So the press conference is over. I did not listen to it, but the gist of it, from the press release, seems to be that they’ve observed several more supernovae to pin down even more accurately what the universe’s expansion rate was at very early times (up to nine or ten billion years ago). Image below from their site:
From the site, we learn (for background):
Continue reading ‘Further Information on Dark Energy’
From NASA, tomorrow, at 1:00pm EST: An announcement about Dark Energy. If the pattern of last time is to be followed, there must be new evidence from the space telescope team (represented by Riess and Livio at the press conference) in favour of one interpretation or another. Since they are saying that they will “announce the Continue reading ‘Less In The Dark Than Before?’
Well, do you know the show on Bravo, “Inside the Actors Studio”? The host interviews an actor of some sort -pick your favourite- and you get an in-depth conversation about their life, work, motivations, loves, hates, passions, etc. Not in the service of frivolity, but in pursuit of an understanding and further appreciation of the craft of acting itself. A lot of people like the show for those reasons.
Imagine the same thing, but with an academic in the hot seat. This is what happens tomorrow, hence the title of this post. I will be the interviewer, and my new colleague cosmologist/astrophysicist Elena Pierpaoli will be the interviewee. It will be in front of a live audience.
No, it won’t be on Bravo, or any other tv channel, as far as I know. It is a local USC event, part of a series, and a jolly good idea I must say. It got me thinking:- What academic in history would I like to have sit in my interview chair, and if I only had one question, what would it be? Off the top of my head (and stretching the definition of the word “academic” a bit, I’d like very much to have Galileo, Leonardo da Vinci, Beethoven, Dirac… oh and several more… But what would I ask them? Don’t know yet…. need to think about it.
Here is blurb about it. And yes, I’ve already been teased by my students and a colleague about being described as a “super string theorist” in the advertising.
I may well wear a cape to the event.
-cvj
Well, you’re sitting there at the desk, so might as well put on the radio to keep yourself company. Do in on the web, and I suggest that you listen to:
Radio Lab episode #205
This one was about Space. It has a lot of good stuff in it: excellent speakers, very good clips, and playful (rather successfully, surprisingly often) presenters. My favourite bit? Neil DeGrasse Tyson being interviewed about our place in the universe. If you’re not an expert on the anatomy of the idea, please have a listen, since this is one of the best (and quite funny) layperson’s quick descriptions I’ve heard on the subject.
Tim Ferris (on the unlikelihood or likelihood of travelling vast distances for expeditions in space) and Brian Greene (on the geometry of our universe - another good layperson’s level chat) are also in this segment, just before. Direct mp3 file link to that particular piece
Audio clip: Adobe Flash Player (version 9 or above) is required to play this audio clip. Download the latest version here. You also need to have JavaScript enabled in your browser.
. Main link here for all the other really good segments.
-cvj
So I must apologize. I went to the preview of the Griffith Observatory so long ago now and did promise to blog about it with more than just one nice picture, but it did not happen. Partly because I had to go back across the Atlantic to do some work, and then got ill over the weekend I was planning to do it, and then...
Anyway, here are some of my thoughts. First note that my two week delay means that this is no longer a scoop, since even the LA Times had a spread on the whole thing on Thursday. A rather nice one as well. I urge you to consult it for a lovely pull-out graphic of the whole site. There is also a special website with picture tours, nifty 360 degree interactive shots of the spaces, and other information. The Griffith opened yesterday.
What they’ve done over the last four or five years is simply shut down the entire building and rethink and redo a great deal of it. How to preserve the lovely 70 year old landmark, while making it even better? Simple question - simple answer: Get $93 million for your project (I find this number, the earth-sun distance in miles, suspicious), and then go underneath the existing building and hollow out about the same amount of space that is has, but underground. Fill it with lots of goodies. And I mean lots and lots. What goodies? We’ll see.
Continue reading ‘Some Observations at Griffith Observatory’
Ah! The joy of new colleagues! I have somehow forgotten to tell you one piece of the great news that we had here at USC Physics and Astronomy recently. We got three new faculty, and one of them is here in action (I’ll tell you about the others later), telling us about the physics behind the 2006 Physics Nobel Prize. This is Cosmologist/Astrophysicist Elena Pierpaoli:
She’s one of those people who works closely on (among other things) the data from Continue reading ‘New Colleagues’
From the press release:
The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2006 jointly to
John C. Mather
NASA Goddard Space Flight Center, Greenbelt, MD, USA,and
George F. Smoot
University of California, Berkeley, CA, USA“for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation”.
COBE is the experiment that really blazed the trail for all the wonderful physics that was to come from WMAP, and various other experiments such as Boomerang. And Planck is about to fly as well, giving even more precise information about our universe.
I was an undergraduate when this was announced. [Update: Oops...not quite: I had just started graduate school. Thanks Chad!] It was a wonderful feeling that all of us students had, partly gleaned from the feelings of our lecturers, I suspect. The thing that struck us as most appealing (I think) was the idea that the black body radiation spectrum (click on the image on the right for larger) that we’d been learning about in the abstract, during lectures, was sort of “out there”, writ large…. as large as can be in fact, on the whole universe! It’s always good to learn that physics -or any field- is still alive, especially when you’re still on the cusp of making a career in it.
Some more imformative background information (forgive the pun) from the press release: Continue reading ‘Physics Nobel Prize 2006′
Well, before disappearing into a long session of thinking about some funny behaviour my strings are up to (more later) I’d like to do a quick report on the departmental colloquium that I went to just now. We had Gary Zank, the Director of the Institute for Geophysics and Planetary Physics of the UC system (he’s based out of UCR) give us a talk entitled: “Particle Acceleration in Cosmic Plasmas”, and it was quite fascinating (and very well presented).
It is all about the physics of cosmic rays (here’s a NASA link called Cosmicopia for a little background on them). Here is a section of the abstract he sent to us prior to the talk:
An outstanding problem in astrophysics is to explain the origin of the almost featureless cosmic ray spectrum extending up to energies of some 1020 eV. A very small feature is apparent at between about 1013 – 1015 eV, the “knee.†In the late 1970’s, a suite of papers was published establishing the idea of diffusive shock acceleration for cosmic rays, essentially a first-order Fermi mechanism, which appeared to provide an explanation for the observed cosmic ray spectrum up to the knee. Diffusive shock acceleration is probably the most widely used particle acceleration mechanism in astrophysics and space physics, yet the theory is based on some stringent simplifications. The detailed [plasma] physics of the acceleration mechanism requires elucidation. We are fortunate in that very detailed observations of particle acceleration at shock waves, particularly in the guise of Space Weather, are providing considerable experimental insight into the basic physics of particle acceleration at a shock wave.
He gave us an overview of the remarkably detailed series of studies that his group has been carrying out (with the aid of an impressive multitude of computer simulations of the magnetohydrodynamics involved) in converting the various suggested acceleration mechanisms into detailed output that can be compared to experimental observations. Here’s a bit from their website:
The dynamical acceleration of particles at shocks waves propagating in the heliosphere is very poorly understood, yet shock waves are ubiquitous and almost all shocks are observed to energize ions and electrons. An understanding of particle acceleration at solar wind shocks has far reaching astrophysical implications. Furthermore, since energetic particles accelerated in either solar flares or in CME-driven shocks arrive at the Earth well before solar ejecta driven disturbances, an understanding of particle acceleration at interplanetary shocks is an integral part of the NSF and NASA Space Weather program.
He spoke quite a bit about shock wave mechanisms and how they work in supernovae Continue reading ‘Explaining Cosmic Rays’
I learned from New Scientist just now that various researchers working on modified gravity theories are casting doubt on the direct evidence of Dark Matter that was presented by Douglas Clowe and collaborators a few weeks ago. Recall an earlier post on it, here, and Sean Carroll’s post with more detail here.
Some quotes from the New Scientist article, written by Stuart Clark:
“One should not draw premature conclusions about the existence of dark matter without a careful analysis of alternative gravity theories,” writes John Moffat, of the University of Waterloo in Ontario, Canada
There’s more in the paper astro-ph/0608675, where there is an analysis of the gravitational lensing seen in the merging cluster observations. Recall that the it is the lensing that was used as a key part of the story to show the separation of the dark matter from the ordinary matter. Moffat claims that this lensing can be explained in his modified gravity theory, “MOG”. There’s a real calculation suggesting this, apparently, although a full computation is still in progress:
Moffat has worked this out for the Bullet cluster using a one-dimensional model, and is now trying to extend this to two dimensions. If he succeeds, it will contradict Clowe’s direct evidence of dark matter.
(In other words, Moffat has not worked this out for the Bullet cluster.)
In related work,
HongSheng Zhao of the University of St Andrews in the UK and his collaborators applied a theory of modified gravity called TeVeS to the Bullet cluster.
This theory uses at least one extra field, which kicks in to affect the modification when Continue reading ‘Bullet Not Silver?’
Well, the press conference I told you about has happened! This is so exciting! There’s new and very direct proof from observations of the Bullet Cluster with the Chandra X-ray Observatory that Dark Matter really exists.
So the need to make modifications to how gravity works on large scales in order to explain observations seems to be something we can put aside for now.
Your mission: Go to the press release website for more information, and lovely Continue reading ‘MOND Laid to Rest?’
NASA is about to make an exciting announcement, apparently. On Monday 21st August there will be a press conference, and there will be actual information (they say) at several places mentioned in this link.
I have not the slightest idea of the details of the announcement [but see update below], except that the title of the page is “NASA Announces Dark Matter Discovery”! It concerns observations with NASA’s Chandra X-ray Observatory. The Chandra site says “Astronomers will announce how dark and normal matter have been forced apart in an extraordinarily energetic collision at 1 p.m. EDT Monday, Aug. 21.”, so I infer from this that they might not have completely pinned down the nature of the Dark Matter so much as found a completely new kind of smoking gun pointing to its existence.
On the other hand, Continue reading ‘Watch That Space!’
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