NIST atomic clock gets more accurate
Most clocks get progressively less accurate as time goes on, the only deviance from this near-universal truth is by how much. However the atomic fountain clock has gotten more accurate with time. By the latest measurement, the clock will neither gain nor lose a second in 60 million years, with a certainty of 0.53e-15. Some of you might recall that atomic clocks generally lose roughly one second every few million years. Atomic clocks function by measuring the oscillation of cesium atoms, which oscillates roughly 9 billion times per second.
The NIST-F1’s improved accuracy comes from better lasers, software and equipment; the cesium atoms being spread over a larger space which reduces the frequency of particle interaction; and the ability to control the magnetic fields within the clock, and are able to quantify and compensate for them.
The usefulness of a more accurate atomic clock seems somewhat unclear to me. The press release states that the improved accuracy allows for better precision: navigation systems, telecommunications networks, and wireless and deep space communications all may benefit, though I question whether the “benefit” has any measurable, real-world impact.
The cheerio effect
If you’re like me, you probably used to play with your cheerios as a means of stalling in the morning before going to school. I used to play with my cheerios and see what sorts of patterns I could make without actually touching them. I used to do the same with bubbles in my juice. I used to try to influence them and then figure out why they were behaving the way they did. Apparently I wasn’t the only one who was fascinated by liquids and the way they interacted with solids because there’s a new study that is due to be published in the American Journal of Physics that explains the physics of cheerios a bowl of milk. I always used to like eating cheerios because they didn’t break down into particulate matter, and I never had to hunt for the last cheerio in a bowl full of milk. Now I know why.
The clumping effect is a result of a combination of surface tension, buoyancy, and gravity. Cheerios float, but they also press down on the surface of the milk, creating little concave indentations in the surface. So when two cheerios float near one another, they “fall down” each other’s cave, creating the appearance of an attractive force.
Cheerios on the edge of a bowl of milk are sitting atop the meniscus of the milk, and when there’s a chain of them along the edge, it’s because they’re atop the meniscus, forming their own little concave indentations making them seem sticky.
From MSNBC.
The Space Cycle
A month ago to the day, I wrote about Sergei Krikalev’s record-setting time in space: 748 days. I also mentioned that it was at possible detriment to his health: being in a “zero G” environment takes its toll on the body in numerous way. Chief among them is bone density and muscle loss. The body doesn’t need the excess bone and muscle tissue to support itself in space so it gets rid of it to be more efficient. Obviously this poses some problems when you return to Earth and are unable to stand up or otherwise function normally, so astronauts on long space missions exercise to minimize the impact to their health.
Typically, they exercise on a treadmill, running with elastic suspender-like contraptions to simulate gravity in a crude way. Now a new device, called the Space Cycle, being developed at UC Irvine utilizes artificial gravity through centrifugal forces. The device scales from 1G to 5Gs, and allows two people to exercise on it simultaneously. One on an elliptical machine or bike, and the other doing a sort of squat. The one pedalling causes the cetrifuge to spin (video).
It’s a cool idea, though looking at the video leads me to believe that unless the device is shrunk somewhat, it’ll be too large to fit inside current space quarters. Honestly, I’m not sure how much more it could be reduced, but its radius seems too great to store easily. Another problem with the cycle is that in “zero gravity,” any spinning object can cause torque on the vessel as well, so a way of counteracting this torque will have to be developed.
In any case, it’s nice to see some progress being made towards allowing astronauts and cosmonauts to stay in space for extended periods of time. Along the same vein, I mention in the writeup that I wondered about drugs like Fosamax and other bisphosphonates being used to prevent bone loss. Dr. Jay Buckey, a doctor at Dartmouth Medical School returned my email, stating that while such drugs had been investigated in bed rest studies (physiological analogs), they are not actually utilized, and that several people in space have reduced their bone density loss to minimal levels simply by exercising.
Global warming and mitigating a hurricane
Many news sources are disagreeing with my earlier post on the effect of global warming on hurricanes. Overall, it seems, global warming is at least increasing the intensity of hurricanes. There have been more Category 4 and 5 storms over the last 35 years outside of the normal waxing and waning of the normal hurricane cycles. I stand by what I said, though, regarding the assertion that global warming is solely to blame for the destruction of New Orleans and the Mississippi delta: it was bound to happen eventually.
This brings us to the next question: could humans realistically mitigate a hurricane before it makes landfall? I think most people’s first thought would be “no way” — mine included. But upon further reflection, it might be possible. There are a couple of ideas being tossed around, some more far-fetched than others.
- One plan calls for using jet engines to create small cyclones ahead of a hurricane to suck the energy out of the atmosphere, but this doesn’t seem feasible given the amount of air that would have to be moved. It is doubtful that even a large array of jet engines could trigger even a small storm.
- Another is putting a layer of oil on the ocean waters in front of a hurricane to decrease the lubrication, thereby robbing a storm of its power. Doing this, however, would entail an enormous amount of oil, and a sufficiently powerful enough storm could disrupt the water enough that it wouldn’t make a difference.
- Still another plan called for seeding storm clouds with soot to disrupt, but tests by the US Naval Research Laboratory were inconclusive.
- The last, most far-out (literally) idea calls for using space mirrors to reflect radiation back on the storm on Earth, heating the atmosphere and disrupting the storm.
The biggest problem with hurricane mitigation what happens if the hurricane still hits land and causes significant harm. Could the scientists involved with altering the storm be sued? There is no way to conclusively prove that any one strategy or combination of strategies will work all the time, and as such, there is enough legal room to sue if something goes wrong.
Legal issues aside, the physical challenges of all the ideas aside, I don’t think that creating a massive oil slick, putting tons of soot in the air, fashioning a giant blow dryer, warming the atmosphere artificially is good for the environment in any way. Who will clean up an oil slick once it’s laid? How will the soot be removed once it’s released? How will we cool the atmosphere once it has been warmed? Global warming is already a big issue, and heating an area large enough to disrupt a hurricane might perhaps kill a single hurricane, but the long-term effects of atmospheric warming will exacerbate the overall global warming which will in turn lead to more hurricanes.
I think humanity’s best bet lies in weathering the hurricanes as best we can; decreasing global warming; and not building major cities in areas vulnerable to natural disasters. But somehow I don’t see any of these things happening in the near future: we’ll go after the symptoms, but not the causes.
Global warming and Katrina
Two global warming posts in a row! I’m hesitant to write about global warming again because people see the term and their eyes glaze over. Nonetheless, a fairly popular article from the Boston Globe has been spreading around the Internet, and I think it’s time someone called it out and said “No, you’re wrong.” The opening paragraph is as follows:
THE HURRICANE that struck Louisiana yesterday was nicknamed Katrina by the National Weather Service. Its real name is global warming.
Right away you’re either running away screaming or nodding your head vigorously. The article makes some good points, but is overzealous in driving home the fact that global warming exists, and that it’s a real problem. I picture someone frothing at the mouth gnashing his teeth rather than a well thought-out discussion of the environmental factors that influenced Hurricane Katrina.
As I’ve written before, the hurricane cycle is an intricate dance of four cycles each within one another. Influences like El Nino and La Nina also play a small role in how severe a hurricane season can be. Remember that El Nino is the natural warming of the Atlantic and Pacific oceans, and that during this regular warming period, the hurricane season tends to be more mild.
Although Katrina began as a relatively small hurricane that glanced off south Florida, it was supercharged with extraordinary intensity by the relatively blistering sea surface temperatures in the Gulf of Mexico.
Blaming “global warming” for warm water temperatures in the Gulf of Mexico is disingenuous and cheapens what global warming really does do. While warm waters can supercharge a floundering tropical storm — this is neither rare nor earthshattering — even if the Gulf of Mexico was warmer than usual, this would likely have a calming effect on the hurricane season as a whole, as evidenced when El Nino is in effect. Acutely, warmer waters do have the ability to charge a hurricane that might happen to form (such as Katrina), but I have read no reports of the Gulf of Mexico being warmer this year than in recent years past. Even if the Gulf was warmer, any temperature difference would likely be miniscule (in the short run) and would have had a negligible effect on charging a storm more this year as compared to last.
Blaming “global warming” for something like Katrina is foolish, because it was only a matter of time before a hurricane like Katrina came along and did Louisiana in — global warming or no. Such is the price to be paid for a poorly-designed city in a hurricane-prone area: witness this transcript from a PBS program which aired back in 2002 which explained exactly what would happen if a strong hurricane were to strike New Orleans. It’s eery how accurate the prediction was.
If Katrina had hit in 1925, the effect would have been as devastating then as it was today. Perhaps even moreso. But alluding to the idea that Katrina wouldn’t have happened in 1925 because global warming wasn’t as bad is absurd.
Climate change: it’s not so new after all
Lately in the news, there’s been quite a bit of news about “global warming.” The public has a tendency to dismiss such claims as fear mongering by groups with an agenda. I used to dismiss them out-of-hand as well. The fact of the matter, though, is that global warming is real: there is no debate among real scientists doing real work in the field. The earth is getting warmer.
What is up for debate is whether humans have always caused global warming. It seems that we have. We succeeded in altering the climate by setting large forest fires to clear land for settlements and farming. (Ash, of course, is excellent fertilizer.) The old fashioned global warming trend was discovered by analyzing methane found trapped in pockets of air in 2,000 year old arctic ice.
The chemical fingerprint of stable types, or isotopes, of carbon atoms gives a record of methane in the atmosphere over the course of history, and where it came from.
It appears that much of the gas came from the burning of biomass - the likes of wood and grass - rather than other known sources of methane, such as the burning of fossil fuels, or natural emissions of methane from swamps and wetlands.
So it seems that we humans have been altering the climate for a long time. It should be noted that global warming thousands of years ago, while present, wasn’t present to the degree as it is today, given the mass fossil fuel consumption fueling established economies like the West, and the up-and-comers like China. It is the emerging economies that tend to skimp on things like pollution controls. It would be interesting to find a comparison of the levels of emissions comparing China to the US or Europe. Whatever the outcome of that would be, the fact remains that we’re seeing unprecedented evidence of global warming, such that the ice caps are beginning to melt and break away. The amount of useable land for smaller island groups like Micronesia has also decreased as ocean levels rise. Eventually, these islands will be totally submerged, and in the meantime, higher ocean levels make them more vulnerable to tsunamis.
I would hate to see someone point to this research and use it as an excuse to abuse the environment some more, because comparing climate change today with the climate change of thousands of years ago is spurious and misleading.
The intricate hurricane cycle
By now, you’ve heard about what Hurricane Katrina has done to the Gulf Coast, specifically, to New Orleans. Many people have been wondering why there’s been so much hurricane activity in the last few years, myself included. There have been more hurricanes and tropical storms, and on average, they’ve been fiercer and more destructive. So what’s going on? NASA’s Earth Observatory has got an article up about the hurricane cycle.
Using mathematical models, Doctors Xie and Pietrafesa developed a way to analyze patterns relating to tropical storms dating from 1887 to 1999. By analyzing patterns, they predict that the current hurricane resurgence will continue for the next 10 to 40 years. Not a very exact (or encouraging) prediction, but it does indicate that if New Orleans is rebuilt the same way the old city was, it could very well be wiped out again by another powerful hurricane like Katrina. In the the prophetic words of the Times-Picayune, “It’s only a matter of time.”
Their model is based on four cycles, shorter cycles within larger ones. A long-term cycle contributes one or two tropical storms per year to the total number, and a short-term cycle contributes up to five per year for the North Atlantic. Since 1995, there has been a dramatic increase in hurricane activity, with storms like Fran and Floyd causing widespread destruction.
An earlier, July 20 study published in Science suggests that the recent increase in hurricanes and tropical storms is the beginning of a 20 to 50 year trend in hurricane activity. But Xie and Pietrafesa believe that their analysis technique, called Empirical Mode Decomposition (EMD) more accurate describes the patterns of tropical storm occurences.
The most energetic cycle - the one that shows the greatest variation in the number of landfalling storms between its peak and low-point - is one that lasts three to five years. That cycle, Xie says, essentially adds or subtracts one or two landfalling tropical storm events every year on the East Coast. The eight-to-12-year cycle can add or subtract an average of one and a half hurricanes per year; the 20-40-year cycle can add or subtract an average of about one-half hurricane per year; and the longest, 40-60 year cycle (similar to the cycle described by Goldenberg and his colleagues) can add or subtract about one hurricane per year.
The causes of these trends are not immediately clear, but global warming has been implicated, along with the oscillations of ocean currents in the Atlantic and Pacific Oceans. Among these oscillations are El Nino (the warming) and La Nina (the cooling) of these two oceans.
During the 112-year period for which the NC State researchers have data, an average of 3.23 tropical cyclones pounded the East Coast each year. During El Nino years, that number dropped to an average of 2.47 storms. North Carolina saw an overall average of 0.81 tropical cyclones annually, and 0.56 during El Nino years.
Jonathan has great coverage of more of the science behind how and why Katrina got as powerful as she did in this week’s Science.Ars. I will investigate the global warming angle on the hurricane season in the next few days. The scientific understanding of the ferocity of a given hurricane season is not fully understood, but headway is being made. Observing patterns is the first step towards explaining them, and right now it seems we’re on the upswing of a few of the observed hurricane cycles — possibly all four.