Tag Archives: science

A few words for global warming skeptics

[Updated 2012-07-31.]

If you’re still considering yourself a ‘global warming skeptic’ in 2012, then we need to talk.

Let’s start off by looking at Wikipedia’s summary of scientific opinion on climate change, and look at the list of statements by dissenting organizations. It notes that since 2007, no national or international scientific body has made any statement rejecting the reality of anthropogenic (human-caused) climate change. The last organization to express ‘skepticism’? The American Association of Petroleum Geologists, of course.

The consensus among climate scientists—that is, scientists who have actually published peer-reviewed papers on climate science—is overwhelming. But let’s take a cue from the Petroleum Geologists, and look at how the petroleum industry sees the world today. And rather than ask the scientists (who might be biased, right?), let’s ask the money men, the CEOs who stand to lose out if we try to cut greenhouse gas emissions, the people who are most likely to be wary of admitting that global warming is real.

Remember, the oil companies are going to be some of the first businesses hit financially by any serious reduction in greenhouse gas emissions. It is absolutely in their best financial interests to pretend that global warming is a myth, and for years they did—but now, even they have conceded that the evidence is too strong to ignore. Think about that for a while.

Maybe you think the change is all because of solar activity? That hypothesis was abandoned by scientists years ago, and a new round of study by the Berkeley Earth Surface Temperature Project has been converting even former skeptics:

Although the I.P.C.C. allowed for the possibility that variations in sunlight could have ended the “Little Ice Age,” a period of cooling from the 14th century to about 1850, our data argues strongly that the temperature rise of the past 250 years cannot be attributed to solar changes. [...]

How definite is the attribution to humans? The carbon dioxide curve gives a better match than anything else we’ve tried.

Note that this was an independent study partly founded by the billionaire Koch brothers, with a multidisciplinary team of scientists including a Nobel prize winner — it wasn’t government funded, and it wasn’t performed just by climate scientists. So the argument that global warming is being hyped up by climate scientists to increase their government grant money no longer stands up either.

Maybe you think scientists are faking the figures anyway for some other reason? You maybe recall the so-called “Climategate” controversy, which led to allegations that data was being systematically manipulated. There was NASA’s correction to its data after finding a bug, which seemed to suggest shenanigans too, right? Well, you might not have heard that the complete source code to the GISTEMP software was released to put an end to the conspiracy theories.

More than that, a team of completely independent software engineers, working for free, then reimplemented the algorithms from the ground up, using a different programming language, and not implementing any data manipulation until they understood what it did, and that it was legitimate. The result? Their code gives exactly the same output. Same graph. Same global warming. Oh, and their code is also open source, and you can download it yourself, read the overview of what the code does, and look at the comments that try to explain clearly what’s going on in each step.

In spite of all this work, there are still people who claim that the data is being manipulated. But then again, there are people who claim that Barack Obama is a Kenyan Muslim, and that his birth certificate from Hawaii was faked. I think those two claims are about equal in plausibility at this point, as both require some sort of global conspiracy to support them. And it seems that people who refuse to believe in anthropogenic global warming also tend to be the kind of people who believe in other conspiracy theories.

The ccc-GISTEMP project is an example of how science works: people publish their data and explain how they processed it, and other people then examine the work, point out flaws, try to reproduce it, and so on. This brings up the question: Where are all the scientific papers with evidence that global warming is not happening? Sure, there’s a scientific consensus, but that doesn’t stop dissenting opinions from being published.

Or perhaps you think it does? Maybe you feel that scientific evidence against global warming is somehow being suppressed from all the journals? Again, I’m afraid that’s a conspiracy theory quality explanation. In reality, it has never been easier to get dubious claims published in scientific journals. The rate of retractions is at a record high. Even outright doctored data is slipping through the net. Papers challenging consensus aren’t rare in any other field; just look at some of these:

Fact is, scientists love overturning consensus and discovering new things that don’t fit theory. Consider the hunt for the Higgs Boson, where as one paper put it, the nightmare scenario is that the Higgs Boson is discovered—and nothing else is. Scientists want to test exotic and controversial theories like string theory, and if they find any data to support those controversial theories you can be sure it’ll be published. There aren’t any recent papers outlining evidence that no man-made global warming has occurred, simply because nobody can find any evidence to support that conclusion.

So if you’re still a ‘global warming skeptic’ in 2012, you’re pretty much in conspiracy theory land. Global warming is undoubtedly real. It’s almost a certainty that mankind has caused most of the recent change. It’s time to accept that and start asking yourself what we should do in response, especially given that things might be a lot worse than was believed back when it was possible to think nothing was wrong.

The man who dies every day

A month ago, I wrote about myself and other myths–some interesting scientific results from research into the nature of consciousness. I missed a couple, however.

For many years, scientists have studied the nature of sleep, and of dreams. These studies have started to overlap with those looking at the nature of consciousness. One experiment involves stimulating the brain using transcranial magnetic stimulation or TMS, and watching the outcome on an FMRI scanner as the patient is gradually anesthetized or allowed to fall asleep.

In the conscious, self-aware mind, TMS results in patterns of excitation that range over large areas of the brain. This kind of non-localized excitation is now being used to prove that coma victims are not brain-dead; they are asked to visualize playing a game of tennis, which produces an easily measurable and distinct excitation pattern in FMRI scans.

So similarly, TMS excitation of a conscious mind produces a clearly distributed pattern of neural firing. In a non-conscious mind, the excitation is highly localized and remains wherever the stimulation occurs. In a dreaming mind, the excitation stimulates adjacent areas, but doesn’t range as far as in the conscious mind. This new model of consciousness is known as the global workspace theory.

So in effect, the difference between being alive and being in a coma is like the difference between a lab full of disconnected computers, and a lab full of computers connected via a network. Dreaming is like a degraded network where the signals are rerouted to nearby systems instead of their proper destination.

What struck me as shocking is this: When you’re in deep sleep, not dreaming, the network is down–exactly like when you’re in a coma, or have just died. The difference between being awake and being in non-dreaming sleep is a difference of kind, not of degree. Awake versus dreaming, on the other hand, that’s a mere difference of degree. And non-dreaming sleep versus coma–well, that’s a difference so subtle that we don’t really understand it, and it seems to have nothing to do with thought patterns.

In other words: My conscious self-awareness, the mythical “myself”, literally ceases to exist every night, just as much as it would if I actually died. There is no “me” until I start dreaming, at which point self-awareness re-emerges partially as the network comes back online. The fact that I’m a lucid dreamer is probably just my network activating more than average.

As the ancient Greeks put it, “sleep and death are brothers”. The Bible uses sleep as a metaphor for death. Now science is starting to discover that our ancient intuitive guesses about the nature of sleep and of death are pretty close to the truth.

I had always assumed that what made me me was some sort of continuity of mental process; that when I went to sleep, the activities that are me continued–just at a lower level, beneath my conscious awareness. It now looks as if this is completely wrong. But if there’s no continuity of thought process between me and the consciousness that will be animating this body tomorrow morning, then in what sense is that person actually me? He’ll have my body, and my memories, but surely that isn’t enough?

I’m only beginning to adjust my worldview to this new knowledge. The odd thing is, rather than keeping me awake at night, it’s almost comforting. If I’ve died over 10,000 times already, the thought of dying one last time seems like much less of a big deal.

Myself, and other myths

I just watched a BBC documentary, Horizon: The Secret You, about recent results in the scientific study of consciousness. There were three experiments discussed in the program which seemed to me to be particularly key.

The first experiment was carried out at the Karolinska Institute in Sweden. It involves having the subject wear a stereoscopic VR helmet attached to two video cameras. Using this simple apparatus, the subject can be given an out-of-body experience, without drugs or meditation. In fact, the subject’s sense of self can be relocated into another person’s body, by having them wear the cameras on a helmet.

This experiment shows that the brain tries to work out where “I” am based on sensory data; if the data are confused, it guesses wrong, and locates my consciousness outside my body. So the feeling that “I” exist in my body (or my mind) is really no more than a feeling.

The second experiment involves measuring brain activity resulting from transcranial magnetic stimulation. Basically, an electromagnetic pulse is delivered to a specific part of the brain, and the resulting firing of neurons is mapped. The process is then repeated when the subject is asleep–that is, no longer conscious.

The result is interesting. The first part of the brain fires the same way in both cases. In the conscious mind, the pattern of activity then rapidly spreads out to multiple areas of the brain. In the unconscious mind, the activity remains localized. This seems to indicate that the difference between an unconscious and a conscious mind is interconnectedness. This fits nicely with my pet theory that consciousness is an emergent property of certain classes of sufficiently complex network systems.

The third experiment is the most disturbing. The subject is placed in an MRI scanner, and asked to periodically choose whether to click the button in his left hand, or the one in his right hand, and then immediately click the appropriate button. That’s all.

Based on the patterns scanned, the scientists at the Bernstein Centre for Computational Neuroscience in Berlin can predict which button the subject will push, six seconds before the subject makes the conscious decision.

In other words, the sense that you might be consciously choosing brand ‘A’ over brand ‘B’ at the supermarket may be utterly illusory. Even if you stand there and deliberate, what’s actually happening is that your brain is making a choice at a very low level, and the networked subsystems of the brain are then elaborating on that information to provide the sensation of having decided, several seconds after the decision was actually made.

It seems to me that science is rapidly converging on Zen Buddhism, and telling us that there is no “I” or “self”; it’s all an illusion generated by the brain as a side effect of trying to work out where we are and what’s going on. The illusory self then inserts itself into our thought processes and makes us think that it is important in decision making.

Or as Emo Philips put it: “I used to think that the brain was the most wonderful organ in my body. Then I realized who was telling me this.”

The show is available on YouTube, though who knows how long that will last.

The science of FOX News

A study of the brains of political partisans shed some scientific light on the obvious, and will be worth remembering in this upcoming year:

The Democrats and Republicans were given a reasoning task in which they had to evaluate threatening information about their own candidate. During the task, the subjects underwent fMRI to see what parts of their brain were active. What the researchers found was striking.

"We did not see any increased activation of the parts of the brain normally engaged during reasoning," says Drew Westen, director of clinical psychology at Emory who led the study.

Yeah, no shit.

Once partisans had come to completely biased conclusions — essentially finding ways to ignore information that could not be rationally discounted — not only did circuits that mediate negative emotions like sadness and disgust turn off, but subjects got a blast of activation in circuits involved in reward — similar to what addicts receive when they get their fix, Westen explains.

"None of the circuits involved in conscious reasoning were particularly engaged," says Westen. "Essentially, it appears as if partisans twirl the cognitive kaleidoscope until they get the conclusions they want, and then they get massively reinforced for it, with the elimination of negative emotional states and activation of positive ones."

In other words, Washington was right.

Smarter people get less sex

From a neat blog posting summarizing some research on sex and intelligence:

By the age of 19, 80% of US males and 75% of women have lost their virginity, and 87% of college students have had sex. But this number appears to be much lower at elite (i.e. more intelligent) colleges. According to the article, only 56% of Princeton undergraduates have had intercourse. At Harvard 59% of the undergraduates are non-virgins, and at MIT, only a slight majority, 51%, have had intercourse. Further, only 65% of MIT graduate students have had sex.

The bar chart of results from a Wellesley college survey is amusing, with the percentage of students who are virgins ranging from 0% for the Art students, up to 83% for the Mathematics students.

The only mystery is why the figure for Computer Science students is only half that for Mathematics. My guess is that it’s because Wellesley is a female-only college, and female computer scientists can basically get on the Internet and find any number of desperate male computer scientists to hook up with.

Also:

…another revealing finding from the Counterpoint survey was that while 95% of US men and 70% of women masturbate, this number is only 68% of men and 20% of women at MIT!

So the hypothesis is that smarter people have a lower sex drive. Obviously there are going to be exceptions, however.

The eyes have it

Some people believe that they perceive the world as it actually is. There are many experiments that can disprove this notion. For instance, take a look at Edward H Adelson’s checker shadow illusion. To me, the two squares A and B look so obviously different that if I didn’t know it was an optical illusion, I would never pause to think that they might be exactly the same color.

Similar experiments can demonstrate that your hearing is just as subjective. There are tone mixes that can be played that some people will hear as ascending tones, some as descending tones. The sense of touch can be fooled too. I’ve not heard of any demonstrations of the subjectiveness of smell-based perception, but I don’t doubt that it could be done.

Nevertheless, we like to think that we see things as they are. Sure, maybe the colors aren’t always right, or the angles look distorted, but the basic details are correct, or so we assume. You were probably taught, like me, that the eye works like a camera—the scene before it is focused by the lens onto the retina, and the signals from the rods and cones are transmitted to the brain where they are processed into an image, right?

Wrong, it turns out.

In April’s Scientific American magazine there was a fascinating article that described how the eye actually works. Further details from the same researchers were published in Nature.

It turns out that the rod and cone cells connect to 10 different kinds of neurons known as bipolar cells. The bipolar cells have long axons which extend into one of 10-12 different layers of what’s known as the plexiform layer. Also connecting into those layers are 12 different types of ganglion cells, which are the cells that actually transmit to the optic nerve. There are also at least 27 types of amacrine cells, which can affect signal transmission between the layers and change propagation of signals within a layer.

Basically, the eye isn’t at all like a camera. It’s more like a chunk of brain tissue that has been wrapped around the inside of the eyeball. (Stranger still, all the sensor cells are on the outside, and all the wiring is on the inside, so light has to pass through everything else to get to the sensors. Intelligent design? I don’t think so.)

Anyway, the sensory data from the rod and cone cells is processed by this retinal tissue into 12 separate streams of information, all of which are sent to the brain in parallel.

One signal stream consists of only the edges detected in the scene; another is only the moving edges. One has just the shadows. One detects and emphasizes highlights. One seems to notice changes of brightness with respect to time. One detects large uniform areas. Another seems to detect backgrounds around central figures. And so on.

The 12 streams of data are sent to different parts of the brain. The brain then somehow uses all of these special purpose signals to work out a mental model of the external world, which it uses to “color in” the photo-like perception we imagine we have.

This is, of course, why optical illusions work. Given the nature of the signals sent to the brain, the bigger mystery is how the brain mostly does such a good job of fooling us into thinking we have cameras for eyes.

Mast debate

A recent BBC Panorama documentary has suggested that wifi Internet might be a major health hazard. Scary quotes about chromosome damage and radiation exposure have appeared all over the Internet.

Unfortunately, the documentary’s conclusions are junk science.

Let’s start off by noting the inverse square law, a piece of basic physics which applies to electromagnetic radiation exposure. Basically, the strength of a signal varies in proportion to the distance squared.

The people who put together the documentary measured the wi-fi signal at a distance of 1m, and the cell phone tower signal at a distance of 100m. From their measurements, they concluded that the wifi signal was “three times the highest level of the mast”.

Well, no, it wasn’t. Because the cellphone signal was measured 100x further away, it was attenuated by a factor of 100×100 = 10,000×. So an accurate quote would be that the wi-fi signal was “three times the level of the cell phone mast divided by 10,000″. Not as exciting, though, is it?

You might argue that it’s reasonable to measure at different distances because people don’t tend to sit close to cell phone masts, but they do tend to sit close to wi-fi equipment. However, think for a moment about how a cell phone works. Yes, the mast transmits a signal to your phone, which is 10,000× weaker by the time it gets to you. However, you don’t just listen to your phone; hence, it must also transmit your voice back to the network. And the same physics works the other way: the signal your phone transmits is 10,000× weaker by the time it gets back to the mast.

So as you might guess, the radiation your phone emits is much, much more powerful than the radiation that reaches you from any nearby mast. That’s the radiation levels the BBC program should have been measuring and comparing with wi-fi.

While raw power is measured in watts, the relevant measurement for assessing radiation danger levels is the Specific Absorption Rate or SAR, which is measured in watts per kilogram. An adult’s body has much more bulk to dissipate the electromagnetic field, hence it’s less susceptible than (say) a lab rat’s body.

The US limit on radiation from consumer mobile phones is 1.6W/kg. (That’s lower than the European limit, so we’ll take that as our guideline.) The limit for devices like wifi is a mere 0.08W/kg. (Figures are in FCC OET Bulletin 56.)

Those are the maximums. The actual SAR ratings of common mobile phones are well documented. A value of 0.9 is fairly normal, with few phones below 0.5. So already, it’s clear that the average mobile phone actually exposing you to 0.9W/kg is likely far more dangerous than the 0.08 W/kg theoretical maximum allowed for devices like wi-fi.

Let’s look at some actual figures for wi-fi output compared to phones. I haven’t managed to find SAR ratings for wi-fi (if you have any, let me know), so we’ll have to compare power output in both cases. Peak power output from a phone is around 2W, with the average being around 250mW, according to a handy page from the Australian Radiation Protection and Nuclear Safety Agency.

Coincidentally, 250mW is the absolute maximum power output you can get from my wi-fi router (a Linksys WRT54GS). But to get that, you have to hack the firmware. The default power output for the router is around 20mW, 100× less than the phone. Now add in the fact that mobile phones are held against your head, whereas your wifi antenna is likely at least 30cm away from you at all times, and invoke the inverse square law again. The end result is that the electromagnetic radiation you get from wifi is a tiny fraction of that which you get from mobile phones.

As a UK Health Protection Agency scientist puts it in The Times, “a year sitting in a classroom near a wireless network is roughly equivalent to 20 minutes on a mobile.”

Aha, you say—what if you don’t use the mobile phone much? I’m afraid you still get irradiated. As you travel around, the signal from the nearest cell will get weaker. The phone checks signal strength every 7 seconds. If it drops off too far, the phone sends out an “I’m here!” transmission in order to locate another cell.

Given that each cell covers a square km or two, or as little as a few blocks in cities, taking a quick drive across town can involve your phone transmitting dozens of times. So wi-fi is a pretty negligible concern compared to carrying a mobile phone, let alone using one.

Wi-fi and phones aren’t the only sources of electromagnetic radiation, though. Wi-fi operates at 2.4GHz, which just happens to be the same frequency as your microwave oven. In fact, you may have noticed that your wi-fi signal strength is lower if you’re cooking something in the microwave, especially if your laptop is in the kitchen.

You might wonder why wi-fi operates at the same frequency as microwave ovens. Well, microwave ovens operate at 2.4GHz because that’s the frequency that’s best for heating up water molecules. For the same reason, it’s a bad frequency for long distance telecommunications through damp air, so it hadn’t been grabbed for any major commercial purpose. Hence, it was declared as free unlicensed spectrum for local low-power radio. This lack of regulatory hurdles led to innovation such as cordless phones, wireless video surveillance systems, and (eventually) wi-fi.

This also means that the effect of microwave exposure at wi-fi frequencies is simply heat. It’s not like nuclear radiation, it doesn’t mutate your genetic material; it simply warms up your water molecules a bit. From a scientific perspective, people are having a hard time coming up with theories to explain why localized warming of the body might cause damage. (In fact, it’s reported anecdotally that sailors on night watch on deck during WW II would stand in front of the radar in order to keep warm. They got hundreds of times the electromagnetic radiation warming you could ever get from a phone, yet they apparently didn’t suffer major damage.)

But let’s head back to the kitchen. Microwave ovens are allowed to leak up to 5mW/cm² at 5cm distance. A leaky oven may expose you to 0.256W/kg, at the same 5cm distance, according to measurements of leaky microwave ovens from the Australian Radiation Protection Agency. So at typical watching-lunch-rotate distance, it’s about the same level of danger as the radiation from your wifi router. So if you’re worried about wi-fi, you should be worried about your microwave oven too.

But there’s a much larger source of microwave radiation in your life. It’s called the sun. Summer sunlight at ground level can be up to 100mW/cm² of electromagnetic radiation. So standing outside on a sunny day irradiates you with 20× the radiation of a leaky microwave or wifi router, and a good chunk of it is microwave frequency.

So if you’re worried about electromagnetic radiation, perhaps the rational thing to do is what us computer scientists do—stay inside and browse the Internet via wi-fi, but never emerge blinking into the daylight…

Meanwhile, there are a growing number of people who believe that they are sensitive to low levels of microwave radiation like that found in wi-fi and sunlight. They call the phenomenon “electrosensitivity”. They claim that wi-fi and mobile phones give them headaches, make them nauseous, and so on, after just a few minutes. So, what’s the evidence?

Well, so far there have been at least 7 separate scientific trials in which allegedly electrosensitive people were asked to tell researches whether a mobile phone signal was present. In proper double-blind trials, “electrosensitive” people were unable to detect a mobile phone signal even after 50 minutes of continuous exposure. (Update: Here’s a very recent one.)

And even if they could have detected the signal—which they couldn’t—that wouldn’t have proved that the signal was responsible for their reported symptoms.

So if you believe wi-fi or mobile phones are making you ill, please do see a doctor—specifically, a psychiatrist. You may have a psychosomatic illness, you may be schizophrenic and believe you are picking up radio waves with your teeth, but you are not being made sick by people’s wireless Internet. If you truly believe you can tell when a mobile phone or wi-fi system is transmitting, sign up for a research study and prove it. You’ll be the first.

The sad thing is, though, that there are crackpots in even the highest levels of government. So expect to see more scare stories about wi-fi in the next few years.

I’m old enough to remember that back in the 80s, the scare story was about overhead power lines. They were making us nauseous, giving us cancer and leukemia, causing headaches. Funny how that risk seemed to vanish.

How to choke on popcorn

Microwave popcorn uses an artificial butter flavoring called diacetyl.

Numerous studies have now linked diacetyl fume inhalation to a rare condition called bronchiolitis obliterans, in which the bronchioles of the lungs get blocked by masses of fibrous tissue.

The problem has been known about since 1999, but so far federal agencies haven’t done anything. There’s now a bill in California proposing to ban diacetyl by 2010.

The Delve Special episode “Food for Thought” just seems more and more relevant as the years go by.  Random quote: “Everyone has to die of something, so it might as well be something delicious.”