Top right: HST image of the core of galaxy M87. Bottom left: Simulated MAXIM image of the region near the black hole in M87.

The Hubble Space Telescope represents the greatest clarity of vision ever achieved by a major observatory at visible wavelengths. The 0.1 arcsecond resolution it achieved is only 600 times finer than that experienced with the naked eye. But, the results have been stunning anyway.

Intercontinental baseline radio interferometry has produced images with milli-arcsecond resolution, 100 times finer than that of HST. With these images, astronomers have probed deep into the hearts of quasars and the Milky Way Galaxy.

The MAXIM concept utilizes X-ray interferometry to achieve micro-arcsecond angular resolution. A NASA mission built around this concept could achieve resolution as fine as 300 nano-arcseconds. This resolution is 3,000 times finer than VLBI and 300,000 times finer than HST.

X-ray interferometry has the potential to resolve the event horizon of a supermassive black hole in the nucleus of a nearby galaxy and at the center of our galaxy. This is equivalent to

• resolving a feature the size of a dinner plate on the surface of the sun,
• observing a 100 km emission knot on the surface of Alpha Centauri,
• imaging the disk of a star in the Magellanic CLouds,
• mapping in detail the accretion disk at the center of the Milky Way,
• directly measuring the parallax of a star in the Virgo Cluster of galaxies, or
• resolving one-tenth of a light year at the far extent of the visible Universe.

Of course, X-ray images differ greatly from visible images. X-rays are emitted only under conditions considered extreme by humans. Temperatures of millions of degrees and magnetic fields of millions of Gauss can create X-rays. They are often associated with the dramatic events heralding both the birth and death of astronomical objects. As such, they come from compact regions and image the core structures in some of the most interesting events in the Universe. This is the antithesis of structures viewed in radio VLBI, which are usually created by high energy electrons expanding away from the central structure. With X-rays we see the central engine itself.

An advance of three to five orders of magnitude in clarity is guaranteed to provide a basic new view of the Universe.