Astronomy for RVers – Black holes are real!

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We finally got the mug shot where only finger prints existed before.

By Chris Fellows, Serenity Mobile Observatory

On Wednesday, April 10, 2019, astronomers announced that they had captured the first-ever image of a black hole. More than 100 years ago, in 1915, Albert Einstein finished and published his General Theory of Relativity (GTR), upsetting the apple cart that Sir Isaac Newton built more than 220 years earlier, in 1687, with his publication of Philosophiæ Naturalis Principia Mathematica. After that, everyone knew WHAT gravity did but not HOW it did it.

Albert Einstein circa 1912

Newton was silent on the mechanism and figured it was a force that worked at a distance, like electromagnetism. Einstein’s math said no, gravity isn’t a force, it’s a shape, a geometry of the fabric of space itself. After the publication of GTR people started playing with it, solving problems and making predictions based on solutions to the mathematics of GTR.

One of these guys, Karl Schwarzschild, was the first to publicly predict that under extreme circumstances of mass, matter could collapse into a state of infinite density and zero size. Einstein didn’t like this solution and thought that nature must have a mechanism for preventing it from happening – but there it was, big as day, in his own math.


By ALMA (ESO/NAOJ/NRAO), J.Pinto & N.Lira – https://www.eso.org/public/usa/images/eht-infography/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=67896776

GTR makes many predictions: These include the bending of light around a gravitational source (Gravitational lensing), time dilation where time slows down near a massive body or near the speed of light, gravitational waves caused by violent events such as two massive bodies colliding and sending ripples of space throughout the universe, and of course, black holes. Einstein himself doubted that any of these predictions would ever be observed due to the extreme conditions required for them to be seen. He was wrong.

In 1979, Gravitational Lensing was directly observed in optical light in the Twin Quasar (also known as Twin QSO, Double Quasar, SBS 0957+561, TXS 0957+561, Q0957+561. In 1959, Robert Pound and Glen A. Rebka measured time dilation in light emitted at a lower height, where Earth’s gravitational field is more intense. On February 11, 2016, the LIGO (Laser Interferometer Gravitational-Wave Observatory) collaboration announced the first observation of gravitational waves, from a signal detected at 09:50:45 GMT on September 14, 2015. And finally, on April 10, 2019, the final nail was put in the doubter’s coffin when a gigantic scientific collaboration called The Event Horizon Telescope produced the first image of the super massive black hole at the center of galaxy M87. Einstein was da man!

This observation is extremely difficult to make. By their very definition, black holes emit nothing. Not visible light, not radio waves, nothing at all. Once you go past the event horizon you never come out … period … end of story. If Einstein is right, and at this point I will lean in on this, and light is the ultimate speed limit in the universe, we will never observe the singularity that lies at the heart of a black hole. Ever.

Compounding the problem is that super massive black holes tend to be at the center of galaxies. These are very dense regions of space with lots of gas, dust, stars and other stuff blocking the view and making direct observations difficult.

Finally there is the problem of size and distance. As the universe goes, black holes are tiny – most have event horizons smaller than an average star. And they are very far away: The closest one that we know about is at the center of the Milky Way at about 26,500 light years away from earth.

But, like a pebble dropped into a pond, even though you can’t observe the pebble you can observe its effects: ripples on the pond or the sound it made when it broke the surface tension for example. Stuff falls into black holes: Gas dust and even entire stellar systems are consumed if they wander too close to one of these monsters. As they spiral in, increasing in speed and therefore friction, they heat up to crazy temperatures and blast out electromagnetic radiation in all directions. This radiation can be observed and therefore you can also observe the shadow of the black hole itself.

The first ever direct image of a black hole

In order to perform this observation you would need a telescope the size of the earth that could “see” in a wavelength that will pass through all that space junk, and have a resolution to see a stellar-sized object trillions of miles away. Luckily we have some pretty smart people working on these problems and they invented a method called very-long-baseline interferometry (VLBI).

This is a complex subject but in a nutshell it is combining, in both time and space, multiple observatories around the planet to effectively create an earth-sized radio dish telescope. Amazing. Huge amounts of data were collected from this observatory over the last couple of years. There was so much data they couldn’t send it over traditional internet communication channels and had to physically fly the hard drives from all over the world to combine the information and then run it through super computers to finally produce the image. This is by far the most difficult snapshot ever taken.

There is much more to be learned about this observation. Please look around the web and seek out this amazing discovery for yourself. Science rocks! You should enjoy the music for yourself!

Till next time!

Clear Skies,
Chris Fellows, Serenity Mobile Observatory

Find Chris on Facebook (or, if you’re lucky, at your campground). (Editor: Check out his amazing photos on his Facebook page!)

 


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Roger Marble
Roger Marble

This is one example of why I love the process we identify as Science. A hypothesis is suggested and then it is tested. The results of the testing or examination may require the hypothesis be adjusted or even rejected. However sometimes the results confirm the idea so we end up with a bit more useful knowledge. This is a never ending process. Unless when confronted with something unknown and you say “It must be magic” and you stop looking for an answer supported by the facts. This has always been my approach to answering the question of why a tire… Read more »

Serenity Mobile Observatory
Serenity Mobile Observatory

Science delivers the goods my friend. It’s an amazing time we live in where new discoveries and confirmation or rejection of hypothesis happen almost daily. I love it.