Where did Earth’s water come from? That’s one of the most compelling questions in the ongoing effort to understand life’s emergence. Earth’s inner solar system location was too hot for water to condense onto the primordial Earth. The prevailing view is that asteroids and comets brought water to Earth from regions of the Solar System beyond the frost line.
But a new study published in the journal Nature Astronomy proposes a further explanation for Earth’s water. As the prevailing view says, some of it could’ve come from asteroids and comets.
But most of the hydrogen was already here, waiting for Earth to form.
There are lots of potential uses for a Mars colony. It could be a research outpost, mining colony, or even a possible second home if something happens to go drastically wrong on our first one. But it could also be a potential source of what is sure to be one of the most valuable elements in the space economy – hydrogen.
White dwarfs are supposed to be dead remnants of stars, doomed to simply fade away into the background. But new observations show that some are able to maintain some semblance of life by wrapping themselves in a layer of fusing hydrogen.
We’re waiting patiently for telescopes like the James Webb Space Telescope to see first light, and one of the reasons is its ability to study the atmospheres of exoplanets. The idea is to look for biosignatures: things like oxygen and methane. But a new study says that exoplanets with hydrogen in their atmospheres are a good place to seek out alien life.
The Sun. It’s a big ball of fire, right? Apparently not. In fact, what’s going on inside of the Sun took us some time and knowledge of physics to finally figure out: stellar fusion. Let’s talk about the different kinds of fusion, and how we’re trying to adapt it to generate power here on Earth.
We have comets and asteroids to thank for Earth’s water, according to the most widely-held theory among scientists. But it’s not that cut-and-dried. It’s still a bit of a mystery, and a new study suggests that not all of Earth’s water was delivered to our planet that way.
Ever since the existence of antimatter was proposed in the early 20th century, scientists have sought to understand how relates to normal matter, and why there is an apparent imbalance between the two in the Universe. To do this, particle physics research in the past few decades has focused on the anti-particle of the most elementary and abundant atom in the Universe – the antihydrogen particle.
Until recently, this has been very difficult, as scientists have been able to produce antihydrogen, but unable to study it for long before it annihilated. But according to recent a study that was published in Nature, a team using the ALPHA experiment was able to obtain the first spectral information on antihydrogen. This achievement, which was 20 years in the making, could open up an entirely new era of research into antimatter.
Measuring how elements absorb or emit light – i.e. spectroscopy – is a major aspect of physics, chemistry and astronomy. Not only does it allow scientists to characterize atoms and molecules, it allows astrophysicists to determine the composition of distant stars by analyzing the spectrum of the light they emit.
In the past, many studies have been conducted into the spectrum of hydrogen, which constitutes roughly 75% of all baryonic mass in the Universe. These have played a vital role in our understanding of matter, energy, and the evolution of multiple scientific disciplines. But until recently, studying the spectrum of its anti-particle has been incredibly difficult.
For starters, it requires that the particles that constitute antihydrogen – antiprotons and positrons (anti-electrons) – be captured and cooled so that they may come together. In addition, it is then necessary to maintain these particles long enough to observe their behavior, before they inevitable make contact with normal matter and annihilate.
Luckily, technology has progressed in the past few decades to the point where research into antimatter is now possible, thus affording scientists the opportunity to deduce whether the physics behind antimatter are consistent with the Standard Model or go beyond it. As the CERN research team – which was led by Dr. Ahmadi of the Department of Physics at the University of Liverpool – indicated in their study:
“The Standard Model predicts that there should have been equal amounts of matter and antimatter in the primordial Universe after the Big Bang, but today’s Universe is observed to consist almost entirely of ordinary matter. This motivates physicists to carefully study antimatter, to see if there is a small asymmetry in the laws of physics that govern the two types of matter.”
Beginning in 1996, this research was conducted using the AnTiHydrogEN Apparatus (ATHENA) experiment, a part of the CERN Antiproton Decelerator facility. This experiment was responsible for capturing antiprotons and positrons, then cooling them to the point where they can combine to form anithydrogen. Since 2005, this task has become the responsibility of ATHENA’s successor, the ALPHA experiment.
Using updated instruments, ALPHA captures atoms of neutral antihydrogen and holds them for a longer period before they inevitably annihilate During this time, research teams conduct spectrographic analysis using ALPHA’s ultraviolet laser to see if the atoms obey the same laws as hydrogen atoms. As Jeffrey Hangst, the spokesperson of the ALPHA collaboration, explained in a CERN update:
“Using a laser to observe a transition in antihydrogen and comparing it to hydrogen to see if they obey the same laws of physics has always been a key goal of antimatter research… Moving and trapping antiprotons or positrons is easy because they are charged particles. But when you combine the two you get neutral antihydrogen, which is far more difficult to trap, so we have designed a very special magnetic trap that relies on the fact that antihydrogen is a little bit magnetic.”
In so doing, the research team was able to measure the frequency of light needed to cause a positron to transition from its lowest energy level to the next. What they found was that (within experimental limits) there was no difference between the antihydrogen spectral data and that of hydrogen. These results are an experimental first, as they are the first spectral observations ever made of an antihydrogen atom.
Besides allowing for comparisons between matter and antimatter for the first time, these results show that antimatter’s behavior – vis a vis its spectrographic characteristics – are consistent with the Standard Model. Specifically, they are consistent with what is known as Charge-Parity-Time (CPT) symmetry.
This symmetry theory, which is fundamental to established physics, predicts that energy levels in matter and antimatter would be the same. As the team explained in their study:
“We have performed the first laser-spectroscopic measurement on an atom of antimatter. This has long been a sought-after achievement in low-energy antimatter physics. It marks a turning point from proof-of-principle experiments to serious metrology and precision CPT comparisons using the optical spectrum of an anti-atom. The current result… demonstrate that tests of fundamental symmetries with antimatter at the AD are maturing rapidly.”
In other words, the confirmation that matter and antimatter have similar spectral characteristics is yet another indication that the Standard Model holds up – just as the discovery of the Higgs Boson in 2012 did. It also demonstrated the effectiveness of the ALPHA experiment at trapping antimatter particles, which will have benefits other antihydrogen experiments.
Naturally, the CERN researchers were very excited by this find, and it is expected to have drastic implications. Beyond offering a new means of testing the Standard Model, it is also expected to go a long way towards helping scientists to understand why there is a matter-antimatter imbalance in the Universe. Yet another crucial step in discovering exactly how the Universe as we know it came to be.
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Scientists have understood for some time that the most abundant elements in the Universe are simple gases like hydrogen and helium. These make up the vast majority of its observable mass, dwarfing all the heavier elements combined (and by a wide margin). And between the two, helium is the second lightest and second most abundant element, being present in about 24% of observable Universe’s elemental mass.
Whereas we tend to think of Helium as the hilarious gas that does strange things to your voice and allows balloons to float, it is actually a crucial part of our existence. In addition to being a key component of stars, helium is also a major constituent in gas giants. This is due in part to its very high nuclear binding energy, plus the fact that is produced by both nuclear fusion and radioactive decay. And yet, scientists have only been aware of its existence since the late 19th century.