Asymptotia

Tomorrow is the Big Day. For what? The launch of Planck and Herschel - Major new windows on our universe. Keep your fingers crossed for luck!

They’re on the launch pad right now. See here.

So, what are the missions and objectives of these fine spacecraft, I hear you ask.

Well, from the Planck site:

Continue reading ‘The Big Day!’

The next Categorically Not! is on Sunday February 1st. 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.

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

Continue reading ‘Categorically Not! - Dark Matters’

Just the other day, while coordinating some work being done on my house, I was thinking that it is time I learned Spanish. Most of the people working in the construction industry here in Los Angeles have Spanish as their first language, and besides the usefulness it would give in communicating difficult ideas about a piece of work to be carried out, I really don’t like the feeling that I’m disconnected from them. I’d like to be able at least to, in Spanish, offer a cup of coffee, or a glass of iced water, and have a little small talk - treat them like fellow human beings as opposed to “the help” as is done so much in this city, to my disgust. I interact a lot with the Spanish-speaking parts of the city through my use of public transport, places I go to grab tasty food from time to time, and so on, but there is still a sense that there is an entire alternative Los Angeles out there that I am only barely touching upon by not knowing the language.

Then yesterday this whole Spanish language issue came up again in a big way. There was a phone call to the department from Univision, the Spanish-language TV network. Probably most of you are wondering what that is. You know those several channels that you never watch and when you flick by them, all clustered together, they’re always speaking Spanish and discussing issues or people that you seldom (if ever) have heard of? Yes. This is one of those channels. There’s a huge part of America (and elsewhere) that tune to those channels primarily.

Well, the people at Univision had heard about the excitement about the Large Hadron Collider (see, e.g. last post) and wanted to do a piece on it, and have someone in the studio to talk about it live on their breakfast show. They were looking for a Continue reading ‘Tales From The Industry XXII - Live LHC Chats’

Well, the new orbiting instrument, GLAST (Gamma-ray Large Area Space Telescope - launched June 11th this year) has passed all its tests with flying colours, apparently, and is working well. NASA has now renamed the craft the Fermi Gamma-ray Space Telescope, after Enrico Fermi. There’s a press release here.

The craft is a wonderful combination of the fields of particle physics, astrophysics and cosmology, and will teach us so much about the universe (such as the nature of dark matter), and so it is exciting to hear that it all on track.

Excitingly, they’ve also released images of the early results of the observations, and you can read more about them in the press release too. Here’s a sky map made from the observations.

Some words from the release:
Continue reading ‘GLAST, Fermi, and Early Results’

Good news everyone! GLAST has been launched successfully. GLAST stands for Gamma-ray Large Area Space Telescope, and it does exactly what it says on the packet. It is an instrument designed to look more closely at gamma rays from outer space. More here. It will help (alongside other instruments such as SWIFT) get better understanding of a wide range of gamma-ray emitting objects, that pertain to a wide range of issues, astrophysical to cosmological.

“Gamma ray bursters” are obvious super-powerful sources of gamma rays out there, largely due to macroscopic astrophysical objects (collapsed stars or stars in the process of doing so, or merging with each other - see earlier posts) doing violent things, or interacting violently with their surroundings. So are active galactic nuclei, powered by black holes. We’d like to better understand all of the processes that allow these objects to generate gamma rays.

Other sources could include particles and antiparticles annihilating each other and (by Continue reading ‘At Last - GLAST!’

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’

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

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’

While 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’

(Click for larger view.)

This lovely composite image of Abell 520 that includes an inferred distribution of dark Continue reading ‘Dark Puzzles’

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’

Have a look at this:

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’

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

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?’

I learned from an article in New Scientist by David Shiga that there have been recently found four more small satellite galaxies of our Milky Way galaxy.

The satellites are dwarf galaxies a few hundred to a few thousand light years across. The tiny galaxies are thought to be the building blocks of large galaxies, such as our own Milky Way – which is about 100,000 light years wide.

As you may know, we’ve known for some time that there have been such satellites (the number knwon has gone from 10 to 20 in the last two years, and some models expect as many as 50), but the small ones are very hard to detect. How do you distinguish them from other stars in the way? As part of the Sloan Digital Sky Survey (SDSS), the researchers have been looking for….

the particular types of stars expected to lie in dwarf galaxies, then detect the dwarfs as slight “overdensities” in these types of stars – patches of the sky where there are more of the stars than in surrounding areas.

The Cambridge team named them after the constellations in which they were found:

[...] Coma Berenices, Canes Venatici II, Hercules, and Leo IV, all of them lie between roughly 100,000 and 500,000 light years from Earth.

[...]The largest and smallest are Hercules and Coma Berenices, which are about 1000 and 200 light years across, respectively. Like most of the other dwarfs discovered by SDSS, the new finds are much smaller and fainter than the 10 dwarfs that were known previously, [Vasily] Belokurov [the team leader] says. “They should not really be called dwarfs – they are more like hobbits,” he told New Scientist.

Hobbits. Right. Does that make the Milky Way a Cave Troll? Or maybe a Numenorian? (Picture above is one of them. This one’s Farmer Maggot, I think. They’re not as Continue reading ‘From Dwarf Planets to Hobbit Galaxies’

I learned a new term from a producer at a television studio the other day (in a context I do not know if I’m allowed to blog about yet): “Spinach TV”. I love it. This is a term expressing the idea of television programming that is supposed to be “good for you” since it is educational in some way. Some of us are doing this sort of thing in the blogging world, for better or worse. See my about page.

With that in mind, I’d like to offer some words about this week’s science coverage of the two big Astronomy/Astrophysics stories. I’ve heard the issue raised a number of times today (including by my colleague Sean over on CV) that it is somehow to be thought of as a bad thing that there’s more coverage in the press of the Pluto demotion than there is of the new results giving new direct evidence of Dark Matter. The former is supposed to be all about the politics of science while the latter is supposed to be covered more since it is a profound new result.

With all due respect to my friends and colleagues who have expressed that opinion, I would say that such a view is somewhat short-sighted and has more than a whiff of elitism about it. They’re just missing the big picture. I completely agree that the Dark Matter result is vastly more important new science than the simple fact of Pluto’s demotion, but from the perspective of science education, the value of the Pluto coverage is immensely important, and maybe at least as important as the Dark Matter coverage. I can think of several reasons, and here are some:

Continue reading ‘Spinach Blogging’

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?’