Saturday, September 27, 2008

Close Call

Frank, a friend, recently posted a nice article about his white water rafting trip on the Lower New River in West Virginia, including photos.

His post reminds me of a time about 8 years ago when I floated down the Youghiogheny River (the "Yough") in southwestern Pennsylvania with friends. One of the friends was kind enough to arrange the trip, including lodging us in his vacation house (which he built!), and hiring a rafting outfitter. Unlike Frank's experience, our outfitter simply provided us with rafting equipment, a short safety talk, and then we had to prepare for our two minute time window at the put-in site. No guide. And all equipment was optional, including helmets. Guess which option I chose.

We had a lot of fun on the upper part of the run. A few of us fell out on some of the more challenging rapids, but we stayed safe. Then we came to Dimple Rock. The outfitters had warned us about Dimple Rock during the safety talk. Basically it's a small rapid with a large rock at the bottom. If you don't approach at the right angle, it's easy to hit the rock and flip your raft.

Well, we definitely did not approach at the right angle, and we definitely flipped our raft. It was a little bit eerie to hear people from the shore trying to coach us, "stroke, stroke! STROKE!" but as we approached the rock, the coaching subsided to, "UH OH!" We bonked into the rock, tossed over, and the whole crew fell into the drink. (The safety instructions we were given about the "high side" technique were forgotten.) I actually fell into the water on top of our host. I popped up after a few seconds, and the host did a few seconds later, and we both scrambled out. Some of our raft crew actually floated down river over some more rapids without a raft!

I realize now that there was a significant chance of me or someone in my crew dying. I could have hit my head and been knocked unconscious, or I could have been pinned under a rock, and drowned. Those few seconds underwater, at the mercy of the currents, seemed like forever. I will never take something like that so lightly again.

Here are two videos on YouTube showing the rafting wrecks at the same Dimple Rock. However, one difference is that the year we ran it, the water was much lower, and there was actually a small falls approaching the rock. I found out later several people have died there. There's a hollow below the rock which sucks people under.

Thursday, September 25, 2008


As I've said before, I'm lucky to work at a place which has some reasonably natural areas, with basically no urban development. I regularly walk through these areas, and once in a while I see some great wildlife scenes. On the even rarer times when I remember to take a camera along, I can capture the scene.

My best moment so far was finding two owls perched together over a small creek on September 3rd. I'd seen a single owl several times perched near the same location, and some bird-watchers had told me they had spotted an owl's nest nearby as well. I had imagined it to be a solo owl nest, so imagine my surprise when I saw two next to each other! I actually ran all the way back to my office to get my camera, and the pair was still there when I got back for this photo (in fact they had gotten a little closer!). This is a pair of barred owls, which is common in North America. I assume they are pair-bonded, but I never saw any owlets. The fact that they are out of the nest together suggests that, if the pair reared any owlets, they are now out of the nest. This was probably a relaxing evening out for them! (please see OwlCam and their wonderful DVD to find out more about their young-rearing cycle). Just after I took this photo, one owl flew away, and then about a minute later the other owl flew right over my head to another perch. They were very silent.

The next day I did remember to take my camera, and caught this fox crossing the road. I've seen the same fox at the same place several times, so this is his local hunting grounds. He spotted me while I was setting up for the photo, thankfully posed, and then walked off into the brush on the side of the road. There is a nearby pond, so I suspect he has lots of frogs, birds and ducks to go after.

Of course, there are the ever present deer. This photo was taken last year when there were a lot of deer seen roving the workplace, even in the more urbanized parts. This year, however, the deer have been a lot more scarce. Perhaps they have been removed or lured away by maintenance staff. However, today I came across a herd of eight deer, about three does and six fauns, which is the most I've ever seen at one time! They were very close to the trail and I walked right past. The largest doe stared me down, stomped her hoof and snorted, but I held my ground too. The others retreated into the forest.

Here's another shot from last year, with a smaller herd near the edge of the forest. There is a feeder on-site for deer, which is supposed to reduce the number of ticks and tick-borne disease, and this photo was taken near that feeder.

(Previously, previously.)

(Sorry about the image quality, but all of these photos are taken near dusk with a cheap consumer camera with few manual settings. The red-eye is due to flash. Non-flash photos are hopelessly blurry due to long exposure times.)

Wednesday, September 3, 2008

Unstable Physical World

A very interesting paper just appeared on the preprint server. It presents the work of two different groups measuring the radiactive decay rates of two specific isotopes, Silicon-32 and Radium-226, who found some strange and intriguing results indeed.

Scientists believe we live in a universe where physical "laws" apply the same everywhere. It shouldn't matter whether we are on the earth, the moon, or the depths of outer space, the equations and theories should be the same. Radioactive decay is governed by the so-called "weak force," which is in principle a nuclear-scale force that shouldn't really care about the anything beyond the nucleus itself. So it is natural to expect that Silicon and Radium should decay radioactively at the same rate wherever we find it.

But that's not what was found by Jenkins et al. in their analysis. Taking data from two different laboratories, at Brookhaven National Laboratories in New York State and another in Germany, the authors found the decay rate goes up and down with an annual cycle. See this blog entry for a graph. The variations are less than a tenth of a percent over the course of a year for both radioisotopes.

The authors speculate that the effect is dependent on the distance between the sun and earth, which also has an annual periodic modulation as the earth moves in its orbit between perihelion and aphelion. Of course, this would violate our precepts about the physical laws governing radioactive decay. They further speculate that this may be due to a changes in the amount of solar neutrinos that reach the earth, which might somehow modulate the nuclear decay rates. Or, perhaps it is a variation in the "fine structure constant" with distance from the sun (the fine structure constant dictates the strength of the weak force).

However, if you look closely at the graph, you will see that the radioactive decay rates and the distance variations do not match up quite that well. In fact, the measurements lag the distance template by a few months. I can't imagine what force law could describe such an oddity, but it is definitely not a simple distance relationship.

An experimenter needs to be worried about subtle biases. Both of the experiments were done in the northern hemisphere. Perhaps there is some kind of earth-bound seasonal effect? For example, there could be seasonal temperature variations that affect the sensors. Or, it could be something even more subtle, like annual changes in the cosmic ray flux which affect detector dead-time. An interesting test would be to use a southern hemisphere lab where any seasonal biases would be reversed. There have been some other spectacular results which have been later retracted due to failure to account for equipment (mal)function. A famous example of this was the discovery of a 2000 Hz optical pulsar in Supernova 1987a, which later turned out to be electrical interference from another piece of equipment. These people are not dumb, it's just that the physical world can be more complicated than the ways we can control.

It's worth noting that this paper has apparently not yet been refereed. It's quite possible that during the refereeing process, a lot of these points will be addressed, or the conclusions of the paper might change. Until then, it's still a quite fascinating result!

Tuesday, September 2, 2008

We'll Tell You How Much Democracy You Can Have

Slashdot Headline: In MN, Massive Police Raids On Suspected Protestors

I have no doubt these people were planning some kind of disruption, but is disruption necessarily illegal? No, but it would be embarassing during the convention. Unfortunately there is no such thing as embarassment in the first degree, so the police and FBI went for bogus fire code violations instead. I would think that the house I live in is a "free speech zone." Yay for democracy.

My friend Tod says it more forcefully. And Glenn Greenwald is all over the issue. It's very disturbing.

Location Does Not Compute

I just got an iPod Touch about a month ago. iPhones and iPod Touches have a cool "locate-me" feature which allows you to press a button and find where you located on the map, anywhere in the country. The Ipod does this over Wi-Fi only by finding known wireless access points, based on a drive-by scan done by SkyHook Wireless.

A few days ago this feature started going haywire and putting me in Boulder, Colorado. No matter what I did, I ended up there.

Now I know why. My next door neighbor moved to Boulder a few months ago and must have brought his wireless access point along! Crap! This is a case where a very cool technology, the ability locate yourself anywhere in the country by interrogating the wireless environment, has gone wrong. The problem is that SkyHook has made a simplifying assumption that the environment does not change between the times that they do their surveys. In reality, people move and bring the wireless gear with them. I don't doubt that the iPod software sends all wireless access points it finds, so SkyHook can dynamically expand its database when new access points pop up, but that doesn't handle the case when an access point is physically moved. The result is a frustration for me.