Archive for August, 2013


Blinky, a denizen of Springfield

From a recent blog post, high on hyperbole and low on science:

[Fukushima: At the Very Least, Your Days of Eating Pacific Ocean Fish Are Over  We’re writing this post becasue [sic] we feel that it is extremely important for everyone to be aware of this crisis, and it’s not being sufficiently reported on. In our entire month in the US, we did not see this in the mainstream media and hardly anyone knew about it…In a nutshell, Japan’s nuclear watchdog has now declared the leak of radioactive water from Fukushima a “state of emergency.” Each day, 300 tons of radioactive water seeps into the ocean…]

Ok.  Time out.  We need a reality check.  First of all, what’s “radioactive water”?  If I take a Geiger-Müller tube and wave it over any seawater, I will detect radioactivity.  I will also detect radioactivity in any banana (from 40K), and in my dog Banjo (from 14C).



In fact, just going outside in the open air I will detect radioactivity; in fact, over the course of a day I will absorb something like 10 μSv.  Why?  Because radioactivity is everywhere.  Radioactive isotopes aren’t like some nefarious pixie dust that is sprinkled here and there, giving us rare cancers and making us sprout third eyes.  Radioactive isotopes are everywhere.  So when you say the water is “radioactive” you’d better define what that means.

I assume that the author is just parroting what he or she read in some other blog, and doesn’t even know what “radioactive water” means (much less understand the difference between units such as Bequerels, Sieverts, Curies, Grays, rads, rems, and BED’s).  But let’s try to understand: what might “radioactive water” actually mean?  Some frustrated Google searching yielded little real science, until I stumbled upon a National Geographic article.  “…radiation levels in its groundwater observation hole on the east side of the turbine buildings had reached 310 becquerels per liter for cesium-134 and 650 becquerels per liter for cesium-137.”  Finally something we can work with!  I don’t know if this contaminated groundwater is leaking directly into the ocean, but let’s assume that it is…we might as well give in to some of the hyperbole.

650 Bq.  Is that a lot?  Well, it’s hard to say; Bq is a unit of activity (meaning decays per second) but it doesn’t tell you how much energy a person would be exposed to (for that, use the Gray; 1 Gy = 1 Joule/kg).  It also doesn’t take into account the type of radioactivity in question and how such radioactivity affects biological tissue (for that, use the Sievert, which includes a human-centric biological fudge factor).  But, as a physicist I have the right to make an educated guess, and (conservatively) say that drinking a liter of the water contaminated with 137Cs represents an exposure approximately equivalent to the EPA’s recommended limit on exposure for one year; that is, 1 mSv (one millisievert).

(It’s funny: the EPA recommends no more than 1 mSv per year, but the average person is exposed to 4 mSv per year, mostly from the air around us.  I suppose they mean to warn us not to expose ourselves to more than 1 mSv/yr beyond the 4 mSv/yr we normally get…but I digress.)

Don’t get me wrong; it’s quite a bit of radioactivity all at once, like getting 50 chest x-rays all at the same time.  But it’s still only half the dose you’d get if you got a single head CT scan.

And to get that dose, you’d have to drink the water.

But still.  The water’s “radioactive”, right?  And 300 tons of the stuff are being pumped into the Pacific every single day!

Here’s another good opportunity to practice unit conversion.  Go get a pencil.  I’ll wait.  Ready?  300 tons of water is 272,155 kg.  So that water has a volume of 272.155 m3, which is 272,155 liters.  OK so far?

272,155 x 1 mSv = 272 Sv.  A fatal dose is around 8 Sv, so this is a lot.  But you’d have to drink all 300 tons of water.

And the Pacific ocean is kinda big: maybe 6.4 x 1020 kg, or a volume of 6.4 x 1020 liters.  Imagine: each day, 300 tons of “radioactive water” enter the Pacific; but this water gets diluted (surely, it has mixed thoroughly before reaching California?)  272,155 kg / 6.4 x 1020 kg is a very, very, very small number: 4.25 x 10-16 .

This means that your initial dangerous level of radioactivity, 272 Sv, is diluted by a factor of 4.25 x 10-16, giving you 1.16 x 10-13 Sv, per day.  That is, if you drank 300 tons of water on the California coast.  If you’re numerically challenged, here’s a hint as to what this means.  1.16 x 10-13 is basically zero.  Go ahead.  Drink those 300 tons.

The hyperbolic blog continues:

[The contamination has made it’s [sic] way to the USA. A Stanford University study…]

Wait…what study?  Citation please!  Otherwise you’re just making stuff up!

[…just showed that every bluefin tuna tested in the waters off California has shown to be contaminated with radiation that originated in Fukushima. Every single one. Our FDA assures us that our food supply is safe. They LIE. Don’t trust the government testing. They are covering up the magnitude of this situation. The only safe level is zero.]

This is breathtaking.  For one thing, even if I take a Geiger counter and detect radioactivity from a fish—which I don’t doubt in the slightest; fish contain 14C, after all—how could I possibly know that the individual radioactivity events “came” from Japan?  And that final sentence…“The only safe level is zero.”  Wow.  Just, wow.  Doesn’t the author know that a “zero level of radioactivity” does not exist on this Earth?  Should we give up breathing, and eating bananas, and having basements, and walking out into the open air?

Imagine Frankenstein’s monster saying “Fire bad!”  Now imagine sciencephobes saying “Radioactivity bad!”  It amounts to the same thing.  People don’t like what they don’t understand.  And there are too many science illiterates in the world.

Here’s one more gem:

[In the wake of Fukushima, The White House has given final approval for dramatically raising permissible radioactive levels in drinking water and soil. The EPA says the new levels are within the “safe” range, but they keep moving those safe levels higher as things unfold. In soil, the PAGs allow long-term public exposure to radiation in amounts as high as 2,000 millirems. Welcome to the new normal.]

2000 millrems = 20 mSv, which is equivalent to getting 3 chest CT scans, but spread out over a whole year (which is a good thing).  This is still less than the maximum permitted yearly dose for radiation workers, which is 50 mSv.

Here’s a summary of what I’m saying.  Fukushima was a disaster, sure.  But no one in America should worry in the slightest.  You get way, way, way more radiation exposure from the person you’re sleeping next to, than you do from some water in the western Pacific.

Don’t blame the blog author.  I mean, the blog is called “Sprinter Life”.  Enough said.

[For help with radioactivity units, see this excellent graphic.]


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In 1992, ranch dressing overtook Italian to become the most popular salad dressing in the USA.  If you’re interested in why that happened, click here.  I don’t care for ranch dressing.  I don’t really like milk on my lettuce.



But thinking about ranch dressing made me wonder: whatever happened to thousand island?  Growing up, thousand island dressing seemed ubiquitous; ranch was unheard of.  I don’t recall even tasting ranch until around the mid 1980’s; cool ranch Doritos came out around that time.  But thousand island dressing was everywhere.  If you asked a waiter in 1980 what salad dressings were available, he’d be likely to say “Thousand island, Italian, oil and vinegar, blue cheese, or French.”

Today you’d get “Honey mustard, ranch, vinaigrette, Caesar, or balsamic.”

What has happened?

I have no pat answers; I offer no sweeping theories; I haven’t got a clue.  I can only point to the slings and arrows of outrageous fortune.  The mind searches for a pattern, for answers, when in reality there’s just arbitrariness, fashion, randomness.  Balsamic is in, thousand island is out.  End of story.  Move on to something more interesting.

And yet…

And yet I do have a theory, nebulous, half-formed, rising to the surface.  My theory is this: most people don’t feel strongly for any particular salad dressing.  But people are strongly against.

I have a brother who is disgusted by ketchup.  I bet he wouldn’t go near thousand island, because (according to popular folklore) thousand island is just ketchup + mayonnaise.  True or not, it’s the reputation that counts; a reputation built in part on the “secret sauce” of the Big Mac and the Reuben and god knows what else.  How many people have the following associations in their mind: thousand island…Big Mac…disgusting fast food?  I wonder if the backlash against fast food (Supersize me!) is mirrored by the downfall of thousand island.

A lot of people today find thousand island, well, gross.

What about French?  Or about my personal favorite, Russian…a dressing so rare, now, that you can barely even find it in the grocery store?  I’m going to guess that these dressings suffer because of their names.  Russians have been gauche since the cold war 1950’s; the French since…well, since the last incident in which the French incurred the wrath of America.  (It’s sad, really, that I remember a movement to rename French fries to “freedom fries”, but have long since forgotten the international incident that sparked such outrage.)  Anyway, if you eat Russian dressing then you’re a commie, and if you eat French dressing then you wear a beret, enjoy Jerry Lewis movies, and hate America.

I love both French and Russian dressings.

I dislike ranch.

C’est la vie.

[Note: I’d be curious to hear from the denizens of other countries.  What salad dressings are de rigueur in the UK, or in South Africa, or Argentina, or Macao?  And how have the fashions changed over time?  Please don’t say you like ranch, too.]

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When I was in elementary school, at some indeterminate age, I made a model of the atom with pipe cleaners and Styrofoam balls.  It probably looked something like this:


These models are about as accurate as depicting the Taj Mahal as a decrepit hovel:


The Taj Mahal, built from 1632–1653.

Sure, the atom has a nucleus; this nucleus has protons and (usually) neutrons.  And electrons “orbit” the atom (although quantum mechanics tells us that this “orbit” is a much more nebulous concept than Bohr would have us believe).  But—and here’s the main problem with 5th grade Styrofoam ball models—the scale is completely, totally, massively wrong.

Let’s do a simple calculation.  A typical atomic radius is one the order of 0.1 nm.  A typical nucleus, about 10 fm.  What is the ratio of these two lengths?

About 10,000 to 1.

This bears repeating.  A nucleus is something like 10,000 times smaller than an atom, by length.  By volume, it’s even more dramatic:

A nucleus is 1,000,000,000,000 times smaller than an atom, by volume.

You don’t really get that impression from the Styrofoam ball model, do you?

A typical football stadium has a radius of maybe 120 m.  One ten-thousandth of this is 1.2 cm, about the size of a pea.  To get a sense of what an atom really looks like,  place a pea at the center of a field in the middle of a football stadium.  Then imagine, at the outskirts of the stadium, there are a few no-see-um gnats (biting midges, of the family Ceratopogonidae).  These bugs represent the electrons.  The atoms are the bugs and the pea.  That’s it.  The rest of the atom is empty space.


Another way to think about it is this:

In terms of volume, a nucleus is only 0.0000000001% of the volume of the atom.

That means, for those of you scoring at home, that 99.9999999999% of an atom is nothing.

That is, you are mostly nothing.  So am I.  So is Matt Damon.

So the next time you’d like to help your kids make a model of the atom, just forget it.  Whatever model you make will be about as accurate as the physics in The Core.  I’d recommend instead getting some nice casu marzu, having a strong red wine, and watching True Grit.  You’ll thank me for it.


There’s flies in this, too.

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