Thursday, April 26, 2007

Philosophia Naturalis #9

I'm going to try something a little different this time. There have been (as usual) some interesting news stories in the physical sciences recently, and I'm going to start by featuring blog articles that discuss them. So let's get to work.

Extrasolar planets

Undoubtedly, if judged by number of blog posts, the most popular recent news in the physical sciences has concerned extrasolar planets.

And within this category, the biggest buzz has centered on the announcment of the first discovery of an Earthlike planet, orbiting the red dwarf star Gliese 581. Some of the better articles on this are Planet in the Zone at Dynamics of Cats, Another Earth? at Asymptotia, First possibly Earthlike extrasolar planet found! at Bad Astronomy, A Potentially Habitable Earth-like World at Centauri Dreams and "Habitable planet"? Maybe not! at Astroprof's Page.

As if those (and other references they cite) weren't enough, special attention should be called to this and this at Systemic, because the whole blog is about extrasolar planets and contains additional discussion of the discovery at Gliese 581. No word yet, however, on when the first tourist flights will be offered.

Next up is the detection of water vapor in the atmosphere of a distinctly un-Earthlike gas giant planet called HD 209458b. Centauri Dreams, again, has the story on that: Water Vapor in an Exoplanet’s Atmosphere. This followed close on the heels of the announcement about a month before of the detection of any type of molecule in an exoplanet atmosphere – specifically, HD 209458b and another (HD 189733b). Atmosphere of Exoplanets at Blog Physica has some details. Ironically, it was first thought that water was (surprisingly) not present.

And last but not least, an extensive survey has found that almost 30 out of 69 binary systems between 50 and 200 light years from Earth have at least the disks consisting of dust and debris out of which planets could form – though actual planets have yet to be confirmed. See Multiple Suns? at Astroprof's Page and Double Stars May Be Aswarm with Planets at Centauri Dreams for details.

Neutrino oscillation

This news item is about something that wasn't discovered, and on the whole it might be considered a non-event. However... what wasn't discovered was an experimental violation of the standard model of particle physics. Just the latest in a long string of "failures". Specifically, several years ago an experiment turned up possible evidence that in addition to the three known varieties of neutrinos (corresponding to electrons, muons, and tau particles) there might be others, which hardly interact with anything else at all, and hence were called "sterile" neutrinos. Such neutrinos would be completely outside the standard model. Further efforts have been made to confirm this result... and they found nothing. Yet this "failure" is still noteworthy in itself, as yet another case of being unable to find something specific wrong with the standard model, even though just about everyone believes the model is incomplete.

MiniBooNE Neutrino Result, posted by one of the experimenters, Heather Ray, at Cosmic Variance, gives a thorough account. Additional accounts: The Unsinkable Standard Model at Uncertain Principles, MiniBooNE for Neutrinos at Asymptotia, and Working Blind at Charm &c.

Quantum mechanics

QM also continues to be perplexing to just about everyone, because it's so "unreal". Here "reality" is a technical term that refers to definite properties a system might have even though they cannot be measured directly. (This is sometimes called a "hidden variables" theory.) Einstein hated the idea, implicit in the leading interpretations of QM, that this kind of "reality" was, well, an illusion. But all experiments to date point towards that being the case.

QM Says Goodbye to Reality? at Physics and Physicists calls attention to the latest finding of Anton Zeilinger's group in Austria that further disconfirms the notion of "reality".

As Niels Bohr said, "Anyone who is not shocked by quantum theory has not understood it." Another recent post at Physics and Physicists has some thoughts on that: No One Understands Quantum Mechanics?, as a follow-on to the earlier Why is Quantum Mechanics SO Difficult?

Gamma-ray bursts

There was a brief period of a few months last year when astronomers concerned with gamma-ray bursts thought they had these things largely figured out. GRBs came in just two kinds, and there were fairly good models for both kinds. Or so they thought. But nature continues to surprise. New cases keep turning up that don't quite fit previous models. But that's OK, really. Just some additional circumstances that can produce bursts of gamma-rays in ways that haven't (yet) been anticipated.

Dirk Grupe, writing at Scitizen, discusses the most recent example: Gamma-Ray Burst Afterglow That Challenges Gamma-Ray Burst Theory.

Meanwhile, the 11D Space Surfer at Quasar9 writes on the relation of GRBs to an exotic type of neutron star known as a magnetar: GRBs & Magnetars.

Miscellaneous

And finally, everyone's favorite category: everything else.

Mollishka at A Geocentric View tells us about her recently published research: Variable Stars Near the Galactic Center.

For readers with a philosophical bent, Ponder Stibbons at The truth makes me fret ponders a recent paper of Max Tegmark questioning the validity of the traditional distinction between initial conditions and fundamental laws of physics: Eliminating Initial Conditions — Or Not. And a sequel just showed up today: Confusing Baggage.

As part of an edifying tutorial on concepts of special relativity, Richard Baker at Sharp Blue explains Spacetime and coordinates to us.

Besides GRBs and magnetars, Quasar9 is also interested in the mysteries of black holes: Black Hole (Paradox).

For more along the lines of philosophical musing, Clifford Johnson at Asymptotia offers some observations on an interview with Brian Greene about string theory and suchlike, and in particular with the concept of a "theory of everything": Questions and Answers about Theories of Everything.

And finally, still in the philosophical vein, CuriousCat at The Old Curiosity Shop ruminates on Irreversibility.

Envoi

That wraps it up for this month. PN will be back again next month, on May 24. There's some quantum uncertainty about its precise location (Δx) in cyberspace, but don't worry. In just Δt we should have more information on that. There'll be an update about it here, and further details here.

Update: As promised, here's the scoop on the next edition of PN: It will be hosted by Stuart Coleman at Daily Irreverence on May 24. Watch for a message there about how to suggest an article for the carnival – Stuart and I both hope you'll help us out with some great suggestions.

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1 Comments:

Blogger QUASAR9 said...

Hi Charles, that's some post
There's enough links and reading material there to fill a day -
or to write several books.

I like the non-event outlook on the neutrino announcement.
Very interesting blog ...

and, Thanks for the mention!

4/27/2007 04:26:00 AM  

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