Polites,+Viktor

1/22/11 Could Cell Phone Radiation Damage Our Brains? I found this article very intriguing. Though it does display significant evidence against cell phones causing brain damage, I think the research has been approached from the wrong direction. All evidence either supporting or refuting the hypothesis of cell phones causing brain damage given in this article refer to long term studies on adults. There are too many variables present in a large, long-term study of people to accurately determine if the radiation from cell phones causes brain damage. First, tests should be done in a lab, testing if radiation from cell phones can even penetrate a human skull. If so, then tests should be done to determine if this radiation has any effect on brain cells (neurons) grown in cell culture. This eliminates all variables that might skew the results, and it will be certain that any effect on the brain cells is directly caused by exposure to radiation.

Viktor, Interesting proposal. I suppose one should attempt an in vivo study if you wanted to be sure the test tubes and such aren't variables when subjecting the neurons to radiation. Perhaps a group of volunteers could be brought together. Good post! 5 stars. MW

2/8/11 Redifining the Kilogram One fact from this article that I found very interesting was that the kilogram is the only SI base unit that uses a physical standard. After reading more through the article, and learning that the international standard has lost about 50 ug over time, I realized how important it is that SI base units not rely on a physical standard which is subject to change. I also found the manner in which the kilogram may be redifined. Though I didn't completely understand Planck's constant or Avogadro's constant, I understood that using either one to redifine the kilogram would make the new standard much more accurate than the current standard. The last fact from the article that I found not only interesting but a little humorous was that there is a rivalry between chemists and physicists of what the international standard should be derived from. Physicists say it should be derived from Planck's constant. Chemists say it should be derived from Avogadro's constant. I personally think deriving the kilogram from Planck's constant makes the most sense because deriving the kilogram from Avogadro's constant would make the mass of the kilogram 5.0194515 **×** 10^25 carbon-12 atoms, and the masses of all atoms of the same element vary slightly.

Viktor, Good thought. I think you are right in the sense that it is difficult to separate the isotopes from one another so getting all those carbon-12's together could be tricky. 5 stars. MW

2/25/11 Motion Detectors I found it very interesting that light creates an electric current when it hits certain objects. It is because of the ejection of electrons from objects that light shines on that we can see these objects. Though not mentioned in the article, this makes it more clear to me how solar cells work. Light hits a semi-conductor (most likely silicon), and causes electrons from the silicon to be ejected, creating an electric current. Back to the article, I was fascinated by the observation of Heinrich Hertz who showed that a strong, low-frequency beam of light would cause less electrons to be ejected from an object than a weak, high-frequency beam of light. I was even more intrigued by Einstein's proposal that light behaves like both particles and waves. I had heard of this theory by Einstein a long time ago, and I still don't quite get, but it does help explain Hertz's observation. If a huge number of photons with low energy (high-intensity, low-frequency) hit an object, they won't do much to eject electrons from a material, whereas a smaller number of photons with high energy (low-intensity, high-frequency) hit an object, they'll eject many more electrons from the same material. One question I have is do all forms of electromagnetic radiation (e.g. ultraviolet, visible, and infrared light) behave as both particles and waves?

Viktor, Good post and good question! The answer to your question is yes. It has been shown that all photons and electrons travel in waves - regardless of the energy. 5 stars. MW