Archive for the 'cosmology' Category

Good Company

by
Clifford
on May 8, 2008
in Los Angeles, astronomy, cosmology, music and personal
. 2 Comments

Brian May. Photo from: http://www.guitar-poll.com/BM.phpHey, guess who was at Griffith Observatory recently? Brian May! He’s that astrophysicist who took some time off to play (excellent) guitar and compose songs in the band called Queen. Ring any bells? (I found the nice photo here.) So why was he in town? Well, a slightly giggly (but always great) Madeline Brand (of the NPR program “Day To Day”) went along to interview him, and you can listen to the interview here, and read a transcript, as well as see extracts from him book (written with Patrick Moore and Chris Lintott), charmingly and blatantly (but knowingly?) unrealistically called “Bang! The Complete History of the Universe”. I actually looked through it in a bookstore the other day - looks rather nice. Wonderfully produced and I read some well-written passages, so might be worth picking up if you’re looking for a fresh read about the universe.

As a side note, I was a huge fan of his during my middle to late teenage years and Continue reading ‘Good Company’

Sad Ending

by
Clifford
on May 1, 2008
in Los Angeles, cosmology, science and work
. 0 Comments

sam smith’s oatmeal stoutThat’s it. The class is over… I have to admit that I’m pretty sad to see the end of it, although I’m very very tired. It was such a great group. (I’ll be toasting the end of it all with some of the splendid stuff to the right.)

Recall that we stepped away from black holes. After a look at cosmology for some lectures, where we understood the role of four crucial components in determining a universe’s properties (curvature, matter, radiation, and vacuum energy) we dove back into formalism for a short while (one lecture) to develop a little more the tools we needed to properly under stand how to formulate Einstein’s field equations.

It did not take long… You need only the idea that it makes sense to formulate everything in terms of objects that allow you to express the full sense of an equation in any coordinate system you care to write. Once that is done (the objects are called tensors, and the idea and how they work is pretty simple to get to grips with) the key to formulating the field equations of gravity is to have a look at the structure of other familiar systems. The field equations of electromagnetism (Maxwell’s equations) and the field equations for Newton’s formulation of gravity give the required clues. A rummage around the geometry to find the appropriate object to express the physics in terms of uncovers the Riemann tensor and its cousins (”contractions” to get Ricci and so forth), and you’re almost there. A step back to learn how to package energy Continue reading ‘Sad Ending’

Tales From The Industry XX - Sporting Locations

by
Clifford
on April 28, 2008
in Los Angeles, cosmology, dark energy, fun, media, science, television and work
. 2 Comments

Wow, doesn’t time fly when you’re having a busy semester! I meant to tell you about this early March shoot a while back, but got swamped and it fell off the desk. I recalled that I’ve been neglectful because I learned that the show in which some of this will be used will air on Tuesday night (9:00pm I think - “The Universe” on the History Channel). The episode discusses the end of the universe, as far as I know. The point is to discuss the various speculations that have been made about how the universe might end, and what current knowledge (such as the famous 1998 supernova observations showing that the universe’s expansion is accelerating) seems to suggest about which of those scenarios might be more likely. Of course, for the discussions to make sense, you need someone to talk about some of the basics, such as what it means for the universe (indeed, the whole of spacetime) to expand and collapse. Who you gonna call? history channel shoot - end of the universe
Ok. I’m one of many you can call. It was a new (to me) producer/writer, Savas Georgalis, who called this time, and we worked together on plans about how we might Continue reading ‘Tales From The Industry XX - Sporting Locations’

Tipping the Light Cone: Black Holes

by
Clifford
on March 10, 2008
in art, astronomy, black holes, cosmology and science
. 26 Comments

Black Holes by Tamsin Van Essen: http://www.vanessendesign.com/

Black Holes, by Tamsin Van Essen. Part of a series of lovely ceramics with a physics theme. For more, visit the websites here and here.

As you may recall from the post I did some time ago, the “Light Cone” is a rather important concept in physics, and keeping track of it in a given physical scenario is an extremely important tool and technique for understanding many physical situations. (I urge you to review that post before continuing reading this one.)

One way to understand a most important concept - the event horizon - is by keeping track of lightcones, and so let’s go ahead and explore that here. The outcome is that Continue reading ‘Tipping the Light Cone: Black Holes’

Still Crazy After All These Years

by
Clifford
on March 6, 2008
in astronomy, cosmology, dark energy, dark matter and science
. 0 Comments

5 year WMAP Sky Map

I don’t mean that in a bad way. It is what it is. Quite varied and wonderful, our universe is, with unexpected features I don’t think many would have guessed at not long ago (like the fact that we only understand what about 4% of it is!! Crazy, in a Continue reading ‘Still Crazy After All These Years’

Beyond Einstein: Fixing Singularities in Spacetime

by
Clifford
on March 3, 2008
in black holes, cosmology, mathematics, science, string theory and work
. 21 Comments

Not long ago David Morrison (UCSB) came to the mathematics department here at USC to give a colloquium.

David Morrison Colloquium at USC

This was a treat for me for many reasons. Here are three:

  1. It’s always good to see Dave. He’s one of the people I’ve known in the field was since my very first postdoc when I was learning to survive in the big bad world on my own after graduate school. I mostly could not understand a word he or anyone there else said in those days (IAS Princeton, right in the belly of the Continue reading ‘Beyond Einstein: Fixing Singularities in Spacetime’

Two Rings

by
Clifford
on January 13, 2008
in astronomy, cosmology, dark energy, dark matter, galaxies and science
. 1 Comment

Now have a look at this object (and its enlargement on the right):

double einstein rings

What is it? It’s a double Einstein ring! An Einstein ring is formed by gravitational lensing - the bending of light from one object by the gravity of another object - and is typically formed when a distant galaxy lines up with another, closer galaxy. The result is a rather nice ring shape.

To find a double Einstein ring is rare! In fact, this is the first one that’s been announced. Not only is it novel, it can also use used to do a good deal of science, such Continue reading ‘Two Rings’

Categorically Not! - Beginnings

by
Clifford
on December 14, 2007
in Los Angeles, art, astronomy, cosmology, music, religion and science
. 0 Comments

Bob Miller at Categorically Not!The next Categorically Not! is on Sunday December 16th (upcoming). The Categorically Not! series of events that are held at the Santa Monica Art Studios, (with occasional exceptions). It’s a series - started and run by science writer K. C. Cole - of fun and informative conversations deliberately ignoring the traditional boundaries between art, science, humanities, and other subjects. I strongly encourage you to come to them if you’re in the area.

Here is the website that describes past ones, and upcoming ones. See also the links at the end of the post for some announcements and descriptions (and even video) of previous events. (Above right: The artist Bob Miller speaking at the event entitled “Really?” on 23rd April, 2006. He died recently on Oct. 28th 2007, and this week’s event is dedicated to him.)

The theme this month is Beginnings. Here’s the description from K C Cole:

Every thing (and every body) began sometime. Even matter, space and time have a history. So do music, religion and galaxies (and along with them, musicians, religious scholars and astronomers.) Of course, how things begin determines to a large extent how they evolve and go on to influence both human culture and the universe at large. So for this month’s Categorically Not, we’ll look at beginnings from three widely (and somewhat wildly) diverse perspectives.

categorically not! Beginnings Speakers
Continue reading ‘Categorically Not! - Beginnings’

The History Channel Joke

by
Clifford
on December 4, 2007
in Los Angeles, astronomy, cosmology, humour, science, science education, science in the media and television
. 8 Comments

If you saw it, did you get the joke? They included it!

Ok, here it is:

Continue reading ‘The History Channel Joke’

The Universe Tomorrow

by
Clifford
on December 3, 2007
in Los Angeles, astronomy, black holes, cosmology, science, science education, science in the media and television
. 6 Comments

Over on Correlations, I talked a bit about the History Channel’s science show “The Universe” (as I have here), and pointed out that the new season (season two) has already begun being broadcast. Here’s hoping that it’s a good series of programmes that will be enjoyable and informative. The show’s website is here.

Well, I’ve learned that the second episode, tomorrow’s (showing at 9:00pm), is one of those that i did some shooting for over the last two months at a number of places around LA. Rather than repeat, here’s what I said:

The next one, to air on Tuesday the 4th December, is called “Cosmic Holes” (yeah, I know), and the subject matter will be right on the edge of the known and the unknown, talking about black holes, white holes, and wormholes. While we know that the first are out there, the second two, while also solutions of Einstein’s General Relativity, are still theoretical constructs (and not without problems). The show explores some of the ideas and the prospects for the ideas surrounding Continue reading ‘The Universe Tomorrow’

The Flat Universe

by
Clifford
on November 30, 2007
in Los Angeles, astronomy, cosmology, dark energy, dark matter, galaxies and science
. 2 Comments

chuck steidelkc coleWhile searching through their site to find something else, I noticed that there was a conversation on KPCC’s Zocalo between science writer K C Cole and Astrophysicist Chuck Steidel not long ago. Have a look at their listing of past conversations here - there’s a lot of good stuff about various topics and people in the Los Angeles area. I listened to it, and it’s very interesting indeed.

It is not quite your usual light touch conversation that you hear on public radio - it is a little more involved, taking you a bit further (without losing you) and gives you more insights into the work, the puzzles, the discoveries and the hopes for future ones. As a journalist, and the guest host of the program, K C Cole knows her material, and so is able to steer things rather well, while inserting useful remarks to help the listener keep up. This might be perfect listening if you want to get a sense of what it’s like to work in Chuck’s area of expertise (finding and characterizing the youngest galaxies and understanding their cosmological implications), either out of general curiosity or if you’re planning a career in that area. Take out some time and have a listen. Here’s the blurb from the site:

Continue reading ‘The Flat Universe’

A Return

by
Clifford
on November 9, 2007
in cosmology, personal, science, travel and work
. 6 Comments

I’m in Lexington, Kentucky, for a couple of days to give three presentations at the University of Kentucky (or “UK” as everyone refers to it here - I hope that explains the previous post). I should be preparing two of them instead of blogging, but… you know how it is. Here’s how I got here:

lexington visit On Wednesday afternoon, after a class on magnetostatics, and an attendance of a lunchtime event where four of our faculty (Biology, Geology, Cosmology (our very own Elena Pierpaoli!), Biology) presented their research, I dashed for a plane. Some hours later, at 10:45pm local time, I touched down in Chicago, and 15 minutes later was on the highway in the company (and car) of Nick Halmagyi.

Our mission? To hang out for a few hours in an excellent bar or two of his acquaintance and catch up on what’s been going on with each other, workwise and otherwise. The Charleston was indeed excellent, and (after chortling a bit about the memory of my annoyance at being charged $29 for a serving of a single malt scotch in a bar in Aspen during the Summer) proceeded to order the same here (he the Macallan, me the Talisker). At about 1:00am, the music stops and a guy with a face full of character sits down at the upright piano, is introduced to a scattering of applause, and proceeds to play some Chopin. Everybody shuts up and turns to listen. Appropriately, the piano sounds like all upright pianos in all bars all around the world sound (the tuning is just a bit wobbly), and the guy is good - really good. He stops playing the piece, and there’s some more scattered applause; someone (jokingly?) offers his a dollar as he walks away which he waves away enthusiastically; the music comes back up, and everybody turns back to their conversations. Nick and I continue to chat about various aspects of life, and order a couple more whiskeys.

At 1:25am or so we wander over to another bar. Nick seems a bit surprised by my suggestion to do this (’cos I’m supposed to be going to sleep), but I’m just enjoying walking for a bit in the cold, wearing a cozy hat and coat that normally get no use these days, and there’s something nice about a proper bar hop in a neighbourhood with good bars and in the company of someone who appreciates it. This bar has an Continue reading ‘A Return’

Tales From The Industry XIII - Magnetic Moments

by
Clifford
on October 23, 2007
in Los Angeles, cosmology, fun, science, science and society, science education, science in the media and television
. 3 Comments

[Post reconstructed after 25.10.07 hack]:

magnetism shoot

The strange object pictured above is a rather nice demonstration of the “field lines” around a bar magnet. It is not a great photo (all my fault), but the demo is great. The designers suspended the tiny bits of iron in oil, inside a sealed chamber, forming a block. There’s a little cylindrical hole through the centre of the block (but still outside the chamber) that allows you to put a bar magnet in. This makes for a demo far more exciting than any shake-it-up snow scene: You shake block and the iron filings are all over the oil in three dimensions, randomly arranged. You then insert the magnet. They slowly but determinedly arrange themselves into the familiar pattern, in three dimensions. It’s great. (Why didn’t they have these when I was growing up?! I might have gone into science… Oh, wait…)

I was looking around one of our demo labs last week for things to use to demonstrate some of the principal effects of magnetism. The above demonstration was one of the Continue reading ‘Tales From The Industry XIII - Magnetic Moments’

The Walk Up Mount Wilson

by
Clifford
on August 3, 2007
in Los Angeles, astronomy, cosmology, galaxies, hiking, science, science and society and women in science
. 1 Comment

[A friend of mine in LA told me today that she was planning to go with a group of friends to do some observing up at the big telescope on Mount Wilson. This put me in mind of a post that I did on CV two years ago (how time flies!) about some of the science done up there at the Mount Wilson Observatory, thoughts surrounding, all combined with a hike up to it that I felt compelled to do upon seeing it from the air. I thought I’d bring that old post back for you to read, with enlargeable pictures as a bonus. Enjoy. -cvj]
___________________________________________________________________________________

sign to mount wilsonAs you know from an earlier post, I left Aspen on Friday and headed home. This involves changing planes at Denver, and then flying over the strange, beautiful, and changing landscape West to Los Angeles. It only takes about a couple of hours. I was thinking hard about our discussion about the Greatest Physics Paper! and trying to think of those forgotten examples of great work. The people who’s songs are seldom sung. The unglamourous “bread and butter” works that seldom get written up in the newspapers near the time that they are produced, if ever. These solid works are examples of what every scientist should do as a matter of course: You look at the evidence you have before you, gather more if necessary, make some assumptions, form a hypothesis, and test it against the data. Next, come to a conclusion, and report your results as clearly and honestly as you can, and so on.

Whether or not you have some vision about what it all means does not necessarily qualify or disqualify the resulting paper as a candidate for being a great paper. It can still take its place in the tapestry that is the sum of efforts of generation after generation of physicist to make sense of our world, and find its meaning there.

Mount Wilson Hike - foliageSo I was thinking about this all, and my mind switched to some recent reading I’d been doing. Simon Singh’s excellent book, “Big Bang” had been on my bedside table recently, and although I’d not had a lot of time to read it, I was curious to dip into it from time to time. This is partly because, while I know several of the stories and the history that he tells, it is always of great value to see how another tells those stories. I always learn something, either in the facts or in the telling.

As we’d been discussing before, Einstein’s papers are modern examples of work that changed our entire view of how the universe that we inhabit is really put together. How can those fail to be top candidates for the best physics papers ever? Same thing for Newton, and for Galileo, etc.

However, it’s easy to forget that for several years after Einstein’s breakthrough with General Relativity [see a later post I did here], the world still thought that the entire universe was just the Milky Way Galaxy. It was not until the year 1923 that Edwin Hubble (in one of his many great contributions) established extremely cleanly that the Andromeda Galaxy was several times further away from the center of the Milky Way than the edge of the Milky Way itself. This was a truly shattering change of perspective Continue reading ‘The Walk Up Mount Wilson’

More Than A Hint Of The Old Days, II

by
Clifford
on July 26, 2007
in academia, cosmology, dark energy, science and work
. 17 Comments

A strange but satisfying aspect of my time here (I’m at the Aspen Center for Physics, recall) has been the fact that due to some odd serendipity, there’s a ton of people from the “old days”. Which ones? My Princeton years, in the early 90s, as a postdoc at the Institute for Advanced Study (and later at Princeton University). These are not all people doing what I do, but in a wide range of fields such as high energy physics, astrophysics, condensed matter physics. Several of us were postdocs together. I’ve been chatting with people I’ve not seen for a while, sometimes not since those days, or they are people I met back then, and with whom I have a pool of shared memories from those days. So it has put me in mind of those times somewhat.

A quick example. Soon after I arrived last week, I was walking along, chatting with Petr HoÅ™ava (Berkeley) about various things, and we got on to reminiscing a bit about our time together as postdocs in Princeton. And then minutes later, as though conjured from the very substance of our conversation, who should walk by but one of the Gods/Legends of the field (then and now), Princeton’s Alexander Polyakov. He walked by in exactly the same sort of way he would back then, either coming from or going to a walk along the river or canal, perhaps to give us a lecture. Petr and I looked at each other, and continued our walk and talk.

The great news for me last week was that Polyakov then gave a talk. I’ll admit to being a big fan of his physics. When he gives a talk nearby, I show up, no matter how confused I might end up at the end. There’s going to be good stuff in there - it’s only a matter of time before it sorts itself out in your head. Often years. Decades. Several of us sat in on his graduate class back in Princeton in the early 90s just to try to catch the pearls of wisdom which we’d pick up as he lectured on….. Well, I’ve no idea to this day what the class was really about. He would show up (probably fresh from a walk), with no notes or anything, and just pick up a piece of chalk, stare out the window for a few seconds, and then start writing stuff. Essentially, he was randomly jumping around the subject matter in his widely under-read book “Gauge Fields and Strings”. He was all over the book. It was not always a simple and coherent path through the subject matter, and it seemed that he was largely exploring whatever took his mood in the moment, but I suspect that was largely my ignorant young mind’s impression.

Polyakov in Aspen
A. M. Polyakov in the middle of giving what for me was an excellent and intriguing seminar at the Aspen Center for Physics. Click for larger view.

Sadly, it is the type of course that these days would score close to zero in most Continue reading ‘More Than A Hint Of The Old Days, II’

TASI@Home

by
Clifford
on June 4, 2007
in cosmology, science, string theory and work
. 14 Comments

This year’s month-long Theoretical Advanced Study Institute -TASI- looks especially good, from my point of view, with a great combination of topics and lecturers. As usual, it is held in Boulder, Colorado. It’s all about current ideas and experiments and observations in particle physics and cosmology. Three USC students are there and I’ve heard from them that things have been great so far.

raphael bousso at TASIWell, the great news is that the TASI people are making the lectures available online a fairly short time after their delivery. The link is here. So even though not there, you can schedule some time to take these lecture courses if you like. I glanced for a while at Raphael Bousso’s first lecture in the series “Cosmology and the Landscape”, and it was clear and very well presented. (This is not entirely surprising - Raph is always an excellent lecturer.)

Continue reading ‘TASI@Home’

Through a Lens Darkly

by
Clifford
on March 6, 2007
in cosmology, dark matter and science
. 6 Comments

Richard Massey

Well, yesterday’s colloquium by Caltech’s Richard Massey was a lot of fun, and really excellent. When faculty, postdocs and students are all chatting about it afterwards, you know it went well. This is what a departmental colloquium is supposed to do, and it happens when subject, level of delivery and speaker all come together in just the right way.

When the news about that lovely dark matter result broke some months ago, I got in Continue reading ‘Through a Lens Darkly’

Dark Matter in 3D

by
Clifford
on January 7, 2007
in astronomy, cosmology, dark matter, galaxies and science
. 24 Comments

Have a look at this:

hubble 3d dark matter

What is it? It is an image of part of the three dimensional (see below) distribution of clumps of dark matter in our universe, produced by an extensive survey using the Hubble telescope. How did they produce it, given that dark matter is -by definition- not visible? They deduced the presence of the chunks of dark matter by looking at the Continue reading ‘Dark Matter in 3D’

Really Old Stars?

by
Clifford
on December 26, 2006
in astronomy, cosmology and science
. 11 Comments

One sees them a lot around here, given the town I’m in, but that’s not what I’m talking about.

There’s a Spitzer telescope press release about the possible discovery of the most early stars detected to date. These would be the very first stars to have formed in the universe. Remembering that the universe is 13.7 billion years old, pause for a moment to be impressed by the claim of Kashlinsky, Arendt, Mather and Moseley that these stars appeared less than a billion years after the big bang. You should also read some discussion in John Baez’ recent post. [Update: See remarks from Ned Wright at the end of this post.]

The new milestone on the timeline of the universe’s history, if this is correct, would look roughly as in this image (from the press release):

timeline of the universe from spitzer

Extraordinary claims (like this one) require extraordinary evidence, and so there’ll no Continue reading ‘Really Old Stars?’

CMB Anomalies

by
Clifford
on December 26, 2006
in cosmology and science
. 1 Comment

CMB anomaliesYoung1 Bee does it again, this time with an excellent post entitled “Anomalous Alignments in the Cosmic Microwave Background”. You’ve heard a huge amount about the success of modern precision cosmology, driven so muchn in recent times by the extraordinary data from the Cosmic Microwave Background measured by experiments such as WMAP. Well, there are some very interesting anomalies in the CMB data that have yet to be properly understood, and Bee discusses them in her post. I’ll do no more than send you over there to read it and join in the discussion if you wish. Nothing wrong with a bit of Cosmology conversation during the holidays.

-cvj

1Just trying to help, in case you’re wondering. See the first paragraphs of her post. :-)

The Paper

by
Clifford
on November 20, 2006
in astronomy, cosmology, dark energy and science
. 56 Comments

I learned from Often In Error that the paper of Riess et al, reporting on the research that was in the recent NASA press release, is out. It is here.

(Aside:- I must use the term “cosmic jerk” in an everyday sentence one day…. probably not as a term of endearment….)

-cvj

Further Information on Dark Energy

by
Clifford
on November 16, 2006
in astronomy, cosmology, dark energy, science and science in the media
. 61 Comments

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:

supernovae from hubble

From the site, we learn (for background):

Continue reading ‘Further Information on Dark Energy’

Less In The Dark Than Before?

by
Clifford
on November 15, 2006
in astronomy, dark energy and science
. 2 Comments

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?’

Inside the Academics Studio

by
Clifford
on November 8, 2006
in academia, cosmology, fun, science and work
. 1 Comment

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

Copernican Reality

by
Clifford
on November 6, 2006
in astronomy, cosmology, dark matter and science
. 0 Comments

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 here. Main link here for all the other really good segments.

-cvj

Some Observations at Griffith Observatory

by
Clifford
on November 4, 2006
in Los Angeles, architecture, art, astronomy, cosmology, design, galaxies, planets, science and science and society
. 21 Comments

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..

Griffith Observatory

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’

New Colleagues

by
Clifford
on October 17, 2006
in academia, astronomy, cosmology, science and work
. 14 Comments

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:

elena pierpaoli

She’s one of those people who works closely on (among other things) the data from Continue reading ‘New Colleagues’

Physics Nobel Prize 2006

by
Clifford
on October 3, 2006
in astronomy, cosmology and science
. 19 Comments

cmb flucts from COBE

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

COBE black body spectrumI 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′

Explaining Cosmic Rays

by
Clifford
on September 25, 2006
in astronomy, cosmology, galaxies and science
. 3 Comments

gary zankWell, 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’

Bullet Not Silver?

by
Clifford
on September 7, 2006
in astronomy, cosmology, dark matter and science
. 6 Comments

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?’

MOND Laid to Rest?

by
Clifford
on August 21, 2006
in astronomy, cosmology, dark matter and science
. 18 Comments

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.

Bullet Cluster Composite

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?’

Watch That Space!

by
Clifford
on August 15, 2006
in astronomy, cosmology and science
. 15 Comments

chandra x-ray observatory (NASA image)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!’