam filter adjustments, I’ve lost several moderated comments that I had intended to post today. If you submitted a comment within the last three hours that didn’t appear, please re-submit, and sorry for the confusion!
by Paul Gilster | Feb 15, 2007 | Deep Sky Astronomy & Telescopes, Exoplanetary Science |
Stellar clusters make useful tools in the exoplanet hunt. Think of the transit search of the globular cluster 47 Tucanae, which has brought in statistically significant findings about the occurrence of hot Jupiters. As recently discussed in these pages, David Weldrake’s team found no transits in either 47 Tucanae or Omega Centauri, an indication that massive planets in short-period orbits are unlikely to form around older, metal-poor stars. We’ve already reviewed Weldrake’s work, but let’s turn to the general method of studying stars in clusters and its benefits.
For clusters give astronomers the chance to examine groupings of stars that are similar in their properties, making it possible to draw conclusions about how planets form in the presence of certain stellar parameters. That similarity also makes the work of separating true transits from false positives somewhat easier. Even so, no confirmed exoplanet has yet been identified in either a globular or open cluster. [My mistake! Epsilon Tauri b, as a reader just pointed out, is in the Hyades cluster, and more about that interesting world next week]. Unlike globular clusters on the order of 47 Tucanae, open clusters are much more loosely bound gravitationally, and are in most cases relatively young.
Both types of cluster are under active investigation. A team led by Scott Gaudi (Ohio State) and Matt Holman (Harvard-Smithsonian Center for Astrophysics) using the Multiple-Mirror Telescope in Arizona is studying the open cluster M37. Its recent report comments on the difficulties of open cluster work:
So far the open cluster surveys have only provided upper limits on the planet frequency, all of which lie above the frequency inferred from the other surveys. The fundamental problem facing an open cluster survey is that very few rich open clusters exist. Moreover, the richest clusters, which have at most a few thousand members, all lie more than a kilo-parsec away. Surveys of open clusters are necessarily deep surveys for which the expected number of planet discoveries is low (typically one or two planets).
But the thinking is that planets down to Neptune-size may be detectable here. Given that we are now finding planets of this mass and even lower by radial velocity methods, the ability to generalize about their formation through a broad-based cluster study is helpful. And because the properties of these stars are well characterized, a transit would make it possible to pin down the mass and radius of the planet with great precision.
Image: The open cluster M37. Transit surveys of clusters like these help us understand the link between planet formation and the properties of the stars they orbit. Credit: G. Puglia & C. Zannelli (ORSA, Palermo).
Twenty-four nights of observations went into this run, compiling a total of 4500 images. The details of the image-gathering using the Megacam wide-field mosaic CCD camera on the MMT are found in the team’s paper. The preliminary results:
While we have marginal detection capability for planets as small as Neptune, transiting planets smaller than Saturn should be easily detected if they exist. Using the above pipeline we have identified a number of candidate transiting planets; spectroscopic follow-up of these systems to rule out false positive scenarios is underway.
So we’re going to be learning a lot about planet formation in the smaller size ranges as this work unfolds. Remember that these are far younger stars than those considered in Weldrake and team’s work. Among the stars within observing range of the MMT, M37 stood out for Gaudi and Holman because its stars show Sun-like metallicity, and because at 520 million years, it is in the intermediate age range for this type of cluster.
The Weldrake and Gaudi/Holman surveys are telling us interesting but different things. Weldrake’s team targeted hot Jupiters in globular clusters whose stars are ancient, with an eye to the effects of metals on planet formation. Gaudi and Holman are looking at considerably younger stars in a much more metal-rich environment, and — using a larger telescope than has been used for cluster surveys in the past — may be able to identify transits of smaller planets. It will be interesting to see how the metallicity question looks when these and other open cluster results are in, but one would suspect that younger stars will yield their share of planets, as the Hyades cluster has begun to do.
The paper is Hartman et al., “A Search for Transiting Hot Planets as Small as Neptune in the Open Cluster M37,” slated to appear in ASP Conference Series: “Transiting Extrasolar Planets Workshop” MPIA Heidelberg Germany, 25-28 September 2006. The preprint is available online.
