Got Fireflies? Try Talking To Them With A Green LED

August 6, 2023 by Donald Papp 25 Comments

[ChrisMentrek] shares a design for a simple green LED signal light intended for experiments in “talking” to fireflies. The device uses simple components like PVC piping and connectors to make something that resembles a signal flashlight with a momentary switch — a device simple enough to make in time for a little weekend experimenting.

Observe and repeat flashing patterns, and see if any fireflies get curious enough to investigate.

Did you know that fireflies, a type of beetle whose lower abdomen can light up thanks to a chemical reaction, flash in patterns? Many creatures, fireflies included, are quite curious under the right circumstances. The idea is to observe some fireflies and attempt to flash the same patterns (or different ones!) with a green LED to see if any come and investigate.

[ChrisMentrek] recommends using a green LED that outputs 565 nm, because that is very close to the colors emitted by most fireflies in North America. There’s also a handy link about firefly flashing patterns from the Massachusetts Audubon society’s Firefly Watch program, which is a great resource for budding scientists.

If staying up and learning more about nocturnal nightlife is your thing, then in between trying to talk to fireflies we recommend listening for bats as another fun activity, although it requires a bit more than just a green LED. Intrigued? Good news, because we can tell you all about the different kinds of bat detectors and what you can expect from them.

LK-99: Diamagnetc Semiconductor, Not Superconductor?

August 5, 2023 by Jenny List 70 Comments

Every so often, along comes a story which, like [Fox Mulder] with his unexplained phenomena, we want to believe. EM drives and cold fusion for example would be the coolest of the cool if they worked, but sadly they crumbled when subjected to scientific inquiry outside the labs of their originators. The jury’s still out on the latest example, a claimed room-temperature superconductor, but it’s starting to seem that it might instead be a diamagnetic semiconductor.

We covered some of the story surrounding the announcement of LK-99 and subsequent reports of it levitating under magnetic fields, but today’s installment comes courtesy of a team from Beihang University in Beijing. They’ve published a paper in which they characterize their sample of LK-99, and sadly according to them it’s no superconductor.

Instead it’s a diamagnetic semiconductor, something that in itself probably bears some explanation. We’re guessing most readers will be familiar with semiconductors, but diamagnetic substances possess the property of having an external magnetic field induce an internal magnetic field in the opposite direction. This means that they will levitate in a magnetic field, but not due to the Meissner effect, the property of superconductors which causes magnetic field to flow round their outside. The Beijing team have shown by measuring the resistance of the sample that it’s not a superconductor.

So sadly it seems LK-99 isn’t the miracle it was billed as, unless there’s some special quirk in the production of the original Korean sample which didn’t make it to the other teams. We can’t help wondering why a sample from Korea wasn’t subjected to external evaluation rather than leaving the other teams to make their own. Never mind, eh!

Stack of Si3N4-LiNbO3 forming the integrated laser and integrated into test setup (d). (Credit: Snigirev et al., 2023)

Fast Adjustable Lasers Using Lithium Niobate Integrated Photonics

August 4, 2023 by Maya Posch 14 Comments

Making lasers smaller and more capable of rapidly alternating between frequencies, while remaining within a narrow band, is an essential part of bringing down the cost of technologies such as LiDAR and optical communication. Much of the challenge here lies understandably in finding the right materials that enable a laser which incorporates all of these properties.

A heterogeneous Si3N4–LiNbO3 chip as used in the study. (Credit: Snigirev et al., 2023)

Here a recent study by [Viacheslav Snigirev] and colleagues (press release) demonstrates how combining the properties of lithium niobate (LiNbO₃) with those of silicon nitride (Si₃N₄) into a hybrid (Si₃N₄)–LiNbO₃ wafer stack allows for an InP-based laser source to be modulated in the etched photonic circuitry to achieve the desired output properties.

Much of the modulation stability is achieved through laser self-injection locking via the microresonator structures on the hybrid chip. These provide optical back reflection that forces the laser diode to resonate at a specific frequency, providing the frequency lock. What enables the fast frequency tuning is that this is determined by the applied voltage on the microresonator structure via the formed electrodes.

With a LiDAR demonstration in the paper that uses one of these hybrid circuits it is demonstrated that the direct wafer bonding approach works well, and a number of optimization suggestions are provided. As with all of these studies, they build upon years of previous research as problems are found and solutions suggested and tested. It would seem that thin-film LiNbO₃ structures are now finding some very useful applications in photonics.

(Heading image: Stack of Si₃N₄-LiNbO₃ forming the integrated laser and integrated into test setup (d). (Credit: Snigirev et al., 2023) )

Accelerating Electrons To TeV Levels Using Curved Laser Beams

August 1, 2023 by Maya Posch 12 Comments

There are many applications for particle accelerators, even outside research facilities, but for the longest time they have been large, cumbersome machines, not to mention very expensive to operate. Here laser wakefield accelerators (LWFAs) are a promising alternative, which uses lasers to create accelerated particles along the wake in a plasma field. One of the major struggles has been with reinjecting the thus accelerated particles into another stage of a multi-stage accelerator, which would be required to obtain energies closer to one TeV. In this area researchers have now demonstrated a way around this, by using curved channels for the laser beams (paywalled paper) which inject the laser beam into the continuous cavity. Continue reading “Accelerating Electrons To TeV Levels Using Curved Laser Beams” →

“Room Temperature Superconductor” LK-99, Just Maybe It Could Be Real

August 1, 2023 by Jenny List 66 Comments

To have been alive over the last five decades is to have seen superconductors progress from only possible at near-absolute-zero temperatures, to around the temperature of liquid nitrogen in the 1980s and ’90s, and inching slowly higher as ever more exotic substances are made and subjected to demanding conditions. Now there’s a new kid on the block with an astounding claim of room-temperature and pressure superconductivity, something that has been a Holy Grail for physicists over many years.

LK-99 is a lead-copper-phosphate compound developed by a team from Korea University in Seoul. Its announcement was met with skepticism from the scientific community and the first attempts to replicate it proved unsuccessful, but now a team at Huazhong University of Science and Technology in China claim to have also made LK-99 samples that levitate under a magnetic field at room temperature and pressure. This is corroborated by simulation studies that back up the Korean assertions about the crystal structure of LK-99, so maybe, just maybe, room temperature and pressure superconductors might at last be with us.

Floating on a magnetic field is cool as anything, but what are the benefits of such a material? By removing electrical resistance and noise from the equation they hold the promise of lossless power generation and conversion along with higher-performance electronics both analogue and digital, which would revolutionize what we have come to expect from electronics. Of course we’re excited about them and we think you should be too, but perhaps we’ll wait for more labs to verify LK-99 before we celebrate too much. After all, if it proves over-optimistic, it wouldn’t be the first time.

Location of the Duvanny Yar outcrop on the Kolyma River, northeastern Siberia. (Credit: Anastasia Shatilovich et al., 2023)

Nematodes From The Siberian Permafrost Woke Up After A 46,000 Year Long Nap

July 31, 2023 by Maya Posch 25 Comments

The general consensus among us mammals is that if we get very cold, we die. Within the world of nematodes, however, they’d like to differ on that viewpoint. This is demonstrated succinctly after researchers coaxed a batch of these worms back into action after they had been frozen in Siberian permafrost for an estimated 46,000 years. The mechanism underlying this phenomenon is called cryptobiosis, which is essentially a metabolic state that certain lifeforms can enter when environmental conditions become unsuitable.

In the case of nematodes, they hold a number of records, with a group of them having survived the STS-107 Space Shuttle Columbia in 2003 when it broke up during reentry, making it the first known lifeform to have achieved such a feat. During arctic experiments it was found that these roundworms can withstand intracellular freezing even while active depending on its diet. Continue reading “Nematodes From The Siberian Permafrost Woke Up After A 46,000 Year Long Nap” →

Timeline of the universe. A representation of the evolution of the universe over 13.77 billion years. The far left depicts the earliest moment we can now probe, when a period of "inflation" produced a burst of exponential growth in the universe. (Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe. The afterglow light seen by WMAP was emitted about 375,000 years after inflation and has traversed the universe largely unimpeded since then. The conditions of earlier times are imprinted on this light; it also forms a backlight for later developments of the universe. (Credit: NASA)

ESA’s Euclid Space Telescope And The Quest For Dark Energy

July 31, 2023 by Maya Posch 30 Comments

Most of what humankind and other mammalian species on Earth experience of the Universe is primarily restricted to the part of the electromagnetic spectrum which our optical organs can register. Despite these limitations, we have found ways over the centuries which enable us to perceive the rest of the EM spectrum, to see both what is incredibly far away, and what is incredibly small, to constantly get a little bit closer to understanding what makes the Universe into what we can observe today, and what it may look like in the future.

An essential element of this effort are space telescopes, which gaze into the depths of the Universe with no limitations imposed by the Earth’s atmosphere, or human activity. Among the many uses of space telescopes, the investigation of the expansion of the Universe is perhaps the most fascinating, as this brings us ever closer to the answers to the most fundamental questions about not only its shape, but also to its future, which may include hitherto unknown types of matter and energy.

With the recently launched Euclid space telescope, another chapter is being opened in the saga on dark energy and matter, and their nature and effects on the Universe, as well as whether they exist at all. Yet how exactly do you use a space telescope to ferret out the potential effects of dark energy?

Continue reading “ESA’s Euclid Space Telescope And The Quest For Dark Energy” →