Magnetic monopoles are hypothetical objects that act like the isolated north or south pole of a magnet. Ordinarily when you break a magnet in half, you end up with two smaller magnets, but some theories predict independent existence for monopoles — though they obviously must be rare in nature, because we haven’t seen one yet.
When detectors fail, sometimes ingenuity can provide another way. As Richard Feynman realized, quantum systems can be used to simulate each other if the structure of their quantum states is the same. A group of researchers used a Bose-Einstein condensate — a collection of very cold atoms that behave like a single quantum system — to emulate the behavior of a magnetic monopole.
Thus, in lieu of hunting for particles that are monopolar, M. W. Ray, E. Ruokokoski, S. Kandel, M. Möttönen, and D. S. Hall emulated the behavior of a north magnetic charge using ultracold atoms. The result was behavior described as a Dirac magnetic monopole, something never before seen. This experiment relied on the quantum character of monopoles and might provide hope that isolated magnetic charges could exist in nature.
Quantum simulations work like simulations run on an analog computer: researchers construct electric circuits that obey the same basic mathematical equations as a more complicated physical phenomenon, which allows them to emulate the complicated system without trying to solve the (possibly unsolvable) equations that describe it. A quantum simulation lets physicists substitute a controllable physical system for one that might be too challenging to ever construct in the lab. [Read more….]
Cartoon showing X-ray laser probing of Rydberg states in argon atoms. [Credit: Adam Kirrander]
I really love how many experiments are beginning to probe to the limits of quantum measurement. I wrote about a pair of cool studies in December that revealed the quantum wavefunction — the mathematical structure governing the behavior of particles. Today, my latest article in Ars Technica examined a proposed experiment using X-ray lasers to study the dynamics of electrons
in argon (and other inert gases) in both space and time.
Rydberg atoms have the electrons in their outer layers excited until the electrons are only weakly bound to the nucleus, making the atoms physically very large. The increased size allows light to scatter off the outermost electrons without much interference from the nucleus or from the inner core of electrons. In other words, it’s a way to isolate the electron dynamics from other messy phenomena. Noble gases like argon are particularly useful for this, since they are largely non-reactive chemically and relatively easy to model theoretically. [Read more….]
Ball lightning is weird: a spherical glowing object that zooms horizontally at a fast rate before vanishing. (I wonder how many UFO sightings are ball lightning.) It’s a rare phenomenon — far more so than ordinary lightning — so nobody had been able to measure its properties with scientific equipment until now. As it happened, a group of scientists in China who were studying regular lightning serendipitously spotted a ball lightning event, and measured its chemical signature. The verdict?
Now, a team of researchers serendipitously observed ball lightning at a time when they had the right equipment to study it. Jianyong Cen, Ping Yuan, and Simin Xue were in the field measuring the properties of ordinary lightning when they happened to catch ball lightning with both their high-speed cameras and their spectrographs. They found the chemical composition of the event matched that of soil. That strongly supports the hypothesis (proposed nearly fifteen years ago) that ball lightning is basically a dirt clod dislodged and heated to incandescence by a cloud-to-ground lightning strike. [Read more…]
Ball lightning and spectrum
Two images of the supernova detected early this morning in M82, the Cigar Galaxy. The bright circle near the image center is the supernova, which you can see more clearly in the negative-color version at the right. [Credit: Ernest Guido, Nick Howes, Martino Nicolini]
Pardon me, I’m a little excited. When I logged onto my computer this morning, I found that every astronomer and astronomy fan was talking about the same thing: a new observation of a probable white dwarf supernova
in M82, also known as the Cigar Galaxy. This is exciting because M82 is practically a neighbor in cosmic terms, a mere 12 million light-years distant. That makes this supernova the closest of its kind in decades (though I’m still trying to sort out which was closer, and when it happened). Suffice to say, the galaxy is close enough that the supernova is sufficiently bright to be visible with relatively small telescopes, and will continue to get brighter over the next few weeks. It’s projected to reach a magnitude of +8, which is bright enough to be seen with binoculars!
Type Ia supernovae are triggered either by the explosion of white dwarfs that accrete too much matter and exceed their maximum stable mass, or by the collision of two white dwarfs. (That’s as opposed to core-collapse supernovae, which are the explosions of stars much more massive than the Sun.) Because they all explode in very similar ways, Type Ia supernovas are “standard candles”: objects that can be used to measure distances to very distant galaxies. The use of them to track the expansion of the Universe was recognized by the 2011 Nobel Prize. [read more…]
What’s cool is that various astronomers, including a number of amateur astronomers, spotted the supernova before it was identified as such. M82 is a popular observing target because it’s distinctive and (yes) not far away. My colleagues at Universe Today and CosmoQuest actually highlighted the galaxy during their Virtual Star Party on Sunday evening, meaning they saw the supernova before we knew what a big deal it was going to be!
GLaDOS, the manipulative computer system from the Portal games. The title of this post is a line from the Aeon article that was cut before publication, but I loved it so much I had to use it anyway. [Credit: Half-Life wiki]
It’s one of those nagging thoughts many of us have had: is our existence a reality or an illusion? Philosophers and scientists have grappled with the question, though today much of the discussion focuses on a related question: do we live in a computer simulation? In my (first hopefully of multiple) essays for Aeon
magazine, I discussed one possible formulation of the question
and how it could be answered — but also why the question may be less scientifically meaningful than many popular accounts would have you believe.
The idea isn’t as crazy as it sounds. A pair of philosophers recently argued that if we accept the eventual complexity of computer hardware, it’s quite probable we’re already part of an ‘ancestor simulation’, a virtual recreation of humanity’s past. Meanwhile, a trio of nuclear physicists has proposed a way to test this hypothesis, based on the notion that every scientific programme makes simplifying assumptions. If we live in a simulation, the thinking goes, we might be able to use experiments to detect these assumptions.
However, both of these perspectives, logical and empirical, leave open the possibility that we could be living in a simulation without being able to tell the difference. [read more….]
Astronomers have identified a filament in the cosmic web
A quasar (the bright circle at the image center) is illuminating a cosmic filament, marked out in blue. [Credit: S. Cantalupo]
, which is the pattern formed by dark matter. That web in turn dictates the distribution of galaxies, since the dark matter attracts ordinary matter — atoms — through its gravity. However, it’s hard to spot the filaments connecting the different halos of dark matter, because they are far less massive and contain less gas than galaxies. The trick in this new study was to spot the faint glow of gas as it was lit up by a quasar: a bright energetic black hole in a nearby galaxy.
Sebastiano Cantapulo and colleagues observed the light emitted by the filament’s gas as it glowed under bombardment from a quasar, a powerful jet of particles propelled from a massive black hole. However, the researchers also found at least ten times more gas than expected from cosmological simulations, which suggests that there may be more gas between galaxies than models predict. [Read more….]
Artist’s conception of the Kuiper belt. [Credit: Don Dixon]
When we talk about big advances in planetary science, we often are thinking about Mars rovers or the discovery of exoplanets. However, one area where we’ve learned a lot over the last few decades is the Kuiper belt: a region beyond the orbit of Neptune inhabited by small bodies of ice and rock. Before 1992, Pluto was the most distant known Solar System object, but between then and now, astronomers have discovered a wealth of Kuiper belt objects (KBOs).
A new paper (coauthored by Mike Brown of Pluto-killing infamy) describes a puzzle arising from a survey of many KBOs: some of them don’t fit in with the standard model of planet formation:
A new study of large scale surveys of KBOs revealed that those with nearly circular orbits lying roughly in the same plane as the orbits of the major planets don’t fit the Nice model, while those with irregular orbits do. It’s a puzzling anomaly, one with no immediate resolution, but it hints that we need to refine our Solar System formation models. [Read more…]