UBC Connects with Donna Strickland: Laser Focus: Insight from a Nobel Laureate

[@timanon1368]

Let's see if Univ of BC shadow bans just like WIRED does. Here's what I wrote in response to Dr. Strickland's WIRED piece on lasers. Yeah, I'm critical because her presentation had a LOT of problems. Level 1: Too stupid to warn the laser neophyte not to look into a laser. In fact, Donna encourages her to look at a supermarket laser. Dumb. Level 2: Says: "light shines back and forth between 2 mirrors until it comes out". Huh? If it's reflecting back and forth, how does it come out? Hand-waving. Also the different sizes of paper have the opposite effect that she wants because the smaller papers contains less mass, but for the laser, the focused light retains the same amount of energy, but is just more concentrated. What did he learn? "Lasers are not like particles". Oops! Wrong conclusion. "[they] just move electrons out of the way?" Hello particle nature! Level 3: The experimentalist that she is says "I like to see the things happening" as she talks about knocking electrons out of atoms....Her description of "shirt pulses" is really muddled. The way that she uses the multicolored spring is confusing and conflates several ideas. Use a prism to explain dispersion (because Bragg diffraction is way too complicated). Use a spring to talk about waves. She really should have found a way to accurately depict a pulse. And then, she waits until the end to explain that we always think about lasers as being perfectly monochromatic, but her work is multichromatic. She doesn't really explain how she creates this other than by talking about dispersion. Dispersion in what? Is that how you make the multiple colors? Totally opaque explanation at this level. Level 4: Why is 10^29th (units often dropped) the Holy Grail? And what did she say? She doesn't know about medical applications for lasers? Really? Level 5: Ah, 10^29th Watts/sq. cm (units now, good), Schwinger Limit. What is the Schwinger Limit? They don't explain it. It's a really profound concept. Her partner gives a cool, "ooh, ah" explaining why he is using electron beams to change the rest frame to boost the collisions. But, hey, isn't the whole point of Special Relativity that the speed of light is the same in all reference frames? So what is he doing? E=hbar*omega. So he is relatively compressing the wavelength to effectively increase the relative frequency [from the electron's point of reference] and thus upping the apparent energy. But energy is always conserved, so the apparent increase in energy is from the speed of the electron, which from it's own frame of reference can be thought of at rest. Kinda mind-boggling. Ain't relativity cool? Not to mention that light is massless, so how can a massless thing knock out electrons from atoms? I'm still not sure after all of that that I know how Chirp lasers work. I'd call this explanation a fail on all wavelengths. Clearly, there are those who can do, those who can teach, and a rare few who can do and teach. She is not one of the latter.