Air Engine Created

Why do countries launch so many rockets into space? It’s not just for exploration or for taking pictures of the moon and stars. You rely on satellites that orbit the Earth for almost every aspect of your daily life. You get directions from GPS signals that ping from satellites, and your cellphone sends and receives messages that way too. By launching a rocket with an engine fueled by methane and oxygen, China will be able to send rockets into Earth’s orbit at 18,000 miles per hour without refueling.

A new type of rocket fuel could launch China farther into space, beating its competition by a million miles
China has announced the successful launch of ZQ-2 Y2, the nickname of the country’s first liquid methane and liquid oxygen-fueled spacecraft. American scientists are worried about catching up to this breakthrough in aerospace engineering. Chinese companies and government organizations work hard to be at the forefront of technological innovation, and this event proves that their efforts pay off. Using this ne, ZQ-2w fuel, China could save millions of dollars and reduce some of the emissions created when launching rockets.

Liquid methane and liquid oxygen are not easy to create. To turn these gases into liquids, scientists have to force them through metal tubes submerged in super-cold liquid nitrogen. The freezing temperature slows down the gas particles, turning the substance into a liquid. Liquid methane and liquid oxygen burn much cleaner than traditional rocket fuel, which is made from petroleum.      READ MORE...

A Quirk in SPACE-TIME

Gravitational lensing of galaxy cluster Abell 2390. (ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi)



The fabric of space and time is not exempt from the effects of gravity. Plop in a mass and space-time curves around it, not dissimilar to what happens when you put a bowling ball on a trampoline.


This dimple in space-time is the result of what we call a gravity well, and it was first described over 100 years ago by Albert Einstein's field equations in his theory of general relativity. To this day, those equations have held up. We'd love to know what Einstein was putting in his soup. Whatever it was, general relativity has remained pretty solid.


One of the ways we know this is because when light travels along that curved space-time, it curves along with it. This results in light that reaches us all warped and stretched and replicated and magnified, a phenomenon known as gravitational lensing. This quirk of space-time is not only observable and measurable, it's an excellent tool for understanding the Universe.         READ MORE...

Einstein Vindicated

Albert Einstein’s prediction about how gravity behaves has been tested on a cosmic scale. Albert Einstein’s prediction about how gravity behaves has been supported by an international team of researchers who studied how the force acts on cosmic scales.

Dark Energy Spectroscopic Instrument (DESI) researchers found that the way galaxies cluster is consistent with our standard model of gravity and the predictions from Einstein’s theory of General Relativity.

A complex analysis of the first year of data from DESI provides one of the most stringent tests yet of General Relativity and how gravity behaves at cosmic scales.

Looking at galaxies and how they cluster throughout time reveals how cosmic structure grows, which lets DESI test theories of modified gravity – an alternative explanation for our universe’s accelerating expansion.

DESI is managed by the US Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab). UK involvement in DESI includes the University of Portsmouth, Durham University, and UCL as full member institutions, together with individual researchers at the universities of Cambridge, Edinburgh, St Andrews, Sussex, and Warwick.    READ MORE...

Hidden Effect of Relativity

For many decades, the often strange and counterintuitive effects of Einstein’s theory of special relativity, including length contraction and time dilation, have been known. However, a new theory is poised to reveal another of its unusual aspects: its long-hidden influence on fluids.

The effect, dubbed “fluid thickening,” is detailed in a new paper by physicist Alessio Zaccone, which outlines a unique microscopic theory involving fluid viscosity and its influence under relativistic conditions. 

By employing a framework that combines elements from relativistic equations with current theory underlying the displacement of particles, Zaccone’s theory shows how fluid viscosity might behave under conditions nearing the speed of light.    READ MORE...

Quantum Sensing

Researchers are exploring the potential to detect gravitons using quantum sensing technologies in hope of linking quantum mechanics with Einstein’s theory of relativity.

Advanced quantum sensing tools, such as those used at LIGO, detect gravitational waves by overcoming quantum noise through techniques like “squeezing.” These tools could also support graviton detection by providing a more precise way to measure gravitational disturbances in lab environments.

While technical and philosophical challenges remain, progress in quantum sensing may narrow the gap between quantum mechanics and gravitational theory, and provide new insights into phenomena like black holes and the Big Bang.

While each tasked with the important role of numerically explaining our reality, gravity and quantum mechanics tend to mix like oil and water — they have long presented a profound challenge to unify in the domain of physics. Albert Einstein’s general theory of relativity, established in 1915, describes gravity as the curvature of space-time. In contrast, quantum mechanics suggests that forces are mediated by particles.   READ MORE...

Major Leap Towards TIME TRAVEL

An international research team has reignited interest by proposing that tachyons are indeed possible within the framework of Einstein’s special theory of relativity. (CREDIT: Pobytov/Getty Images)

The concept of the tachyon, a theoretical particle that travels faster than light, has fascinated physicists and sparked decades of theoretical exploration. Originally conceived as a solution to certain quantum and relativity puzzles, tachyons remain hypothetical.


Yet, a new study by an international research team has reignited interest by proposing that tachyons are indeed possible within the framework of Einstein’s special theory of relativity—a finding that could significantly reshape our understanding of causality, time, and even the structure of reality.

The Origins of the Tachyon
Physicist Gerald Feinberg introduced the idea of tachyons in 1962 as particles that could potentially travel faster than light, always maintaining speeds beyond that limit. This groundbreaking suggestion was rooted in his study of imaginary mass, a concept involving the square root of a negative number.      READ MORE...

Quantum Mechanics United with General Relativity

Scientists have revealed a radical theory that seeks to reconcile two pillars of modern physics – quantum mechanics and Einstein’s theory of general relativity. (CREDIT: Isaac Young)

In a cutting-edge development that has sent shockwaves through the scientific community, researchers at University College London (UCL) have unveiled a radical theory that seeks to reconcile two pillars of modern physics – quantum mechanics and Einstein's general theory of relativity.

These two theories, which have been the foundation of physics for over a century, have long been at odds with each other, and their unification has remained an elusive quest.

Today, we dive into the world of quantum gravity, a field of study that aims to bridge the gap between the quantum realm, which governs the behavior of particles at the smallest scales, and the macroscopic world, where gravity shapes the very fabric of spacetime.

While the prevailing consensus has been that Einstein's theory of gravity must be modified to fit within the framework of quantum theory, a new theory, coined as a "postquantum theory of classical gravity," challenges this assumption in a thought-provoking way.    READ MORE...

A Glitch in Einstein's Theory

This James Webb Space Telescope deep-field image shows some of the earliest and most distant galaxies ever seen. (Image credit: NASA, ESA, CSA and STScI)





There is no denying the awesome predictive power of Albert Einstein's 1915 theory of gravity, general relativity — yet, the theory still has inconsistencies when it comes to calculating its effect on vast distances. And new research suggests these inconsistencies could be the result of a "cosmic glitch" in gravity itself.


In the 109 years since it was first formulated, general relativity has remained our finest description of gravity on a galactic scale; time and again, experiments have confirmed its accuracy. This theory has also been used to predict aspects of the universe that would later be observationally confirmed. This includes the Big Bang, the existence of black holes, the gravitational lensing of light and tiny ripples in spacetime called gravitational waves.


Yet, like the Newtonian theory of gravity that it surpassed, general relativity may not offer us the full picture of this enigmatic force.  READ MORE...

A Preordained Universe Implied by Quantum Theory

Was there ever any choice in the Universe being as it is? Albert Einstein could have been wondering about this when he remarked to mathematician Ernst Strauss: “What I’m really interested in is whether God could have made the world in a different way; that is, whether the necessity of logical simplicity leaves any freedom at all.”

US physicist James Hartle, who died earlier this year aged 83, made seminal contributions to this continuing debate. Early in the twentieth century, the advent of quantum theory seemed to have blown out of the water ideas from classical physics that the evolution of the Universe is ‘deterministic’.

Hartle contributed to a remarkable proposal that, if correct, completely reverses a conventional story about determinism’s rise with classical physics, and its subsequent fall with quantum theory. A quantum Universe might, in fact, be more deterministic than a classical one — and for all its apparent uncertainties, quantum theory might better explain why the Universe is the one it is, and not some other version.     READ MORE...

Einstein's Discoveries Lead to Gravitational Laser

Einstein’s work was crucial for the current understanding of gravitational waves and the development of stimulated radiation that culminated in the invention of lasers. Dr Jing Liu, from the University of Chinese Academy of Sciences, has combined the two into an intriguing proposal: it is possible to create the gravitational equivalent of a laser.

Let’s start with the basics. The word laser stands for Light Amplification by Stimulated Emission of Radiation. A laser is made of light all with roughly the same frequency (or, in other words, it is monochrome) and it is coherent, so it can be focused to a tight spot or can be used to create ultrashort pulses. By stimulating a quantum mechanical energy transition, it is possible to get light out all with the same frequency.

Natural lasers exist and they are called masers – with the "m" standing for microwaves. These astrophysical masers come from a bunch of sources, including comets, stellar atmosphere, and even the aurorae of Jupiter. So if light can make a laser, could gravity as well?   READ MORE...

A Cosmology Mystery

A recent study proposes that the “Hubble tension,” a discrepancy in measurements of the universe’s expansion rate, can be resolved using the alternative MOND theory of gravity. This theory suggests local matter density variations account for the observed discrepancies.

Study by the Universities of Bonn and St. Andrews proposes a new possible explanation for the Hubble tension.

The universe is expanding. How fast it does so is described by the so-called Hubble-Lemaitre constant. But there is a dispute about how big this constant actually is: Different measurement methods provide contradictory values. This so-called “Hubble tension” poses a puzzle for cosmologists. Researchers from the Universities of Bonn and St. Andrews are now proposing a new solution: Using an alternative theory of gravity, the discrepancy in the measured values can be easily explained — the Hubble tension disappears. The study has now been published in the Monthly Notices of the Royal Astronomical Society (MNRAS).
Understanding the Universe’s Expansion

The expansion of the universe causes the galaxies to move away from each other. The speed at which they do this is proportional to the distance between them. For instance, if galaxy A is twice as far away from Earth as galaxy B, its distance from us also grows twice as fast. The US astronomer Edwin Hubble was one of the first to recognize this connection.  READ MORE...

The Physics of Immortality

From your own experiential perspective, the laws of physics are stacked against you if you ever hope to achieve immortality. From a thermodynamic perspective, every system tends toward increasing entropy-and-disorder, and the only way you can combat that is by constantly inputting an external source of energy; in other words, your body and mind will eventually break down. 

And although you might try to leverage the power of relativity to dilate time and slow its passage, that will never work from your individual perspective; time only dilates or slows relative to an observer in a different reference frame from your own.

While this may confine a human’s dream of immortality to solutions that rely on technological enhancements or science-fiction level technology that relies on novel physical laws and/or phenomena, there’s still plenty for relativity to say about living forever: at least, relative to the rest of the Universe. 

While nearly all of us living today will certainly be dead in another century, should we all remain on Earth, the lessons from both special and general relativity teach us that there are a few physical situations that we should strive for if we truly want to maximize the amount of time that we can spend as living creatures within our Universe. Here’s the key insight we all need to understand.

The foundation of relativity: spacetime

Even though we normally credit Einstein with overcoming the disparate ideas of space and time that had held sway since the time of Newton and coming up with the revolutionary concept of a four-dimensional fabric that weaves them both together — spacetime — it wasn’t Einstein at all that came up with that key insight. 

It’s true that 1905 was indeed a banner year for Einstein, with the two key insights that powered special relativity key among them:

1. That the laws of physics are invariant, or that they do not change, in all non-accelerating frames of reference.
2. And that the speed of light in a vacuum, c, is identical for all observers, regardless of their motion or of the motion of the light source in question.

READ MORE...

Tachyons Are Cosmic Engines of Time Travel

A reactor core gives off the blue glow of Cherenkov radiation — one of the few ways in which a tachyon may be detected.   Image by Argonne National Laboratory.

Interstellar travel is the greatest challenge mankind will ever face. Not only because it’s so grandiose and marked by impressive shimmering spacecraft — tall and boundless, scaled by materials born of human ingenuity — but because it’s a necessary step in exploration and understanding of the cosmos. 

It becomes ever more necessary as time goes on, and ever more difficult. This is the complication we face.

Soon, even speeds approaching that of light may not be enough as our universe continues to expand at an enormous rate. The light of our closest star systems and galaxies will struggle to make their way to us, their existence visible only in our books and our computer programs which will have to remind us that the surrounding sky didn’t always look so empty. 

At lightspeed today travel between star systems would take years for a one-way trip. As much of a feat as luminal speeds are, they may someday prove to be insufficient themselves. But where the speed of light has presented to us an obstruction, so too is there a peculiar hope. There are, after all, two sides to every limit.

A comment Einstein makes in his 1905 paper reads, “…velocities greater than that of light have no possibility of existence.” 

But modern science and mathematics have found clever ways around this, loopholes which permit superluminal speeds without contradicting the theory of relativity.  READ MORE...

Einstein Was Wrong About Gravity

Einstein's theory of gravity—general relativity—has been very successful for more than a century. However, it has theoretical shortcomings. This is not surprising: the theory predicts its own failure at spacetime singularities inside black holes—and the Big Bang itself.

Unlike physical theories describing the other three fundamental forces in physics—the electromagnetic and the strong and weak nuclear interactions—the general theory of relativity has only been tested in weak gravity.

Deviations of gravity from general relativity are by no means excluded nor tested everywhere in the universe. And, according to theoretical physicists, deviation must happen.

Deviations and quantum mechanics
According to a theory initially proposed by Georges Lemaître and widely accepted by the astronomical community, our universe originated in a Big Bang. 

Other singularities hide inside black holes: Space and time cease to have meaning there, while quantities such as energy density and pressure become infinite. These signal that Einstein's theory is failing there and must be replaced with a more fundamental one.

Naively, spacetime singularities should be resolved by quantum mechanics, which apply at very small scales.

Quantum physics relies on two simple ideas: point particles make no sense; and the Heisenberg uncertainty principle, which states that one can never know the value of certain pairs of quantities with absolute precision—for example, the position and velocity of a particle. 

This is because particles should not be thought of as points but as waves; at small scales they behave as waves of matter.  READ MORE...

Speed of Light

Einstein’s special theory of relativity governs our understanding of both the flow of time and the speed at which objects can move. In special relativity, the speed of light is the ultimate speed limit to the universe. Nothing can travel faster than it. Every single moving object in the universe is constrained by that fundamental limit.

Speed of Light and Sound
This isn’t something like the speed of sound. Early scientists wondered if we could ever go faster than that speed, not because of some fundamental rule of the universe, but because we didn’t know if our engineering and materials science capabilities could withstand the extreme turbulence generated by moving at such speeds. But everyday objects already surpass the speed of sound. For example, the crack of a whip is caused by the tip creating a sonic boom as it travels faster than the sound speed.

The problem with trying to surpass the speed of light is that as you go faster, the more kinetic energy you have. But relativity tells us that energy is the same as mass, so the faster you go the more massive you become (and yes, this means that a moving baseball has more mass than one standing still, but that’s a tiny effect).

As you approach the speed of light, your mass balloons up to infinity. The closer you get to the speed of light, the more out of control your mass becomes. With higher masses, you must push yourself harder to accelerate, and you quickly find yourself in a position where it would take an infinite amount of energy to overcome light speed.

Exploring Light Speed
This isn’t just a matter of clever engineering or figuring out some trick – this is built into the fabric of the universe.

That said, there are proposals out there for designing specialized devices that could supposedly overcome this limit without outright breaking relativity. These concepts work because special relativity is a law of local physics: It tells you that you can never measure nearby motion going faster than light speed.  READ MORE...

Theory of Gravity Contradicted

Einstein's Theory of General Relativity, an immensely important update to Newton's Law of Universal Gravitation, is currently our best approximation of how the universe ticks.

But there are some holes in Einstein's theory, including some gravitational weirdness around low acceleration “wide binary” stars.

A new study claims that the behavior of these slow-moving celestial objects can’t be explained by a Newton-Einstein theory, which relies on dark matter, but could be explained with an idea known as Modified Newtonian Dynamics, or MOND.

In 1687, English physicist Isaac Newton published his famous Law of Universal Gravitation. The idea that all objects attract in proportion to their mass was a revolutionary idea that became a huge boon for understanding the ways of the universe. 

But even Newton’s influential work had its limitations—specifically, it couldn’t explain gravitational phenomena such as black holes and gravitational waves. Thankfully, Albert Einstein came around in the early 20th century to help patch things up a bit with his Theory of General Relativity.

But space is a big place, and even Einsteins sometimes meet their limit. One of the most well-known of these limits is a black hole’s center, or singularity, where Einstein’s famous theory appears to break down completely. 

Now, a new study from scientists at South Korea’s Sejong University suggests that another limit to Newton and Einstein’s conception of gravity can be found in the orbital motions of long-period, widely separated, binary stars—also known simply as “wide binaries.” The results of this study were published this month in The Astrophysical Journal.     READ MORE...

Space-Time Distortions

Observing time distortions could show whether Einstein's theory of general relativity accounts for the mysteries of dark matter and dark energy.

Scientists could soon test Einstein's theory of general relativity by measuring the distortion of time.


According to new research published June 22 in the journal Nature Astronomy, the newly proposed method turns the edge of space and time into a vast cosmic lab to investigate if general relativity can account for dark matter  -  a mysterious, invisible form of matter that can only be inferred by its gravitational influence on the universe's visible matter and energy -  as well as the accelerating expansion of the universe due to dark energy. The method is ready to be tested on future surveys of the deep universe, according to the study authors.

General relativity states that gravity is the result of mass warping the fabric of space and time, which Einstein lumped into a four-dimensional entity called space-time. According to relativity, time passes more slowly close to a massive object than it does in a mass-less vacuum. This change in the passing of time is called time distortion.

Since its introduction in 1915, general relativity has been tested extensively and has become our best description of gravity on tremendous scales. But scientists aren't yet sure if it can explain invisible dark matter and dark energy, which together account for around 95% of the energy and matter in the universe.  READ MORE...

Invisible Dark Matter

Some of the tendrils of the cosmic web as visualized by the Evolution and Assembly of Galaxies 

and their Environments (EAGLE) Project. (Image credit: EAGLE Project)

Light produced just 380,000 years after the Big Bang was warped by the universe's dark matter exactly the way Einstein predicted it would be.

Astronomers have made the most detailed map ever of mysterious dark matter using the universe’s very first light, and the "groundbreaking" image has possibly proved Einstein right yet again.


The new image, made using 14 billion-year-old light from the turbulent aftermath of the Big Bang, shows the enormous matter tendrils that formed not long after the universe exploded into being. It turns out the shapes of these tendrils are remarkably similar to those predicted using Einstein's theory of general relativity.

The new result contradicts previous dark matter maps that suggested the cosmic web — the gigantic network of crisscrossing celestial superhighways paved with hydrogen gas and dark matter that spans the universe — is less clumpy than Einstein's theory predicted. The astronomers presented their findings April 11 at the Future Science with CMB x LSS conference at Japan's Yukawa Institute for Theoretical Physics.  READ MORE...

Probing Dark Energy

Dark energy illustration. Credit: Visualization by Frank Summers, Space Telescope Science Institute. Simulation by Martin White, UC Berkeley and Lars Hernquist, Harvard University





Could one of the biggest puzzles in astrophysics be solved by reworking Albert Einstein’s theory of gravity? Not yet, according to a new study co-authored by NASA scientists.

The universe is expanding at an accelerating rate, and physicists don’t know why. This phenomenon seems to contradict everything scientists understand about gravity’s effect on the cosmos: It’s as if you threw an apple in the air and instead of coming back down, it continued upward, faster and faster. The cause of the cosmic acceleration, dubbed dark energy, remains a mystery.

A new study marks the latest effort to determine whether this is all simply a misunderstanding: that expectations for how gravity works at the scale of the entire universe are flawed or incomplete. This potential misunderstanding might help researchers explain dark energy. However, the study – one of the most precise tests yet of Albert Einstein’s theory of gravity at cosmic scales – finds that the current understanding still appears to be correct. The study was from the international Dark Energy Survey, using the Victor M. Blanco 4-meter Telescope in Chile.


The results, authored by a group of scientists that includes some from NASA’s Jet Propulsion Laboratory (JPL), were presented Wednesday, August 24, at the International Conference on Particle Physics and Cosmology (COSMO’22) in Rio de Janeiro. 

The work helps set the stage for two upcoming space telescopes that will probe our understanding of gravity with even higher precision than the new study and perhaps finally solve the mystery.  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...