Sunday, June 26, 2011
It's been six years since I last went to the Paris Airshow, so when France24 announced on Twitter that they were giving tickets in exchange for tweets, I was in like flynn. And so it was on a sunny Friday morning I find myself on the RER B heading out to Le Bourget. Not too crowded, but still there was a 45 minute wait for the free shuttle to the airport.....I remembered it as not being too far a walk and arrived at the entrance in about 20 minutes. After checking in on Foursquare (of course) I pull out my camera and away we go. First stop: Ariane 5, dominating the Le Bourget skyline. I took a couple of snaps of the engines for old times sake (I have tons from previous visits, but why not?). Then off to see the Americans. A little light this year - no Navy or Army aircraft, but the Air force F15E, F16, C130, C5, C17 and Marine Corps AH1Z and UH1Y still made for nice viewing. I had an interesting talk with a Marine Corps mechanic who told me that the AH1Z is brand new; declared combat-ready only in September 2010 and hasn't yet been on the ground. Interestingly, both the AH1Z and UH1Y share 84% of the same components making maintenance a lot easier. The mechanic also said (in true jarhead style) that the Army's AH-64 Apaches have a big problem with launching Sidewinders but, ahem, the Marine Corps AH1Z has no such issues.....Semper Fi :)
I dropped in to the ESA exhibit before the flight demos and saw a presentation on the joint ESA-NASA Cassini-Huygens mission (incidentally, it's still ongoing, click here for more info). The speaker paraphrased Carl Sagan's Pale Blue Dot when talking about this photo of Earth through the rings of Saturn ; The video on the Huygens probe landing on Titan was wonderful.
And after spending what seemed like an hour trying to get a sandwich at the Paul stand (more like 15 minutes, but still) it's flight time!!
I can't hep but let slip a big goofy grin when I hear screaming jet engines and see full afterburners flaming......yep: military high performance jets. In the air today was the Dassult Rafale, the Eurofighter Typhoon and the Lockheed Martin F16. Even after seeing lots of this, I'm still blown away when I see 30-40 tonnes of metal flitting around the sky like a bat.....awesome.
The French Air Force display team, La Patrouille de France, put on a beautiful display, as alway.
There was an interesting demo by a Russian Altair amphibious aircraft configured as a firefighter - pretty cool to see it dumping twelve tonnes of water in two seconds!
And then there's the A380 - the biggest commercial airliner in service today. I saw its first public display flight here 6 years ago and it's still a wonder to watch in the air....just goes to show that airliners can put up with a LOT more than their daily grind. It's simply amazing to see it float around like a bubble in the small airspace available above Le Bourget for displays, a testament to both the engineering skills required to build it and the skills of the display pilots.
All in all: I took a truckload of photos (some of which can be viewed here), got a dose of howling jet engines and a little sunburned - a great day :)
Friday, June 3, 2011
How do we know this? (Bear with me here, we'll get to cellphones shortly!) Albert Einstein won a Nobel Prize for discovering the Photoelectric Effect which, essentially, says that light above a certain frequency falling on a metal induces a current. This happens because the energy in the light's photons is sufficient to cause electrons in the metal to move. He showed that red light won't induce a current, but blue light will. Max Planck later found a relationship between the frequency of light and the energy of its photons. As we can see above, red light has a frequency of 700nm (7*10^ -7m), blue light 400nm (4*10^ -7m). It's clear from Planck's discovery that blue light is more energetic than red.
Now, back to cellphones. Where does this radiation figure on the spectrum? Look at where red light is on the spectrum. Go below it, you find Infra-red, then below it again you find the microwave region, a range of wavelengths from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz. Cellphones typically operate in the low end of the microwave region, overlapping with the high end of UHF radio frequencies, usually below 2Ghz. Obviously, this is well below the level of ionising radiation, which is beyond the UV region of the spectrum, in x-ray and gamma-ray territory. It can't be carcinogenic.