Daily Archives: March 31, 2021

Quantum physics is, in short, the physics that explains how everything works. It explores the nature of the particles that make up matter and the sheer force with which they interact. Its the study of matter and energy at the most core level explaining how electrons move through a microchip or how the sun is a consistent ball of fire.

A great example is fluorescent lighting. The light you get from the tubes is a result of a quantum phenomenon its basically the reaction of a small amount of mercury vapour into the plasma.

Now, a bachelors, masters or PhD in quantum physics per se is not a thing. Its usually studied as part of the physics programme. However, you can aim for a masters or PhD that specialises in this field by taking on concentrations in quantum mechanics or quantum science.

To be a physics major, youll need a high school diploma, ACT or SAT scores, transcripts and letters of recommendation. Before declaring a major in physics, students are asked to complete coursework in general physics, algebra and calculus.

Those who are looking for a PhD programme in physics with a focus on quantum physics should have a strong undergraduate and masters background in physics with sufficient coursework in the domain. To add to that, an interest in independent research or a bachelors degree from an accredited college or uni is also needed.

NASA photo showing engineers and technicians insert 39 sample tubes into the belly of the Mars rover, as each tube is sheathed in a gold-coloured cylindrical enclosure to protect it from contamination, the perseverance rover will carry 43 sample tubes to the Red Planets Jezero Crater. Source: NASA/JPL-CALTECH/AFP

The more common courses cover thermodynamics, electromagnetism, statistical physics and quantum physics and mechanics. Many schools offer physics degree programmes that include quantum physics coursework, so when choosing, students might want to look closer at these details.

When pursuing a PhD with an interest in quantum physics, topics such as quantum mechanics, applied electrodynamics, quantum theory of solids, advanced solid state physics, statistical mechanics, quantum physics of matter, modern optics and quantum electronics are covered.

With a degree in this field, you can be a theoretical or experimental physicist, a researcher and even work with a quantum computer. Not only can you work in the engineering field (the highest paid jobs at NASA are the engineers), but in the world of medicine too, as quantum mechanics are used to make different compounds. A quantum physicist takes home an average annual pay of US$120,172.

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Quantum physics: what to expect - Study International News

There are two kinds of geniuses, argued the celebrated mathematician Mark Kac. There is the ordinary kind, whom we could emulate if only we were a lot smarter than we actually are because there is no mystery as to how their minds work. After we have understood what they have done, we believe (perhaps foolishly) that we could have done it too. When it comes to the second kind of genius, the magician, even after we have understood what has been done, the process by which it was done remains forever a mystery.

Werner Heisenberg was definitely a magician, who conjured up some of the most remarkable insights into the nature of reality. Carlo Rovelli recounts the first act of magic performed by Heisenberg in the opening of Helgoland, his remarkably wide-ranging new meditation on quantum theory.

Rovelli has taken the title from the name of the rocky, barren, windswept island in the North Sea to where the 23-year-old German physicist fled in June 1925 to recover from a severe bout of hay fever and in need of solitude to think. It was during these few days on the island (also called Heligoland) that, on completing calculation after calculation, Heisenberg made a discovery that left him dizzy, shaken and unable to sleep.

With the light touch of a skilled storyteller, Rovelli reveals that Heisenberg had been wrestling with the inner workings of the quantum atom in which electrons travel around the nucleus only in certain orbits, at certain distances, with certain precise energies before magically leaping from one orbit to another. Among the unsolved questions he was grappling with on Helgoland were: why only these orbits? Why only certain orbital leaps? As he tried to overcome the failure of existing formulas to replicate the intensity of the light emitted as an electron leapt between orbits, Heisenberg made an astonishing leap of his own. He decided to focus only on those quantities that are observable the light an atom emits when an electron jumps. It was a strange idea but one that, as Rovelli points out, made it possible to account for all the recalcitrant facts and to develop a mathematically coherent theory of the atomic world.

For all its strangeness, quantum theory explains the functioning of atoms, the evolution of stars, the formation of galaxies, the primordial universe and the whole of chemistry. It makes our computers, washing machines and mobile phones possible. Although it has never been found wanting by any experiment, quantum theory remains more than a little disturbing for challenging ideas that we have long taken for granted.

One of the most well-known counterintuitive discoveries was arguably Heisenbergs greatest act of quantum conjuring. The uncertainty principle forbids, at any given moment, the precise determination of both the position and the momentum of a particle. It is possible to measure exactly either where a particle is or how fast it is moving, but not both simultaneously. In a quantum dance of give-and-take, the more accurately one is measured the less precisely the other can be known or predicted. Heisenbergs uncertainty principle is not due to any technological shortcomings of the equipment, but a deep underlying truth about the nature of things.

According to some, including Heisenberg, there is no quantum reality beyond what is revealed by an experiment, by an act of observation. Take Erwin Schrdingers famous mythical cat trapped in a box with a vial of poison. It is argued that the cat is neither dead nor alive but in a ghostly mixture, or superposition, of states that range from being totally dead to completely alive and every conceivable combination in between until the box is opened. It is this act of observation, opening the box, which decides the fate of the cat. Some would argue that the cat was dead or alive, and to find out one just had to look in the box. Yet in the many worlds interpretation of quantum theory, which is popular among physicists, each and every possible outcome of a quantum experiment actually exists. Schrdingers cat is alive in one universe and dead in another.

With the fate of Schrdingers cat in the balance and Heisenbergs idea that quantum theory only describes observations, Rovelli inevitably asks the tricky questions: what is an observation? What is an observer?

He admits he is not an innocent bystander; he has skin in the game when it comes to trying to understand the quantum nature of reality. He is the champion of the relational interpretation that maintains quantum theory does not describe the way in which quantum objects manifest themselves to observers, but describes how every physical object manifests itself to any other physical object. The world that we observe is continuously interacting; it is better understood as a web of interactions and relations rather than objects.

Individual objects are summed up by the way in which they interact. If there were an object that had no interactions, no effect on anything, it would be as good as non-existent. When the electron does not interact with anything, Rovelli argues, it has no physical properties. It has no position; it has no velocity.

If all wasnt challenging enough, Rovelli reveals that he is not afraid to mix quantum physics and eastern philosophy, something that others have done in the past with little success and some derision. It says much about him and his argument that he is not so easily dismissed. He has help in the form of one of the most important texts of Buddhism, Mulamadhyamakakarika, or The Fundamental Verses of the Middle Way. Written in the second century by the Indian philosopher Nagarjuna, its central argument is simply that there is nothing that exists in itself, independently from something else. Its a perspective that Rovelli believes makes it easier to think about the quantum world. He may be right, but the words of Niels Bohr still come to mind: Those who are not shocked when they first come across quantum theory cannot possibly have understood it.

Helgoland, translated by Erica Segre and Simon Carnell, is published by Allen Lane (20). To order a copy go to guardianbookshop.com. Delivery charges may apply.

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Helgoland by Carlo Rovelli review a meditation on quantum theory - The Guardian

We take for granted the western concept of linear time. In ancient Greece, time was cyclical and if the Big Bounce theory is true, they were right. In Buddhism, there is only the eternal now. Both the past and the future are illusions. Meanwhile, the Amondawa people of the Amazon, a group that first made contact with the outside world in 1986, have no abstract concept of time. While we think we know time pretty well, some scientists believe our linear model hobbles scientific progress. We're missing whole dimensions of time, in this view, and our limited perception could be the last obstacle to a sweeping theory of everything.

Theoretical physicist Itzhak Bars of the University of Southern California, Los Angeles, is the most famous scientist with such a hypothesis, known as two-time physics. Here, time is 2D, visualized as a curved plane interwoven into the fabric of the "normal" dimensionsup-down, left-right, and backward-forward. While the hypothesis is over a decade old, Bars isn't the only scientist with such an idea. But what's different with spacekime theory is that it uses a data analytics approach, rather than a physics one. And while it posits that there are at least two dimensions of time, it allows for up to five.

In the spacekime model, space is 5D. Besides the ones we normally encounter, the extra dimensions are so infinitesimally small, we never notice them. This relates to the KaluzaKlein theory developed in the early 20th century, which stated that there might be an extra, microscopic dimension of space. In this view, space would be curved like the surface of Earth. And like Earth, those who travel the entire distance would, eventually, loop back to their place of origin.

Kaluza-Klein theory unified electromagnetism and gravity, but wasn't accepted at the time, although it did help in the search for quantum gravity. The concept of additional dimensions was revived in the 1990s with Paul Wesson's Space-Time-Matter Consortium. Today, proponents of superstring theory say there may be as many as 10 different dimensions, including nine of space and one of time.

Spacekime theory was developed by two data scientists. Dr. Ivo Dinov is the University of Michigan's SOCR Director, as well as a professor of Health Behavior and Biological Sciences, and Computational Medicine and Bioinformatics. SOCR stands for: Statistics Online Computational Resource designs. Dr. Dinov is an expert in "mathematical modeling, statistical analysis, computational processing, scientific visualization of large datasets (Big Data) and predictive health analytics." His research has focused on mathematical modeling, statistical inference, and biomedical computing.

His colleague, Dr. Milen Velchev Velev, is an associate professor at the Prof. Dr. A. Zlatarov University in Bulgaria. He studies relativistic mechanics in multiple time dimensions, and his interests include "applied mathematics, special and general relativity, quantum mechanics, cosmology, philosophy of science, the nature of space and time, chaos theory, mathematical economics, and micro-and-macroeconomics."

Drs. Dinov and Velev began developing spacekime theory around four or five years ago, while working with big data in the healthcare field. "We started looking at data that intrinsically has a temporal dimension to it," Dr. Dinov told me during a video chat. "It's called longitudinal or time varying data, longitudinal time varianceit has many, many names. This is data that varies with time. In biomedicine, this is the de facto, standard data. All big health data is characterized by space, time, phenotypes, genotypes, clinical assessments, and so forth."

"We started asking big questions," Dinov said. "Why are our models not really fitting too well? Why do we need so many observations? And then, we started playing around with time. We started digging and experimenting with various things. And then we realized two important facts.

"Number one, if we use what's called color-coded representations of the complex plane, we can define spacekime, or higher dimensional spacetime, in such a way that it agrees with the common observations that we make in (the longitudinal time series in) ordinary spacetime. That agreement was very important to us, because it basically says, yes, the higher dimensional theory does not contradict our common observations.

"The second realization was that, since this extra dimension of time is imperceptible, we needed to approximate, model, or estimate, one of the unobservable time characteristics, which we call the kime phase. After about a year, we discovered that there is a mathematically elegant tool called the Laplace Transform that allows us to analytically represent time series data as kime-surfaces. Turns out, the spacekime mathematical manifold is a natural, higher dimensional extension of classical Minkowski, four-dimensional spacetime."

Our understanding of the world is becoming more complex. As a result, we have big data to contend with. How do we find new ways to analyze, interpret and visual such data? Dinov believes spacekime theory can help in some pretty impressive ways. "The result of this multidimensional manifold generalization is that you can make scientific inferences using smaller data samples. This requires that you have a good model or prior knowledge about the phase distribution," he said. "For instance, we can use spacekime process representation to better understand the development or pathogenesis to model the distributions of certain diseases.

"Suppose we are evaluating fMRIs of Alzheimer's disease subjects. Assume we know the kime phase distribution for another cohort of patients suffering from amyotrophic lateral sclerosis, Lou Gehrig's disease. The ALS kime-phase distribution could be used for evaluating the Alzheimer's patients," and many other neurodegenerative populations. Dinov also thinks spacekime analytics could help improve political polling, increase our understanding of complex financial and environmental events, and even the innerworkings of the human brain, all without having to take the huge samples required today to make accurate models or predictions. Spacekime theory even offers opportunities to design novel AI analytical techniques. But it goes beyond that.

Spacekime theory can help us make headway on some of the most pernicious inconsistencies in physics, such as Heisenberg's uncertainty principle and the seemingly irreconcilable rift between quantum physics and general relativity, what's known as "the problem of time."

Dinov wrote that the "approach relies on extending the notions of time, events, particles, and wave functions to complex-time (kime), complex-events (kevents), data, and inference-functions." Basically, working with two points of time allows you to make inferences on a radius of points associated with a certain event. With Heisenberg's uncertainty principle, according to this model, since time is a plane, a certain particle would be in one position or phase, time-wise, in terms of velocity, and another phase, in terms of position.

This idea of hidden dimensions of time is a little like Plato's allegory of the cave or how an X-ray signifies what's underneath, but doesn't convey a 3D image. From a data science perspective, it all comes down to utility. Dinov believes that if we can calculate the true phase dispersion of complex phenomena, we can better understand and control them.

Drs. Dinov and Velev's book on spacekime theory comes out this August. It's called "Data Science: Time Complexity, Inferential Uncertainty, and Spacekime Analytics".

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'Spacekime theory' could speed up research and heal the rift in physics - Big Think

For the real black holes that exist or get created in our Universe, we can observe the radiation ... [+] emitted by their surrounding matter, and the gravitational waves produced by the inspiral, merger, and ringdown phases. Although only a few X-ray binaries are known, LIGO and other gravitational wave detectors should be capable of filling in any mass gap ranges where black holes do abundantly exist.

If you take enough mass and compress it into a small enough volume of space, youll inevitably form a black hole. Any mass in the Universe will curve the fabric of spacetime around it, and the more severely curved that spacetime fabric is, the more difficult it is to escape from that masss gravitational pull. The smaller the volume becomes that your mass occupies, the faster youd have to travel, at the edge of that object, to actually escape it.

At some point, the escape velocity youd need to obtain would exceed the speed of light, which defines the critical threshold for forming a black hole. According to Einsteins General Relativity, any mass in a small enough volume would be sufficient to form a black hole. But in our physical reality, there are real limitations that our Universe is subjected to, and not every mathematical possibility comes to fruition. Many of the black holes that we could imagine forming simply dont in our Universe. To the best of our knowledge, heres whats impossible.

An illustration between the inherent uncertainty between position and momentum at the quantum level. ... [+] The better you know or measure a particle's position, the less well you know its momentum, as well as vice versa. Both position and momentum are better described by a probabilistic wavefunction than by a single value.

Black holes have a quantum limit. Below a certain scale, reality is not what it seems. Instead of matter and energy having specific properties that are limited only by our ability to measure it, weve found that there are inherently uncertain relationships between various properties. If you measure a particles position, youll know its uncertainty inherently less well. If you measure its lifetime or its behavior over extremely short timescales, the less well-known you can inherently know its intrinsic energy, or even its rest mass.

Theres an inherent limit to how well you can know any two complementary quantities simultaneously, which is the key point of the Heisenberg uncertainty principle. Even empty space if you were to remove all the various forms of matter and energy entirely exhibits this uncertainty. Well, if you consider a distance scale of ~10-35 m or smaller, the amount of time it would take a photon to cross it would be minuscule: ~10-43 s. On those short timescales, the Heisenberg uncertainty principle tells you that your energy uncertainty is so large, it corresponds (via E = mc) to a mass of about 22 micrograms: the Planck mass.

This visualization shows the fluctuations in the quantum vacuum under the strong interactions. On ... [+] smaller distance scales and over smaller timescales, the fluctuations in energy and momentum can be larger. Once you go down to Planck-scale sizes and distances, the fluctuations are indistinguishable from black holes: a clear indication that physics has broken down.

If you had a black hole a perfect singularity whose mass was 22 micrograms, how large would its event horizon be? The answer is that same distance scale (the Planck length) you started off with: ~10-35 m. This fact illustrates why physicists say that the laws of reality break down at the Planck scale: the quantum fluctuations that must spontaneously occur are so large in magnitude, on scales so minuscule, that theyre indistinguishable from black holes.

But those black holes would immediately decay, as the evaporation time due to Hawking radiation would be less than the Planck time: ~10-43 s. We know that the laws of physics we have, both in quantum physics and in General Relativity, cannot be trusted on these small distance scales or on these tiny timescales. If thats true, then we cannot accurately describe, with those same equations, a black hole whose mass is 22 micrograms or lower. Thats the quantum lower limit for how small a black hole can be in our Universe. Below it, any assertion we could make would be physically meaningless.

When a black hole is created of a very small mass, quantum effects arising from the curved spacetime ... [+] near the event horizon will cause the black hole to rapidly decay via Hawking radiation. The lower the mass of the black hole, the more rapid the decay is.

Black holes below a certain mass would all have evaporated away by now. One of the remarkable lessons from applying quantum field theory in the space around black holes is this: black holes arent stable, but will emit energetic radiation, eventually leading to their complete evaporation. This process, known as Hawking radiation, will someday cause every black hole within the Universe to evaporate.

Although theres a lot of confusion around why this happens much of which can be traced back to Hawking himself the key things you must understand are that:

As a result, lower-mass black holes evaporate more quickly than higher-mass ones. If our Sun were a black hole, it would take 1067 years to evaporate; if the Earth were one, it would evaporate much more quickly: in just ~1051 years. Our Universe, since the hot Big Bang, has existed for about 13.8 billion years, meaning any black holes less massive than ~1012 kg, or around the mass of all the humans on Earth combined, would already have evaporated away entirely.

Just as a black hole consistently produces low-energy, thermal radiation in the form of Hawking ... [+] radiation outside the event horizon, an accelerating Universe with dark energy (in the form of a cosmological constant) will consistently produce radiation in a completely analogous form: Unruh radiation due to a cosmological horizon.

Black holes below about ~2.5 solar masses probably dont exist. According to the laws of physics as we understand them, there are only a few ways that a black hole can be formed. You can take a large chunk of matter and let it gravitationally collapse; if theres nothing to stop or slow it down, it could collapse directly into a black hole. You could, alternatively, let a clump of matter contract down to form a star, and if that stars core is massive enough, it can eventually implode, collapsing down to form a black hole. Finally, you can take a stellar remnant that didnt quite make it like a neutron star and add mass, either through a merger or accretion, until it becomes a black hole after all.

In practice, we believe all of these methods occur, leading to the formation of the realistic black holes that form in our Universe. But below a certain mass threshold, none of these methods can actually give you a black hole.

The visible/near-IR photos from Hubble show a massive star, about 25 times the mass of the Sun, that ... [+] has winked out of existence, with no supernova or other explanation. Direct collapse is the only reasonable candidate explanation.

Weve seen clumps of matter suddenly wink out of existence, like stars that magically disappear. The most logical explanation, as well as the one that best fits the data, is that a fraction of stars do spontaneously collapse into a black hole. Unfortunately, they tend to be on the massive side: dozens of times as massive as our Sun at the very least.

Stars with massive cores do often end their lives in spectacular supernova explosions, where the cores of these stars do implode. If youre born with about 800% or more of our Suns mass, youre an excellent candidate for going supernova. The stars with less massive cores will eventually form neutron stars, with the more massive ones forming black holes. The heaviest neutron star ever discovered likely formed through this process, weighing in at 2.17 solar masses.

And finally, you can take object that are lighter than black holes like the aforementioned neutron stars and either allow them to accrete/siphon mass from a companion, or collide them with another massive, compact object. When they do, theres a chance they could form a black hole.

Numerical relativity simulation of the last few milliseconds of two inspiraling and merging neutron ... [+] stars. Higher densities are shown in blue, lower densities are shown in cyan. The final black hole is shown in gray; you can identify the transition from neutron star to black hole by the change in color.

Although there have been only two neutron star-neutron star mergers ever directly and definitively observed, theyve been incredibly informative. The second one, with a combined mass of about 3.4 solar masses, went directly to a black hole. But the first one, which had a combined mass of more like 2.7 solar masses, revealed a far more complex story. For a few hundred milliseconds, this rapidly-spinning, post-merger mass behaved like a neutron star. All of a sudden, however, it switched to behaving like a black hole. After that transition, it never went back.

What we now believe occurred is that theres a narrow mass range somewhere between 2.5 and maybe 2.8 solar masses where a collapsed objects like a neutron star can exist, but it requires a particularly high value for its rotation rate. If it drops below a critical value, and it will change its spin rate as it settles down to a more spherical shape, it will become a black hole. Below that lower value, there are only neutron stars and no black holes. Above that upper value, there are only black holes and no neutron stars. And in between, you can have both, but what youll ultimately wind up with depends on how fast the object is spinning.

The most massive black hole binary signal ever seen: OJ 287. This tight binary black hole system ... [+] takes on the order of 11-12 years to complete an orbit. Despite making an orbit 1/5th of a light year in size (hundreds of times the Sun-Pluto distance), it should merge in just thousands of years.

What about heavier black holes? Is there a gap where no black holes exist? Is there an upper limit to black hole masses? Black holes can get much, much heavier than just a few times the mass of our Sun. Initially, there were theoretical concerns that there might be a gap where black holes didnt exist; that appears to conflict with the data we now have after ~6 years of advanced LIGO. There was a worry that intermediate mass black holes might not exist, as theyve proven very difficult to find. However, they now appear to be out there as well, with superior data confidently revealing numerous examples.

There will be a limit to how big they can get, however, although we havent hit it just yet. Black holes approaching 100 billion solar masses have been found, and we even have our first candidate for crossing that vaunted threshold. As galaxies evolve, merge, and grow, so too can their central black holes. Far into the future, some galaxies may grow their black holes as large as ~100 trillion (1014) solar masses: 1000 times larger than todays largest black hole. Owing to dark energy, which drives distant galaxies apart in the expanding Universe, we fully expect that no black holes will ever grow substantially larger than this value.

Constraints on dark matter from Primordial Black Holes. There is an overwhelming set of pieces of ... [+] evidence that indicate there is not a large population of black holes created in the early Universe that comprise our dark matter.

What about primordial black holes: black holes that formed directly after the Big Bang? This is a sticky one, because theres no evidence that they exist. Observationally, many constraints have been placed on the idea, which has been around since the 1970s. When the Universe was born, we know some regions were denser than others. If one region was born with a density that was just ~68% greater than average, that entire region should inevitably collapse to form a black hole. While their masses cant be less than ~1012 kg, they could, in theory, have any value thats larger.

Unfortunately, we have the fluctuations in the cosmic microwave background to guide us. These temperature fluctuations correspond to the overdense and underdense regions in the early Universe, and show us that the overdense regions are only about ~0.003% denser than average. Its true: these are on larger scales than the ones wed look for black holes on. But with no compelling theoretical motivation for them, and no observational evidence in their favor, this idea remains purely speculative.

When matter collapses, it can inevitably form a black hole. Penrose was the first to work out the ... [+] physics of the spacetime, applicable to all observers at all points in space and at all instants in time, that governs a system such as this. His conception has been the gold standard in General Relativity ever since.

For a long time, the very notion of black holes was highly contentious. For about 50 years after they were first derived in General Relativity, no one was sure whether they could physically exist in our Universe. Roger Penroses Nobel-winning work demonstrated how their existence was possible; just a few years later, we discovered the first black hole in our own galaxy: Cygnus X-1. Now the floodgates are open, with stellar-mass, intermediate-mass, and supermassive black holes all known in great and ever-increasing numbers.

But theres a lower limit to black holes in the Universe: we believe that none exist below about 2.5 times the mass of the Sun. Additionally, while the heaviest black holes today are right around 100 billion solar masses, theyll eventually grow to be up to 1000 times as heavy as that. Studying black holes provides us with a unique window into the physics of our Universe and the nature of gravity and spacetime themselves, but they cant reveal everything. In our Universe, some black holes truly are impossible.

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Some Black Holes Are Impossible In Our Universe - Forbes

Peer long enough into the heavens, and the Universe starts to resemble a city at night. Galaxies take on characteristics of streetlamps cluttering up neighborhoods of dark matter, linked by highways of gas that run along the shores of intergalactic nothingness.

This map of the Universe was preordained, laid out in the tiniest of shivers of quantum physics moments after the Big Bang launched into an expansion of space and time some 13.8 billion years ago.

Yet exactly what those fluctuations were, and how they set in motion the physics that would see atoms pool into the massive cosmic structures we see today is still far from clear.

A new mathematical analysis of the moments after a period called the inflationary epoch reveals that some kind of structure might have existed even within the seething quantum furnace that filled the infant Universe, and it could help us better understand its layout today.

Astrophysicists from the University of Gttingen in Germany and the University of Auckland in New Zealand used a mix of particle movement simulations and a kind of gravity/quantum modelling to predict how structures might form in the condensation of particles after inflation occurred.

The scale of this kind of modelling is a little mind-blowing. We're talking about masses of up to 20 kilograms squeezed into a space barely 10-20 meters across, at a time when the Universe was just 10-24 seconds old.

"The physical space represented by our simulation would fit into a single proton a million times over," says astrophysicist Jens Niemeyer from the University of Gttingen.

"It is probably the largest simulation of the smallest area of the Universe that has been carried out so far."

Most of what we know about this early stage of the Universe's existence is based on just this kind of mathematical sleuthing. The oldest light we can still see flickering through the Universe is the Cosmic Background Radiation(CMB), and the entire show had already been on the road for around 300,000 years by then.

But within that faint echo of ancient radiation there are some clues on what was going on.

The CMB's light was emitted as basic particles combined into atoms out of the hot, dense soup of energy, in what's known as the epoch of recombination.

A map of this background radiation across the sky shows our Universe already had some kind of structure by a few hundred thousand years of age. There were slightly cooler bits and slightly warmer bits which might nudge matter into areas that would eventually see stars ignite, galaxies spiral, and masses pool into the cosmic city we see today.

This poses a question.

The space making up our Universe is expanding, meaning the Universe must once have been a lot smaller. So it stands to reason that everything we see around us now was once crammed into a volume too confined for such warm and cool patches to emerge.

Like a cup of coffee in a furnace, there was no way for any part to cool down before it heated up again.

The inflationary period was proposed as a way to fix this problem. Within trillionths of a second of the Big Bang, our Universe jumped in size by an insane amount, essentially freezing any quantum-scale variations in place.

To say this happened in the blink of an eye would still not do it justice. It would have begun around 1036 seconds after the Big Bang, and ended by 1032 seconds. But it was long enough for space to snap into proportions that prevented small variations in temperature from smoothing out again.

The researchers' calculations focus in on this brief instant after inflation, demonstrating how elementary particles congealing from the foam of quantum ripples at that time could have generated brief halos of matter dense enough to wrinkle spacetime itself.

"The formation of such structures, as well as their movements and interactions, must have generated a background noise of gravitational waves," says University of Gttingen astrophysicist Benedikt Eggemeier, the study's first author.

"With the help of our simulations, we can calculate the strength of this gravitational wave signal, which might be measurable in the future."

In some cases, the intense masses of such objects could have pulled matter into primordial black holes, objects hypothesized to contribute to the mysterious pull of dark matter.

The fact the behavior of these structures mimics the large-scale clumping of our Universe today doesn't necessarily mean it's directly responsible for today's distribution of stars, gas, and galaxies.

But the complex physics unfolding among those freshly baked particles might still be visible in the sky, among that rolling landscape of twinkling lights and dark voids we call the Universe.

This research was published in Physical Review D.

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Scientists Have Simulated The Primordial Quantum Structure of Our Universe - ScienceAlert

Department of Physics

Location: EghamSalary: 35,931 starting salary per annum - including London AllowanceClosingDate: Wednesday 12 May 2021InterviewDate: To be confirmedReference: 0321-077

Full-Time, Fixed Term (for 24 months)

The Quantum Matter Group of the Department of Physics, Royal Holloway, University of London, invites applications for a two-year Post-Doctoral Research Associate position to work on neutron scattering from frustrated magnets. The role is funded by EPSRC. It is hoped that the candidate would be in post by 1stOctober 2021.

The post holder will engage in experimental research in the group of Professor Jon Goff, with the specific aim to investigate the role of disorder in frustrated magnetism, encompassing both classical and quantum spin liquids. It is anticipated that neutron scattering experiments will be performed at the ISIS Facility in the United Kingdom, the ILL in France, FRM II in Germany and SNS in the United States. This work is part of an ongoing collaboration with experimental and theoretical groups in Oxford and Cambridge.

The successful candidate will be required to carry out experimental and computational research in Condensed Matter Physics, present results at international conferences and in high impact journals and collaborate with UK and international institutions. Applicants should hold (or be close to obtaining) a Ph.D. in Physics and have a track record of high-quality research. Preference will be given to candidates with experience in neutron scattering, and in research fields relevant to this post. Strong computing and communication skills would be highly beneficial.

The post is based in Egham, Surrey where the College is situated in a beautiful, leafy campus near to Windsor Great Park and Heathrow Airport, and within commuting distance from London.

For an informal discussion about the post, please contact Professor Jon Goff at:jon.goff@rhul.ac.uk.

To view further details of this post and to apply please visithttps://jobs.royalholloway.ac.uk.For queries on the application process the Human Resources Department can be contacted by email at:recruitment@rhul.ac.uk.

Please quote the reference:0321-077Closing Date: Midnight, 12 May 2021Interview Date:TBC

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Post-Doctoral Research Associate Experimental Condensed Matter Physics job with ROYAL HOLLOWAY, UNIVERSITY OF LONDON | 250229 - Times Higher Education...