[A]fter much debate among the Physics World editorial team, this year’s honour goes to Aephraim Steinberg and colleagues from the University of Toronto in Canada for their experimental work on the fundamentals of quantum mechanics. Using an emerging technique called “weak measurement”, the team is the first to track the average paths of single photons passing through a Young’s double-slit experiment – something that Steinberg says physicists had been “brainwashed” into thinking is impossible.
Nugent says, “We caught the supernova just 11 hours after it exploded, so soon that we were later able to calculate the actual moment of the explosion to within 20 minutes. Our early observations confirmed some assumptions about the physics of Type Ia supernovae, and we ruled out a number of possible models. But with this close-up look, we also found things nobody had dreamed of.”
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“The early-time light curve also constrained the radius of the binary system,” says Nugent, “so we got rid of a whole bunch of models,” ranging from old red giant stars to other white dwarfs in a so-called “double-degenerate” system.
This is what it’s all about: getting data to refine your models.
We have built an imaging solution that allows us to visualize propagation of light. The effective exposure time of each frame is two trillionth of a second and the resultant visualization depicts the movement of light at roughly half a trillion frames per second. Direct recording of reflected or scattered light at such a frame rate with sufficient brightness is nearly impossible. We use an indirect ‘stroboscopic’ method that records millions of repeated measurements by careful scanning in time and viewpoints. Then we rearrange the data to create a ‘movie’ of a nano-second long event.
Unfortunately, there’s also this video (or, more specifically, the first few seconds of this video), which I saw before finding their site.
We have built a virtual slow-motion camera where we can see photons, or light particles, moving through space.
Prof. Raskar has whipped out (and abused) his poetic license: you cannot literally see photons moving through space. You only know light is there if it scatters into your sensor — if it is light that simply goes by you/it, you would never know it’s there. If you shine a laser out into space, you don’t see that light — you only see light that scatters back to you. Unfortunately, by leading off with that sound bite, I fear everybody who sees the video is going to be repeating that line: OMG, we can see actual photons moving through space!
What they have recreated is a way to visualize the photons or a wavefront moving through space. Which is no small feat and is very cool.
And I just saw that Rhett has a post up about this, with some details of how it works, and is also repulsed by the sound-bite. I don’t have a huge problem with the trillion fps claim, because they are pretty clear that this is a virtual, post-processed effect, where you are sort of combining strobe and stop-action to give you the result, with the caveat that the stop-action is static — this generally wouldn’t work if anything were moving.
[T]he Atwater Convention has two big flaws. First, it pays no attention to the extent to which food has been processed. For example, it treats grain as the same calorie value whether it is eaten whole or as highly milled flour. But smaller particles are less work to digest, and therefore provide more net energy. Second, it treats foods as equally digestible (meaning, having the same proportion digested) regardless of processing. But cooked foods, as we’ve seen, are more digestible than raw foods.
In addition to precise temperature control, the ripening process also depends on atmospheric design. Over a 24-hour period, each roomful of bananas is gassed with ethylene, a plant hormone that accelerates ripening (and is also, curiously, the most produced organic compound in the world).
I learned about the role of ethylene a few years back, after wanting to ripen some bananas quickly and being told that putting them in a paper bag would do the trick. I did a test with one banana in the bag and one outside as a control, and the one in the bag did indeed ripen faster. And the internet told me that it was the ethylene that did the ripening, which is why “one bad apple ruins the lot” — as fruit like bananas and apples ripen, they give off ethylene, and that accelerates through the process, so one ripe piece cause the others to ripen pretty quickly. The paper bag concentrates the gas relative to it being out in the open and causes more ripening. Curiously, a plastic bag did not work — this could be because humidity inhibits ripening, and it’s possible the permeability of the paper bag allows water vapor to escape but still retain some ethylene to do its magic chemistry.
So allow me to just say ahead of time that I apologize if this post breaks anyone’s computer. I’m not a web-savvy dude (note the use of Posterous instead of WordPress) so I’m not sure what nightmares could potentially be created by posting a 500 x 284,049 pixel image on the web.
In his job, Matsakis keeps the official time for the United States and the U.S. Department of Defense and, together with the National Institute of Standards and Technology, keeps the official time for the United States. This involves maintaining more than 100 atomic clocks and GPS systems calibrated to within one nanosecond of each other – not a simple task.
We had a nice seminar on what MINOS does and neutrino oscillations recently, as we kicked off this collaboration.
