eddington limit

A whirlpool gulps down water, but splashes most of it back out. That's roughly how a black hole behaves when too much matter falls onto it. In a new study, astrophysicists ran 32 computer simulations to understand how a black hole's parameters — mass, spin, and "appetite"—control these cosmic fountains.

The most massive stars are like overinflated balloons: their envelope stops stretching and instead begins to furiously vent material. At a certain stage, the mass loss becomes so intense that the star stops growing in size. Astronomers see this moment as a kink in the diagram where stars are sorted by luminosity and temperature.

Dark matter remains the inaudible bass line of the cosmic symphony — it emits no light, but its gravitational pull shapes galaxies. Vera Rubin first caught this rhythm in the 1970s by observing the rotation of stars.

A cosmic ray approaches a black hole almost tangentially. Instead of falling straight in, it lingers on an unstable orbit, like an acrobat balancing on a tightrope over an abyss. After a few loops, the light finally escapes toward a distant observer. Such rays produce multiple images of the same source, known as higher-order images.

When a piano falls into an abyss, we think about the abyss. We don't think about the piano's cover. In much the same way, astrophysicists have for decades studied extreme close encounters between small bodies and massive black holes. They focused on the black hole itself and what orbits it. But what the 'bullet'—the small object heading toward doom — is wearing, almost no one asked.

Two tiny mirrors in a vacuum are like figure skaters in a pairs routine. Their oscillations are synchronized by an invisible gravitational thread. When cooled to millionths of a degree above zero, this thread turns them into a single quantum link — the motion of one instantly echoes in the other.

A spotlight shines ever brighter, but at some limit the bulb suddenly burns out, and no more light comes through. Astrophysicists have seen something similar in the distant blazar Markarian 421. This is an active galaxy whose jet of superheated plasma points almost straight at Earth, like the beam of a cosmic lighthouse.

Our Solar System isn't an island in the void: it's a sensitive web stretched in a dark cosmic corner. Planets circle their orbits like dewdrops on threads, and we are the spider sensing the faintest tremor. That tremor betrays the approach of the catastrophe astronomers call the Big Rip.

Hydrogen is the most common element. Its atoms are like antennas: they emit and absorb light at very specific frequencies. Einstein predicted that spacetime can ripple: these are gravitational waves.

Oxygenic photosynthesis requires splitting water. It's kind of like a water wheel: to make it spin, you need a strong current. Light acts as the current, and light particles are the streams. For red dwarfs, the most common stars, the light is "cool" and weak — the streams barely move the wheel.

In the first moments after the Big Bang, the cosmos was like a pot of boiling broth. In it, like lumps of flour, dense clumps of energy — oscillons — curdled and swelled. They grew, gained strength, and soon took over the expansion of the Universe.

About 25,000 light-years from Earth, in the constellation Sagittarius, a dense veil wraps around the neutron star GX 13+1. It scatters X-ray photons the way fog scatters streetlight, and for a long time it hid the source's true power from astronomers.

At Jefferson Lab, electrons are accelerated to 12 GeV and smash into protons to pry out their secrets. But existing detectors are like cameras with a narrow field of view: you either see a lot but dimly, or brightly but only a tiny patch. Electron scattering is the main tool, but statistics are insufficient for subtle effects.