This allowed the deep exposure on the object, resolving it into two separate stars. The Gravity instrument was able to focus on the cluster using a reference star to stay locked on for periods of several minutes at a time, achieving the feat of stabilising all four telescopes simultaneously. Kathryn Nave is a regular contributor to WIRED.The binary star was found in the nebula's star-forming region, in a small group of bright, young stars called the Trapezium Cluster. But I always say: you never bet against Einstein." If what we actually see is an irregular shape, then we'd have to look at scenarios in which it's either not a black hole, or that Einstein was wrong. But if he's right, and if this object is a black hole, then the shape of its shadow should conform to the no-hair theorem, which says that you can characterise a black hole by just its mass and its spin. "He thought that something would prevent the catastrophic gravitational collapse of matter. "Einstein himself disavowed black holes for many years," Doeleman points out. The evidence for them may be strong, but it's still indirect enough to allow for other possibilities, and nowhere do Einstein's theories produce stranger and more unintuitive results than at the event horizon. But there are ways that the quantum states inside the black hole might manifest outside of it, so it's a mystery we may be able to address."Įven the existence of black holes shouldn't be taken for granted. ![]() Quantum-mechanically that doesn't make sense, so understanding where the information goes is a mystery. But if you throw it into a black hole it seems it's just gone. "If you burn an encyclopaedia, an advanced civilisation could still reconstitute it and the information it contained. "The information swallowed by a black hole is seemingly lost completely," says Doeleman. What new information could an image of the event horizon offer? One area of uncertainty is what's known as the information paradox. Of course, Einstein's theory of general relativity has been repeatedly confirmed at every turn, most recently by the Advanced Laser Interferometer Gravitational-wave Observatory's measurement of the gravitational waves produced when two black holes merge. "If we can image this in enough detail we'll be able to test Einstein's theory of general relativity at the event horizon itself," Doeleman says. Thus in the image produced by the radio telescopes' combined signals, the black hole should appear as a shadow, the exact size and shape as that described by Einstein's field equations. So this black hole is sitting in the middle of a luminous soup." ![]() They attract so much gas and dust into such a small volume and, as all this material starts rubbing against itself, the friction heats it up to hundreds of billions of degrees. Yet that gravitational pull also makes black holes some of the brightest spots in the universe. Just outside of that is the event horizon, the point from which even light cannot escape. "Radio waves can go through walls - but at these frequencies, water vapour is a big problem," says Doeleman: "We need clear skies simultaneously at all our telescope locations."Įven with all of this magnification power, how exactly do you produce an image of something characterised by the complete absence of light? "By definition, black holes are unseeable," says Doeleman."Matter is at such densities that gravity compresses everything into a single point. The difficulty, however, isn't just in the data processing, but in the weather. To correct for the Earth's squashed shape, signals from some telescopes will be delayed relative to others. All nine telescopes involved will still represent only small fragments of a virtual lens, but as the Earth rotates, so their movement will trace out a much fuller parabola - if a less than perfect one. The final telescopes required to make the observation, including the Atacama Large Millimeter Array in Chile, are due to come online in spring 2017, but a partial EHT has already been used to assess the size of Sagittarius A* and to make the first ever measurements of a black hole's magnetic fields.
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