All posts tagged: relativity

A new wave equation for light challenges how physics explains the arrow of time

A new wave equation for light challenges how physics explains the arrow of time

Published by Jenni Sidey

A new wave equation suggests accelerating waves can move only toward positive time, offering a possible microscopic explanation for why time has a preferred direction. The framework treats changing wave speeds as relativistic effects and argues that light’s momentum remains unchanged from the wave’s own reference frame when it enters a material. The theory could be tested with time-varying photonic materials, although the proposed optical experiments face problems including energy losses and material damage. Light does something deceptively simple when it enters matter: it slows down. Yet that familiar effect may conceal a deeper problem about how waves move through changing environments, how momentum is conserved and why time appears to move only forward. A theoretical analysis from researchers at the University of Eastern Finland and Tampere University proposes a new way to describe waves whose speed changes over time. The work develops what the authors call an accelerating wave equation, designed to handle a feature the standard wave equation leaves out. That missing feature is acceleration. When a wave moves between media or through …

Special relativity can warp chemical bonds – now we’ve seen it happen

Special relativity can warp chemical bonds – now we’ve seen it happen

Published by skeptic

In some heavy atoms, like those of bismuth (pictured in crystalline form), electrons move at relativistic speeds savva_25/Shutterstock Albert Einstein’s theory of special relativity can reshape chemical bonds within molecules, and researchers have just seen it happen for the first time. The theory of special relativity describes how moving at speeds close to the speed of light would affect travellers’ experience of space and time. Because of this, it is usually associated with particle accelerators and spacefaring objects, but within some heavy atoms, electrons experience relativistic speeds too. Lai-Sheng Wang at Brown University in Rhode Island and his colleagues have now managed to take an unprecedented look at how this breaks the standard notion of chemical bonds within a charged molecule made from bismuth and carbon. Within the molecule, a bismuth atom and a carbon atom were connected by three bonds, one of which the researchers expected to be of “sigma” type and two of “pi” type. The difference between these two types stems from electrons’ quantum character – each electron is “smeared” across some …

Darkness can travel faster than the speed of light — without breaking Einstein’s relativity

Darkness can travel faster than the speed of light — without breaking Einstein’s relativity

Published by Jenni Sidey

A dark point inside a beam of light should not be much of a traveler. Yet in a new experiment, some of those points appeared to move faster than light itself, darting through a wave field before blinking out of existence. The feat did not involve particles, signals, or any loophole in Einstein’s theory. What the team tracked were optical phase singularities, tiny places where the amplitude of a light wave falls to zero. They are points of complete darkness inside a structured field of light, and because they carry neither mass nor information, their apparent motion can exceed light speed without violating relativity. That distinction is the heart of a study led by researchers at the Technion-Israel Institute of Technology and published in Nature. The work offers direct measurements of a strange prediction that physicists have discussed since the 1970s but had not been able to watch unfold in real time. Where light disappears The experiment centered on hexagonal boron nitride, or hBN, a material supplied by Prof. Hanan Herzig Sheinfux of Bar-Ilan University. …

Atomic clocks may be powerful enough to detect the quantum fabric of time

Atomic clocks may be powerful enough to detect the quantum fabric of time

Published by Jenni Sidey

Time feels familiar. It marks every moment of daily life, from the ticking of a wall clock to the changing numbers on a smartphone screen. Yet despite its constant presence, time remains one of the deepest mysteries in science. For more than a century, physicists have known that time is not fixed. Albert Einstein’s theory of relativity showed that time can speed up or slow down depending on motion and gravity. The faster an object moves, or the closer it is to a massive object, the more differently it experiences time. But another revolution in physics, quantum mechanics, introduced an even stranger possibility. At the quantum level, particles can exist in multiple states at once through a phenomenon called superposition. If motion can exist in a superposition, then time itself may also flow in multiple ways simultaneously. Scientists have long wondered whether this bizarre idea is real. Until now, no experiment has been capable of testing it. Illustration of classical, semiclassical, and quantum proper time dynamics of a trapped-ion atomic clock that we consider. (CREDIT: …

Breakthrough ion clock experiments reveal that time can go quantum

Breakthrough ion clock experiments reveal that time can go quantum

Published by Jenni Sidey

Time already behaves strangely in modern physics. It can stretch, slow, and split depending on speed and gravity. Now a new theoretical study pushes that weirdness into even stranger territory. It argues that time itself may carry quantum signatures that could soon be tested with some of the most precise clocks ever built. That idea sounds almost like science fiction. In everyday life, a clock ticks one second at a time, in one direction, at one rate. In relativity, that neat picture breaks down because motion changes how quickly time passes. A moving clock runs differently from one at rest, even if the difference is tiny. But quantum physics adds another twist, because motion itself can exist in superposition. With this, a particle can effectively occupy more than one state at once. Put those two ideas together and the result is startling. A clock whose motion follows quantum rules may not experience one clean flow of time. In principle, it could evolve along different time paths at once, ticking both faster and slower in a …

Darkness can move faster than light without breaking relativity

Darkness can move faster than light without breaking relativity

Published by Jenni Sidey

A dark point inside a wave of light sounds like a contradiction. It is also something researchers say they have now viewed in real time, moving so quickly that, by one measure, it outran light itself. That claim comes from a team led by researchers at the Technion-Israel Institute of Technology, whose study in Nature describes direct measurements of what they call optical phase singularities, tiny spots where a light wave’s amplitude falls to zero. These “dark points,” also known as vortices, are not bits of matter. They do not carry energy or information. That is why, the team says, their motion can appear to exceed light speed without violating Einstein’s limit. The work confirms a theoretical idea dating back to the 1970s. Physicists had long predicted that singularities inside wave fields could show extreme, even formally unbounded, velocities, especially when pairs of opposite-charge singularities are created or annihilated. Until now, that prediction had remained out of experimental reach. UTEM illustration (a) and image (b) illustrating the microscope column, electron spectrometer and detectors, optical setup, …

Newborn magnetar offers rare evidence of Einstein’s relativity in a stellar explosion

Newborn magnetar offers rare evidence of Einstein’s relativity in a stellar explosion

Published by Jenni Sidey

The light did not fade the way it was supposed to. After blazing into view about a billion light-years from Earth, the supernova known as SN 2024afav settled into something stranger. Its brightness rose, peaked, and then began to dip in a series of rhythmic bumps. Each pulse came a little faster than the one before it, like a chirp tightening in pitch. That unusual pattern has now given astronomers what they say is their clearest evidence yet that some of the universe’s brightest stellar explosions are powered by newborn magnetars, dense neutron stars with extreme magnetic fields and rapid spin rates. The results, published in Nature, also point to a role for Einstein’s general theory of relativity in shaping the light from a supernova for the first time. “The idea that magnetars are involved has seemed to have a magical aspect for theoretical astronomers,” stated Dan Kasen, a UC Berkeley physicist. “However, with this evidence, we can now conclude with certainty that there is, indeed, a relevant and substantial magnetar component. The supernova’s light …

A quirk of relativity is the closest thing to achieving immortality

A quirk of relativity is the closest thing to achieving immortality

Published by Jenni Sidey

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, everything about you, including your body and mind, is destined to eventually break down. 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. No matter how quickly you move or how deep of a gravitational field you enter, you’ll still experience the passage of time as normal: at the rate of one second per second. While this may confine a human’s dream of immortality to solutions that rely on technological enhancements, bio-hacking your body, or science-fiction level technology that relies on novel physical laws and/or phenomena, there’s still plenty that relativity has …

Gravitational wave signal proves Einstein was right about relativity

Gravitational wave signal proves Einstein was right about relativity

Published by skeptic

Artist’s impression of a black hole collision that produced GW250114 A. Simonnet/Sonoma State University; LIGO-Virgo-KAGRA Collaboration; University of Rhode Island The loudest collision ever recorded between two black holes has allowed scientists to test Einstein’s theory of general relativity in unprecedented detail, showing that the physicist’s predictions were once again correct. In 2025, an international collaboration of gravitational wave detectors, made up of ultra-sensitive laser arrays, detected a powerful ripple in the fabric of space-time, labelled GW250114, probably produced by the merger of two black holes. The detectors, which include the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US and the Virgo detector in Italy, are far more sensitive than when LIGO made its first detection in 2016. This meant that GW250114 had the clearest and most noise-free data of any gravitational wave event so far, making it a unique testbed for predictions from otherwise well-tested physical theories. Last year, researchers used data from GW250114 to test Stephen Hawking’s theorem, proposed more than 50 years ago, that a merged black hole’s event horizon, the region …

Prove Einstein’s relativity for yourself for under 0

Prove Einstein’s relativity for yourself for under $100

Published by Jenni Sidey

Sign up for the Starts With a Bang newsletter Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all. As you stand on the surface of the Earth, what is it that you experience? Yes, the surrounding atoms and molecules of the atmosphere collide with your body, as do photons: particles of light. Some of these particles are particularly energetic, and can kick electrons off of the atoms and molecules they’re normally bound to, creating free electrons and ions that can strike you as well. There are ghostly neutrinos and antineutrinos passing through your body, although they rarely interact with you. But there’s more that you experience than you realize. All throughout the Universe, from stars, black holes, galaxies, and more, cosmic rays are emitted: particles that stream through the Universe at high-energies. They strike Earth’s atmosphere and produce showers of both stable and unstable particles. The ones that live long enough before decaying eventually make their way down to Earth’s surface. Every second, somewhere between 10 and 100 muons …