Archive for November, 2018

Nov 06 2018

Electron Quantum Metamaterials

Published by under Technology

Material science is, in my opinion, one of the most underappreciated of the sciences. Perhaps because it is so wonky, it doesn’t seem to get much public attention, and yet the development of new materials arguably has the potential to change our civilization more than any other single advance. Our level of technology is largely defined by the materials we have mastered, and discovering a new material is literally a technological game changer.

It’s always hard to predict the next big advance, but there are some intriguing candidates. Interest seems to be clustering around anything on the nano scale – such as carbon nanofibers. Two-dimensional materials that are only one or a few atoms thick (which includes carbon nanofibers) is an area of intense research as well. There is also a relatively new class of materials called metamaterials, which do interesting things with light and other forms of electromagnetic radiation. Metamaterials essentially have emergent properties, and could have potentially exotic applications such as rendering objects invisible in certain frequencies.

A new paper attempts to codify and name one particular type of metamaterial that the authors (Justin C. W. Song & Nathaniel M. Gabor)  are proposing be called “electron quantum metamaterials.”

These types of materials are comprised of two or more layers of two-dimensional nanomaterial that are rotated with respect to each other so that special patterns emerge. This is likened to a moire pattern, where two sets of thin parallel lines are offset from each other by a certain amount and that creates an interference pattern. The interference patterns emerges from the specific relationship between the lines.

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Nov 05 2018

Oumuamua and the Alien Hypothesis

Published by under Astronomy

One year ago, in October 2017, astronomers detected the first confirmed interstellar visitor to our solar system – an asteroid dubbed Oumuamua. The name is Hawaiian for “scout”, as if the asteroid is a messenger from a distant system. A Hawaiian name was chose because the object was discovered by the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii. Determining that Oumuamua was an interstellar object was not difficult – the determination was based on its trajectory. It was traveling really fast, too fast for any object originating from our own system. It’s velocity would also take it out of our system – it was moving too fast to be captured by the gravity of our sun.

All of that is cool enough, but astronomers carefully analysing the trajectory of Oumuamua discovered (and published their findings in June 2018) that its acceleration could not be explained entirely by gravity. Some force was pushing, ever-so-slightly, on the object. This acceleration could be explained by outgassing, if there were any volatiles on Oumuamua that were heating up as it got closer to the sun. These gases would be like tiny rocket engines. Observations of the object did not detect any comet-like tail, which is why it was thought to be an asteroid. But if this new observation were correct, then it would have the ices and gases associated with a comet.

Oumuamua was discovered 40 days after its closest approach to the sun, when it was already on its way out of our solar system. At this point it should have been slowing down a bit from the pull of the sun’s gravity, but instead it was speeding up slightly. This could be explained by outgassing caused by heat from the sun.

This led to a debate about whether or not Oumuamua was an asteroid with a small amount of ice, or a comet that had lost most of its ice. It seems that the object exists in the gray zone between asteroid and comet (and we run into yet another definition demarcation problem). Further, close analysis showed that Oumuamua is very elongated (often described as “cigar-shaped”) and quickly tumbling end-over-end.

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Nov 02 2018

That Rat Cellphone Study – I’m Still Not Impressed

Published by under Skepticism

In May I reported on the preliminary report of an extensive study of cancer incidence in mice and rats exposed to radio-frequencies. Yesterday the researchers released the final report, with essentially the same conclusions. This is prompting another round of the media reporting that a study links cell phone use to cancer – but the data does not show that, and what it does show is still not impressive.

To summarize the results, and the points I made in my previous review of this study – there were actually two studies, one in mice and one in rats. The researchers exposed some of the animals to intermittent (10 minutes on, 10 minutes off) radio frequencies in varying strengths, whole body, from the womb until death. They found a statistically significant increase in some types of brain and heart tumor in male rats only exposed to the radio frequencies, but not in female rats, and not in male or female mice.

Right there, this is a strange result. Why only male rats? If this effect does not even extend to female rats, or to mice, why should we suspect it extends to humans? Further, whenever study results are quirky like this, in my opinion that calls into question the relevance, and even the reality, of the claimed effect. It smacks of random noise.

Another red flag is the large number of comparisons being made in the study. For example, the researchers looked for a particular type of tumor, schwannoma, in various tissues. They found a statistically significant increase in the heart, but not in other tissues, and not when you look at all schwannomas – only when you consider the heart separately. This looks suspicious for not controlling for multiple comparisons. You have to make a statistical adjustment for doing so, and I see no mention that they did.

Further, the absolute numbers are fairly low, with affected rats all being in the single digits. This makes subtle confounding effects and also random quirky effects more likely.

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Nov 01 2018

Learning from Video

Is putting your toddler in front of an educational video harmful or helpful? This is an important question for many parents, especially in homes where both parents work and taking care of young children can be hectic. Putting a child in front of a video is the closest things parents have to an off switch for their kids, so it can be very tempting to rely upon the distraction of an iPad or TV to keep their attention while you make dinner or attend to some other task.

There is also a cottage industry of videos marketed to parents with very young children. Some are clearly nothing more than an entertaining distraction, like videos of other children playing with toys (which are incredibly popular). But parents can also be sold on the idea that their children are learning while being distracted, thereby alleviating any guilt from relying on the video-nanny.

There has therefore been increasing research into the effectiveness of video learning for very young children (and older children and adults, but we’ll focus on young children for now).  Here is a recent study of this topic which includes a great overview of prior research.

Previous research has mostly shown that young children do not respond to video the same way they respond to a live person. Exposing toddlers to their native language or a foreign language through a video or just audio seems to have no benefit, compared to the identical content presented through a live person. The probable reason for this is that we are programmed from birth to be extremely social, and young children typically will pay great attention to other people – more than anything else. A video of a person, unfortunately, just doesn’t cut it.

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