Seeing the unseeable: humanity’s first image of a black hole

Yesterday, the Event Horizon Telescope collaboration released the first image of a black hole humanity has ever seen. That simple-looking image represents a century of scientific work: from the first theoretical calculations describing black holes; to the earliest hints that every large galaxy contains a supermassive black hole at its heart; to the technological advances needed to network a world-spanning array of radio telescopes. When I was in college and graduate school, many people thought this very thing was impossible — I know I did. I am happy to say I was wrong then, and this picture of the 6.5 billion solar-mass black hole at the heart of the galaxy M87 is the most thrilling image of my scientific and science-writing career thus far.

the black hole at the center of the M87 galaxy, as seen by the Event Horizon Telescope

The first image humanity has ever captured of a black hole: the supermassive black hole at the heart of the M87 galaxy. [Credit: Event Horizon Telescope]

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The incredible story behind our first image of a black hole

For the first time ever, scientists have captured a direct image of a black hole. The image, captured by the Event Horizon Telescope, allows us to see something that was thought to be invisible

For WIRED UK:

A black hole is invisible by nature. One of the strangest predictions to come out of Albert Einstein’s theory of general relativity, a black hole emits no radiation we can detect, and it swallows up everything that falls on it, matter and light alike. The boundary of a black hole — its event horizon — is a border that can only be crossed from the outside to the inside, not in reverse.

So it might seem paradoxical to talk about capturing an image of a black hole, but this is precisely the mission of the Event Horizon Telescope (EHT). Today, April 10, 2019, will go down in history as the day EHT scientists released the very first direct image of a black hole.

It’s not one in our own Galactic centre, but is at the centre of the galaxy M87 – a resident of the neighbouring Virgo galaxy cluster, which is the home of several trillion stars. The feat marks the first time in history that astronomers have seen the shape of an event horizon. It’s an unprecedented map of gravity at its strongest, involving hundreds of astronomers, engineers, and data scientists from around the world.

[Read the rest at WIRED UK…]

Earth is a freeeeee faaaallin’ laboratory for testing general relativity

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And if I can be shameless: Forbes pays according to traffic, so the more of you who click on the link below and read my stuff, the better they pay me. Ahem.

Scientists Check Einstein’s Predictions Using Earth Itself As The Laboratory

For Forbes:

The modern description of gravity, Albert Einstein’s general relativity, is one of the most successful and best-tested theories we have. The core of that theory is a set of principles that say basically “physics is physics, wherever you are and no matter how fast you’re moving”. In particular, an experiment performed under the influence of gravity alone should work exactly the same as if you’re performing the same experiment deep in space without any gravity at all.

That’s a tricky concept to verify, but scientists at the National Institute of Standards and Technology (NIST) in Colorado have provided the best test for it yet, using Earth itself as the laboratory. They performed precision experiments in atomic physics (one of NIST’s specialties) and compared those results to those obtained at labs around the world, with data taken over a period of 14 years. The result: general relativity’s predictions were upheld once again.

[Read the rest at Forbes…]

Testing Einstein’s theory with a new space probe to Mercury

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And if I can be shameless: Forbes pays according to traffic, so the more of you who share and visit and read my stuff, the better they pay me. Ahem.

New Mercury Space Probe Will Put Einstein’s Gravity To The Test

orbit of Mercury, including effects from general relativity and other planets in the Solar System

The orbit of Mercury, including effects from general relativity and other planets in the Solar System. I’ve exaggerated the effect for easy viewing; in real life, the orbit is very nearly an ellipse. [Credit: Matthew R Francis]

For Forbes:

Despite the discovery of other galaxies, black holes and other marvelous astronomical bodies, we keep returning to the orbits of planets to understand gravity at its most basic. Partly that’s simplicity: We’re inside the Solar System and can make measurements without spending billions of dollars or building virtual observatories the size of the whole planet. But that doesn’t mean we’ve exhausted all the ways to learn about gravity from the dance of the planets.

In a new paper in Physical Review Letters, University of Florida physicist Clifford Will showed that the upcoming BepiColombo space probe may be able to test an aspect of Albert Einstein’s theory of gravity, general relativity, that’s been out of reach so far. This effect comes from the gravity of other planets in the Solar System, leading to a tiny shift in Mercury’s orbit. But small doesn’t mean unimportant: If general relativity needs to be modified on this tiny level, the BepiColombo probe may be able to spot that discrepancy.

[Read the rest at Forbes…]

When testing gravity, no news is good news

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Looking for nothing to test gravity

When they look for violations of Einstein’s general relativity, physicists deliberately plan experiments to find nothing at all.

For Symmetry Magazine:

In 1887, physicists Albert Michelson and Edward Morley performed one of physics’ most famous experiments (at Case Western Reserve University, coincidentally, across the street from where this article was written). Unlike other important experiments, they didn’t find what they were looking for, but unexpectedly their “null” result prepared the way for the theory of relativity.

Sometimes researchers deliberately set out to generate null results—while on the lookout for something new. One type of experiment is looking for deviations from Einstein’s general theory of relativity.

“General relativity has been the staple of gravitational understanding for 100 years,” says Katie Chamberlain, a physics student at Montana State University. “We have to rule out the potential for other existing theories to come in and replace [it].”

[Read the rest at Symmetry Magazine]

Seeing the invisible monster at the Milky Way center

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This is my second print magazine feature for Smithsonian Air & Space Magazine. The first was about gravitational waves, published not long before the LIGO detector found the first gravitational wave signals. The new piece is about the black hole at the center of our galaxy, published just a few months before…well, read the article to see why this is a good time to be writing about that particular black hole.

The First Sighting of a Black Hole

We know one lurks at the center of the Milky Way, but to these astronomers, seeing will be believing

For Smithsonian Air & Space Magazine:

he center of the galaxy doesn’t look like much, even if you’re lucky enough to live in a place where the night sky is sufficiently dark to see the bands of the Milky Way. In visible light, the stars between here and there blur together into a single brilliant source, like a bright beam hiding the lighthouse behind it.

But in other types of radiation—radio waves, infrared, X-rays—astronomers have detected the presence of an object with the mass of four million suns packed into a region smaller than our solar system: a supermassive black hole.

Astronomers call it Sagittarius A*, or Sgr A* (pronounced “sadge A star”) for short, because it’s located (from our point of view) in the Sagittarius constellation. Discovering the Milky Way’s black hole has helped cement the idea that the center of nearly every large galaxy harbors a supermassive black hole. But despite mounting evidence for black holes, we still haven’t seen one directly. [Read the rest at Smithsonian Air & Space Magazine]

Some heavy facts about gravity

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I’m not generally the type of writer who makes listicles, but I’m producing a few for Symmetry Magazine this year. The first covers the OG of fundamental forces: gravity!

Six weighty facts about gravity

Perplexed by gravity? Don’t let it get you down

For Symmetry Magazine:

Gravity: we barely ever think about it, at least until we slip on ice or stumble on the stairs. To many ancient thinkers, gravity wasn’t even a force—it was just the natural tendency of objects to sink toward the center of Earth, while planets were subject to other, unrelated laws.

Of course, we now know that gravity does far more than make things fall down. It governs the motion of planets around the Sun, holds galaxies together and determines the structure of the universe itself. We also recognize that gravity is one of the four fundamental forces of nature, along with electromagnetism, the weak force and the strong force.

The modern theory of gravity—Einstein’s general theory of relativity—is one of the most successful theories we have. At the same time, we still don’t know everything about gravity, including the exact way it fits in with the other fundamental forces. But here are six weighty facts we do know about gravity. [Read the rest at Symmetry Magazine]

Be very very quiet, we’re hunting gravitational waves

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Gravitational waves and where to find them

Advanced LIGO has just begun its search for gravitational waves

For Symmetry Magazine:

For thousands of years, astronomy was the province of visible light, that narrow band of colors the human eye can see.

In the 20th century, astronomers pushed into other kinds of light, from radio waves to infrared light to gamma rays. Researchers built neutrino detectors and cosmic ray observatories to study the universe using particles instead. Most recently, another branch of lightless astronomy has been making strides: gravitational wave astronomy.

It’s easy to make gravitational waves: Just flap your arms. Earth’s orbit produces more powerful gravitational waves, but even these are too small to have a measurable effect. This is a good thing: Gravitational waves carry energy, and losing too much energy would cause Earth to spiral into the sun. [Read the rest at Symmetry Magazine…]