Last-minute gravitational wave predictions, June 28th 2023, hot damn

My predictions as to what the International Pulsar Timing Array will announce it has found, at 1pm Eastern US time, June 29th...

OK, this is a short and dirty post: important (to me, at any rate), but written in a hurry, and thus messy. Forgive typos, and general sloppiness… It contains some hasty and highly ambitious predictions that could be proved horribly, and publicly, wrong tomorrow. So, high risk, high reward. The fun stuff.

(Later note, as I am about to post: dirty, yes, short, no. It ended up long. They all end up long. When will I learn? Also there is too much swearing, which happens when I type late at night while excited, but I don’t have time to take it all out now.)

WHY THE HURRY?

Why the hurry? Because there is about to be an announcement, tomorrow, June 29th, at 1pm Eastern US time (you can watch it live here) of the results from the International Pulsar Timing Array. (I'll explain what that is in a minute – it's extremely cool.) Yes, I should have seen this coming long ago (they've been running this experiment for DECADES), and carefully crafted a perfect post full of exquisitely-calibrated predictions months back, but that's not how I roll, baby.

By the way, there is a HUGE buzz in the cosmology, astronomy and astrophysics communities about this announcement. Plus plenty of irritated anti-buzz blowback, mostly from the physics community. Sample buzzy tweet:

Sample anti-buzz counter-tweet, from the gloriously grumpy Sabine Hossenfelder (dunking directly on a colleague while quote-tweeting her):

Sample grumpy anti-anti-buzz counter-counter-tweet:

And then a general degeneration into simple swearing:

So, you are in on the ground floor of an excellent astrophysical pie-fight.

A PEDANT ASKS: Do pie fights have ground floors? 

TO WHICH I REPLY: Look, buster, I told you I'm writing this in a hurry. You can either have carefully crafted metaphors, or REVOLUTIONARY PREDICTIONS THAT WILL ASTONISH THE WORLD, but you can't have both.

Where were we?

Oh yes. So, why is this imminent announcement relevant to you and me, here, and now? Well, remember, this blog explores the idea of an evolved universe... (Old readers, bear with me, I'm going to recap the theory, because there are always new readers, and if they don't get a few lines of deep background, they will be completely lost. Plus, I know most of you haven’t in fact read the early theoretical stuff. But feel free to skip to the next section if you have, or indeed to the predictions at the end…)

BACKGROUND ON COSMOLOGICAL NATURAL SELECTION – AND THE EVEN DEEPER IDEA OF OUR UNIVERSE AS A COMPLEX EVOLVED ORGANISM

OK, we’re just going to have to gun through about a book’s worth of ideas in a couple of pages, so, deep breath, and let’s go.

The Egg and the Rock explores the idea that our universe is the result of an evolutionary process at the level of universes. That evolutionary process has fine-tuned the basic parameters of matter so that our universe self-assembles itself upward, from a simple cloud of undifferentiated hot gas into the startlingly intricate network of nested complexities you see all around you. (Highly improbable complexities of which you are a prime example.)

If our universe as a whole is the result of an evolutionary process that took place over many generations of previous universes, then the complex hierarchy of structures that comprise our particular universe– the fundamental particles, atoms, molecules, stars, galaxies, planetary systems, and biospheres – also evolved, as part of that deep, universe-level, evolutionary process – just as (in the case of DNA evolution) the internal cells and organs and limbs and circulatory/nervous/immune systems of a particular giraffe evolved, over many earlier generations, as giraffes evolved. That evolution goes for black holes too – which will become important later in this piece.

That’s because the evolutionary mechanism I’m exploring is cosmological natural selection, a fascinating, much misunderstood, hypothesis, tentatively put forward in the 1990s by physicist Lee Smolin, that builds on John Wheeler’s ideas about black holes. (Smolin was Wheeler’s student.) Let’s call it this hypothesis a theory, because that’s the word normal people use for such hypotheses.

The theory was overlooked at the time for sociological, rather than scientific reasons (published in the wrong place at the wrong time); my argument is that it’s true; that recent evidence is starting to validate it; and that predictions (like this one) can be made, based on it, that give better results than the existing theories.

SHUT UP AND GIVE ME THE THEORY

Sure. In it, black holes give birth to big bangs. (Put another way, the singularity of our Big Bang in our universe is merely the “other side” of the singularity that is a black hole in a parent universe). So, baby universes are born in big bangs. It's an elegant theory – it explains two otherwise inexplicable things:

1.) Where matter and energy vanish to when they become black holes (and thus leave our space time), and

2.) Where matter and energy come from in big bangs (when a new space-time comes into being).

Here’s where Smolin improved on Wheeler: if there is a slight variation in the basic parameters of matter with each new generation of universe, then there will be a potential variation in how many black holes those baby universes will produce in their lifetime – and thus universes will evolve. Because every universe is both organism and environment, and not in direct competition for resources with other universes, runaway reproductive success is possible. Eventually, universes whose basic parameters have been (blindly but relentlessly) fine-tuned by evolution to produce huge numbers of black holes (and thus offspring) will totally dominate the overall number of universes.

So, basically, over time, universes should get REALLY REALLY GOOD at producing black holes…

But there is an important implication here: black holes have to have appeared right at the start of the evolutionary history of universes. No black holes = no big bangs = no new universes.

Put another way, universes that don’t produce black holes have no kids.

So every single ancestor universe to ours produced at least one black hole. Everything else is a bonus: Stars and galaxies and planets and biospheres and people like you and me faffing about on things like the internet... they all arose later, for reasons I explain elsewhere (this is already getting long). They are all more recent than black holes, in evolutionary terms. Big bangs, black holes (and some kind of matter to pass from one to the other) are primary; everything else is secondary.

That is, black holes are fundamental.

But what kind of black holes did early universes produce? Our universe today contains a colossal number of stellar-mass black holes – that is, black holes with the mass of a single decent-sized star, only a few times bigger than our sun. (Stellar-mass black holes are formed when a single star collapses after it runs out of fuel.) In fact, as of just last year, there are now estimated to be 40,000,000,000,000,000,000 black holes in our universe. (I told you that the reproductive success of universes, in the absence of environmental or resource constraints, could get out of hand.) But our universe also contains a smaller number of supermassive black holes: black holes with the mass of millions or even billions of stars the size of our sun. There is, for some odd reason, almost always one such supermassive black hole sitting at the heart of every galaxy.

I think I know the reason.

My argument is that supermassive black holes must form first – before stars, before galaxies. (And thus before stellar-mass black holes, which are a later evolutionary development, and have a different and more complex formation mechanism.) The logic of an evolved-universe theory strongly suggests that the early universe, just after the Big Bang, is optimised by evolution for supermassive black hole production, not star formation.

There are two arguments for this, one theoretical, one observational.

Theoretical: if universes evolve, then early, primitive universes would have produced small numbers of very large black holes, very directly. The simplest possible reproducing universe would simply flip-flop back and forth, black hole to big bang to black hole to big bang: the next simplest would produce two black holes and thus two big bangs, and thus potential variation, allowing evolution to kick off.

As you can see, with a rapid lifecycle – like early prokaryotic bacteria – those ultra-primitive universes would have done basically nothing except swiftly reproduce, through something that looks awfully like direct collapse supermassive black holes. (Direct collapse means no stars are required: the gas just collapses directly to create an incredibly massive black hole.) So direct collapse supermassive black hole production is baked into the fabric of an evolved universe; it just falls straight out of the theory. (An aside: As far as I have been able to discover – and to my absolute astonishment – literally nobody in the cosmological community seems to see this incredibly important, obvious, and consequential, implication of cosmological natural selection, even though it leads directly to better predictions about the early universe than all mainstream theories; if you know of anyone who is working on this, please PLEASE point me in their direction.)

So our more advanced universe (great at producing stunning numbers of small stellar-mass black holes through a complex process of star formation) would be an evolutionary elaboration of those early, primitive universes – which were extremely good at directly producing supermassive black holes. Why on earth would we lose such an attribute? Especially if it can be built upon, elaborated upon, to drive the more complex later form of small-black-hole-production-through-star-formation, which allows you to have more offspring. OK, that’s the theoretical argument. Now…

Observational: It is clear from the extraordinary regularity of the Cosmic Microwave Background Radiation (the CMBR) that in its very early stages – immediately after the Big Bang – the gas of our universe was too smooth and featureless for efficient star formation (being without those many little pockets of higher density required to seed star formation): but of course that makes it ideal for the formation of direct collapse supermassive black holes. Because it's so smooth, once a large area of gas does start to collapse, there are no smaller, locally dense, areas to separate out and collapse into stars. An entire ultra-vast area of ultra-smooth gas, massive enough to form tens of thousands or hundreds of thousands or even millions of stars, can thus simply keep on collapsing (without breaking up into lots of sub-clouds, and forming stars).

(My argument here: the basic parameters of matter are fine-tuned by evolution to enable exactly that unlikely-seeming outcome. Such a wave of direct collapses LOOKS highly unlikely, if you assume our universe is a random one-shot with arbitrary properties: in fact, it’s just exquisitely finely balanced, by evolution, to give that result.)

So you get a wave of supermassive black hole formation well inside the first 50 million years of the universe (and probably far, far earlier) by direct collapse – a couple of hundred billion of the blighters, one for each future galaxy – and those supermassive black holes then generate the conditions for star formation. (I’ve outlined the mechanism for that in detail here, but we need to keep moving, I’m on a deadline and I’m running out of chocolate.)

That is, direct collapse supermassive black holes form before stars and galaxies, and each one then generates a galaxy around itself (and yes, the central black hole grows with that galaxy’s growth, pulling in more gas and stars – but it starts off big, and first. You have an active galactic nucleus BEFORE you have a galaxy – it’s the supermassive black hole “nucleus”, pulling in the surrounding hydrogen gas with its tremendous gravity, then processing and enriching that gas by making small quantities of carbon and oxygen through fusion at a pinch-point in its accretion disc, and then redistributing that enriched gas through relativistic jets, that builds out the galaxy, that generates the conditions for rapid star formation.)

(AN ASIDE, WHICH YOU CAN SKIP IF IT’S TOO TECHNICAL: The evolutionary back-and-forth over many generations of universe might have led to a slightly more complex mechanism whereby a small number of large, primitive stars do form early on {so-called Population III stars – terrible name – made of only hydrogen and helium, because the heavier elements haven’t been formed yet}, and basically act as spark plugs, their ultraviolet light being of just the right wavelength to help the gas clouds to collapse, but I can't explain the whole fucking theory and all its variations here, I've got exciting predictions to get to. Follow excellent astrophysicists like Priyamvada Natarajan, if you want to know more.).

Anyhow, if I'm right, and this is how galaxies form, then that has huge implications for things like gravitational waves, and thus for tomorrow's big announcement. So I want to make some predictions in advance of the release.

But to understand my predictions, you'll need some background on gravitational waves…

BACKGROUND ON GRAVITATIONAL WAVES AND THE INTERNATIONAL PULSAR TIMING ARRAY

OK, let’s start with Gravity 101.

GRAVITY

As Einstein showed, you can think of gravity as the distortion (the curving or bending) of spacetime by a mass. The classic way to visualise this is in two dimensions – so, horribly simplified – with spacetime as a rubber sheet, and stars, planets, etc, as balls of various sizes and densities on the rubber sheet. Each ball sits at the bottom of a dip it has made in the rubber sheet. Try to roll a marble in a straight line across the sheet, and its path will be distorted by the dips in the sheet – just as an object moving through space has its path distorted by the gravity of the stars and planets it passes. If the marble gets too close to a ball in a deep dip, it might swing around it – orbit it – while descending deeper and deeper into the dip (ie, deeper into the gravity well) until it arrives at the bottom of the dip and hits the ball (crashes/merges). The larger the mass, the larger the curvature, the deeper the dip, the faster other objects will slide down the curve.

GRAVITATIONAL WAVES

Gravitational waves are ripples in this rubber sheet of spacetime. They are produced when a mass accelerates in a way that isn't symmetrical (more technically, in a way that isn’t spherically or cylindrically symmetrical, but you know, whatever, we’re in a hurry here). Basically, if a mass politely expands, or contracts, or rotates extremely symmetrically, it doesn't produce gravitational waves. But if a mass swings wildly about the place, unsymmetrically, it produces gravitational waves. (If a ball on the rubber sheet simply rotates – symmetrically, on the spot, where it is – it doesn’t send waves through the rubber sheet. But if, say, two balls rotate around each other while getting closer and closer, that’s not symmetrical, and they send waves through the rubber sheet as they move.)

AN ASIDE ON HOW MOBILE PHONES VIBRATE

If you want a more everyday analogy, this is rather like the way our phones vibrate: a normal electric motor spinning inside your phone wouldn't make it vibrate, because the rotating mass of an electric motor is, normally, symmetrical. (A nice example of symmetrical cylindrical rotation, in fact.) But the tiny motors designed to make mobile phones vibrate have a little weight stuck to one side of the motor shaft: now, when it rotates, the movement is no longer symmetrical, so it shakes the shit out of the phone.

AN ASIDE TO THE ASIDE: TOOTHBRUSH ROBOTS

(One of the most amusing things you can do for, or with, your small child is to get the tiny vibrating motor out of an old mobile phone, wire it to a small, 3-volt button-battery, tape them both to the plastic back of the severed head of an old toothbrush, and put the toothbrush-head, bristles-down, on a tray. Toothbrush robot! The vibration motor will make it slip and slide all over the place, on the many legs of its bristles, in a chaotic and semi-random way that looks alarmingly and amusingly alive.)

BACK TO GRAVITATIONAL WAVES

But back to gravitational waves… What do gravitational waves do? And how do you detect them? Well… They’re ripples in space-time. When such a gravitational wave passes through a galaxy, or a solar system (or you and your cup of coffee), space-time stretches, and contracts. Things either side of the wave get pulled a little bit further apart, and then pushed a little bit closer together. Again and again, until all the waves from the merger (or whatever caused these ripples) have passed. How much further apart, and closer together?

Well… that’s kind of hard to detect, and thus measure. (Until very VERY recently, it was impossible.) Because gravitational waves are loooooonnng. Way too long to fit between you and your cup of coffee.

That is, you can’t just watch your cup move away from you, and back again, and measure that, because you and the cup can't be on opposite sides of a wave that is a kilometre long; or a lightyear. Without sophisticated instruments, you can't “hear” gravity waves, just as you can't hear the tectonic plates of the earth colliding, even though tectonic plates are literally moving mountains, which makes a lot of noise (ie, releases a lot of energy that vibrates the rock, and the air above it – but in the ultrasound range). In both cases, the objects involved are too large, the waves are too enormously long: a soundwave that measures several meters from crest to crest simply can't be detected by an eardrum that is only a couple of centimetres wide. And a gravity wave that’s a kilometre long… well, you won’t see your cup move, no matter how long you stare at it.

So to detect even high-frequency gravity waves – that is, relatively short gravity waves – the kind produced by the merger of two neutron stars, or a couple of small black holes – you need a detector that is several kilometres long. (We built one starting in the 1990s, it’s called LIGO – the Laser Interferometer Gravitational-Wave Observatory – which has arms four kilometres in length.) And even then, the two ends of an arm of the detector will only be moved apart by a fraction of the width of a proton by the passing wave. (Which explains why they started building LIGO in 1994, and it only first detected a gravity wave in 2016. Incredibly hard work to refine it and refine it to get it to be that sensitive. But yes, it is astounding that we can now measure this. Rainer Weiss, Kip Thorne and Barry C. Barish rightly won a Nobel Prize in 2017 for the breakthrough. OH, QUICK INTERESTING ASIDE: Kip Thorne knows so much about the weird things gravity does that he was the main scientific consultant for Christopher Nolan’s Interstellar.)

So, anyway, until a few decades ago we had no way of detecting such gravitational waves, even though when black holes merge, about 5% of their total mass is radiated away as gravitational waves. In seconds. It’s a ludicrous, unimaginable amount of energy, equivalent to… well, you’re not going to believe me, and will think I missed a couple of decimal points in my haste, so I will quote the official, er, Powerpoint slide from Caltech/LIGO on that first gravitational wave detection in 2016:

“LIGO estimated that the peak gravitational-wave power radiated during the final moments of the black hole merger was more than ten times greater than the combined light power from all the stars and galaxies in the observable Universe.”

A simply incomprehensible quantity of energy – it shakes the universe! – but not aimed at our human-scale senses.

Now if black holes with the mass of a couple of dozen suns make such waves when they merge (that first merger was between two black holes with masses of 29 and 36 times that of our sun), then imagine what the merger of two supermassive black holes – the kind found at the centre of galaxies – should produce. Black holes with the mass of MILLIONS of suns – maybe even a BILLION suns. MORE. Why doesn't LIGO detect them?

OK, NOW IT GETS REALLY EXCITING

Good question.

Because gravitational waves, like all waves, have frequencies, and as the frequencies get lower, the waves get longer. LIGO can't hear supermassive black holes colliding for the same reason that you and your coffee cup can’t detect ordinary black holes colliding. (Or hear mountains being formed.)

LIGO's arms are four kilometres long. But the gravitational waves produced by two supermassive black holes as they spiral closer and closer to each other would be lightyears long. And if your coffee cup happened to be a light year away from you, such gravitational waves would only move you and the cup apart by a few meters. Imagine trying to see if your cup had briefly moved by a few metres… from a lightyear away.

HOW THE FUCK DO YOU DETECT THAT???

OK, let me now hand you over to Chiara Mingarelli and Melize Ferrus, two excellent young gravitational waves researchers who spend a lot of time trying to explain this shit to people. (Mingarelli is an assistant professor of physics at Yale, and last year recorded a fascinating hour-and-a-half of detailed conversation about gravitational waves and how to detect the blighters, with theoretical physicist Sean Carroll, on his (always interesting) Mindscape podcast. Check out that episode if you want to dive deeper into this; great starting point.) Let them describe in slightly more technical language the tremendously difficult problem they are trying to solve:

"Potentially millions of supermassive black holes are slowly orbiting their partner, with each of their gravitational wave signals stacking up on top of each other to create gravitational noise—or a gravitational wave background. This background has an amplitude which is set by the number of supermassive black hole binaries which create it, their distance from the Earth, and the masses of the black holes themselves. This amplitude also varies as a function of gravitational-wave frequency, from the nanohertz regime to the microhertz regime—millions of times lower frequency than the LIGO detectors can ever measure. But how can we detect such low-frequency gravitational waves? Concretely, a billion solar mass supermassive black hole binary at a frequency of 1 nanohertz takes about 30 years to complete an orbit."

That’s from an excellent piece Mingarelli and Ferrus wrote together for the (also excellent) Nautilus, called A Supermassive Test for Einstein’s Famous Theory, well worth a read.

So, to sum up the problem: the BIGGEST signals… are so big you’d need a detector the size of the Milky Way to detect them. Running for decades. Put another way, the waves are so absurdly long – millions of times longer than the ones we can detect on earth – that we would need an eardrum the size of a galaxy to hear them.

And… they built it.

It’s called the International Pulsar Timing Array, and it might be, in some ways, the cleverest and most audacious thing human beings have ever done. We, recently descended from the trees, built a gravitational wave detector with arms thousands of lightyears long – using parts that were just lying around. Nobody had to build anything. Seldom in history has anyone got more bang for less bucks.

The first part of the International Pulsar Timing Array is… all the existing telescopes just lying around earth. (This detector uses a lot of them: Australian ones, British, American, Dutch, Indian…)

The second part… is all the millisecond pulsars just lying around our galaxy.

A READER WRITES: What’s a pulsar, you dick?

A pulsar is a neutron star that pulses.

ANOTHER READER WRITES: What’s a neutron star, you even bigger dick?

Glad you asked. A neutron star is a star a bit more massive than our own sun that, having run out of fuel, has collapsed under its own gravity. It’s not quite massive enough to collapse all the way into a black hole – a singularity – but it gets pretty damn close. The atoms (which are usually mostly empty space) end up squished so tightly together that the protons all become neutrons (ouch), to form a neutron soup so dense, a glass of it would weigh as much as Lake Geneva. Or, if you prefer, a sugar cube of it would weigh as much as all 1.5 billion cars on earth.

SPIN, DAMN YOU, SPIN!

Because angular momentum is conserved, this new, tiny, miniature, but super-dense star has to spin like a motherfucker. It contains all the spin of a star bigger than our own sun, but now it’s jammed into something the size of Manhattan. (Astrophysicists always use Manhattan to illustrate the size of neutron stars, I don't know why. Anyway, I’m just going to go with it, I don’t have time to come up with a new analogy, everybody else has left the office and gone home, I’m down to my last three squares of chocolate, the Manhattan is hereby declared the official unit of size for neutron stars. NO! SLEEP! TILL BROOOOOOOK…LYN!))

So you have a star that has shrunk to the size of Manhattan, and it's spinning hundreds or even thousand of times a second. (Yeah, I know, Jeeeeeeesus. It’s really hard to imagine. OK, it’s impossible to imagine.) And it’s so dense, the gravity on the surface is incredible. How incredible? Well, some neutron stars have mountains on their surface. Those mountains are believed to be up to four inches high… That's how much gravity.)

Now, spinning like that, even though they are mostly made of neutrons, they generate a hell of an electrical field. (Long story; trust me.) So electrons get captured by that field, and are accelerated along the magnetic field lines smack into the relevant magnetic pole at close to lightspeed. That generates a ferocious beam of energy that jets out of the neutron star’s magnetic pole. But if the neutron star is spinning in such a way that the beam swings past the Earth (like a lighthouse beam)… We can detect it, as a pulse of light. That neutron star is a pulsar.

Some spin (and thus pulse) faster than others. A millisecond pulsar spins (and thus pulses) over 1000 times a second.

And those pulses are far more regular than any normal clock. Which opens up an astonishing opportunity: The pulses are so quick, and close together, and regular, that if a gravitational wave passed between you and the pulsar, stretching the intervening spacetime and briefly leaving you both slightly further apart… the tiny extra distance that the pulse would have to travel would cause a noticeably delay in the pulse.

You would be able to detect it.

And if you monitored hundreds of such pulsars, you could look for the pattern in such delays, and look for the delays that affected all the pulsars… And if you monitored those pulsars for decades… You could eventually detect the kind of gravitational waves given off by enormous supermassive black holes merging. And so that's what the International Pulsar Timing Array has been doing, for many years now. Looking for that signal.

And tomorrow they issue their results.

FOR THE LOVE OF GOD, MAN, JUST GIVE US YOUR PREDICTIONS 

So, what are my predictions? Well, I'm not going to predict precisely what they are going to announce: I have no idea. But I can predict what an evolved universe theory suggests they could find; and if I’m right, and they announce some of that, I will go out and buy myself a very big icecream indeed.

OK. Predictions. Deep breath… I think that there will be a weird messy signal, from inside the first 50 million years of our universe’s lifetime, generated by the direct collapse of a couple of hundred million supermassive black holes.

It will be the gravitational wave equivalent of the Cosmic Microwave Background Radiation (CMBR). The Cosmic Microwave Background Radiation is the fossil light originally released when the universe finally cooled down enough to form atoms, and to be transparent to light; half of all the photons in our universe were released in that phase transition: that extraordinary shift from a universe dominated by energy into a universe dominated by matter – and we can still see that primal surge of light, red shifted right down into the microwave range. It's the fizz and hum scientists can still pick up on their instruments, cracking away like the lonely noise you can hear on a radio at night, between the stations, or an endless waterfall.

I think we will be able to “hear” a similar phase transition: the transition from an almost, but not quite, totally smooth universe of hot gas to a universe containing a a couple of hundred million supermassive black holes. To the extent that those collapses are symmetrical, there will be no gravitational waves. But a couple of hundred million such collapses are unlikely to all be totally symmetrical; some kind of gravitational fizz or hum should surely be detectable someday.

And remember, fifty million years after the Big Bang, our universe is estimated to have been roughly sixty times smaller than it is now. So if a couple of hundred million supermassive black holes were generated in a universe less than 2% the size of our own… well, it’s very likely there were some very early mergers of very large black holes. And such mergers between early supermassive black holes would have been a lot louder than the relatively symmetrical formation of those black holes. 

(There’s also a wildcard here: will direct collapse supermassive black holes turn out to form as binaries? (Just as we now know most stars do.) If so, early binary collisions will be off the fucking charts, as those huge binaries will start off in extremely close proximity. I don’t have a strong take on this, but I suspect it is very possible.

Of course, what they are trying to measure is the full gravitational wave background – the merger history of all the supermassive black holes across the entire cosmos. So those low frequencies will be packed with a huge amount of cumulative signal, smeared across the entire lifetime of the universe. Picking out my early (and thus necessarily faint) signals – the ones I am interested in – from all that noise, might be tricky, or even impossible.

Technically speaking (I’m running out of time to explain all the terms, sorry), I think the number density of supermassive black holes in the very early universe will be hugely more than people now anticipate. But it might be hard to separate that out from the overall signal.

So I predict that tomorrow they will announce that a surprisingly strong signal, indicating many supermassive black hole mergers, has been detected. I also predict that they will be surprised by evidence in the signal that many of these mergers happened much earlier than was anticipated.

So, more of them than expected, bigger signal than expected, and coming from earlier than expected. That's my prediction. 

(Look, it wouldn't be entirely surprising if they also, or indeed only, announced the crisp detection of a specific merger of a specific pair of nearby supermassive black holes. That finding in itself would be extraordinary, though it’s of less interest to me because it has no effect on an evolved universe theory. Recent nearby mergers will happen, and be detected, whether I’m right or wrong. Remember, I am mostly predicting what will ultimately be found, as the detectors get better and better, if my theory is true; not necessarily what will be announced tomorrow. Though I do, in fact, think they will announce the finding of a full-on gravitational wave background signal. And a strong one. And an early one.)

So, that’s it. I’m out of chocolate. We are done here. To the extent that they announce the detection of lots of gravity waves tomorrow, from early in our universe's life, the evolved universe theory is doing good. To the extent that they announce very few, very faint, gravitational wave detections, or only recent ones, it's bad. From my point of view, from the point of view of my predictions, the more the better. And the stronger the better. And the earlier the better. (Though earlier is further away is fainter, so we will see how that plays out; I don’t have time to talk you through all the permutations…) But anyway, a huge quantity of gravitational waves coming from the earliest era in our universe’s life would be SPECTACULARLY GOOD.

(This was written in a ferocious hurry, without much deep fact-checking, so it’s bound to have some godawful mistakes here and there; please point them out to me in the comments below, and I can fix them in a followup post. I don’t want to edit this one, even if I’m embarrassingly wrong, as it’s a predictions post, and editing it after the fact would be silly, and negate the point of the post. Being wrong in public is also interesting, and a potentially useful contribution to the whole conversation about these things. The whole idea is to get closer to the truth, whatever it is.)

Something interesting to watch out for: Gravitational waves emitted by ultra-early supermassive black hole mergers (ie, shortly after the Big Bang), would, by the time they reach us, be PHENOMENALLY stretched by the expansion of the universe. (Just as visible light gets stretched, and thus redshifted way down into the infrared.)  They could easily be a dozen, or dozens, of times their own original length (depending on just how close to the Big Bang they had occurred). Which means their frequency would have dropped by over an order of magnitude. Depending on the frequency of the initial waves, that might drop them too low to be detected. Now, because the longer the time period in which you observe these pulsars, the lower the frequency you can detect, it might take another decade or more to detect the lowest frequency gravity waves, from that early on.

But also, even if they don’t drop so far in frequency that they are hard to detect, there is a significant chance of another interesting problem: The International Pulsar Timing Array uses models to interpret the data: Those models most definitely do not contain a couple of hundred million extremely early direct collapse supermassive black holes, so if they announce tomorrow that they have detected the gravitational wave background, their models may wrongly interpret a huge signal from the first fifty million years after the Big Bang, which has been significantly lowered in frequency by the subsequent expansion of the universe, as a more modest signal from a smaller number of larger supermassive black holes, closer to us, and much later in the life of the universe.

Or maybe their models are sophisticated enough to extract the meaning from the data! That would be nice.

Okay, that'll do for now. Got to post something. No time to factcheck and fix this, so fingers crossed. Sorry about all the swearing, I got excited. The announcement is set for tomorrow, June 29, at 1pm Eastern US time, and you can watch it live here. See you on the other side!