All That Matters

Photo by piglicker via flickr.

I don’t have much time this week and next to blog, but yesterday Science published an interesting paper by Hui Cao and colleagues at Yale that is hard to ignore. It is the ‘anti-laser’.

In short, this anti-laser does exactly the same what a laser does, just with time reversed. You can do that because the physics involved in the laser doesn’t change when you reverse the time. It is as if you play a laser backwards.

A laser requires at least two energy states that are placed between two mirrors. An electron in an upper energy state relaxes to the lower one and emits light. If the electrons are continuously pumped into the upper state, the light that bounces between the mirrors becomes increasingly intensive and at some point lasing kicks in. One of the two mirrors is semi-transparent, so the laser light can get out of the device.

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Credit: Yushin Kim, Korea Advanced Institute of Science and Technology

How does a lens work? Well, as the light arrives at the lens it gets bent towards the focal point of the lens. The denser the lens material is in comparison to the surrounding air, the more it is deflected. The materials property that quantifies this effect is the refractive index.

For lenses, the general rule is that a larger refractive index is better. That’s because the maximum resolution of a lens gets better as the refractive index increases. This is of crucial importance for applications where resolution matters, for example in the fabrication of semiconductor transistors, says Xiang Zhang, a physicist from the University of California in Berkeley. “A large index is very useful for high-resolution imaging and lithography. That’s what the billion dollar semiconductor industry critically needs and have investigated in heavily.”Typically, the refractive index varies anywhere between 1 (air) and 3. That of window glass is about 1.5.

Bumki Min from the Korea Advanced Institute of Science and Technology (KAIST) along with colleagues from other institutions now have demonstrated an artificial material whose refractive index is a staggering 38.6. Their paper is published in this week’s issue of Nature.

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Photo by UncaughtException via flickr.

This week Science magazine has an interesting special issue on scientific data, covering a variety of topics from data backup and data visualization to open data. It seems these contributions are free to access for registered user of their web site, and it certainly is worthwhile to have a look.

The editorial in particular lays out Science’s policy on open data. Sharing scientific results is of course a motivation for publishing a paper in the first place. And to allow for independent verification of scientific results, the data contained in a publication has to be available and shared with other scientists. This sharing has to be done in a permanent way that guarantees access to archives also in future.

Is the data analysis traceable?

However, there is another point that hasn’t come across that strong from this special issue, but one that I also consider to be very important. And that is that data processing itself needs to be tracked, by which I mean the steps from the raw scientific data as measured all the way to the plots in a scientific paper need to be traceable. […]