Albert Einstein was famous for doing something he called gedankenexperiments (German for “thought experiments”). Some of his most incredible discoveries came out of instances when he just let his mind wander and imagine how things worked. This sort of “free range” thinking was crucial when imagining concepts (such as chasing a beam of light) which might be too difficult (or even impossible) to prove experimentally. I fear that this kind of untethered mental meandering is becoming unachievable, undervalued, and increasingly undesirable with both the advent of modern technology and the frenzied pace of daily life.
I think that we humans are not only capable of gedankenexperiments, but we are well-equipped to solve most global problems using nothing more than our brains and something to write with, and on. Not every problem can be solved. Can we protect our power grids from a coronal mass ejection (CME)? I believe we can. Is it possible to protect our species from a gamma ray burster? I don’t think that’s possible.
Let’s perform a gedankenexperiment of our own by re-examining a question which has plagued humanity since we first began looking up into the night sky. Thanks to the groundwork laid down for us by Albert Einstein decades ago, we may even now have answers to previously unanswerable questions.
What I’m going to ask you to imagine will not require math, or a background knowledge of astrophysics or cosmology. I will tell you, right up front, that there are some things in astronomy and astrophysics which are known with a large degree of confidence, some things which are merely suspected, and some things which are theorized and shown to be true in mathematical equations (but which may not yet be observed, or which are not yet observable). So I’m betting that I can give you enough information to conduct your own gedankenexperiment in which you imagine and see how our Universe began. I can actually do it in one sentence, but where’s the fun in that?
The Big Bang
Scientists know with a high degree of certainty what was happening when our Universe was born, even when it was less than one minute old (actually less than 1/1000th of a second old); however, they don’t know where it call came from, or what prompted the Big Bang, which seemingly sprang from something they call a “singularity” which is an infinitesimally small point of immense density and mass. Our Universe came out of seemingly nowhere, sort of popped out, and then kept expanding from “there.”
Albert Einstein’s general theory of relativity, now 100 years old, discussed the effects of gravity, and how it distorted space and time (now called space-time). Einstein’s calculations also predicted the existence of black holes (and even wormholes). In fact, their theoretical existence “came out” of his equations well before anyone knew what they were.
Nigel Calder writes in his incredible book, “Einstein’s Universe:”
“Special Relativity permits forward travel in time – the Methuselah Effect – but rules out the reversal of time by faster-than-light travel. That’s in ordinary space, but General Relativity on the other hand allows for an extraordinary condition of space called a wormhole. An object might enter at one end, proceed by a route outside the known universe, and come out at the far end of the wormhole in a quite different place and/or time.”
For many years, black holes weren’t even considered real. Physicists believed they were merely theoretical constructs. In fact, black holes weren’t proven to exist (by physical observation) until astronomers observed one at the heart of galaxy M87 (located in the Virgo cluster) in April 1978. And it was only very recently discovered (within the last few years) that black holes are actually at the center of literally every galaxy (including our Milky Way), which begs the question: which came first, the black hole or the galaxy? We now know that galaxies are tied to (anchored to), and rotate around, their own supermassive black holes. Once matter is sucked into a black hole (or supermassive black hole), it crosses something called the event horizon, and it’s believed that the matter then proceeds towards a singularity, or infinitely compressed single “point.”
No one can see what’s going on at a singularity because it’s protected by (and beyond) the event horizon of a black hole, which is sort of like a trap door, or “barrier.” Physicists consider what happens at a singularity “cloaked.” This cloaking “protects” the observer (and by “observer,” they actually mean any one or any thing outside the black hole), from seeing what transpires at the point of the singularity where the laws of physics break down. In laymen’s terms, all kinds of crazy shit happens there. If a singularity weren’t beyond our “view,” it would be considered a “naked singularity.”
Keep in mind that this notion of a sort of “firewall,” also applies to the singularity which immediately preceded our Big Bang (in other words, what happened right BEFORE the Big Bang). These singularities are considered “unseeable,” by most physicists, even though the Big Bang which created our Universe (technically) means that we are causally connected to that singularity because it created our own Universe. This concept of not being able to see a singularity is also referred to as the cosmic censorship conjecture, summed up nicely by some physicists below (note the part that I boldfaced and underlined – it’s important):
Given high enough densities, Einstein’s theory of general relativity predicts that matter can suffer a cataclysmic collapse to a point-like region where both the density of matter and the curvature of spacetime diverge (tend towards infinite values). This is referred to as a singularity, and also describes the formation of a black hole.
In the case of a black hole, the singularity is hidden from view by an event horizon, but there is nothing in general relativity that says that this has to be the case. In other words, general relativity does not preclude the existence of naked singularities. This is very disturbing on both theoretical and observational grounds, as physical conditions become increasingly extreme, and ultimately the laws of physics break down entirely, as one approaches a singularity.
To avoid this situation, in the late 1960s Roger Penrose proposed that there be some physical principle, as yet not understood, that excludes naked singularities as solutions to the equations of general relativity. In other words, every singularity must possess an event horizon that hides the singularity from view.
Now flip back to the Big Bang, which came out of a random and unidentifiable point in space and time, roughly 13.7 billion years ago. Our Universe, all space, time, and matter, everything, literally sprang out of some infinitely dense point, again, called a singularity. We’re not talking about physicists just using the same language and terminology to describe what happens both inside a black hole and right before our Big Bang which gave birth to our Universe. We’re talking about the same thing.
Here’s something to gedanken about for a moment:
Supermassive black holes & the galaxies that love them
We now know that black holes are everywhere throughout our Universe. Tons and tons of stuff (planets, stars, gas, dust, etc.) gets literally sucked into these things, where it is dragged down to an invisible point of unimaginable density (a singularity). But where does all that stuff go? We haven’t a clue. Or do we? Keep in mind that black holes don’t just suck everything in – they also shoot enormous amounts of matter out in jets, forming the “bulges” just outside their opening which can be found at the centers of galaxies. When the black holes are shooting stuff way out, we know it aids and abets galaxy growth. You may have heard of quasars, blazars, and Seyferts. How about gamma ray bursters and X-rays? Yep. They’re supermassive black hole “burps.”
In my opinion, one of the absolutely craziest things about black holes and their galaxies is how closely tied they are to one another. Not only do galaxies rotate around the black hole at their center, but the size of the galaxy is TIED TO, and constrained by, its black hole. I don’t know how to explain how freaking bizarre this detail is, except to compare it to a universal “speed limit,” or size limit, of sorts, which, for over 13 billion years, has maintained a 1,000-to-1 ratio, starting from the very beginning of our Universe until today. In other words, there is some process (for lack of a better word), or connection, between black holes, galaxy formation, and the Universe. One balances, or controls, the other. To drive home this point, and in the words of astrophysicist Timothy Heckman (I’ll excerpt part of one of his papers below, but this paper is only 3 1/2 pages long, and can be read in full here):
“One of the most unexpected and important discoveries of the past decade has been that the lives of galaxies and their supermassive black holes are inextricably intertwined. The galaxy is more than one billion times larger than the black hole and contains more than one thousand times as much mass. Many astronomers now believe that we cannot understand how galaxies formed and evolved without understanding their black holes in detail.
…astronomers were able to assemble a sample of supermassive black holes with accurate mass determinations. To their surprise, the astronomers then found that the mass of each supermassive black hole was roughly a fixed fraction (about one part in one thousand) of the mass of its bulge….The most massive galaxies and black holes grew rapidly in the history of the universe, and their masses then remained nearly constant…Put another way, the sites of the most vigorous star formation and the most active black hole growth have moved from the most massive galaxies to progressively smaller and smaller systems as the universe evolved. Given the marked similarity in the histories of galaxy and black hole growth, the natural conclusion is that the formation and evolution of these two kinds of objects are tightly linked.
If we average over a suitably large sample of such black holes, we find that the ratio between the rate of star formation in the inner regions of the galaxy and the rate of black hole growth is about 1,000. One thousand-to-one is the same as the ratio of the mass of stars to that in the black hole for the most massive galaxies…Thus, the process that determined the 1,000-to-1 ratio in the early universe is still in action today. What exactly is that process?
The co-evolution of galaxies and supermassive black holes clearly requires more than a common source of fuel. It also requires some physical communication between the black hole and galaxy that limits the growth of each component – in other words, some type of feedback.”
Dark matter, haloes, and (accelerating) cosmic expansion
There are some seriously freaky things about our Universe. Things that don’t make sense and which seem entirely opposite to how everything should “work.” It turns out that every single thing in our Universe which most of us would consider solid and important “stuff” only makes up about 4% of what our Universe is made up of. So that means that planets, stars, galaxies, you, me, your dog, dust, gas…the whole enchilada = 4% of what’s out there. Scientists call the stuff that repels, or pushes everything outwards (causing our Universe to not only expand, but to speed up its expansion every day since the Big Bang) dark energy, which actually makes up 74% of our Universe. They don’t know what it is, they can’t see it, but they know it’s there. Dark energy works on a very immense scale, a la affecting the entire Universe.
There’s also something scientists call dark matter, which makes up 21% of our Universe and which attracts, or pulls together, galaxies. Scientists can’t see dark matter, either, but, again, they know it’s there. Without it, our galaxy (the Milky Way), and all the other galaxies, couldn’t hold themselves “together.” They’d either never have formed, or they’d never have been able to stick together. There just isn’t enough “stuff” to keep pushing the outer limits of galaxies inward, and keep them together, gravitationally speaking.
Here’s a good graphic about dark matter, dark energy, and normal matter, and to read more, here’s a good link about dark energy and dark matter:
So here’s what I think, and have thought for years: our Big Bang is the other side of a black hole, which is called a white hole. I also think that black holes are the source of dark matter, which gets spewed (or “burped”) out in enormous jets that look like this:
I think the gas jets that come out of black holes create what scientists call dark matter haloes, which are actually visible gigantic haloes around clusters of galaxies, holding them together. Scientists can’t see the dark matter, but they can see the “halo” surrounding galaxies, which sort of “hems them in,” and keeps them together. Kind of like a corral for wild horses.
Here’s an image of a dark matter halo between two galaxy clusters (called Abell 399 and Abell 401) as seen by the Planck space telescope (to read more about dark matter haloes, click this link):
What I’ve written up until now makes sense, intuitively, right? And Einstein’s equations not only “allow,” black holes to have white holes and wormholes, but actually lay out their existence in his equations. I’ve seen where the equations reveal the existence of such things, and you can too. Even if you don’t think you understand the math (which I do not), I ask you to just read the words and allow yourself to absorb the message by backing out the symbols, naming rights (like “Hawking Radiation”) and extensive citations. If you want to give it a try, I suggest going to the bottom of this page and clicking on the paper titled, “Radial motion into an Einstein-Rosen bridge,” for starters. It’s like Shakespeare. At first, you try to understand every single word and you get bogged down and it seems impossibly difficult, but if you just let yourself sort of relax and fall into it, you do get the full impact, and it will blow you away.
Beyond white holes to the Holographic Principle
Once you let the black hole/white hole/Big Bang thing sink in, it gets a LOT weirder. Unlike a lot of papers and articles I might link to which are very technical and may be off-putting, there was a very read-able article with a different “take” on the black hole → white hole → Big Bang theory that appeared on the cover of the August 2014 issue of Scientific American magazine titled, “The Black Hole at the Beginning of Time.” Unfortunately, I can’t provide a link to it (because they want people to pay for it with a subscription, which some of you may not have), however, that Scientific American article is summarized and freely available here and here.
The actual paper which the Scientific American article is about can actually be read in its entirety (and free) here, and is called, “Out of a White Hole: A Holographic Origin for the Big Bang” by Pourhasen, Afshordi, and Mann. Those scientists actually take the idea of our Universe vis-a-vis black holes to a much stranger “place,” which is that our three-dimensional Universe is a sub-universe embedded in a larger space of four or more dimensions, the result of a collapsing four (or more) dimensional star. This is called the Holographic Principle and it means that we are (get ready for it…) living in a hologram inside a black hole. If you read their paper, or the Scientific American article, you’ll see how this makes sense and isn’t as crazy as it sounds.
Here is a graphic which helps explain it:
Pourhasan, et al say:
“While most of the singularities of General Relativity are expected to be safely hidden behind an event horizon by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity…
…However, we show that the singularity always happens inside a white hole horizon, and only happens later than Big Bang Nucleosynthesis (BBN)…this yields an alternative holographic origin for the big bang, in which our universe emerges from the collapse of a 5D (dimension) “star” into a black hole, reminiscent of an astrophysical core-collapse supernova. In this scenario, there is no big bang singularity in our causal past, and the only singularity is shielded by a black hole horizon.”
The importance of gedankenexperiments
I’m writing about this now because I recently read an article about black holes in a different issue of Scientific American, which itself linked to an article in Seeker.com (which I’ve marked up in the iFrame below). In my opinion, both fell short of where they could have “gone.” Keeping in mind all the information you’ve just read about black holes, the Big Bang and the mysteries in our Universe, click on the iFrame below (to read the article directly, click here):
As I was reading the Seeker.com article, I was literally at the edge of my seat waiting for them to connect their own dots, but then…nothing. It’s like they’re orbiting what is, to me, a logical conclusion, and then they just veered off the road into Back to the Future-ville. To be fair to Seeker.com, the actual paper it refers to, for some reason, states, and then re-states that the wormholes they’re talking about aren’t suggested for actual time travel, or as a viable method of zipping around the Universe using a (entirely possible) wormhole. I have no idea why the authors of the paper, which can be read here, felt the need to spell this out because no one is actually going to try and get swallowed up by a black hole just so they can get across the Universe, but whatever.
As I see it, we have a lot of dangling questions and paradigms from many different scientific disciplines, which, at first, don’t seem related, or connected. However, I beg to differ. There are scientists working on such questions as A) what is dark matter, B) what is dark energy, D) what came before the Big Bang, and D) why is our Universe not only continuing to expand, but that expansion is speeding up? While I don’t claim that black holes are the answer to every astrophysical question, I do think they are the answer to many questions. But if someone is trying to decide how the galaxy created the black hole residing at its own center, maybe they’ve got it backwards.
And if our Universe is not only expanding, but the expansion is speeding up because of the 74% of dark energy which keeps getting pumped in from somewhere while, in another corner of science, we know that the most intense forms of energy have always been, and are currently being, shot out like fire hydrants on crack from black hole jets…um, well, duh.
Two things in closing
The first is that you may get to the end of this post and think, “What damn gedankenexperiment? Schatzie told me what to imagine.” Wrong. I bet that you imagined what I was trying to explain as you read this post. Do you know what a Schwarzschild radius is, or what the value of Ω (omega) is? How about λ (lambda) which is also known as the cosmological constant? Or what the Chandrasekhar Limit means? Most people don’t. You don’t need to know all the foundational equations and theories to know what I’m talking about. You can imagine the concepts and maybe even take it further if you give yourself the opportunity to relax and just lean into it regardless of how young or old you are. I daresay Einstein would be proud.
Secondly, some of you may think, “I don’t have time for this crazy stuff!” I understand. Completely. Here’s the thing: so much of what I see in the world leaves me filled with despair and left with the feeling that we are doomed, as a species. When I read about the mind blowing discoveries that we silly humans are making each and every day, it gives me hope and makes me so proud to be a part of this species. I’ll end with another quote from Nigel Calder’s book about Albert Einstein:
“So do not be deterred from trying to understand what Einstein said, by any thought that he may become outdated. On the contrary, if you have not felt the ground move under your feet while contemplating his ideas, you have missed the frisson of the century. The ideas are not entombed in textbooks that students mug up for their examinations. In so far as present-day scientists understand the universe we live in, Einstein’s theories are the bedrock. He supplied no finished work of art to be admired but not touched by his successors. He created an imaginative framework for them, and specific theories to serve, directly, or indirectly, in almost every serious attempt to consolidate and extend his understanding. It is Einstein’s universe.”
Further reading on black holes and white holes:
The Revival of White Holes as Small Bangs (2011);
“Ask the Van” question and 2 good answers about black holes/white holes (2009);
Radial motion into an Einstein-Rosen bridge (2010);
Out of the White Hole: A Holographic Origin for the Big Bang (2013);
NatGeo article: “Every black hole contains another universe?” (2010);
UPDATE to further reading about black holes:
July 7, 2016 Scientific American article about black holes and galaxy formation;
Further reading about galaxies and their black holes:
The Coevolution of Galaxies and Supermassive Black Holes: A Local Perspective (2011);
Seyferts, quasars, blazars, and radio galaxies;
NASA’s NuSTAR mission website;
Further reading (or listening via audiobook) to blow your mind:
Brian Greene’s excellent books The Elegant Universe, The Fabric of the Cosmos, and (especially) The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos. Greene’s audiobooks are excellent, by the way, and can be purchased on iTunes.
Max Tegmark’s Our Mathematical Universe, which is also excellent in audiobook format.
In Einstein’s own words (and without math): “The Evolution of Physics: From Early Concepts to Relativity and Quanta,” 1938. This book was done with the help of Einstein’s friend, Leopold Infeld and instead of gedankenexperiment, Einstein refers to what he calls “idealized experiments.” The back story to this book is good. Einstein did at with Infeld to help him out, financially (which it did).