Twenty-seven years

 Environment, Physics, Politics  No Responses »
Apr 252013
 

Twenty seven years ago tonight, an ill-prepared overnight crew at reactor #4 at the Chernobyl nuclear power station in the Ukraine began an unauthorized experiment, originally scheduled to run during the day, and designed to test how much power the reactor was able to supply while it was shutting down, keeping emergency systems powered while waiting for backup generators to kick in. Trouble is, this particular reactor type was known to have instabilities at low power even at the best of times. And these were not the best of times: the reactor was operated by an inexperienced crew and was suffering from “poisoning” by neutron-absorbing xenon gas due to prolonged low-power operations earlier and during the preparation for the test.

The rest, of course, is history: reactor #4 blew up in what remains the worst nuclear accident in history. A large area around the Chernobyl plant remains contaminated. The city of Pripyat remains a ghost town. And a great many people were exposed to radiation.

The number of people killed by the Chernobyl disaster remains a matter of dispute. Most studies I’ve read about estimate several thousands deaths that can be attributed to the accident and the resulting increased risk of cancer. But a recent paper by Kharecha and Hansen (to be published in Environ. Sci. Technol.) cites a surprisingly low figure of only 43 deaths directly attributable to the accident.

This paper, however, is notable for another reason: it argues that the number of lives saved by nuclear power vastly exceeds the number of people killed. They assert that nuclear power already prevented about 1.8 million pollution-related deaths, and that many million additional deaths can be prevented in the future.

I am sure this paper will be challenged but I find it refreshing. For what it’s worth, I’d much rather have a nuclear power plant in my own backyard than a coal-fired power station. Of course the more powerful our machines are, the bigger noise they make when they go kaboom; but this did not prevent us from using airplanes or automobiles either.

 Posted by at 9:34 pm

Global warming slowdown

 Physics, Space, Weather and Climate  No Responses »
Apr 202013
 

It’s official (well, sort of): global warming slowed down significantly in the last decade and a half.

No, this does not mean that the climate skeptics were right all along. Far from it: their attacks on science, their ad hominem attacks on scientists, their conspiracy theories are all nonsense.

What it does mean, though, is that the climate alarmists were not exactly right either. Overstating the case did not help. Far from creating public support, it may have in fact fueled climate skepticism.

The basic science is not wrong. Take a gas like CO2 that is transparent to visible light but absorbs IR a little more efficiently. Pump it into the atmosphere. Visible sunlight still reaches the surface, but less heat escapes radiatively to space at night. So, the surface gets warmer. Simple. This much was known back in the 19th century, to people like Fourier in 1827, Tyndall in 1872, and last but not least, Arrhenius from Sweden who, in 1896, actually calculated the amount by which the Earth would warm up, or cool, if the amount of CO2 were to change in the atmosphere.

But the devil is in the details. The Earth’s atmosphere is not just a column of static, transparent air with various amounts of CO2. It is a turbulent thing, with many feedback mechanisms, some positive, some negative. The oceans play a big role. Foliage plays a big role. Changes in industrial practices, fewer particulates in the air, play a big role. And so on.

And we also know that the Earth’s climate is not exactly a fragile little thing. After all, it has been relatively stable over geological timescales, allowing life to flourish and evolve. So I always thought that it is rather preposterous to assume that a few hundred years of industrial pollution can do what geological upheavals, global catastrophes, and so on could not: tip the balance and cause a runaway effect.

So we are left with the basic questions. How much will the climate change in the foreseeable future? What are its effects on humanity? And what can we do about all this?

The answer, I fear, remains as elusive as ever. And ridiculous schemes like “carbon trading” don’t help either.

 Posted by at 10:40 pm

One way trip to Mars

 Space  No Responses »
Apr 162013
 

There is another ambitious Mars project in the works: unlike Inspiration Mars, the Mars One project aims to send colonists to Mars, people determined to live out the rest of their lives on the Red Planet, with no return ticket.

Mars_One

I wrote about how I would be willing to risk a very dangerous, very uncomfortable 501-day flight to Mars and back. But staying there for good? Now that’s another matter. Leaving the Earth in the company of a dozen or so other people, knowing that from now on, those will be the only people you will ever see face to face? That you will never see a blue sky again, hear a bird sing, or swim in the sea?

Fortunately, this is not a choice I’ll ever have to make. Unlike Inspiration Mars, the Mars One project is not (to the best of my knowledge) looking for middle-aged couples as participants.

 Posted by at 3:29 pm

Pioneer 11 anniversary

 Personal, Physics, Space  No Responses »
Apr 162013
 

In all the excitement (okay, I wasn’t that excited. But, I was busy) I almost forgot to celebrate an anniversary: it was 40 years ago on April 5 that Pioneer 11 was launched at Cape Canaveral.

In a recent Letter to the Editor published in the newsletter of the American Physical Society, a correspondent suggested that Pioneer 11 may still reveal some anomalous behavior. I do not believe this to be the case. While it is true that our investigation of Pioneer 11 was not as thorough as our investigation of Pioneer 10 (due, in part, to the fact that we have less Doppler data from Pioneer 11) there are no statistically significant inconsistencies.

This Letter also reveals two misconceptions about the anomaly. One is that if the anomaly is Earth directed, which would presumably be inconsistent with a thermal cause. This is not so: quite the contrary, since the spin axis and the Earth direction mostly coincide, an Earth directed anomaly is exactly what one would expect to see in case of a thermal cause. Second, I don’t think it is even relevant to say that “a new physics cause may still be possible”. Of course new physics is always possible. But before one can speculate about new physics, “old physics” must be excluded, i.e., there must be an incontrovertible demonstration that conventional physics cannot account for the observed phenomena. This is not the case for the Pioneer anomaly: conventional physics comfortably accounts for the anomalous acceleration. Sure, there are small discrepancies that are within the margin of error, but you don’t fish for new physics within the margine of error. That’s not the way science is supposed to work.

 Posted by at 9:55 am

Say hi to @Cmdr_Hadfield

 Personal, Space  No Responses »
Apr 102013
 

A few moments ago, my wife looked up through our skylight and lo and behold, saw a moving star.

Not just any moving star; it turned out to be the International Space Station, in all its still sunlit glory over the late evening Ottawa sky.

I once managed to capture the ISS through my cellphone; the picture turned out to be surprisingly good, even showing (I think) the somewhat rectangular shape of the station.

Anyhow, I hope Chris Hadfield is having a great time up there.

 Posted by at 9:45 pm

Back from the Perimeter

 Personal, Physics, Space  No Responses »
Apr 052013
 

After another 550 km drive at the end of an already very long day, I finally made it home late last night, concluding a very productive 3-day visit at the Perimeter Institute.

While there, I gave another talk on the Pioneer anomaly. I felt that it went well and as far as I can tell, it was very well received.

All in all, it was time well spent.

 Posted by at 9:49 pm

That groundhog is a lying, thieving bastard

 Canada, Weather and Climate  2 Responses »
Mar 192013
 

Looking out my window this morning, here is the winter landscape that I saw:

This is not what those blasted groundhogs promised. They are bold-faced liars, the little creeps. The next time you run into Punxsutawney Phil or Wiarton Willie, keep an eye on your wallet; you just don’t know what the little sons of bitches are capable of.

 Posted by at 8:23 am

Not so contrarian physics

 Physics  No Responses »
Mar 172013
 

In a post a few days ago, I expressed my skeptical views concerning the interpretation of some of the recent Higgs results from CERN. I used a simple analogy, an example in which measuring the average height of the inhabitants in a set of buildings is used to determine which of them may house the Harlem Globetrotters.

However, I came to realize (thanks in part to some helpful criticism that my post received) that I left out one possibility. What if the buildings are too small? Or the ‘Trotters are just too, hmm, tired after a long party and end up in the wrong building? In that case, a measurement may look like this:

If we have an a priori reason to believe that, for whatever reason, the players are indeed spread out across several buildings, then we can indeed not expect to see a sharp peak at #4 (or whichever building is assigned to the Globetrotters); instead, we should see a broad excess, just what the CMS experiment is seeing when it measured the decay of the presumed Higgs boson into a τ+τ− pair.

So is there an a priori reason for the data to be spread out like this? I believe there is. No instrument detects τ leptons directly, as their lifetime is too short. Instead, τ events are reconstructed from decay products, and all forms of τ decay involve at least one neutrino, which may carry away a significant portion of the lepton’s energy. So the final uncertainty in the total measured energy of the τ+τ− pair can be quite significant.

In other words, many of the Globetrotters may indeed be sleeping in the wrong building.

Nonetheless, as my copy of the venerable 20-year old book, The Higgs Hunter’s Guide suggests, the decay into τ leptons can be a valuable means of confirmation. Which is perhaps why it is troubling that for now, the other major detector at the LHC, ATLAS, failed to see a similar broad excess of τ+τ− events near the presumed Higgs mass.

 Posted by at 10:23 am

Contrarian physics

 Physics  1 Response »
Mar 142013
 

I have been reading a lot today about the latest news from Europe, the supposed confirmation that the elementary particle observed at CERN may indeed by the Higgs boson.

And while they are probably right, I feel that the strong pronouncements may be a little premature and perhaps unwarranted.

Let me demonstrate my thoughts using a simple example and some pretty pictures.

Suppose you go to a camp site. At that camp site there are five buildings, each of the buildings housing a different team. One may be a literary club, another may be a club of chess enthusiasts… but you have reason to believe that one of the buildings is actually occupied by the Harlem Globetrotters.

Suppose that the only measurement available to you is a measurement of the average height of the people housed in each of the buildings. You of course know what the mean height and its standard deviation are for the entire population. So then, suppose you are presented with a graph that shows the average height, with error bars, of the people housed in each of five buildings:

The red dashed line is the population average; the green and yellow shaded areas correspond to one and two standard deviations; and the black dots are the actual data points, with standard deviations, representing the average height of the residents in each of the five buildings.

Can you confirm from this diagram that one of the buildings may indeed be housing the Harlem Globetrotters? Can you guess which one? Why, it’s #4. Easy, wasn’t it. It is the only building in which the average height of the residents deviates from the population (background) average significantly, whereas the heights of the residents of all the other buildings are consistent with the “null hypothesis”, namely that they are random people from the population background.

But suppose instead that the graph looks like this:

Can you still tell which building houses the Globetrotters? Guess not. It could be #2… or it could be #4. But if you have other reasons to believe that #4 houses the Globetrotters, you can certainly use this data set as a means of confirmation, even though you are left wondering why #2 also appears perhaps as an outlier. But then, outliers sometimes happen as mere statistical flukes.

But suppose instead that you see a plot like this one:

What can you conclude from this plot? Can you conclude anything? Is this a real measurement result and perhaps the entire camp site has been taken over by tall basketball players? Or perhaps you have a systematic error in your measurement, using the wrong ruler maybe? You simply cannot tell. More importantly, you absolutely cannot tell whether or not any of the buildings houses the Harlem Globetrotters, much less which one. Despite the fact that building #4 is still about four standard deviations away from the population average. Until you resolve the issue of the systematic, this data set cannot be used to conclude anything.

But then, why are we told that a similar-looking plot, this one indicating the rate of Higgs boson decay into a pair of τ particles (the heaviest cousin of the electron), indicates a “local significance of 2.9σ”? With a “best fit μ = 1.1 ± 0.4” for a 125 GeV Higgs boson?

It indicates no such thing. The only thing this plot actually indicates is the presence of an unexplained systematic bias.

Or am I being stubbornly stupid here?

 Posted by at 10:01 pm

Daylight savings nonsense

 Internet, Politics, Space  No Responses »
Mar 102013
 

To the esteemed dinosaurs in charge of whatever our timekeeping bureaucracies happen to be: stop this nonsense already. We no more need daylight savings time in 2013 than we need coal rationing.

It is an outdated idea, the benefits of which may have been dubious even at the time of its inception, and are almost certainly nonexistent today. But the harm is real: you are subjecting the entire population to a completely unnecessary one-hour jetlag each spring.

Being self-employed and working mostly from my home, I am among the least affected, but I still find this clock-forwarding business just boneheadedly stupid and annoying.

Oh, and while you are at it… would you please get rid of leap seconds, too? Another harmful solution to a nonexistent problem. So what if our clocks are out of whack by a second with respect to the Earth’s rotation? Does it bother anyone?

Oh wait. The organization in charge of leap seconds is the ITU. The same ITU that is busy trying to place the Internet under international regulation, at the bidding of such champions of Internet freedom like China or Russia. No wonder they have little time left in their busy schedule to abolish leap seconds.

 Posted by at 9:07 am

Wingless Dragon?

 Space  2 Responses »
Mar 012013
 

I was watching the seemingly flawless launch of SpaceX’s resupply flight to the ISS and like others, I was flabbergasted when the Webcast was suddenly blacked out (“Please Stand By”), then the flight director came on, announced that the spacecraft was experiencing an anomaly and more information will be provided at a press conference in a few hours and… that’s it. Webcast ends.

So like other good early 21st century netizens, I turned to Twitter: the speculation is that the spacecraft may have failed to deploy its solar arrays, perhaps because there was no fairing separation. This is Bad News. Some speculated that Dragon has sufficient battery power to make it to the ISS and that a spacewalk might fix things, but I don’t think things are that simple.

I guess there is nothing to do but wait for that press conference.

The live video was breathtaking, by the way. Watching the bell of the second stage engine glow yellowish-red was amazing.

spacex-small

So… my fingers remain firmly crossed.

 Posted by at 10:40 am

Trip to Mars

 Space, Transportation  No Responses »
Feb 212013
 

The news is that Dennis Tito, the first ever space tourist to go to the International Space Station, is planning a privately financed manned flyby mission to Mars in 2018.

I don’t know how feasible it is. I actually have doubts that they will succeed. And the scientific value of such a mission would likely be negligible.

Even so… I dearly hope that they succeed. And if they asked me to go, I’d sign up without hesitation, despite the prospect of spending 500 days with another human being locked up in a tiny capsule, despite the significant probability that we won’t make it back alive.

It is okay to think about the economics, technical feasibility, and scientific value of a space mission, but all too often these days, we forget that other thing: inspiration. Sometimes, that’s worth a great deal. A generation of Soviet scientists and engineers inspired by Sputnik or the flight of Gagarin, and a generation of American scientists and engineers inspired by Apollo and Armstrong’s “one small step” can bear witness of this.

 Posted by at 7:01 pm

Meteors, asteroids and media illiteracy

 Space, Television  7 Responses »
Feb 152013
 

Chances are that if you tuned your television to a news channel these past couple of days, it was news from the skies that filled the screen. First, it was about asteroid 2012DA14, which flew by the planet at a relatively safe distance of some 28,000 kilometers. But even before this asteroid reached its point of closest approach, there was the striking and alarming news from the Russian city of Chelyabinsk: widespread damage and about a thousand people injured as a result of a meteor that exploded in the atmosphere above the city.

What I found rather distressing is just how scientifically illiterate the talking heads proved to be on television. First, it was CNN’s turn to be ridiculed after their anchor, Deborah Feyerick, actually asked the astonishing question, “Is this an effect of, perhaps, of global warming, or is this just some meteoric occasion?”

But then came the rest. I think it was on the Canadian network CTV (but I might be misremembering) where an anchor announced that an asteroid “the size of Texas” is about to fly by the Earth. Well… 2012DA14 is not the size of Texas, not unless Texas has shrunk a great deal since the last time I visited the Lone Star State (which was just a few weeks ago); the asteroid was only about 50 meters across.

And then the impact event in Russia. Initial estimates that I heard indicated an object weighing a few tons, traveling perhaps at 30 km/s; that’s still a significant amount of kinetic energy, maybe about a quarter or half of a kiloton if I am not mistaken. But then, a later and apparently more reliable estimate said that the object was perhaps 15 meters in diameter, traveling at 18 km/s. That, depending on the density of the object, is consistent with another estimate that I heard, 300 kilotons of energy released. If this latter estimate is valid, this means the biggest event since the Tunguska impact of 1908.

So where does the illiteracy come in?

One CNN anchor, describing the event, mentioned that thankfully, it occurred over a sparsely populated area, and the outcome would have been much worse had it occurred over a major population center. I wonder if residents of Chelyabinsk, a city of well over a million people, are aware that they qualify as a “sparsely populated area”.

And then there were the completely inconsistent size and mass estimates. A release by The Planetary Society spoke of an object 15 meters in diameter and weighing 8 tons. Say what? That’s just four times the density of air. The object in question actually weighed more like 8,000 metric tons.

Another CNN anchor was interrogating a physicist, wondering what causes these meteors to explode. The physicist was unable to explain coherently, and the anchor was unable to comprehend, the concept that it is just the kinetic energy of a very rapidly moving object that gets converted into heat pretty much instantaneously, heating up the air, which then rapidly expands and creates a shock wave. Come on guys, this is really not that hard!

Later in the afternoon, 2012DA14 finally did make its closest approach, as harmlessly as predicted, but there was obvious confusion in the news media about its visibility; yes, it was over the Indian Ocean at the time, but no, even there nobody could see it with the naked eye, much less find it “spectacular”.

I don’t think I am needlessly pedantic, by the way. On the contrary, I find it alarming that in our world which relies on increasingly sophisticated technology, people who are entrusted with the task of keeping us informed are this illiterate on matters of science and technology. Or even geography.

 Posted by at 10:44 pm

Science, confidentiality and conservatism

 Canada, Politics, Science  No Responses »
Feb 142013
 

I always thought of myself as a moderate conservative. I remain instinctively suspicious of liberal activism, and I do support some traditionally conservative ideas such as smaller governments, lower taxes, or individual responsibility.

So why am I not a happy camper nowadays with a moderate conservative government in Ottawa?

Simple: because they are not moderate. To me, moderate conservatism means evidence-based governance. A government that, once its strategic goals are formulated, puts aside ideology and governs on the basis of available facts and the best scientific advice they can obtain.

But this is not what Mr. Harper’s conservative government is doing. Quite the contrary, they engage in one of the worst of sins: they try to distort facts to suit their ideology. Most recently, it is Fisheries and Oceans that is imposing confidentiality rules on participating researchers that “would be more appropriate for classified military research”.

I am appalled.

 Posted by at 10:58 am

Russia and the USSR

 History, Religion, Space  No Responses »
Jan 252013
 

I came across this image on a Facebook page dedicated to the former glory of the Soviet Union. It is titled “Russia and the USSR: similar, yet noticeably different.”

There is, unfortunately, far too much truth in what the image depicts. It does not make me wish for Soviet times to return, but it does make me wonder why so much good had to be thrown away along with the bad.

 Posted by at 3:31 pm

Constructing reality

 Physics, Politics  No Responses »
Jan 202013
 

John Marburger had an unenviable role as Director of the United States Office of Science and Technology Policy. Even before he began his tenure, he already faced demotion: President George W. Bush decided not to confer upon him the title “Assistant to the President on Science and Technology”, a title born both by his predecessors and also his successor. Marburger was also widely criticized by his colleagues for his efforts to defend the Bush Administration’s scientific policies. He was not infrequently labeled a “prostitute” or worse.

I met Marburger once in 2006, though to be honest, I don’t recall if I actually conversed with him one-on-one. He gave the keynote address at an international workshop organized by JPL, titled From Quantum to Cosmos: Fundamental Physics Research in Space, which I attended.

If Marburger felt any bitterness towards his colleagues or towards his own situation as a somewhat demoted science advisor, he showed no signs of it during that keynote address. Just as there are no signs of bitterness or resentment in his book, Constructing Reality, which I just finished reading. Nor is there any hint of his own mortality, even though he must have known that his days were numbered by a deadly illness. No, this is a book written by a true scientist: it is about the immortal science that must have been his true passion all along.

It is an ambitious book. In Constructing Reality, Marburger attempts the impossible: explain the Standard Model of particle physics to the interested and motivated lay reader. Thankfully, he does not completely shy away from the math; he realizes that without at least a small amount of mathematics, modern particle physics is just not comprehensible. I admire his (and his publisher’s) courage to face this fact.

Is it a good book? I honestly don’t know. I certainly enjoyed it very much. Marburger demonstrated a thorough, and better yet, intuitive understanding of some of the most difficult aspects of the Standard Model and quantum field theory. But I am the wrong audience: I know the science that he wrote about. (That is not to say that his insight was not helpful in deepening my understanding.) Would this book be useful to the lay reader? Or the aspiring young physicist? I really cannot tell. Learning the principles of quantum field theory is not easy, and in my experience, we each take our own path towards a deeper understanding. Some books help more than others but ultimately, what helps the most is practice: there is no substitute for working out equations on your own. Still, if the positive reviews on Amazon are any indication, Marburger succeeded with writing a book “for [his] friends who are not physicists”.

Marburger died much too soon, at the age of 70, after he lost his battle with cancer. His book was published posthumously (which perhaps explains why the back flap of the book’s dust jacket contains his short bio and room for a photograph above, but no actual photo. Or perhaps I am just imagining things.) But his words survive and inspire others. Well done, Dr. Marburger. And thanks.

 Posted by at 10:37 am
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