2019-04-10, #EHTBlackHole #BlackHoleDay #RealBlackHole Event Horizon Telescope (EHT)

On April 10th 2019, the Event Horizon Telescope (EHT) Collaboration will present its first results in multiple simultaneous press conferences around the world, and many satellite events organized by its stakeholder and affiliated institutions. Press conferences will be held simultaneously in Brussels (in English), Lyngby (in Danish), Santiago (in Spanish), Shanghai (in Mandarin), Tokyo (in Japanese), Taipei (in Mandarin), and Washington D.C. (in English), starting at 13:00 UTC.

First image of the shadow of a black hole (M87*) captured by the Event Horizon Telescope


Zwarte gaten afspeellijst
No, Stephen Hawking’s Black Hole Information Paradox Hasn’t Been Solved
Bedrohen kleine Schwarze Löcher unser Sonnensystem?
The most ancient supermassive black hole is bafflingly big
On dark stars, Planck cores and the nature of dark matter
Inventory of Black Holes
Schwarze Löcher – Ursprung unseres Lebens
Gravitational Waves
Stephen Hawking’s Black Hole Theorem Confirmed by Gravitational Waves
Observations of the jet launching and collimation in Centaurus A
Could we harness the power of a black hole?
Sagittarius A*


The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. In coordinated press conferences across the globe, EHT researchers revealed that they succeeded, unveiling the first direct visual evidence of the supermassive black hole in the centre of Messier 87 and its shadow. In this image of M87* taken on 11 April 2017 (a representative example of the images collected in a global 2017 EHT campaign), the shadow of a black hole is the closest we can come to an image of the black hole itself, a completely dark object from which light cannot escape.

The black hole’s boundary — the event horizon from which the EHT takes its name — is around 2.5 times smaller than the shadow it casts and measures just under 40 billion km across. While this may sound large, this ring is only about 40 microarcseconds across — equivalent to measuring the length of a credit card on the surface of the Moon. Although the telescopes making up the EHT are not physically connected, they are able to synchronize their recorded data with atomic clocks — hydrogen masers — which precisely time their observations. These observations were collected at a wavelength of 1.3 mm in the 2017 campaign. Each telescope of the EHT produced enormous amounts of data – roughly 350 terabytes per day – which was stored on high-performance helium-filled hard drives.

These data were flown to highly specialised supercomputers — known as correlators — at the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory to be combined. They were then painstakingly converted into an image using novel computational tools developed by the collaboration. This image is the average of three different imaging methods after convolving each with a circular Gaussian kernel to give matched resolutions. The image is shown in units of brightness temperature, , where S is the flux density, λ is the observing wavelength, is the Boltzmann constant, and Ω is the solid angle of the resolution element.

Zwarte gaten afspeellijst:


No, Stephen Hawking’s Black Hole Information Paradox Hasn’t Been Solved:

De Susskind-Hawking battle, ook wel de black-hole war genoemd, is het debat tussen Leonard Susskind en Stephen Hawking over de vraag of informatie die in een zwart gat valt voor altijd is verdwenen of in de een of andere vorm blijft bestaan, zelfs als het zwarte gat na miljarden jaren verdampt is.

De strijd begon in 1981 tijdens een bijeenkomst in San Francisco van vooraanstaande theoretische fysici. Naast Susskind en Stephen Hawking waren ook Gerard ‘t Hooft en een aantal andere grote wetenschappers aanwezig. De bijeenkomst was belegd om enkele fundamentele eigenschappen van elementaire deeltjes te ontrafelen. Bij die gelegenheid stelde Stephen Hawking dat de informatie van een deeltje dat door een zwart gat wordt opgeslokt voor altijd verloren is als het zwarte gat verdampt.

Susskind is het daar niet mee eens, omdat het indruist tegen een zeer fundamenteel principe: behoud van informatie. Informatie kan veranderen, vervormd worden of in kleine bits uiteenvallen, maar kan nooit verdwijnen. In zijn boek The Black Hole War[1] doet Susskind verslag van het debat dat meer dan 20 jaar duurt en dat uiteindelijk door Susskind wordt gewonnen.

Als informatie zou verdwijnen zou dit vergaande consequenties hebben: dit zou betekenen dat de kwantummechanica geen recht van bestaan meer had. De stelling van Hawking is een paradox: of de kwantummechanica of de relativiteitstheorie is onjuist. Tijdens de bijeenkomst in San Francisco kreeg Susskind weinig bijval, alleen ‘t Hooft was het met hem eens.

On dark stars, Planck cores and the nature of dark matter:

Inventory of Black Holes:

Schwarze Löcher – Ursprung unseres Lebens:

The black-hole area law:


Gravitational Waves:

Stephen Hawking’s Black Hole Theorem Confirmed by Gravitational Waves:

Observations of the jet launching and collimation in Centaurus A:


Could we harness the power of a black hole?:

Sagittarius A*:


Fuzzballs are theorized by some superstring theory scientists to be the true quantum description of black holes. The theory attempts to resolve two intractable problems that classic black holes pose for modern physics:

  1. The information paradox wherein the quantum information bound in in-falling matter and energy entirely disappears into a singularity; that is, the black hole would undergo zero physical change in its composition regardless of the nature of what fell into it.
  2. The singularity at the heart of the black hole, where conventional black hole theory says there is infinite spacetime curvature due to an infinitely intense gravitational field from a region of zero volume. Modern physics breaks down when such parameters are infinite and zero.[Note 1]

Fuzzball theory replaces the singularity at the heart of a black hole by positing that the entire region within the black hole’s event horizon is actually a ball of strings, which are advanced as the ultimate building blocks of matter and energy. Strings are thought to be bundles of energy vibrating in complex ways in both the three physical dimensions of space as well as in compact directions—extra dimensions interwoven in the quantum foam (also known as spacetime foam).

Agenda – Event Horizon Telescope (EHT) Collaboration will present its first results in multiple simultaneous press conferences (TV webcast)

First Results from the Event Horizon Telescope to be Presented on April 10th

Brussels: European Comission Youtube Channel

Santiago: ALMA website

Taipei: Academia Sinica channel on Youtube

Tokyo: National Astronomical Observatory of Japan channels on Youtube

Washngton: US National Science Foundation Live Stream

Verwacht: eerste foto van een zwart gat

The physics of black holes (TV On-demand)

Famous Black Hole Shows Its Wobbly Past in New Movie

What happened before the Big Bang? / Did A Black Hole Give Birth To Our Universe?

Fuzzball (string theory)

Schwarzschild radius

Zwarte gaten – afspeellijst YouTube

Agenda – Is ‘Planet Nine’ Actually A Black Hole In The Solar System? / Searching for Black Holes in the Outer Solar System with LSST

Agenda – Fast-spinning black holes narrow the search for dark matter particles / Constraints on Ultralight Scalar Bosons within Black Hole Spin Measurements from the LIGO-Virgo GWTC-2 – publication

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Agenda – #BlackHoleWeek

Agenda – The black hole at the center of the Milky Way is actually a mass of dark matter?

What is a black hole?

Hawking radiation calculator