Scientists around the world have been abuzz lately about a BIG announcement that’s due to be made live, early tomorrow morning. This announcement concerns the ever elusive, and as-of-yet, unseen, black hole.
In anticipation of what we all hope will be the first ever visual unveiling of that which cannot be seen, El Paso Herald-Post’s own Steven Zimmerman asks, “Why haven’t we seen a black hole before? And, what is a black hole?”
In order to fully explain, I will need to take you all on a journey back to the fundamentals of physics. For this explanation, I will not delve into quantum physics. And don’t worry, I’ll make it as painless as possible.
Everything you see, everything you touch, everything you breathe, is made up of atoms. This is something most people learn in their middle school physical science class. Every atom contains the same things: protons, neutrons, and electrons.
Looking much like microscopic solar systems, the nucleus of an atom houses the protons and neutrons. Zipping around the outside of that nucleus are electrons. The number of electrons that orbit is the same as the number of protons within the nucleus. But between the electrons and nucleus is a vast space of nothing.
In fact, the size of the nucleus of an atom and the size of the electrons are so very, very small that the space between them is huge, by comparison. You could say that everything is mostly made of nothing. Mind blowing, right?
The stars that shine in the sky do so by a process known as fusion. Here’s how that works:
Remember the periodic table of elements? You start off with some hydrogen. This is the lightest element on the periodic table. It has only one proton and one electron. In a star, so huge that the gravity is immense, the hydrogen atoms are smashed together—similar to what happens in the Large Hadron Collider—fusing them into helium atoms: two protons and two electrons.
It is this fusion process that powers the star and creates the light and energy we see every day from our very own Sun.
But the process doesn’t stop there. Throughout its life-cycle, the internal gravity of the star is such that atoms continuously smash into each other, creating heavier and heavier elements. So, what started out as hydrogen, eventually becomes carbon, gold, nickel, and eventually iron and lead.
As this happens, the star becomes heavier and heavier. Once it becomes too heavy, and most of its hydrogen supply has been exhausted, the star eventually dies.
There are several different ways in which a star will meet its end, but for the purposes of Steven’s question, we’ll just focus on one.
During the life-cycle of a very large star, the heavier elements are pulled to the center of the star. The more elements that are pulled in, the more densely packed they become. This diminishes the space between the electrons and nucleus of the atoms that make up these heavy elements.
Imagine being crammed into a bus or train car so tightly that there is literally no space between the passengers.
As the giant star reaches the end of its life, the heavy elements are pulled closer and closer together, until the star literally collapses under its own weight. When this happens, you almost literally have no space between the electrons and nucleus of the atoms. So, now the core of the dead star is so tightly packed, and so dense that it is very small in comparison to what it was.
Here’s an example of what I mean:
The Earth is 12,742km (7,917 miles) in diameter. If our beautiful planet were to become a black hole, it would have a diameter of only 17.4mm (0.69 inches)—about the size of a dime.
Now, because these heavy elements are so tightly packed together, the gravitational field created by them is so immense that anything that comes near it will be pulled in with no hope of escape.
In fact, the gravity of this singularity, which is what the tightly packed core of the now dead star is called, is so intense that not even light can escape.
Thus, the name: Black Hole. And that is why we can’t see them.
Any photographer knows that you can’t take a picture of a black dog in a pitch black room without a flash. All that will show up will be the color black.
But black holes have an interesting feature: the event horizon.
In the most basic terms, an event horizon is the point at which material drawn toward a black hole’s gravity swirls around the singularity, pretty much forever. There are many things that can happen to this material as it encounters an event horizon, but I won’t get into it all right now, since that would involve explaining Einstein’s Theory of General Relativity.
Suffice it to say, event horizons, theoretically, can be spotted.
Here’s the thing, though: black holes are only theorized to exist. Astrophysicists believe that most (if not all) galaxies contain one (or more) super massive black hole at its center.
The belief is that it is the gravity of these giant singularities that keeps a galaxy together. Since we’ve never seen one, we can’t prove they are real…until now.
Basically, it links radio dishes across the globe to create an Earth sized telescope.
It’s been used to measure the size of the emissions of two super massive black holes: Sagittarius A (at the center of our own Milky Way) and M87 (at the center of the Virgo A galaxy).
And apparently, they’ve found something exciting!
April 10th, the Event Horizon Telescope Collaboration will present its first results in a live press conference that will air around the world. It will take place at 13:00UT (6am MST) where they will present their findings up to this point, and hopefully, some of the first actual pictures ever taken of the event horizon of a super massive black hole.
If you are interested in watching this, set your alarms clocks early and tune into the European Commission YouTube Channel, the EHT Facebook, the EHT Twitter, or the National Science Foundation Live Stream.
If you have any questions about their findings, or black holes in general, feel free to ask me. You can message your questions in real time to my Facebook page or send them via email to firstname.lastname@example.org.