Let me be absolutely clear on this: No new studies have been released to spur this decision. The decision was reached by a team of 31 scientists who reviewed the existing scientific literature.
After reviewing the evidence they decided that even though there was no conclusive evidence that cell phones cause cancer, they are going to list it as a possible danger to humans.
They are playing it safe; erring on the side of caution; not counting their chickens before they’re hatched, whatever you want to call it.
[Update (11:57 AM): Here is an excellent explanation on the evidence the WHO used to make its decision, and what their decision actually means.]
This is a touchy subject. While I generally agree with playing it safe, in this case I disagree with the WHO’s decision.
Basically they are saying they need more long-term studies. However, since it is impossible to prove a negative, we will never be able to prove that cell phones don’t cause cancer. You would need an infinite number of studies to do that!
You can’t prove there isn’t a magic teapot floating around the dark side of the moon with a dwarf inside of it that reads romance novels and shoots lightning out of its boobs.
Same deal with cell phones. There is no plausible mechanism by which cell phones can cause cancer since the radiation is non-ionizing. There is also no dramatic increase in cancer rates coinciding with the dramatic increase in cell phone use in recent years.
Critics get around this point by saying that it takes decades for effects to really take hold. On average, yes that is true, but after 10-20 years of regular cell phone use by a large percentage of the population we should still expect to see some signs of adverse health effects.
So I disagree with the WHO. This little announcement is going to cause undo panic and fear.
But the “be afraid of microwaves” crowd has gotten much louder in the last few years, and I suspect this announcement by the WHO is largely due to public pressure rather than scientific evidence.
But who am I, right? I’m just a humble science blogger with a degree is physics who has looked at the scientific evidence and seen that there is no cause for alarm.
So I’m gonna go ahead and say “Don’t panic!”. But I have a sneaking suspicion people are going to anyway…
Its official. True North Sports and Entertainment is about to have a press conference to announce their purchase of the Atlanta Thrashers.
They have already told the Winnipeg Free Press that the deal has been finalized.
The sale still has to be voted on by the Board of Governors in a few weeks, but that vote is expected to go smoothly.
Also, the name of the team won’t be announced today. That seems to indicate to me that the team will not be called the ‘Jets’, but will take on the name of Winnipeg’s current AHL affiliate team, the Manitoba Moose.
But that is speculation. What is for sure though, is that Canada now has 7 NHL teams.
Are you an uber-nerd like me? Then you’ll find this quite amusing.
The actual death scene is still perhaps the single most memorable moment from a video game I’ve ever seen.
The weak shock wave emanating from a trombone was captured on film and presented at the 161st Meeting of the Acoustical Society for America in Seattle.
The researchers used schlieren photography to capture the images. This method is able to image fluids through the changes in their refractive index and is used largely in aeronautical engineering to study air flow around airplanes.
It’s also wicked-cool :)
The paper is entitled ‘Improved measurement of the shape of the electron’ and describes, well, a new method for measuring the electron’s shape.
I love when physics paper titles are easy to understand :)
Anywho, the main thrust of the paper is that the electron appears to be spherical to a very high degree of accuracy. In fact, the press release from the Imperial College of London states that,
the electron differs from being perfectly round by less than 0.000000000000000000000000001 cm. This means that if the electron was magnified to the size of the solar system, it would still appear spherical to within the width of a human hair.
Wow! Now that is pretty darn spherical.
But now you’re thinking “Hey wait, I thought the electron was a wave? Or a string of energy? Or a cloud of virtual particles? How can it actually be spherical?”
These are excellent questions. Indeed, when we first learn about atomic structure in science class the electron, protons and neutrons are all depicted as perfect spheres. As we learn more, we know that this is only an approximation, an easier way of visualizing the complicated subatomic structure.
The truth is, the electron isn’t (well, probably not) spherical. We don’t really know for sure. Current theories point to the most accurate picture being that the electron is a cloud of particles, blinking in and out of existence, which contribute to its mass and size.
So what this paper and these news outlets are actually saying is that this experiment has shown that the electron behaves as though it is a sphere.
Even more accurately, the electric dipole moment of the electron is approximately zero, which is what we would expect from a perfect sphere with uniform charge distribution.
Ok, I know I just said a mouthful. So let’s go through exactly what I mean about the electric dipole moment, and then we’ll go through what this paper actually measured.
Let’s begin with what an electric dipole moment actually is. Imagine you had two particles, one with a negative charge (-q), and one with a positive charge (+q). If you put these two charges close together, you will create special electric field pattern. This type of arrangement creates what is called an electric dipole moment (EDM). The EDM vector (p) is defined as the of the charge on the two particles (q) times the displacement vector between them (d).
However, you can also create an EDM if you were to have a particle with an uneven charge distribution.
For example, imagine you had a sphere with a total charge +q. In this case, the charge is evenly distributed and you don’t get an EDM.
But now imagine you had an oddly shaped particle that was “squished” at one end.
In this case, there is more charge at one end of the particle than there is at the other. This uneven charge distribution gives the particle its own EDM.
So if the electron is not perfectly spherical, it should have an EDM. If it has an EDM, we should be able to measure it to infer the electrons shape. Simple, right?
Now, the Standard Model of Physics predicts that the EDM of the electron is too small for us to currently measure; our equipment is just not sensitive enough. But there are variations on the theory that say the electron’s EDM may actually be larger enough to measure using our current technology.
So finding the electron’s EDM will help narrow down our current theories on the subatomic universe.
The existence of an EDM may also help explain why there is so much matter in the Universe and so little antimatter. If the reason for this apparent imbalance in matter and antimatter is the result of an as-of-yet-undiscovered particle interaction, then the current theories of particle physics predict that there should be a measurable EDM for the electron.
So this explains why this experiment is so important. Now lets explain the experiment.
In a simplified picture, the electron EDM in an applied electric field will either point in the same direction as the field, or in the opposite direction. The energy of an EDM in an electric field depends on the direction of the EDM in relation to the electric field.
This means that the EDMs that align with the electric field will have a different energy than those that align against the field. This difference in energy is proportional to the magnitude of the EDM.
So how does one measure this energy difference? One way is to align the spins perpendicular to the field, which will cause them to precess and you can then measure the precession rate, which is proportional to the energy difference.
This effect can also be described in terms of how the two energy states interfere with one another. This interference between the two states can be measured using an interferometer. If there is an EDM present, then a phase shift should be seen in the interferometer signal. If the applied electric field is reversed, then the phase shift should change sign.
So the authors of the paper went looking for this phase shift. They used molecules of Yttrium Fluoride and fired them at a speed of 590 m/s into an apparatus which has a constant electric and magnetic field.
A radiofrequency pulse is applied which excites the molecules into their respective energy states. They are then allowed to interact for a certain amount of time (a few milliseconds) and it is during this time that the molecules in the different energy states develop a phase difference.
A second radiofrequency pulse is applied and the number of molecules which end up in the lower energy state is measured and is proportional to the phase difference they developed during their interaction time in the electric field.
This phase difference is measured via the applied magnetic field and creates an interference curve.
If the electric field is reversed, then a small phase shift in the interference curve is seen. Remember that the phase shift is proportional to the electron EDM.
So by varying certain parameters like the magnetic field and the frequency of the radiofrequency pulses, the authors were able to extract the numerical of the electron EDM from the data.
Over 25 million pulses of YbF were used to collect this data. Not only that, but many experiments had to be done to determine systematic sources of error in the experimental setup.
Things like fluctuations in the applied magnetic field, electric field plate potentials not being completely symmetric, magnetic fields generated in the magnetic shielding during switching of the electric field are all sources of error which had to be considered.
So after all this work they finally arrived at their calculated value of the EDM for the electron. The value turned out to be de = (-2.4 ± 5.7stat ± 1.5syst) × 10-28 e · cm, where the first error term is from statistical uncertainty and the second is from systematic uncertainty.
Notice that the error on this measurement makes it consistent with zero and consistent with previous work.
However, this measurement is 54 times more precise than
the previous one the author’s previous measurement and puts an upper limit on the EDM of the electron which must be less than 10.5 × 10-28 e · cm.
The next step in these types of experiments is to reduce the uncertainty of the measurements. The authors believe that they should be able to do this using cold molecule techniques and get their measurement down into the 10-29 e · cm range.
Hudson, J., Kara, D., Smallman, I., Sauer, B., Tarbutt, M., & Hinds, E. (2011). Improved measurement of the shape of the electron Nature, 473 (7348), 493-496 DOI: 10.1038/nature10104
Some anti-fog solution he had rubbed onto his visor started to flake off during the spacewalk. Since the anti-fog solution is really just dish soap, it caused a problem because it flaked off into his eye.
If you have ever gotten soap in your eye, you know its terrible, terrible sting.
Aside: I used to put dish soap on my glasses when I played hockey so they wouldn’t fog up. I didn’t realize this was a “space-age” solution.
So poor Drew’s eyes started to water. But because of the lack of gravity, the tears would not fall down, they just sort of hung around on his eyeball.
“Tears in space don’t run down your face,” he said, according to lead spacewalk officer Allison Bollinger
“They actually kind of conglomerate around your eyeball,” Bollinger recounted.
Eventually, he was able to rub his eye on a device inside his helmet to release the fluid from the surface of his eye.
So disaster averted. This indeed sounds like one of the ultimate #firstworldproblems