Put This Anecdote In Your Pipe And Smoke It

Share

Montana Public Broadcasting has produced an interesting documentary on the controversy surrounding medical marijuana. Critics will no doubt cite the anecdotal nature of the evidence in favor of medical use, but supporters will point out the weaknesses of the objections to medical use and the apparent inconsistencies in the federal government’s policies. Did you know, for instance, that federal law allows Schedule II drugs – which include methamphetamine, cocaine, opium and morphine – to be prescribed for medical purposes, but not marijuana, which is listed on Schedule I as a drug with a high potential for abuse but no medical use?

We embed, you decide-

Watch the full episode. See more MontanaPBS Presents.

The Trouble With Internet Filter Bubbles

Share

One of my favorite Yes songs, back in the day, was “Don’t Surround Yourself With Yourself”. Although the lyrics meandered a bit, the title seemed a worthy piece of advice. Unfortunately, for various reasons (including, of course, targeted marketing and advertising), internet search engines – and social networking sites like facebook – are increasingly surrounding each of us with what they “think” we want, and burying or even filtering out search results they “think” we’ll find irrelevant. Eli Pariser, author of The Filter Bubble: What the Internet is hiding from you, would like you to seriously consider the possible long-term consequences of this growing trend. Here’s a ten minute talk he gave on the subject-

Thanks to Laura Knaapen for publicizing this video via a discussion list at my University.

Republicans Contra Science

Share

It’s one thing to disagree about what to do about global warming, and even about the exact causes of global warming, but every single Republican on the House Energy and Commerce Committee voted against a simple statement of the scientifically uncontroversial fact that global warming is occurring! As reported by The Hill

Committee ranking Democrat Rep. Henry Waxman (D-Calif.) offered an amendment Tuesday that called on Congress to agree that climate change is occurring. The amendment failed on a party-line vote of 20-31. No Republicans voted for the amendment.

The amendment says that “Congress accepts the scientific finding of the Environmental Protection Agency that ‘warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.'”

“This finding is so obviously correct that there should be no need to offer the amendment,” Waxman said.

Waxman is right. Denying that global warming is occurring is like denying that the Earth is (roughly) spherical. These Republicans seem to be concerned that admitting a fact might trap them into agreeing to a policy they would find unpalatable, but reality never dictates policy (just as facts don’t dictate values). Perhaps they are denying the facts in order to avoid revealing their true values…

Nuclear Reactors, Control Rods, and Meltdowns

Share

So… I was wondering how an earthquake could possibly cause a meltdown at the Fukushima Daiichi nuclear facility in Japan, given that the plant operators had been able to fully insert the control rods into the core. I had to search for a few minutes to find an explanation by someone who actually knew what they were talking about – in this case, Alexey Petrov, an Associate Professor at the Department of Physics and Astronomy at Wayne State University. Here is an informative excerpt from his post, which can be found here

Diagram of a BWR-type nuclear reactor

Here is the scheme of BWR-type reactor, taken from the Wikipedia page on BWR. The physics here is very simple. Fission reaction in the uranium fuel assemblies (2) heat water (blue stuff, 7), which turns into steam (red stuff, 6) in the reactor vessel (1). The steam exits the vessel and spins the turbine (8 and 9) that generates electricity. That steam is cooled down and returned into the reactor vessel and the process begins again.

Simply speaking, fission reaction happens when a slow (thermal) neutron is absorbed by uranium (U-235) nucleus, which then splits into several (two) lighter daughter nuclei, neutrons (about 3) releasing energy that is converted into heat. In order to have sustained nuclear reaction one needs to slow down those produced neutrons so that they could be absorbed by other U235 nuclei to initiate fission reaction. Different reactor designs use different moderators to do that: water (BWR, PWR), graphite (RBMK), etc.

This simple excursion into nuclear physics tells us that the rate of power generation can regulated by controlling the flux of thermal neutrons. This is indeed what is done by the control rods (3) that are usually made of a material (boron) that absorbs neutrons.

What happens in case of an earthquake? Well, the automatic control systems first and foremost would kill the sustained fission reaction that is going in the fuel elements. This was done at the Fukushima plant immediately by inserting the control rods (notice that the control rods are inserted from below). So, what’s the problem then? Why is the water vapor’s pressure is rising?

The problem is that during the fission reaction one also produces a lot of short-lived nuclear isotopes. Normally, if you would like to shut down a reactor (say, to refuel), you need some time (several days) for those isotopes to decay. During this time, the water is still being circulated through the reactor core in order to take away the heat produced in the decays of those short-lived isotopes. This is done via pumps that are operated via (1) power grid or (2) diesel generators or (3) batteries. After the earthquake the grid was knocked out and the diesel generators damaged. The pumps are now running on the batteries and the water vapor pressure inside the reactor vessel is rising — by the way, the normal operating pressure there is about 75 atmospheres!!! TEPCo [Tokyo Electric Power Company, the plant’s owner – ed.] reports that the pressure there rose twice that, so the plant operators decided to release steam from the vessel. Now, to cool down the reactor (until those short-lived isotopes decay) they decided to flood the containment vessel with sea water.

So, as you see, the Chernobyl-type of explosion is highly unlikely at the Fukushima plant.

Well, that’s a relief… But (UPDATE 3/15) that doesn’t mean we’re not in for a disaster, according to the New York Times

“We are on the brink. We are now facing the worst-case scenario,” said Hiroaki Koide, a senior reactor engineering specialist at the Research Reactor Institute of Kyoto University. “We can assume that the containment vessel at Reactor No. 2 is already breached. If there is heavy melting inside the reactor, large amounts of radiation will most definitely be released.”

Another executive said the chain of events at Daiichi suggested that it would be difficult to maintain emergency seawater cooling operations for an extended period if the containment vessel at one reactor had been compromised because radiation levels could threaten the health of workers nearby. If all workers do in fact leave the plant, the nuclear fuel in all three reactors is likely to melt down, which would lead to wholesale releases of radioactive material — by far the largest accident of its kind since the Chernobyl.

On Why There Is Something Rather Than Nothing

Share

An article today in the New York Times reports that, in physics anyway, we are on the verge of discovering why there’s something rather than nothing… or at least why the Big Bang has produced more matter than anti-matter. It all has to do with “the behavior of particularly strange particles called neutral B-mesons, which are famous for not being able to make up their minds”-

They oscillate back and forth trillions of times a second between their regular state and their antimatter state. As it happens, the mesons, created in the proton-antiproton collisions, seem to go from their antimatter state to their matter state more rapidly than they go the other way around, leading to an eventual preponderance of matter over antimatter of about 1 percent, when they decay to muons.

Whether this is enough to explain our existence is a question that cannot be answered until the cause of the still-mysterious behavior of the B-mesons is directly observed, said Dr. Brooijmans, who called the situation “fairly encouraging.”

The observed preponderance is about 50 times what is predicted by the Standard Model, the suite of theories that has ruled particle physics for a generation, meaning that whatever is causing the B-meson to act this way is “new physics” that physicists have been yearning for almost as long.

Dr. Brooijmans said that the most likely explanations were some new particle not predicted by the Standard Model or some new kind of interaction between particles. Luckily, he said, “this is something we should be able to poke at with the Large Hadron Collider.”

Okay guys, get poking! But, of course, a new model that explains the matter-anti-matter asymmetry better than the old “standard” model won’t solve the Really Big Question that metaphysicians, like very young children, always have at the ready: why? Why has this (fill in any impressively predictive physical model you like) ever happened? It seems unlikely that any merely descriptive theory, no matter how useful, will ever satisfy those who find this question engaging. Of course, it’s easy to write the question off as presupposing a sort of anthropomorphism, as if a universe had to be designed for a reason or purpose. But I think the question goes deeper than that, because even if you recognize that expecting the universe to have a purpose or a raison d’être is committing a sort of logical error or “category mistake”, the question still feels sensible. Maybe such a feeling just indicates that one is banging up against the limits of the human mind… and maybe not.

Climate-Change Denial Crock Of The Week

Share

I discovered this Peter Sinclair video (and others in the series) over at Little Green Footballs, a blog run by Charles Johnson, a friend of mine from way-way-back. I haven’t always agreed with Charles’ political views, but his latest grand obsession is to highlight examples of critical thinking like this, and to rail against the increasingly loud voices of irrationality by exposing their deceptive tactics. Keep it up, old pal.

Net Neutrality: Are All Packets Created Equal?

Share

I’ve often heard the catch phrase “net neutrality” and thought it meant something like “ISPs can’t favor some sites over others on the internet”, or “no censorship of internet sites by ISPs”. So I was all for it. However, a few days ago, after listening to the Joy Cardin show on Wisconsin Public Radio, I discovered that the issues are more complex than I’d imagined. Congress and the FCC are currently writing rules of the road that will affect every internet user, so it’s not a bad time to educate yourself on the broadband traffic situation, and the potential consequences of continuing to insist that the internet act as a “stupid pipe”. Just to take one example, there’s an argument to be made that as long as the net is going to be used to relay time-sensitive data like real-time voice or video communications, routers should be allowed to give those data priority over other data that would not suffer from a few milliseconds of delay between packets. More generally, perhaps ISPs and others should be allowed to discriminate not between sites, but between different data types. Cardin’s guest, Christopher Davies, wrote two columns, one on each side of the issue. You can read those here and here. Here’s the show in its entirety, which WPR members can also download from here.



L’Chaim!

Share

And now for something completely different…

Although the modern circumcision procedure is often credited to (or blamed on) the longstanding Jewish ritual, the practice was found in many ancient cultures. These days, 79% or so of American men are circumcised, but in recent years the procedure has been scrutinized by many who wondered about the rationale for such mutilation (let’s not mince words here). Two of my closest friends struggled mightily to decide whether to have their newborn son circumcised, and in the end decided to do so mainly because the father was circumcised, and didn’t want the son to feel different from the father. Not a particularly compelling reason, they realized, but a decision had to be made.

As the above article (and many others on the web) attests, the ancient ritual was done for all sorts of superstitious or otherwise misguided reasons. But recent studies have shown that there does seem to be a good medical reason for the practice, and this view was bolstered by an AP article today-

LOS ANGELES – Circumcision not only protects against HIV in heterosexual men, but it also helps prevent two other sexually transmitted infections, a large new study found. Circumcised males reduced their risk of infection with HPV, or human papillomavirus, by 35 percent and herpes by 28 percent. However, researchers found circumcision had no effect on the transmission of syphilis.

Landmark studies from three African countries including Uganda previously found circumcision lowered men’s chance of catching the AIDS virus by up to 60 percent. The new study stems from the Uganda research and looked at protection against three other STDs. The findings are reported in Thursday’s New England Journal of Medicine.

“Evidence now strongly suggests that circumcision offers an important prevention opportunity and should be widely available,” Drs. Matthew Golden and Judith Wasserheit of the University of Washington wrote in an accompanying editorial.

So if you are a circumcised heterosexual man who has wondered whether your parents made the right decision (and what circumcised heterosexual man hasn’t, at least in passing?), you can rest a little easier today. As I’ve previously pointed out, sometimes irrationality, superstition, or just plain tradition happens to get things right.