Category: cosmology

What does a black hole look like up close?

A simulation of what a black hole with a disk of gas swirling around it would look, given the bizarre effects of its fierce gravity on the light from the disk. Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman

Via Bad Astronomy

Precision vs. accuracy

Imagine an archer who has shot ten arrows. In this scenario, precision is a measurement of the arrows’ positions relative to each other and accuracy is a measurement of their positions relative to the bullseye. A precise archer isn’t necessarily an accurate one, and vice versa.

The precision of an archer is analogous to a concept called clock stability. If one thinks of each tick of the clock as a shot and hitting the bullseye as keeping the exact right time between every tick, then a precise but not accurate clock would consistently tick either slower or faster than the desired amount of time. On the other hand, an accurate but imprecise clock would tick sometimes faster and sometimes slower, but the accumulated errors would average out somewhat over time.

Via Inside Science: Why Do We Need Super Accurate Atomic Clocks?

A Close Look at Newborn Planets Reveals Hints of Infant Moons

Via Quanta Magazine

This is the first clear image of a planet caught in the act of formation. The star, PDS 70, is blacked out at the center of the image, while the planet, PDS 70b, is visible as a bright dot to its right. Astronomers just discovered a second newborn planet circling PDS 70.


ESO/A. Müller et al

What’s It Like When You Fall Into A Black Hole?

From outside a black hole, all the infalling matter will emit light and always is visible, while nothing from behind the event horizon can get out. But if you were the one who fell into a black hole, what you’d see would be interesting and counterintuitive, and we know what it would actually look like.

Via Forbes – Ask Ethan

Gif info: General relativistic visualization of a supercomputer magneto-hydrodynamic simulation of a disk and jet around a black hole. The disk and jet were supercomputed by John Hawley at the University of Virginia. The general relativistic rendering was done with the Black Hole Flight Simulator.

On this day a century ago, General Relativity was experimentally confirmed for the first time.

Image via NYT: 

The Eclipse That Made Einstein Famous

The story is nicely told in the BBC/HBO drama Einstein and Eddington” (2008).

Further reading:

Cannonball Pulsar

NRAO press release: Astronomers Find “Cannonball Pulsar” Speeding Through Space

Cool, on April 10, we may see the first ever close-up image of a black hole thanks to the Event Horizon Telescope.


A simulated image shows the turbulent plasma in the extreme environment around a black hole.

Via NSF press note-> NSF press conference on first result from Event Horizon Telescope project


Atheism Is Inconsistent with the Scientific Method, Prizewinning Physicist Says:

I subscribe almost completely Marcelo Gleiser perspectives (and I would have subscribed the same 20 years ago). Watch out, the title is a clickbait, in the context that the phrase is said -in defense of agnosticism as the only non-religious position, it makes perfect sense. Good reading.

Gleiser is the first Latin American (Brazilian) to win the Templeton Prize.

Cool, the Bekenstein-Hawking entropy in a 50p coin. I want one!

Source: New Scientist – 

Stephen Hawking’s legacy will be honoured with a new 50p coin

Wired: Get Ready For Gravitational Waves All Day, Every Day