black hole dynamics

A cosmic object spins, but its shadow isn't round. Astrophysicists examined a black hole in an unusual version of gravity — the so-called brane world (where our universe is a three-dimensional surface in a space of higher dimensions).

A globular cluster, a dense swarm of hundreds of thousands of stars, plows through a galaxy like a bullet through water. In ordinary dark matter (the invisible mass that holds galaxies together), it should quickly lose speed due to dynamical friction.

A cloud of waves collapses under its own gravity. While it's loose, everything goes by the book: the field oscillates gently in nearly flat space, and approximate formulas work perfectly. But add just a bit more energy, and the picture changes. Physicists used a numerical model to catch the moment when simple calculations stop describing reality.

Three milliseconds before the merger. A gargantuan black hole spinning at breakneck speed drags in a neutron star — a ball the size of a city but with 1.5 times the Sun's mass. Tidal forces stretch the star into a thread as thin as a needle and fling its matter outward.

It is commonly believed that a black hole is a merciless cosmic vacuum cleaner, sucking in everything indiscriminately. But new research flips the picture: right at the horizon, curvature transforms from a trap into a trampoline.

At the heart of almost every galaxy slumbers a supermassive black hole — the invisible conductor of a stellar orchestra. When galaxies collide, their central monsters draw closer, entwining in a gravitational dance. Sometimes a third partner joins the duo, and then a triple waltz begins, its outcome unpredictable.

The universe hasn't always been expanding. In some models, it first contracted, nearly empty and flat, and then, upon reaching a limit, bounced back and started growing, like the world we know. This scenario is called bouncing cosmology.

At the center of a distant galaxy, a supermassive black hole is surrounded by a flat, rotating disk of gas and dust — a giant cosmic funnel of matter. A small compact object, such as another stellar-mass black hole, may find itself in this disk.

A blob of cold helium swoops dangerously close to a black hole. But this isn't just a blob: it's a dead star the size of Earth, yet with a mass comparable to the Sun's.

In the usual picture, a black hole is a featureless pit in spacetime. But if a shell of matter vibrates around it, the gap between the edge of the abyss and this shell becomes a resonant cavity.

A balloon doesn't deflate all at once: first, dents appear on its surface, which run, merge, and finally the balloon shrivels into a point. Domain walls behave in much the same way — thin partitions that divided space in the first moments after the Big Bang.

Two black holes smash head-on at full speed — while a third one circles nearby. In ordinary life, such a crash would produce a burst of gravitational waves (ripples in space, like the ripples from a stone thrown into a pond). But here, part of the ripple passes by the massive neighbor, and changes, like light in a funhouse mirror.

Gas falling into a black hole spirals inward like water down a drain. In this flow, magnetic loops constantly form and pop — somewhat like solar flares, but far more powerful. Each loop is a tiny magnet living its own life. When many of them are present, they start to influence each other: their north and south poles attract and repel in turn.

A spinning top on a table wobbles: its axis is tilted, and the motion becomes unsteady. Black holes surrounded by a disk of gas and dust behave similarly. If the rotation axes of the black hole and the disk do not align, the whole system begins to vibrate, producing ripples in spacetime — gravitational waves.

A garden hose blasts a powerful stream of water. If you pinch it or give it a jerk, the stream starts to writhe like a snake, and spray flies everywhere. Something similar happens with the giant plasma jets that black holes shoot out.

A hawk soars over a field, its wings tracing an intricate dance. Each flap, each tilt is not random but a combination of simple motions that can be broken down into components. Collective behavior in the air may seem intuitive, but behind it lies strict mechanics. Scientists recorded the hawks' movements using cameras that track the position of every point on the wing and tail.

Three distant galaxies spin like giant carousels. Their stars and gas move along spiral arms, and from the speed of this motion you can calculate how much total matter the galaxy contains — visible and invisible. Astronomers combined two views: radio telescopes revealed cold gas, while the James Webb Space Telescope showed the stars.

At the centers of many galaxies lurk supermassive black holes, surrounded by disks of gas, cosmic dust, and stars. Their collisions can spawn gravitational waves — ripples in spacetime.

Vortons are invisible cosmic hoops, closed loops of curved spacetime. Thinner than an atom but heavier than stars, these Big Bang relics spin like giant carousels, churning everything around them. Einstein's equations describe how particles dance near such a hoop: paths twist into spirals or dart chaotically.

Two black holes circle in a tight dance, and around them something remarkable is born: a gravitational molecule. A cloud of ultralight bosons, particles with masses below an electronvolt, envelops the pair like the electron cloud in an H2+ ion.