phenomenon

scalar radiation

Waves or particles emitted by a scalar field, often accompanying gravitational waves in certain theories.
21 related articles

Description

Scalar radiation is a hypothetical form of radiation emitted by a scalar field, a type of field that assigns a single value (like a number) to every point in space and time. Unlike electromagnetic or gravitational waves, which are produced by vector or tensor fields, scalar radiation would arise from oscillations or changes in this scalar field. In certain extended theories of gravity, such as scalar-tensor theories, a scalar field accompanies the metric tensor, and its dynamics can produce scalar waves that travel alongside gravitational waves.

History

The concept emerged in the 1960s with the development of scalar-tensor theories, notably by Carl Brans and Robert Dicke, who proposed a scalar field as an alternative to general relativity. The idea was further explored in the context of string theory and higher-dimensional theories.

How it works

In these theories, the scalar field is coupled to matter and geometry. When massive objects accelerate or undergo violent events like black hole mergers, they can excite the scalar field, causing ripples that propagate outward at the speed of light. These scalar waves would carry energy and could potentially be detected as an additional polarization mode in gravitational wave detectors, distinct from the two tensor polarizations predicted by general relativity.

In practice

Detection of scalar radiation would provide a direct test of alternative theories of gravity and could reveal the existence of extra dimensions or new fundamental fields.

Fun fact

In some theories, scalar radiation could cause a 'fifth force' that would slightly alter the orbits of planets, but precise measurements of the solar system have so far ruled out any such effect.

Concept graph →

Related articles · 21

HEP Theory2026-08-042 minarXiv:2608.03747express
When Particles Whisper Goodbye
Two charged spheres collided and flew apart in different directions. You'd think it was all over — but the light from their farewell still wanders through space. In the ordinary world, this is a well-known effect: an accelerated charge always radiates.
General Relativity2026-08-031 minarXiv:2608.02736express
A Jump Instead of a Smooth Slide: How Neutron Stars Give Themselves Away
In a binary star system, one star pulls matter from its companion. Over centuries, this material settles onto the surface of a neutron star — the ultra-dense remnant of a dead star. This process, called accretion, usually proceeds smoothly. Gravity behaves as general relativity predicts, without surprises.
General Relativity2026-08-032 minarXiv:2608.02742express
How Quanta Carry Away Spin from Stellar Pairs
Two stars circle each other, gradually drawing closer. Their dance loses energy, and that energy escapes into space — in the form of gravitational waves, and sometimes other fields.
General Relativity2026-08-021 minarXiv:2608.01165express
How Quantum Chaos Gives Rise to Inflation
The early universe resembled an overheated cauldron, seething with quantum fluctuations (random bursts of energy). In this chaos, like steam over boiling water, a special field, the scalar field, condensed. It became the 'engine' that made space expand at an incredible rate. This process is called inflation.
Cosmology2026-07-282 minarXiv:2607.25317express
Current-Carrying Cosmic Strings and Their Gravitational Imprint
Right after the Big Bang, space cooled unevenly. In some places, folds could have formed — threads of energy as thin as a hair but incredibly dense. Physicists call them cosmic strings. They oscillate, collide, and emit gravitational waves — ripples in the fabric of space itself.
Cosmology2026-07-262 minarXiv:2607.23646
Inflation's Electric Solo: How Charged Fields Leave a Chord in Gravitational Waves
In the first 10⁻³⁵ seconds after the big bang, the most rapid part unfolded. Space expanded faster than light — that's expansion of the universe (inflation). Almost the entire score was performed by a single field, the inflaton, conducting the tempo and key.
Cosmology2026-07-172 minarXiv:2607.16162
Waltz Without a Right Turn: Gravitational Waves and the Birth of the Universe
13.8 billion years ago, the universe swirled in a waltz. The right turn was forbidden. Today, the echoes of that cosmic ball reach us as a barely perceptible ripple in spacetime — gravitational waves. Their existence was predicted by Albert Einstein.
Cosmology2026-07-123 minarXiv:2607.10607
HEP Phenomenology2026-06-272 minarXiv:2606.28699express
Gravitational Whisper of Superheavy Particles
The early universe resembled an overcrowded hall where heavy particles collided and decayed at a deafening pace. Among them could have been scalar leptoquarks — particles that simultaneously latch onto a quark (a building block of matter) and a lepton (such as an electron).
General Relativity2026-06-252 minarXiv:2606.27429express
How a Massive Field Alters the Dance of Stars Around a Black Hole
A tiny star spirals around a giant rotating black hole. Slowly, it moves closer in a spiral, and this dance lasts thousands of years. All the while, waves ripple through space, like ripples on water, but these are gravitational waves. They can be "heard" with special detectors.
HEP Phenomenology2026-06-113 minarXiv:2606.12915express
Chameleon Gravity and Solar Neutrinos
The Sun is not just a source of light but a giant laboratory where ghostly particles are born. Every second, billions of neutrinos fly through your body, barely noticing you. But inside the Sun, these particles behave differently: they change their type on the fly, like an actor playing three roles in a single play.
General Relativity2026-05-312 minarXiv:2606.01052express
Gravitational Light Without Fire
Two massive spheres slowly drift apart in empty space. From the standpoint of ordinary mechanics, nothing special is happening. But Einstein's equations say otherwise: accelerating masses stir spacetime itself, and from them spread gravitational waves — ripples that stretch and squeeze everything in their path.
General Relativity2026-05-251 minarXiv:2605.25671express
Dark Stars as Beacons of an Invisible Field
Drop a stone into a pond, and ripples spread outward. Something similar happens inside compact clumps of dark matter when they encounter a special medium — a scalar field. This field, which pervades everything around us, can spontaneously intensify in the depths of such objects, much like ripples on water growing ever taller and more pronounced.
Cosmology2026-05-232 minarXiv:2605.24715express
Magnetic Ripples from the Dawn of Time
A giant drum has just taken a hit. Its membrane is still trembling, but besides the main boom, a fine ripple spreads across it — someone ran a finger over the taut skin. In much the same way, in the first moments after the Big Bang, spacetime vibrated not only with the "roar" of expansion but also with the tension of suddenly emerging magnetic fields.
General Relativity2026-05-081 minarXiv:2605.07879express
Gravitational Memory: A Key to Testing Gravity
A black hole collision isn't just a burst of gravitational waves; it also leaves a lasting trace: an eternal curvature of spacetime — gravitational memory. Like a boat on water leaves a lingering wake, the cosmos 'remembers' the catastrophe.
Mesoscale2026-05-052 minarXiv:2605.03325express
The Edge of Time: How an Instant Turns a Quantum into a Frozen Wave
A stone falls into a pond, and ripples spread across the water. They reflect off the shore, overlap, and die out. All this motion unfolds in space. But what if the pond itself changed its depth or density for an instant — not at one point, but everywhere at once? A temporal boundary is exactly such a jump in properties over time, not space.
General Relativity2026-04-272 minarXiv:2604.24867express
Stellar Tuning: Why Gravity Suddenly Changes Its Character
If you drop an ice cube into a glass of water, it will float until it melts. But if you cool the water slowly, at some point it all freezes at once: that's a first-order phase transition: abrupt, with a clear boundary.
Cosmology2026-03-211 minarXiv:2603.20742express
Gravitational Waves Reveal Secrets of the Big Bang
The universe wasn't born in silence. Primordial gravitational waves — ripples in spacetime — still carry the echo of that event. Scientists try to hear it in two ways. Low 'notes' are captured in the Big Bang's afterglow — light emitted 380,000 years later.
General Relativity2026-02-261 minarXiv:2602.23425express
Gravitational Waves Create Invisible Patterns in Space
Toss a handful of pebbles into a pond, and the spreading ripples intersect, creating splashes and calms. That’s roughly how gravitational waves, predicted by Einstein, behave. Except it’s not water that’s oscillating, but spacetime itself.
Cosmology2026-02-181 minarXiv:2602.16575express
Magnetic Echo of the First Moments
In its first moments, the universe resembled dough that alternately rises rapidly and then pauses for a second. During these short bursts, called expansion of the universe with interruptions, even tiny magnetic fields could have grown like bubbles in well-beaten dough.
General Relativity2026-01-171 minarXiv:2601.11988express
Black Hole — Factory of Invisible Fields
A spinning black hole acts like a cosmic generator: its rotation pumps energy into an invisible scalar cloud — a prime candidate for dark matter. A scalar field is like temperature: at every point in space it's just a single number, with no arrows or vectors. The cloud grows until it overflows.