Author: Chris Lee

Most of you have probably heard of arXiv.org by now. Basically, every paper I report on is probably on the arXiv in some form. The site hosts draft manuscripts in physics and astronomy. Many of them eventually appear in academic journals, although others will spend their entire existence in the arXiv.

Five years ago, I assumed that every field had its own equivalent of arXiv. So imagine my surprise when I tried to upload my first chemistry paper to the chemistry equivalent. Apparently, there was one—but publisher Elsevier eventually gained control of it and began requiring registration. The site is probably a wasteland by now.

Until recently, biology hadn't even managed to create anything that Elsevier would want to acquire. But now, biologists are finally getting on the pre-print train with a bioRXiv.

Battery research is a fraught area to report on. In the lab, researchers manage to show something spectacular, like high current density or excellent recharge characteristics. But the part where the battery catches fire and destroys the lab is left out when the story makes the popular press. I am guilty of this myself, and I'm about to do it again. (Not really.)

Lithium-oxygen batteries are very promising, but most current iterations manage to destroy themselves after a few charge/discharge cycles. A recent publication in the Journal of the American Chemical Society shows some progress in overcoming the problems associated with lithium-oxygen batteries.

Why lithium-oxygen?

We all love our lithium ion batteries. Even though they are the best that we have, they still suck pretty hard. To put it in perspective, lithium ion batteries top out at about 200mAh/g, so you need a very heavy battery to get much energy. Lithium-oxygen, on the other hand, promises 1675mAh/g, a very respectable energy density.

It was 11am on Christmas Day, and the sounds drifting across the table were anything but melodic: "Sit on my face and tell me that you love me..."

My two eldest started laughing. Donna, my wife, went bright red. I may have been slightly drunk. It is possible that I chose the song for maximum embarrassment. But it was absolutely true that I wanted those two extra cards.

And that, ladies and gentleman is the joy of Monty Python-themed Fluxx. Fluxx is a game that is nearly 20 years old, so for those of you who follow card and board game news, this will be nothing new. For those of you who don't, this is your chance to nearly enter the 21st century.

We have been following D-Wave's claims about its quantum hardware at Ars for a number of years. Over that time, my impression has oscillated between skepticism, strong skepticism, and mild enthusiasm.

Back in November, D-Wave issued a press release that basically asked tech journalists to spray paint a finish line just behind their feet and break out a victory flag. It seemed a bit much. But now that D-Wave has declared victory, perhaps it's time to re-examine the skepticism. What exactly has D-Wave achieved, and does it constitute victory? Either way, where are the company's efforts focused now?

Of course the best way to judge D-Wave is not by its press releases nor by the specifications and benchmarks glued on the boxes of its processors—these should be treated with utmost paranoid suspicion. Instead, it's better to look at what researchers who have access to D-Wave hardware are claiming in publications. And despite my suspicions, the paper accompanying that last press release—plus a couple of other papers on the arXiV that were released earlier—is interesting. All together, they paint a picture that says we should finally be cautiously optimistic about D-Wave's progress.

One of the problems with much of science is that it is often a quasi-sedentary profession. Apart from those lucky few who have to trek through muddy fields in Vietnam or scale icy cliffs in Antarctica, the rest of us mostly took the job because it was indoors and required no heavy lifting.

That said, scientists get a lot of exercise. Usually, this involves energetically jumping to conclusions—there is nothing quite like seeing two data points, fitting a straight line and yelling, “We understand this COMPLETELY.”

The newest craze among the more energetic set is aquatic: shark jumping. Science is undergoing a cultural change at the moment, thanks to the Open Science movement, an idea that I am broadly supportive of. But some of the latest goals and statements seem a little… unrealistic to me.

If I seem a little obsessed with dark matter at the moment, it's only because there is so much interesting stuff going on right now. But I can give it up any time—really! As I reported last month, there has been a lot of excitement among astrophysicists and cosmologists because there seems to be more gamma rays than expected coming from various places, including near the center of the Milky Way and other galaxies. Unfortunately, as I also reported, it seems very difficult to absolutely rule out other possible sources for these extra gamma rays. In particular, there is the problem of unresolved sources. These could be gas clouds or other emitters that we simply haven't spotted in other observations.

The obvious solution is to simply keep looking, using other telescopes that look at the sky at other parts of the electromagnetic spectrum to rule out each and every possible source. Some new research tells us how the gamma ray signal may hold much of the evidence already, however. We just need to look closely.

Watching matter move

The idea comes down to how matter moves. The fact that dark matter doesn't really do anything but suck, gravitationally speaking, means that it doesn't really follow the cool kids around, either. When ordinary matter gets close to another bit of ordinary matter, it says hello. It does the equivalent of standing in the middle of the supermarket aisle having a long conversation about the health and happiness of both parties' electrons. Along with gravity, this meeting doesn't just cause matter to clump together, it also causes it to move together. So in our spiral galaxy, it isn't just the stars that rotate around a common center of mass. All the ordinary matter rotates around that common center of mass, too.

Every year, the Dutch physics community gets together to celebrate the year in physics. These are some highlights from the meeting. Since it is a meeting, it is not possible to link to published work (a talk could cover multiple papers or just parts of papers). Where possible, we've linked to the research group that presented the work.

It seems that this is the year that black hole physics is making a splash—in addition to dark matter, black hole talks seemed to be everywhere at the FOM conference. Appropriately enough, I was sucked right in to these talks. It seems that since Erik Verlinde confused us all five years ago, a lot of progress has been made. In particular, it feels as if the presenters are far more confident about what they can do with the tricks they've been developing.

One sign of the progress is that the session titled "The quantum information nature of spacetime" gave me a feeling other than overwhelming confusion. The entire session was focused on the quantum nature of black holes and how the conflict between general relativity and quantum mechanics was highlighted by black holes. This is not because of the singularity at the center of the black hole but because of what happens at the event horizon.

Every year, the Dutch physics community gets together to celebrate the year in physics. These are some highlights from the meeting. Since it is a meeting, it is not possible to link to published work (a talk could cover multiple papers, or just parts of papers). Where possible, we've linked to the research group that presented the work.

I remember, maybe 12 years ago, attending a talk by an environmental activist who discussed clean and sustainable energy and the difficulties in obtaining it. She was not your average activist—she had, as I recall, qualifications in chemical engineering.

One thing she mentioned in passing (and I may not have remembered this accurately) was that when fresh water flows into salt water, the process of salination releases a relatively large amount of energy, but that no one knew how to harvest it effectively.

Every year, the Dutch physics community gets together to celebrate the year in physics. These are some highlights from the meeting. Since it is a meeting, it is not possible to link to published work (a talk could cover multiple papers or just parts of papers). Where possible, we've linked to the research group that presented the work.

The flow of pedestrians is a critical part of the design of buildings, stadiums, and much more. The obvious reason is that designers need to ensure that people can exit the building quickly in case of a disaster, but it goes much further than that. Are people significantly impeded during normal use? Where will people congregate and will this obstruct access to various parts of the building? All of this and more must go in to the building design.

Most pedestrian models are reasonably simple. Pedestrians are particles that are driven by some force to go in a direction; they don’t collide with each other because there is a repulsive force between them keeping them apart. At their most simple, the models can treat pedestrians as a hard sphere—the pedestrians touch and bounce off each other like billiard balls. However, you can use any number of different physical models to study pedestrian interactions.

Every year, the Dutch physics community gets together to celebrate the year in physics. These are some highlights from the meeting. Since it is a meeting, it is not possible to link to published work (a talk could cover multiple papers, or just parts of papers). Where possible, We've linked to the research group that presented the work.

This year, the search for dark matter seems to be dominating the minds of a lot of physicists. It is quite an intriguing issue. We have lots of gravitational evidence for dark matter at length scales from single galaxies to galaxy clusters—and even the cosmic microwave background. The variety of evidence is such that it is difficult to imagine a suitable modification to the laws of gravitation that would satisfy all these constraints.

Yet, actual dark matter remains elusive. I’ll discuss some details in a moment, but my take home from the dark matter talks is that, if it can be detected at all, then we should see it relatively soon.