I’ve been so woefully remiss in my blogging duties the past several months that most of our dear readers probably aren’t sure that I exist. But there has been a good reason. As some of you know, I was the only member of Cosmic Variance without a faculty job. No longer!

I’m very happy to announce that sometime next fall I will be starting at faculty job at Stanford, affiliated with the couple-year-old Kavli Institute for Particle Astrophysics and Cosmology. It’s a joint position between the Stanford Physics department and the Stanford Linear Accelerator Center, so although I’ll be losing Sean as a colleague, I’m looking forward to sharing a department with another co-blogger, JoAnne.

As I described a few months ago, the past six months or so of job-finding have been quite a whirlwind, and I decided that I needed to really focus on getting a job and deciding on the right one. So I not only stopped writing here, but also took a major break from reading blogs in general and from obsessing about the news. (Instead, for the past month or so I’ve been obsessing about the bay area housing market…)

I have to say that it paid off — I really couldn’t have hoped for things to go better this year, or to find a better job for me either professionally or personally. It’s been a great stint in the midwest (I was at the University of Michigan for two years before coming to Chicago), but I miss the bay area, the ocean, the reasonably-nearby mountains, the burritos and the farmer’s markets. And the job is very exciting — there’s lots of energy for cosmology at the new institute, several new hires planned, great postdocs and students, two brand new buildings, etc, etc… Plus of course, I’ll be joining an amazing physics department and a great lab, and my impression is that the joint position will really give me the best of both worlds.

It is rather too bad that Cosmic Variance will be losing its carefully-planned geographic diversity, and will soon be 80 percent Californian… but then again, Sean and I will both be trading wind and winter for ocean and sunshine, so it’s not really too bad for us.

Andy Albrecht gave a very nice colloquium at Chicago last Wednesday about the Dark Energy Task Force report, the final draft of which was supposed to be available on Friday — such a nice colloquium that I actually think I caught a good fraction of what he talked about and felt like I should pass it on. The basic charge of the DETF was to report back to NSF, NASA & DOE with a summary of the proposed approaches for studying dark energy, characterized their relative merits, identify steps required to get there and evaluate how well proposed projects and approaches will do in sorting this mess out.

Here’s a summary of the report based on what I gleaned from Andy’s talk — but you should all go read the thing yourselves if you’re interested in such things, I make no promise of accuracy or completeness. There’s been lots of talk before on this blog about dark energy and why it’s interesting and why it’s perplexing and what it might teach us about fundamental physics, so I won’t get into that here. But I think cosmologists and particle physicists generally agree that the fact that we have so little understanding of the primary constituent of the energy density of the Universe is one of the most important questions in all of science.

The panel, chaired by Rocky Kolb, was composed of a pretty distinguished crew, both theorists and experiementalists and observers that specialize in the various techniques that have been proposed to measure something about the equation of state of the Universe (Albrecht, Gary Bernstein, Bob Cahn, Wendy Freedman, Jackie Hewitt, Wayne Hu, John Huth, Lloyd Knox, Mark Kamionkowsky, John Mathur, Suzanne Staggs, Nick Suntzeff). They clearly took their job pretty seriously. Over a period of many months, they had weekly phonecons, several meetings, and seem to have actually done lots of calculations. Now, I’m young enough that I don’t know the varied history of task force reports, but I was certainly impressed to see that in addition to ruminating on various things, they clearly actually wrote some code, and produced a lot of interesting numbers from it

As Andy stated it (and I think this is pretty much right), the state of the field was that it was full of conflicting claims about what various projects could do and about the relative merits of various approaches and lacked any way to compare these approaches with any kind of standard. This really made it hard to see clearly or to evaluate what the best way forward was. So the first thing they tried to do was remedy this.

Here’s how the panel framed the issues:

The eventual goal should be to understand the nature of dark energy, but of course that goal is likely a long way away. In the meantime, we can hope to make progress in a few stages. The first thing to note is that the the effect of dark energy is characterized by an equation of state for the Universe, w(a) = P(a)/rho(a) (”a” refers to the scale factor of the Universe, P to the presure, and rho to the energy density). There is now pretty conclusive evidence that the Universe is accelerating, which is true for w < -1/3. In this framework, one can then ask:

• is w(a) constant?
• what are the equation of state parameters w_0 and w_a,
  as specified by w = w_0 + w_a(1-a)

• is there evidence for changes in the nature of general relativity?

They then evaluated what we might learn about these issues in 4 stages:
1) what is known now
2) what will be known upon completion of existing projects
3) medium term projects, on a 5 year time scale, costing ~10’s of millions
eg. the Dark Energy Survey
4) long term projects, ~10 year, costing ~0.3-1 billion
(e.g., LST, JDEM, SKA)

They then chose one figure of merit for evaluating the worth of a given project or method, the inverse area of the error ellipse enclosing 95% confidence in the w0-wa plane. This particular choice of this certainly doesn’t seem unambiguous, but it does seem like one of the most natural way to evaluate it.

The primary observables in the Universe that can say something about the equation of state are the distance-redshift relation D(z), which has a one-to-one relation with w(a), and the growth factor, g(z), which has a one-to-one relation with D(z), if GR is correct. So if one can measure both of them independently it not only provides some independent measures of w(a), but it allows a test of GR and our standard cosmological model on very large scales. Note that by “large”, I mean really large, roughly half the “length” of the Universe; the base line over which most of these methods operate is about z~0 to z~1, which is roughly half the age of the Universe.

There are four main probes of DE that the panel considered, and on which most of the large project work towards constraining DE is focused:

• Type Ia Supernovae, which provide a measure of D(z).
• Baryon acoustic oscillations, a standing wave pattern on ~ 140 Mpc scales, which depends only on timescales in the early Universe and the speed of sound in the baryon-photon plasma, and provides a standard ruler and thus a measure of D(z).
• The abundances of galaxy clusters, which probes the mass function of dark matter halos. The evolution of this abundance probes both g(z) and D(z), but is sensitive to uncertainties in the mass-observable relation
• Weak lensing, which uses measurements of the distortion of galaxy shapes to probe the mass distribution.

The panel assesed these various methods in light of the four stages previously discussed. A few of their basic conclusions about the relative merits and how well one will be able to do with various methods:

• Measuring D(z) with SN is a relatively mature method, limited primarily by the accuracy of photometric redshifts.
• The baryon oscillation method is relatively young, but is less affected by systematics than the other methods — because the length scale of the wiggles is not much affected by the bias of the galaxy population that its measured with.
• The panel concluded that cluster abundances had in principle higher potential than the previous two, but the primary uncertainty here is in understanding the relation between observables and halo mass, and it is not yet clear how well this will be able to be done. (This is one of the main things I’ve been working on with the Sloan Digital Sky Survey and the Dark Energy Survey, a “stage 3″ project in the terms of the DETF, and I can certainly say that most of the assumptions in the literature and probably in various white papers that were contributed to the DETF are still pretty naive on this point).
• Weak lensing is a relatively new method, and has suffered from a lack of standardization that has made different measurements difficult to compare. The biggest noise here is in the intrinsic shape of galaxies. If the systematics can be controlled and understood, this method has the most potential standing on its own.
• From stage 3 projects (~5 year timescale), one can hope to get a factor of ~2 improvement over data from current surveys from individual methods, and a factor of 3-5 improvement if all four methods combined.
• From stage 4 projects, one can hope to get an order of magnitude improvement over data from current surveys using all of the methods.

An essential conclusion that the task force came to was that combining all four methods gets you a lot that none of the methods can do on their own. This is true partially because of the added intrinsic value and the differing systematics of the various methods, but also because the combination of growth and distance tests can provide a fundamental test of general relativity. A second important conclusion of the task force was that stage 3 projects should really target improved and improved understanding of systematics. Because most of the stage 3 and 4 projects depend on large photometric surveys without full spectroscopic followup, understanding and minimizing systematic uncertainties in the photo-zs is one of the most essential for dark energy constraints. I’m currently in Barcelona at a Dark Energy Survey collaboration meeting, and I can tell you that how to do this best is one of the primary things being discussed.

My understanding is that the final version of the report came out last Friday, but I’m not sure where “out” means, and I haven’t had a chance to look. I’m sure one of our commenters can point us to a copy.

I’m back! Sorry for the long absense, but since I last posted here in early November, I’ve submitted 3 papers, sent out many many job applications, and interviewed for 22 solid days, including giving 13 job talks at 11 institutions and talking one on one to about 200 scientists. I’ve been on something like 30 planes, and haven’t been in one place for more than a week at a time. I hadn’t initially planned to completely disappear from this space for so long, but I did manage to visit all of these states (plus a provence) in my absense:

Luckily you’ve been left in very capable hands at cosmicvariance without me. And, luckily for me, all this cavorting around the country has not been for naught. It’s been completely exhausting, but energizing and actually pretty fun at the same time. I’ve really enjoyed meeting and talking science with so many great people. Especially after spending the past few years in a building populated solely by cosmologists, it’s been fun to get to talk to people doing everything from biophysics to quantum computing to string theory to star formation. It was also very interesting to get a sense of how different departments operate, and to see so many parts of the country, and to have the chance to think hard about what it would be like to work and live in some very different places and enviroments. And so far, things are looking very good. I’ll write more about that after the dust has settled, but it does look like I’ll be a proper professor somewhere next year, and not milking the cows.

By the way, I love this map maker, so just in case you are curious where I’ve been in my life and not just in the last couple of months, here’s the states and countries that I’ve visited. You’ll notice a distinct lack of southern hemisphere here, but I’m hoping to rectify that with my first honest-to-goodness vacation in a long long while sometime before I start my new job. Any suggestions?

You can make you own visited states or visited countries map if you like.

A plush version His Noodly Self is for sale on ebay, with proceeds to benefit the Nationl Center for Science Education, tireless defenders of science from creationism. The thing is just too cute not to pass on… bid on it as a gift for someone in Kansas!

(via Panda’s Thumb)

Update: if you can’t afford the plush version, a FSM replacement is now available for your darwin fish.

While we’re on the topic of women in science and children, I thought I’d point to this special section on Woman and Leadership in Newsweek last week, which profiles women leaders in several fields, including Vera Rubin, who discovered some of the first evidence for dark matter, and Eileen Collins, who was commander of the space shuttle Discovery. Both of them mention the effect of children on their careers. Collins didn’t have them until 38, and Rubin had them early — and was described in the Washington Post article about her first AAS talk as a “young mother”. The series of interviews is pretty good for its diversity of viewpoints. Here’s what Rubin has to say about how much progress woman have made in the last few decades:

I’m also impatient about the progress of women in academia, which has been much worse than industry. The statistics for women scientists are pathetic. This is a battle young women may have to fight. Thirty years ago we thought the battle would be over soon, but equality is as elusive as dark matter.

Arnold’s response to losing all of the propositions he pushed for on the CA ballot:

Asked if there was anything he would do differently, Schwarzenegger said, “If I was to make another Terminator movie, I would tell Terminator to travel back in time to tell Arnold not to have another special election.”

… the freedom to redefine science!

Risking the kind of nationwide ridicule it faced six years ago, the Kansas Board of Education approved new public-school science standards Tuesday that cast doubt on the theory of evolution.

The 6-4 vote was a victory for “intelligent design” advocates who helped draft the standards. Intelligent design holds that the universe is so complex that it must have been created by a higher power.

Critics of the new language charged that it was an attempt to inject God and creationism into public schools in violation of the separation of church and state.

All six of those who voted for the new standards were Republicans. Two Republicans and two Democrats voted no.

“This is a sad day. We’re becoming a laughingstock of not only the nation, but of the world, and I hate that,” said board member Janet Waugh, a Kansas City Democrat.

Supporters of the new standards said they will promote academic freedom. “It gets rid of a lot of dogma that’s being taught in the classroom today,” said board member John Bacon, an Olathe Republican.

The new standards say high school students must understand major evolutionary concepts. But they also declare that the basic Darwinian theory that all life had a common origin and that natural chemical processes created the building blocks of life have been challenged in recent years by fossil evidence and molecular biology.

In addition, the board rewrote the definition of science, so that it is no longer limited to the search for natural explanations of phenomena.

I, for one, am delighted that my job has been made that much easier. I think I’m going to submit a paper to the Astrophysical Journal tomorrow, asserting that the accelerating expansion of the Universe is caused by Scott McLellan’s ever increasing excuses for the government’s need to torture people. Seems as good an explanation as any other.

Like Mark, I’m not a big fan of either Condoleezza Rice or Hillary Clinton as a presidential prospect, and I think it’s likely that both may be too tainted by the lies of the respective administrations they are associated with (just you wait, Condi). But this graph (via the polling report) is pretty amazing.
I’m guessing that this must be the first time in American history that a woman has been in the lead for the presidential primaries of both major parties. Must be Geena Davis’s fault.

Also worth noting that the top 3 contenders in the Republican primary (>60% of the vote) are generally referred to (depending on the topic) as “moderates” (the top two are at least moderately pro-choice) — despite the frequent loud claims about the Republican base would never support such people. Poor Frist and Santorum got so little support in the poll that they didn’t even make it onto the graphic…

UPDATE: Pam at Pandagon points to a recent poll indicating that 28% of voters are unlikely to vote for a women of either party for President, no matter who she is. I’m not surprised, but this just points to one more reason it will be difficult for either of the above women to win. As Moshe points out below, these early polls are notoriously unrelated to who actually wins the nomination, but this does still seem like an important milestone.

Stealing my title from Sean’s recent post… the past couple of weeks have been an impressive example of exactly the reasons that I never wanted to commit to blogging and simultaneously of a world that just begs to be written about. A combination of various work commitments (a small conference last week, lots of students, papers, a few real deadlines, combined with the impending onset of job season) have just flattened me the past few weeks, and I’ve been conciously trying to stay away from the blog and the news more than usual. But what news it’s been! A modern-day Scopes monkey trial, a massive and deadly earthquake, a new Supreme court nomination that has the right tearing each other to peices, two indictments of the House Majority Leader, a supoena to the Senate Majority Leader, rumored indictments to both the president’s and the vice-president’s right hand men in the Plame investigation (with hints that the investigation may be going deep into the lies leading up the Iraq war), Judy Miller released from jail and getting nature poetry from Scooter Libby, the first legalization of gay marriage passed by both houses of a state legislature and then promptly vetoed, bird flu spreading to Europe, a vaccine for the Human Papiloma Virus found to be 100% effective, all-time low approval ratings for the president, with approval among blacks that is statistically consistent with zero, 4000 year old noodles unearthed in China, polar ice caps at a record low, and of course, several new ipods introduced.

Anyways, hope to be a bit more present here, but I expect that there will unfortunatly be many more weeks like the past few in the next few months (in my schedule at least, probably not in the number of indictments handed out to top members of the government), so I apologize in advance, and thank my co-bloggers for picking up the slack.

From the Union of Concerned Scientists, an announcement that my Senator Dick Durbin (D-IL) has introduced a bill called the Restore Scientific Integrity to Federal Research and Policy Making Act (S. 1358) (perhaps he’s been reading cosmic variance?) According to the UCS, the bill will:

Help prevent the manipulation of data by prohibiting federal employees from tampering with or censoring federally funded scientific research or analysis or directing the dissemination of false or misleading information;

Protect government scientists and strengthen whistleblower protections by prohibiting supervisors from threatening or taking action against an employee who is developing or disseminating appropriate scientific research or analysis;

Strengthen the independence of federal science advisory committees by banning political litmus tests, requiring that all appointments to science advisory committees be made without regard to political affiliation;

Improve transparency of the science advisory process by requiring agencies to disclose in advance: the makeup of the committee, the process for identifying members and selecting members for balance of viewpoints or expertise, any conflicts of interest that members have, and a summary of the way the committee reached conclusions;

Promote review of government science by requiring that each agency determine a peer review process appropriate for the agency’s functions and needs, and by eliminating the Office of Management and Budget peer review that may lead to unnecessary cost increases and delays in promulgating new health, safety, and environmental regulations;

Establish an annual report to Congress by the Director of the Office of Science and Technology Policy, which must address controversies regarding scientific integrity raised during the year, including any federal policy changes related to or administration efforts to promote scientific integrity.

All steps in the right direction. They have a handy pre-written letter to send to your senators to ask them to cosponsor the bill, which you can edit as you like.
Rep Henry Waxman (D-CA), a leader in the fight against politics-tainted science earlier introduced a similar bill in the House, which is still sitting in committee, so a similar letter to your reps is probably in order.

The UCS also has a sign-on statement for scientists on this general issue, if you are a scientist and interested in showing your support for scientific integrity in policymaking.