Home Front Page Shape of black hole’s shadow may confirm theory of general relativity

Shape of black hole’s shadow may confirm theory of general relativity

Few things in the universe are as mysterious and exotic as black holes. They are born when gravitational pull is so powerful that all matter surrounding it collapses in on itself and nothing, not even light, can escape. There is one lurking in the center of the Milky Way galaxy where planet Earth makes its home, and scientists are hoping to get a glimpse of it.

Although Albert Einstein’s theory of general relativity predicted the existence of black holes back in 1916 and modern scientific instruments are able to observe and measure the effect a black hole has on surrounding celestial bodies, including light—nobody has ever seen one.

“There is no telescope available which can resolve such a small radius,” said David Rabanus, instruments manager for the ALMA observatory high in Chile’s Atacama desert, in comments made to PBS.

Until now, that is.

An international team of scientists is replacing ALMA’s atomic clock with a more accurate one—one that incredibly will not lose a second for the next hundred million years.

ALMA stands for Atacama Large Millimeter/submillimeter Array.

“Basically what we’ve done is perform a heart transplant for ALMA,” Shep Doeleman, an astronomer at MIT and the Harvard-Smithsonian Center for Astrophyscis, told PBS.

Replacing the atomic clock is not an easy operation. Special housing is necessary to protect the clock from Chile’s powerful earthquakes and ALMA’s antennas must be chilled to almost absolute zero so they are able to pick up radiation from the coldest objects in deep space.

“Cold clouds, cold gases, which are maybe 20 Kelvin only,” Rabanus explained. “We have to be colder than that in order to receive it. If we were warmer than those we would actually send out that radiation.”

ALMA has the most sensitive and precise antennas in the world, but to get a wide enough ‘lens’ with high enough resolution to see a black hole, the Event Horizon telescope connects and synchronizes observatories around the world. Each telescope must use the same new atomic clock.

This massive array of telescopes is looking for a clear sign that a cloud of space dust at the edge of the black hole—called the ‘event horizon—is being sucked into it. If so, it will light up and the black hole will cast a shadow against the flare, the PBS report explains.

Because Einstein’s equations predict the size and shape of the shadow, scientists will be able to test the great physicist’s theories at a place where many say his theories break down.

If the shadow matches Einstein’s equations, ‘It would be a wonderful confirmation of one of the most beautiful theories that’s ever come out of physics,” Doeleman said.