Sean Carroll

Author: Sean Carroll

  • Dunbar’s Number

    I never knew this. (Via xkcd.) Wikipedia defines Dunbar’s number:

    Dunbar’s number, which is very approximately 150, represents a theorized cognitive limit to the number of individuals with whom any one person can maintain stable social relationships, the kind of relationships that go with knowing who each person is and how each person relates socially to every other person. Group sizes larger than this generally require more restricted rules, laws, and enforced policies and regulations to maintain a stable cohesion. Dunbar’s number is a significant value in sociology and anthropology. It was proposed by British anthropologist Robin Dunbar, who theorized that “this limit is a direct function of relative neocortex size, and that this in turn limits group size … the limit imposed by neocortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained.”

    In the context of the impending Super Duper Tuesday showdown, I can’t help but thinking of this in terms of politicians. Various famous political figures are occasionally described as having uncanny abilities to connect quickly with a wide variety of people, remember faces, and convince casual acquaintances that they are your best friend. Perhaps their neocortices have the unusual ability to maintain relationships (or at least appear to) with far more than the conventional 150?

  • Any Given Sunday

    As a native Philadelphian who spent many years in Boston, I can sincerely attest that New England has the most insufferable sports fans in the entire country. So I was kind of not looking forward to today’s Super Bowl coronation of the New England Patriots as the Best Football Team in All the Galaxy and Throughout Eternity. And then, against all the various odds I saw in Vegas last week, they lost! And I was happy.

    Then it occurred to me that the winners were the New York Giants. Well, the happiness was brief.

    40756669a22263dadc4c6d7c6211300c-getty-77331464mw093_super_bowl_xl.jpg

  • Rudy

    As many commenters will be quick to tell you, this is a physics blog and we should stay away from politics, about which we are hopelessly naive. But I have the keys to the blog, so I can occasionally quote myself. March 2007:

    The fact that Rudy Giuliani is currently leading in Republican polls, and that smart people occasionally opine that he could win the election or even be a good President, is a source of unlimited amazement to me…

    If Rudy Giuliani wins the 2008 general election, I promise to never again make a political prediction in public for the rest of my life.

    Whew, that was a close one!


    ustopzreps600.png

    Heck, I may do nothing but politics from now on. If Mark Penn and Bob Shrum can pull down millions as Democratic consultants, why not me?

    Best quote     from that comment thread: “Fred Thompson isn’t inspiring anyone? Once again, Sean Carroll erroneously invokes pluralis majestatis.”

  • Everyone’s a Critic

    I got this letter in the mail the other day:

    I Don’t know if you Exist But I Do! I bo not Agree with your Articl and I Do not Beleave that “MOMBO-JOMBO” if you do … Well! it’s Disturbing thought But I know How to Deal with it! I will Not let the Wolb Disiper under My Nose But if you Do I cant say I’m sorry!

    Sincerely

    a ten year old who knows a little more than some Pepeol!

    George Wing

    ps. some peopl Have a little to Much time.

    In response, of course, to the NYT story about Boltzmann’s Brain. George’s father Michael, a high-school science teacher, was moved to send it along (and gave me permission to post it), suggesting that “maybe it is really a Boltzmann brain speaking.”

    To which I can only respond: awesome. A fourth-grader reads an article in the Science Times, and is so moved by outrage that he pens a stern missive to the scientists quoted? It’s not very often that you have a chance to inspire a young mind like that, even if you do inspire him to berate you.

    Of course, George did fall into a slight trap with respect to the logic underlying the article. But that’s okay — he’s only ten years old, and there are plenty of grownups with Ph.D.’s in physics who fell into the same trap! The trap is to imagine, despite explicit disclaimers to the contrary, that the Boltzmann’s Brain argument goes something like this:

    Certain cosmological scenarios predict that it’s more likely for a brain like yours or mine to arise as a random fluctuation, rather than through orderly evolution.

    Isn’t that cool????

    That’s really not the argument that anyone is trying to make. Rather, it goes like this:

    Certain cosmological scenarios predict that it’s more likely for a brain like yours or mine to arise as a random fluctuation, rather than through orderly evolution.

    Our brains aren’t like that.

    Therefore, those scenarios are not correct.

    It’s kind of an old-fashioned argument. Take a theory, use it to make a prediction, the prediction isn’t correct, and therefore the theory has been falsified! Rubs a lot of people the wrong way, but it works for me.

    Other critics are uncharitable for different reasons. For example Don Walton, founder and president of Time For Truth Ministeries:

    I believe the accusation leveled against the Apostle Paul by Festus in Acts 26:24 — “much learning is making you mad” — is most apropos for today’s cosmologists.

    Hey, question my existence and suggest that I have too much time on my hands, fine — I can deal with that. But comparing me to Saint Paul? That is a low blow, sir. And somewhat unprecedented.

    When you’re ten years old, you don’t have to be right — you should be curious and passionate, and George definitely is on the right track. I look forward to recruiting him to grad school some day. For the grownups I have less hope.

  • Win the Smallest Trophy Ever!

    Physics Central is sponsoring a contest with a Super Bowl tie-in — a prize for the best video “that demonstrates some aspect of physics in football.” (Is there such a thing? Need you even ask?) Just load it up to YouTube with the tag “nanobowl,” but hurry — the deadline is this Sunday, February 3rd.

    trophy-thumb.jpg

    The winner will receive (seriously) a nanoscale trophy, visible only with an electron microscope! Oh yes, and the winner will also receive $1,000. In normal-sized money.

  • It’s Not Really a Party…

    … unless you have a white board to doodle on.

    whiteboard

    Jennifer has the scoop. If you look closely, you’ll see not only bits about entropy and Einstein’s equation (twice), but some hurricanes, stem cells, allusion to a recent blog post, and a clever design for a lunar lander.

  • Ain’t Got No…I’ve Got Life

    Every day is better with a little Nina Simone.

    Simone affected an imperturbable demeanor onstage, but she had an eventful life. She gave her first classical piano recital at age ten and later trained at Julliard, but started playing jazz and blues to earn a living at a time when black women pianists were not highly sought-after in the world of classical music. In the 1960’s she became active in the civil rights movement, marching with Martin Luther King and recording protest songs such as Mississippi Goddam. Her struggles with bipolar disorder were kept secret until after her death in 2003. Her music brought together influences from jazz, classical, and soul. And she could rock out when the occasion required.

  • Succumbing to LaTeX

    Update: The original post below was written as part of Cosmic Variance. Every time you move your blog, stuff like this changes. Here, the way to put something into Latex is to start your comment with the tag 

    {latexpage}

    Except — important! — use square brackets [] rather than curly braces {}. Then anything you put inside dollar signs gets interpreted as a LaTeX math formula, as usual. So

    $g_{\mu\nu}$

    should show up as

    g_{\mu\nu}.

    I’m using the QuickLaTeX plugin; more details here.

    This stands in marked contrast with the previous system, explained below.

    ——————————————————-

    For a long time I was reluctant to joint the many other sciencey blogs that had integrated equations by providing support for LaTeX, the technical typesetting system that nearly every physicist and mathematician uses. Possible reasons for this attitude include:

    1. We felt it was important to remain accessible to a wide range of readership, and feared that the appearance of equations would put people off (and tempt us into being unnecessarily technical).
    2. It sounded like work.

    You can decide for yourself which is more true. The good thing is, there is no wrong answer!

    But right now I am uninspired to blog because my brain is preoccupied with real science stuff. So I thought of posting about some of the fun ideas in quantum mechanics I’ve been learning about. But there’s really no way to do it without equations. So for that reason, and in belated honor of Donald Knuth’s birthday, I went and installed the LatexRenderer plugin.

    So now it’s easy to include equations; they should even be available in comments. All you have to do is type [ latex ], then your LaTeX commands, then [ /latex ], except no spaces. So for example

    [ latex ]R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=8\pi G T_{\mu\nu}[ /latex ],

    if you left out the spaces, should produce

    R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=8\pi G T_{\mu\nu}.

    There are a million online tutorials; try this list of commands to get you started. Use comments to this post to try it out. (Sadly, no preview, so be careful, and this post will remain open for playing around.) One thing I’ve noticed: don’t use linebreaks within the formulas, just put everything on the same line. And use “displaystyle” if you want the look of a set-off (rather than in-line) equation.

  • Where the Planes Are

    I do so love the internet. Anyone who has gone to pick someone up at the airport knows that planes don’t always land at their scheduled times. So nowadays, of course, you can check the web page for the appropriate airline and find out whether the plane is delayed or on time.

    But you know what would be even better? If you could call up a Google map that showed the flight plan and current location of the plane.

    flightplan.jpg

    And now you can! At least, for Delta flights. Do any other airlines do this? And if not, why not?

    Wait, I answered my own question, using — you guessed it — the internet. Just go to Flightstats.com (obviously), where they will apparently give you a map of whatever flight you want. And if you’re bored, you can just pick a random flight! And then you will be, if not less bored, at least somewhat bemused.

  • Disinformation Works

    An interesting post by Chris Hayes on what goes through the minds of undecided voters. One telling excerpt:

    Undecided voters aren’t as rational as you think. Members of the political class may disparage undecided voters, but we at least tend to impute to them a basic rationality. We’re giving them too much credit. I met voters who told me they were voting for Bush, but who named their most important issue as the environment. One man told me he voted for Bush in 2000 because he thought that with Cheney, an oilman, on the ticket, the administration would finally be able to make us independent from foreign oil. A colleague spoke to a voter who had been a big Howard Dean fan, but had switched to supporting Bush after Dean lost the nomination. After half an hour in the man’s house, she still couldn’t make sense of his decision. Then there was the woman who called our office a few weeks before the election to tell us that though she had signed up to volunteer for Kerry she had now decided to back Bush. Why? Because the president supported stem cell research. The office became quiet as we all stopped what we were doing to listen to one of our fellow organizers try, nobly, to disabuse her of this notion. Despite having the facts on her side, the organizer didn’t have much luck.

    I remember back in the ’90’s talking to a woman who was between jobs at the time, and consequently without health insurance of any sort. She was worried about her situation, but took some solace in the fact that “at least Hillary’s plan never got passed.” Say what you will about the original Clinton health care proposal, I don’t think that “gives uninsured people even less insurance” would be a valid criticism.

    The lesson I would draw from these stories is not to pat ourselves on the back for being well-informed while the unwashed masses are so clueless. It’s that we have built a system where people who don’t pay that much attention to politics are easy targets for disinformation. Why would anyone believe that Bush was the candidate to back if you support stem cell research? Well, because he and his supporters are happy to tell you that he supports stem cell research. It might not be “true” in any reasonable sense, but if you are generally predisposed to favor Republicans and you’re not following the details, it’s easy enough to believe. And there’s nothing especially partisan about the strategy; Democrats will obviously try to speak of themselves as being on the right side of every issue as well.

    It’s an old story, but I blame the media. A few decades ago when a small number of TV/radio/newspaper outlets were the source of almost all information about politics and governance, one could make the argument that presenting some information and not passing judgment was the right thing to do. (One could also make the argument that such a strategy is simply impossible, but that’s not for right now.) In a world with thousands of such sources, the best thing that the largest news outlets could do is to not simply present all sides dispassionately, but make it clear who is right (factually speaking) and who is wrong. When someone claims that cutting taxes always increases revenue, let us know what the evidence is. In a world where information of some sort is everywhere, the important service is not to simply provide more, it’s to separate the wheat from the chaff.