May 2021 has been quite a happening month in the scientific community. The month witnessed some amazing discoveries in particle physics, quantum mechanics, computational physics, astronomy, and astrophysics. Here are some of the top scientific achievements of the previous month. For your reference, the links to research papers have been provided.

Measuring the expanding universe

Recently, researchers have developed a new technique for measuring the rate of expansion of our universe. This method works by looking at the explosions of light and ripples in the fabric of space caused by a collision between a black hole and a neutron star. A neutron star is a dead star having a core composed of neutrons. While on the other hand, black holes are the most massive objects known in the observable universe. A collision between a neutron star and a black hole is undoubtedly a cataclysmic event that treats spacetime with powerful ripples known as gravitational waves.

To calculate the Universe’s rate of expansion, a graph is plotted showing the variation of an object’s recessional velocity with its distance from us. The slope of this graph, also known as the Hubble constant, finally gives the rate at which the universe is expanding.

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An artist’s illustration showing a key part of the process that created this new black hole, as the two neutron stars spin around each other while merging. Image: NASA / CXC / M.Weiss.

The farther an object is moving, the greater its spectrum is redshifted. The recessional velocity of an object can easily be calculated by looking at its redshift. At the same time, an analysis of the gravitational waves would pinpoint the galaxy where the collision has occurred,  thereby providing the distance.

By combining both parameters, the rate of expansion can be estimated. At present, gravitational waves are detected by interferometric facilities at LIGO and Virgo. Researchers simulated around 25,000 scenarios of black holes and neutron stars collision and found that, by 2030, instruments on Earth would be strong enough to sense ripples in space-time caused by up to 3,000 such collisions.

They even claimed that for around 100 of these events, telescopes would also see accompanying explosions of light. Although no such event of a collision between a black hole and neutron star has been detected so far, the constant technological advancements are expected to open up a new era for astrophysics in the future.

Quantum entanglement observed at macroscopic scales

In a recent experiment, scientists have brought the scale at which we can observe quantum effects into the macroscopic realm by banging on two sets of tiny drums. In other words, scientists have observed the phenomenon of entanglement at macroscopic scales for the first time. If two particles are entangled, then they share a unique connection between them. Suppose you take two entangled particles and perform measurements on one particle, then the other particle’s results automatically become known to you, thanks to their entangled nature.

It’s just that you make a change to one particle and your actions magically teleport a corresponding change to its entangled partner and all of this communication between the two partners occurs at speeds faster than the speed of light.

So far, this spooky action at a distance was only known to exist at quantum scales, specifically for individual atoms and elementary particles. But in a surprising revelation, researchers at NIST have observed it between micron-sized aluminum membranes or “drums,” made of roughly 1 trillion atoms each, and this doesn’t belong to the so-called quantum world at all!

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Researchers entangled the beats of these minuscule, drum-like aluminum membranes and precisely measured their interlinked quantum properties. Systems such as these could someday help perform computations and transmit data in quantum networks. Credit: Teufel and NIST

In the experiment, tiny drums, each around 10 micrometers long, were placed on a crystal chip and supercooled to near absolute zero. The cryogenic temperatures reduced the possibility of the drums’ interaction with the external world. Eventually, the chilled drums were vibrated by hitting them with regular pulses of microwaves.

Surprisingly, the drums appeared to be vibrating in a highly synchronized way. When one drum had a high amplitude, the other had a low amplitude. Moreover, their velocities had exactly opposite values. In simple words, the random motion of one drum appeared to be highly correlated with the other.

And this is similar to what happens in quantum entanglement! Researchers hope that their entangled drums will be sensitive enough to untangle the mysterious associate with gravitational waves and dark matter, along with providing a boost in quantum communication. This has clearly opened up a whole new range of possibilities for measurements to be made at the tiniest scales.

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Parker detects eerie emissions from Venus

For the first time in the last 30 years, the first direct measurement of the Venusian atmosphere was made by NASA’S Parker solar probe. While being closest to the hellish world for just seven minutes, FIELDS detected a natural, low-frequency radio signal emanating from Venus’ atmosphere.

The researchers further used this radio emission to calculate the ionosphere density that Parker Solar Probe flew through. The planet’s ionosphere was much thinner than previous measurements taken during solar maximum in 1992 by the Pioneer Venus Orbiter. The results reported by Parker support the theory that the ionosphere of Venus varies substantially over the 11-year solar cycle.

Signs of antistars

Since its introduction in the first half of the twentieth century, antimatter has occupied a center stage for research in particle physics. It is believed that at the time of the big bang, matter and antimatter were created equally. However, all the efforts to observe antimatter in large amounts have terrible failed. As per some theories, the normal matter particles somehow outnumbered the antiparticles by some mysterious process. The remaining antiparticles were annihilated after interacting with normal matter particles, and that’s why we have not been able to observe any antiparticles around us.

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However, the AMS particle detector onboard the International Space Station recorded something weird in 2018. It unexpectedly detected eight anti helium nuclei, amongst which six were compatible with being antihelium-3 and two with antihelium-4.

Scientists stated that if antihelium-4 were detected coming from space, then it would definitely have to come from the fusion process inside an anti-star. However, the 2018 observations attributed their connection to cosmic rays colliding with molecules in the interstellar medium and producing the antimatter in the process. But the subsequent analysis has cast doubt on the cosmic-ray origin theory,  and the only probable source now seems to be antistars.

Recently, Researchers have examined 10 years of observations from the Fermi Gamma-ray Space Telescope. The catalog contained nearly 5,800 gamma-ray sources, normally pulsars and black holes. However, analysis has shown that this is not the case!

Amongst these sources, 14 unique sources possess energies that are generally an outcome of matter-antimatter annihilation. And if these observations are confirmed, there’s a great possibility that antistars could have shed the stray antimatter detected in 2018. The Milky way should have almost 2.5 anti-stars per one million regular stars or 1 antimatter star to 300000 normal stars per the statistical estimates. Although it’s just a preliminary observation, if anti-stars are actually proven to exist, this will surely alter our view of cosmology, astrophysics, and particle physics.

Voyager 1 detected a steady hum in interstellar space

The Voyagers have never failed to amaze us. Going by this tradition, Voyager 1 again made headlines by detecting an unexpectedly steady ‘Hum’ of Plasma waves in Interstellar Space. The hum, which was persistent and long-lasting with a low frequency, pushed Voyager 1’s limits of what it was earlier thought capable of doing.

The movement of electrons in plasma leads to thermally excited plasma oscillations or the quasi-thermal noise that can be detected by Voyager 1’s inboard plasma wave system. Since 2012, Voyager 1 has detected about eight distinct plasma oscillation events, ranging in length from a couple of days to a full year. These events were mainly caused by instabilities in the motions of electrons as they interacted with shockwaves generated by the Sun.

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However, in 2017, Voyager 1 began to detect a weak yet very steady and persistent plasma signature outside of these energetic events. This newly detected signal was narrower than the plasma oscillation events and held itself steady at about 3 kHz, and bandwidth restricted to 40 Hz. It persisted for nearly three years, the longest continuous plasma signal recorded by Voyager 1.

Since the measured signal lies just above the Voyager 1 Plasma Wave System instrument’s noise threshold, no one was really expecting to find anything like it. These types of weak vibrations mainly originate in the absence of any coronal mass ejections from the Sun. This means that researchers can now use Voyager 1 to measure the frequency of these vibrations and the plasma density whenever they want, even in regions where there is no influence of the Sun. A deep understanding of this hum is also expected to understand better the interaction between the interstellar medium and the solar wind.

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Milky Way’s black hole could be a ball of dark matter

Like in the case of most other galaxies, it was long believed that there existed a supermassive black hole, Sagittarius A* at the very core of the Milky Way, equivalent to the mass of about 4 million Suns. Although the black hole wasn’t observed directly, its presence was inferred by watching the movements of a cluster of neighboring stars.

However, in a recent turn of events, a new study has proposed that the Milky Way’s heart could actually be a dense core of the dark matter, made up of hypothetical particles called darkinos, instead of a supermassive black hole.

The doubts regarding the authenticity of Sgr A* first rose seven years ago when a  gas cloud named G2 was found to be orbiting it. As the gas cloud swept past Sgr A*, it was expected that being a supermassive black hole, Sgr A*  should tear it to shreds. But surprisingly, nothing like this happened, and G2 survived the sweep without any issue.

This led scientists to speculate that maybe G2 wasn’t a gas cloud but a bloated dusty star with enough gravity to keep its shape. However, in the new study, the researchers have questioned Sgr A* itself instead of G2. And it has been proposed that such a gas cloud behavior is also possible if there lies a huge and fluffy ball of dark matter at the Milky Way’s core instead of a supermassive black hole.

A next generation supercomputer launched by the US Department of Energy 

The US Department of Energy officially launched Perlmutter, a next-generation supercomputer expected to deliver nearly four exaflops of AI performance. The supercomputer is based at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. It is the world’s fastest in the regime of 16-bit and 32-bit mixed-precision math used for AI.

Named after Saul Perlmutter, this supercomputer will be used by more than 7,000 researchers at NERSC for advanced scientific research in astrophysics, climate science, microelectronics, and numerous other fields.  Researchers are also aiming to use Perlmutter to help in assembling the largest ever 3D map of the visible universe.

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Carbon dioxide ice clouds in Martian atmosphere

In another turn of exciting revelations, NASA has released images of carbon dioxide ice clouds captured by Mars Curiosity rover in March on Mars.

The picture that is actually a collection of 21 separate color corrected images stitched together revealed Mont Mercou cliff on the red planet. It depicted a beautiful contrast of grey clouds over the brown mountain shot by NASA’s Curiosity rover on March 19, 2021, the day it completed 3,063 Martian days.

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Colour corrected image of clouds captured by Cassini (Image credit: NASA / JPL-Caltech / MSSS.)

Most clouds on the Red planet are known to hover at about 37 miles (60 kilometers) or lower altitudes in the sky, and the majority of these are composed of water ice. However, the latest capture made by Curiosity has revealed the clouds at a comparatively higher altitude, where it is freezing. Discoveries like these can help in getting a better understanding of Martian topography and climatic conditions.

Learn Astrophysics at Home:

Did you always want to learn how the universe works? Read our 30-article Basics of Astrophysics series absolutely free of cost. From the popular topics such as stars, galaxies, and black holes to the detailed concepts of the subject like the concept of magnitude, the Hertzsprung Russell diagram, redshift, etc., there is something for everyone in this series. All the articles are given here. Happy reading!

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