The Universe & Dark Matter

Physicists have long theorized that our universe may not be limited to what we can see. By observing gravitational forces on other galaxies, they've hypothesized the existence of "dark matter," which would be invisible to conventional forms of observation.


Pran Nath, the Matthews Distinguished University Professor of physics at Northeastern University, says that "95% of the universe is dark, is invisible to the eye."


"However, we know that the dark universe is there by [its] gravitational pull on stars," he says. Other than its gravity, dark matter has never seemed to have much effect on the visible universe.    READ MORE...

A New Type of Magnetism

ALL THE MAGNETS you have ever interacted with, such as the tchotchkes stuck to your refrigerator door, are magnetic for the same reason. But what if there were another, stranger way to make a material magnetic?

In 1966, the Japanese physicist Yosuke Nagaoka conceived of a type of magnetism produced by a seemingly unnatural dance of electrons within a hypothetical material. Now, a team of physicists has spotted a version of Nagaoka’s predictions playing out within an engineered material only six atoms thick.   READ MORE...

Living In a Computer Simulation

Physicists have long struggled to explain why the universe started out with conditions suitable for life to evolve. Why do the physical laws and constants take the very specific values that allow stars, planets and ultimately life to develop? The expansive force of the universe, dark energy, for example, is much weaker than theory suggests it should be – allowing matter to clump together rather than being ripped apart.

A common answer is that we live in an infinite multiverse of universes, so we shouldn’t be surprised that at least one universe has turned out as ours. But another is that our universe is a computer simulation, with someone (perhaps an advanced alien species) fine-tuning the conditions.

The latter option is supported by a branch of science called information physics, which suggests that space-time and matter are not fundamental phenomena. Instead, the physical reality is fundamentally made up of bits of information, from which our experience of space-time emerges. By comparison, temperature “emerges” from the collective movement of atoms. No single atom fundamentally has temperature.  READ MORE...

Faster Than Light Travel

For decades, we've dreamed of visiting other star systems. There's just one problem – they're so far away, with conventional spaceflight it would take tens of thousands of years to reach even the closest one.


Physicists are not the kind of people who give up easily, though. Give them an impossible dream, and they'll give you an incredible, hypothetical way of making it a reality. Maybe.

In a 2021 study by physicist Erik Lentz from Göttingen University in Germany, we may have a viable solution to the dilemma, and it's one that could turn out to be more feasible than other would-be warp drives.

This is an area that attracts plenty of bright ideas, each offering a different approach to solving the puzzle of faster-than-light travel: achieving a means of sending something across space at superluminal speeds.

There are some problems with this notion, however. Within conventional physics, in accordance with Albert Einstein's theories of relativity, there's no real way to reach or exceed the speed of light, which is something we'd need for any journey measured in light-years.

That hasn't stopped physicists from trying to break this universal speed limit, though.

While pushing matter past the speed of light will always be a big no-no, spacetime itself has no such rule. In fact, the far reaches of the Universe are already stretching away faster than its light could ever hope to match.  READ MORE...

Using A Drunkard's Walk

(Image credit: Adrienne Bresnahan/Getty Images)

A physics problem that has plagued science since the days of Isaac Newton is closer to being solved, say a pair of Israeli researchers. The duo used "the drunkard's walk" to calculate the outcome of a cosmic dance between three massive objects, or the so-called three-body problem.

For physicists, predicting the motion of two massive objects, like a pair of stars, is a piece of cake. But when a third object enters the picture, the problem becomes unsolvable. That's because when two massive objects get close to each other, their gravitational attraction influences the paths they take in a way that can be described by a simple mathematical formula. But adding a third object isn't so simple: Suddenly, the interactions between the three objects become chaotic. 

Instead of following a predictable path defined by a mathematical formula, the behavior of the three objects becomes sensitive to what scientists call "initial conditions" — that is, whatever speed and position they were in previously. Any slight difference in those initial conditions changes their future behavior drastically, and because there's always some uncertainty in what we know about those conditions, their behavior is impossible to calculate far out into the future. 

In one scenario, two of the objects might orbit each other closely while the third is flung into a wide orbit; in another, the third object might be ejected from the other two, never to return, and so on.

In a paper published in the journal Physical Review X, scientists used the frustrating unpredictability of the three-body problem to their advantage.

"[The three-body problem] depends very, very sensitively on initial conditions, so essentially it means that the outcome is basically random," said Yonadav Barry Ginat, a doctoral student at Technion-Israel Institute of Technology who co-authored the paper with Hagai Perets, a physicist at the same university. "But that doesn't mean that we cannot calculate what probability each outcome has."

To do that, they relied on the theory of random walks — also known as "the drunkard's walk." The idea is that a drunkard walks in random directions, with the same chance of taking a step to the right as taking a step to the left. If you know those chances, you can calculate the probability of the drunkard ending up in any given spot at some later point in time.

So in the new study, Ginat and Perets looked at systems of three bodies, where the third object approaches a pair of objects in orbit. In their solution, each of the drunkard's "steps" corresponds to the velocity of the third object relative to the other two.

"One can calculate what the probabilities for each of those possible speeds of the third body is, and then you can compose all those steps and all those probabilities to find the final probability of what's going to happen to the three-body system in a long time from now," meaning whether the third object will be flung out for good, or whether it might come back, for instance, Ginat said.  READ MORE...

Fusion Reaction Creates More Energy Than It Absorbs

A major milestone has been breached in the quest for fusion energy.

For the first time, a fusion reaction has achieved a record 1.3 megajoule energy output – and for the first time, exceeding energy absorbed by the fuel used to trigger it.

Although there's still some way to go, the result represents a significant improvement on previous yields: eight times greater than experiments conducted just a few months prior, and 25 times greater than experiments conducted in 2018. It's a huge achievement.

Physicists at the National Ignition Facility at the Lawrence Livermore National Laboratory will be submitting a paper for peer review.

"This result is a historic step forward for inertial confinement fusion research, opening a fundamentally new regime for exploration and the advancement of our critical national security missions. It is also a testament to the innovation, ingenuity, commitment and grit of this team and the many researchers in this field over the decades who have steadfastly pursued this goal," said Kim Budil, director of the Lawrence Livermore National Laboratory.

"For me, it demonstrates one of the most important roles of the national labs – our relentless commitment to tackling the biggest and most important scientific grand challenges and finding solutions where others might be dissuaded by the obstacles."

Inertial confinement fusion involves creating something like a tiny star. It starts with a capsule of fuel, consisting of deuterium and tritium – heavier isotopes of hydrogen. This fuel capsule is placed in a hollow gold chamber about the size of a pencil eraser called a hohlraum.  READ MORE...

Laws of Logic

Physicists are translating commonsense principles into strict mathematical constraints on how our universe must have behaved at the beginning of time.  Patterns in the ever-expanding arrangement of galaxies might reveal secrets of the universe’s first moments.

M.C. Escher’s Circle Limit III (1959). M.C. Escher

For over 20 years, physicists have had reason to feel envious of certain fictional fish: specifically, the fish inhabiting the fantastic space of M.C. Escher’s Circle Limit III woodcut, which shrink to points as they approach the circular boundary of their ocean world. If only our universe had the same warped shape, theorists lament, they might have a much easier time understanding it.

Escher’s fish lucked out because their world comes with a cheat sheet — its edge. On the boundary of an Escher-esque ocean, anything complicated happening inside the sea casts a kind of shadow, which can be described in relatively simple terms. In particular, theories addressing the quantum nature of gravity can be reformulated on the edge in well-understood ways. The technique gives researchers a back door for studying otherwise impossibly complicated questions. Physicists have spent decades exploring this tantalizing link.

Inconveniently, the real universe looks more like the Escher world turned inside out. This “de Sitter” space has a positive curvature; it expands continuously everywhere. With no obvious boundary on which to study the straightforward shadow theories, theoretical physicists have been unable to transfer their breakthroughs from the Escher world. orld, the fewer tools we have and the less we understand the rules of the game,” said Daniel Baumann, a cosmologist at the University of Amsterdam.  READ MORE...

Dark Matter Creates Dark Matter From Regular Matter

An international team of physicists is proposing an addition to dark matter theory. In their paper published in the journal Physical Review Letters, the group is suggesting that dark matter came from regular matter and that dark matter is able to create more dark matter from regular matter.

The existence of a material described as dark matter has been proposed by physicists to explain certain behaviors observed by researchers—the way light bends as it makes its way from far away places to telescopes here on Earth, is just one example. 

But some parts of the theory have yet to be worked out, such as how did the amount of dark matter believed to exist today come into being? The team on this new effort has come up with a theory to answer that question.

The theorists begin by citing prior research which suggests that some amount of dark matter was created as part of the 'thermal bath'—where primordial plasma made of regular matter begat dark matter particles—but not the amount that is believed to exist today. 

They suggest that at some point dark matter particles began making more dark matter particles out of regular particles. And the new dark matter particles were also able to create new dark matter particles out of regular particles.  READ MORE...

A New Force of Nature

The Large Hadron Collider (LHC) sparked worldwide excitement in March as particle physicists reported tantalizing evidence for new physics — potentially a new force of nature. Now, our new result, yet to be peer reviewed, from CERN’s gargantuan particle collider seems to be adding further support to the idea.

Our current best theory of particles and forces is known as the standard model, which describes everything we know about the physical stuff that makes up the world around us with unerring accuracy. The standard model is without doubt the most successful scientific theory ever written down and yet at the same time we know it must be incomplete.


Famously, it describes only three of the four fundamental forces – the electromagnetic force and strong and weak forces, leaving out gravity. It has no explanation for the dark matter that astronomy tells us dominates the universe, and cannot explain how matter survived during the big bang. Most physicists are therefore confident that there must be more cosmic ingredients yet to be discovered, and studying a variety of fundamental particles known as beauty quarks is a particularly promising way to get hints of what else might be out there.

Beauty quarks, sometimes called bottom quarks, are fundamental particles, which in turn make up bigger particles. There are six flavors of quarks that are dubbed up, down, strange, charm, beauty/bottom and truth/top. Up and down quarks, for example, make up the protons and neutrons in the atomic nucleus.

The LHCb experiment at CERN. Credit: CERN

Beauty quarks are unstable, living on average just for about 1.5 trillionths of a second before decaying into other particles. The way beauty quarks decay can be strongly influenced by the existence of other fundamental particles or forces. When a beauty quark decays, it transforms into a set of lighter particles, such as electrons, through the influence of the weak force. One of the ways a new force of nature might make itself known to us is by subtly changing how often beauty quarks decay into different types of particles.  TO READ MORE, CLICK HERE...

Quantum Physics: Denying Reality

This morning I had a bowl of plain Greek yoghurt and toasted muesli for breakfast. I could have had a plain bagel with mashed avocado — or, I could have had nothing at all. But I had the yoghurt and muesli. I know, I know, damn millennials and their hipster breakfast food. But, also, who cares what I ate for breakfast? Well, perhaps the universe does.

Imagine that, after breakfast, I dutifully went to the lab to perform some quantum physics experiments. The results of the experiments obviously depend on what I do in the lab. But, they shouldn’t depend on what happens outside of the lab, right? 

I mean, why should laser light bouncing around through crystals and mirrors care what the current value of the S&P 500 is, let alone what I had for breakfast?

The conditions under which an experiment is performed are called its context. In practice, the contexts we consider are very limited to a few settings on the devices in the lab. But, maybe the temperature of the room is important. Were the lights on? Was the door open? Especially when things go wrong — which is more often than not — the context is where you look for answers. 

But some parts of the context are so far removed from the experiment that there is absolutely no way they could affect the results, such as that delicious muesli. (Did I mention it was toasted with a hint of maple and paired with a pot set Greek yoghurt?)

A theory is a set of mathematical rules that make predictions about the outcomes of experiments. Most theories automatically rule out most contexts simply by ignoring them. Dependence on other contexts are ruled out by experimentation. 

If there is no possible experimental arrangement in the lab that can distinguish what I had for breakfast, then the theory shouldn’t make reference to that context. Think of it as an application of Occam’s razor. Indeed, quantum physics makes no mention of breakfast choices.

As successful as quantum physics is, it is merely an operational theory. It’s like a lab manual with instructions about the preparations and expectations of experiments. It’s remarkably accurate, allowing us to engineer materials and devices which form the basis of all modern technology. But, it doesn’t tell us anything about reality — and that bothers a lot of physicists.  READ MORE

Colliding Photons

Collide light with light, and poof, you get matter and antimatter. It sounds like a simple idea, but it turns out to be surprisingly hard to prove.

A team of physicists is now claiming the first direct observation of the long-sought Breit-Wheeler process, in which two particles of light, or photons, crash into one another and produce an electron and its antimatter counterpart, a positron. 

But like a discussion from an introductory philosophy course, the detection’s significance hinges on the definition of the word “real.” Some physicists argue the photons don’t qualify as real, raising questions about the observation’s implications.

Predicted more than 80 years ago, the Breit-Wheeler process had never been directly observed, although scientists have seen related processes, such as light scattering off of light (SN: 8/14/17). 

New measurements from the STAR experiment at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider match predictions for the elusive transformation, Brookhaven physicist Daniel Brandenburg and colleagues report in the July 30 Physical Review Letters.

“The idea that you can create matter from light smashing together is an interesting concept,” says Brandenburg. 

It’s a striking demonstration of the physics immortalized in Einstein’s equation E=mc2, which revealed that energy and mass are two sides of the same coin.  READ MORE

Water Into Metal

Pure water is an almost perfect insulator.
Yes, water found in nature conducts electricity - but that's because of the impurities therein, which dissolve into free ions that allow an electric current to flow. 

Pure water only becomes "metallic" - electronically conductive - at extremely high pressures, beyond our current abilities to produce in a lab.

But, as researchers have now demonstrated for the first time, it's not only high pressures that can induce this metallicity in pure water.

By bringing pure water into contact with an electron-sharing alkali metal - in this case an alloy of sodium and potassium - free-moving charged particles can be added, turning water metallic.

The resulting conductivity only lasts a few seconds, but it's a significant step towards being able to understand this phase of water by studying it directly.

"You can see the phase transition to metallic water with the naked eye!" said physicist Robert Seidel of Helmholtz-Zentrum Berlin für Materialien und Energie in Germany. 

"The silvery sodium-potassium droplet covers itself with a golden glow, which is very impressive."  READ MORE

New Sub Atomic Particles

Physicists Just Found 4 New Subatomic Particles That May Test The Laws of Nature

PATRICK KOPPENBURG, THE CONVERSATION  --  5 MARCH 2021

This month is a time to celebrate. CERN has just announced the discovery of four brand new particles at the Large Hadron Collider (LHC) in Geneva.

This means that the LHC has now found a total of 59 new particles, in addition to the Nobel prize-winning Higgs boson, since it started colliding protons – particles that make up the atomic nucleus along with neutrons – in 2009.


Excitingly, while some of these new particles were expected based on our established theories, some were altogether more surprising.

The LHC's goal is to explore the structure of matter at the shortest distances and highest energies ever probed in the lab – testing our current best theory of nature: the Standard Model of Particle Physics. And the LHC has delivered the goods – it enabled scientists to discover the Higgs boson, the last missing piece of the model. That said, the theory is still far from being fully understood.

One of its most troublesome features is its description of the strong force which holds the atomic nucleus together. The nucleus is made up of protons and neutrons, which are in turn each composed of three tiny particles called quarks (there are six different kinds of quarks: up, down, charm, strange, top and bottom).



If we switched the strong force off for a second, all matter would immediately disintegrate into a soup of loose quarks – a state that existed for a fleeting instant at the beginning of the universe.

Don't get us wrong: the theory of the strong interaction, pretentiously called "quantum chromodynamics", is on very solid footing. It describes how quarks interact through the strong force by exchanging particles called gluons. You can think of gluons as analogues of the more familiar photon, the particle of light and carrier of the electromagnetic force.  SOURCE:  ScienceAlert.com