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Gravity’s Punch
by Tony Daniel

The Heat Death of the Universe Got You Down? Fight Back with Science!

Here’s how things seem to stand. Entropy is increasing. London Bridge is falling down. The Second Law of Thermodynamics is a picture of the fall, and time is its measure. Gravity (and its evil twin, inertia) runs the clock. Particles without mass, such as photons, can’t be made into clocks (that is, structures that measure the passage of time) all by themselves, and as more and more material transforms into such massless particles, the material world degrades to low-level energy in fits and starts, fizzles and pops.

All matter eventually becomes heat lugged outward in the form of force-carrying particles such as photons and, maybe, gravitons. Outward to where? To nowhere.

It’s a picture of the universe as one flaming arrow shot into the dark. The arrow hits no target because there is no target out there.

The expanding pressure is inexorable. The cosmological constant does not allow the universe to contract again. All the black holes evaporate. The coarse-grain irregularities of nature even out. Those force-carrying particles the bosons are all that remain and they spread until they are so far apart they can no longer cause any change in another portion of existence. Their world lines intersect nothing ahead. Without matter and causation, you can’t build a clock.

The clocks don’t stop, they simply cease to exist.

The universe dies.

Or lives on in an ineffectual forever, depending on how you want to look at it.

Every bit of this rather depressing conception is founded on two basic assumptions. Assumption #1: scientific law is deterministic or probabilistic in nature always and everywhere. Assumption #2 (which usually incorporates Assumption #1): the current understanding of physics is more or less correct and we can extrapolate from it.

Both of these assumptions, it seems to me, are dubious when you get to thinking about them. My point here is going to be that a healthy skepticism toward determinism in its various guises is not merely okay from a scientific perspective, but that it actually is the scientific perspective, as opposed to science’s evil orc version, twisted into existence by certain Sarumans of the intellectual class. Let’s call this scientism.

Consider the Heat Death model. Isn’t there something slightly . . . sadistic about the whole affair? Doesn’t it have the feel of somebody attempting to impress you with how puny and ineffectual life is destined to be? I can’t imagine Egyptians bowing to their Pharaoh felt any more in the grip of an uncaring, omnipotent, petty little god than those of us who accept that this, our precious universe, is going to end in frozen bosonic tears.

First, let me put paid to any idea that I’m saying we need to adopt a more subjective or culturally relative outlook on the Big Fizzle or any other scientific question. How do we humans conceptualize time? Is it even possible to escape through happy subjectivity? Might we really decide how we want to look at the end of everything?

The answer is no, of course. Our sense of time is not merely a mental affair. The world is too much with us to believe in that kind of lint-gazing drivel. Time, for us humans, is based on a psychological sense of a personal history and a personal, continuing future. Consciousness and self-awareness depend upon it. And self-awareness and the ensuing ability to conceptualize is our primary species adaptation. Without our sense of time out there, beyond our personality, there wouldn’t be any language or meaningful thought. Nothing would seem real except our own inner nattering. A thinking being’s perception and conceptualization of time defeats its inherent tendency toward narcissism and solipsism.

So how well does our human sense of time match up with the clocks of the universe? We should expect it to match pretty well, since the brain has pretty clearly created a rough-and-ready representational simulation conditioned by existence. Of course, the brain is fully capable of creating false memories and its sense of time can break down due to disease lesion or injury and leave a person stranded in the present, the past, or some alternate and fairly meaningless Erewhon. We recognize these as mental pathologies easily enough, however. By and large, our neurological mapping of time is so reliable it has allowed us not only to survive but to become the dominant species of an entire planet.

A related question that bears in on the difference between science and scientism: does the universe, like us humans, have a memory and a sense of its own future?

The scientism believer is immediately appalled by the idea. It’s so . . . anthropocentric, full of hubris. So pro-human. Ugh.

But the answer is: sure it does. Here on Earth, one glance at sedimentary rock or the magnetic striations on the ocean floor produced by the poles’ fairly regular flip-flops from north to south provide a readable record of the past. Up in the sky, the universe’s base metabolism, the cosmic background radiation, is a present-day record of the big bang birth and a continuing reminder of the cold equations that predict the end of it all.

Of course the convinced disciple of scientism may argue that none of these “memories” mean anything to the universe. That, like a compact disk existing in a future when all audio has been transferred to MP3s and all the old players have broken down, the information sits there for eternity and the music on the CD is never played again (a future probably nearer than we suppose).

But this objection is hypothetical at this point in the universe’s history. Here on Earth, we humans are the CD players for the known universe. We interpret the encoded information we come across like those magnetic stripes on the ocean bottom, and make general deductions about reality from them – in the case of those stripes, we deduce the principles of plate tectonics. But even without us, the effects of the past do affect the present and will affect the future. That’s the whole point of the Second Law of Thermodynamics. There’s meaningful information everywhere, and it creates its own consequences. Time marches on.

Physical time and psychological time (and, in a broader sense, concepts of nature and nature itself), while not the same, are obviously fundamentally related. Witness how easy it is for us to grasp the relativity of time as predicted by the General Theory of Relativity, for instance, once we’ve understood a few appropriate analogies and/or mastered some math. The idea that nobody can understand Einstein is so much hogwash. People have adapted quite nicely to these new ideas. Why? Because something about reality, even undiscovered reality, matches up with the pattern recognition ability that forms our inner sense of time’s passage.

So when I say I’ve got a very bad, ugly and sad feeling about the heat death of the universe, I believe I’m expressing a thought beyond my own personal taste and proclivity, a thought based on a very real conception of time. It isn’t the same as whether or not I think watermelon tastes good (I do!), but more like whether or not I think cold-blooded murder is wrong (I do!). Watermelon is a preference, while being opposed to the murder of innocents is a self-evident moral truth.

Of course, some people are okay with murder. And some people will be okay with the whole heat death of the universe thing. These people we may call . . . how to put it . . . the self-deceived. Who else could wish such a fate upon the blooming buzz of creation?

But can there really be something objectively true about the dislike most of us feel for the unpleasant idea that everything is going to end in ineffectual blahness? Does this uneasy sensation tell us something about the current state of our knowledge? If we ignore scientism’s siren call for despair and a twisted sort of resigned pleasure to our own puniness, might this queasiness really mean that we are missing something important?

First, we need to know if physics as we currently conceive it can come to our rescue. Maybe we’ve simply gotten something wrong. What about time symmetry? It’s a truism that the equations of physics work backward and forward in time – or rather, that the passage of time in a larger sense has no effect upon them. Why, then, are all the clocks ticking the hours until doomsday? Can we simply turn the hourglass upside down and start the sand running backward?

Unfortunately, no. Sure, there’s time reversibility, time commutation so far as it goes, but it goes precisely as far as the Second Law of Thermodynamics allows.

Eggs do not unbreak themselves without the presence of a nearby system of lower entropy, say a magician manipulating smoke and mirrors, a filmmaker playing around with video, or a physicist powering up a particle accelerator. The universe as a whole has no nearby system of lower entropy upon which to draw. We’re all we’ve got, baby. Egg making and breaking generally only proceeds in one direction.

What about black holes? Are they the universe’s saviors? After all, are they not spawning “baby universes” all the time? Doesn’t universe formation follow a kind of natural selection process with universes that are likely to spawn even more black holes “fit” to survive? It’s a stylish idea, but one that seems to be as completely mistaken as the elegant old steady state hypothesis.

Black holes don’t last forever and every bit of matter that falls into one eventually comes back out in another form. Information may or may not be destroyed within – there’s controversy. In any case, the processessing of matter in a black hole takes a long time. A very long time. But the existence of Hawking radiation puts paid to all the grand cosmological theories of the multiverse birthers. Every black hole, from the tiniest singularity to the monster at the center of the Milky Way, is running a slight temperature and is going to vomit up everything in its stomach sooner or later in some form or another.

In the end, every black hole will disappear before the death of the universe. Every bit of matter that falls into a black hole will radiate back out as low-level energy. Those knots of space-time are going to untie themselves. It’s just going to take a long while.

Black holes cannot save us.

Where else might we look for a brighter future, both literally and figuratively?

One thing most definitely missing at the moment in our description of existence as we know it is a theory of quantum gravity. Observable gravity is well handled by modern classical (that is, Einsteinian) physics. The analogy of the stretchy rubber sheet with rocks set upon it works beautifully both to help picture gravitation effects on bodies with mass and, what is a different effect, gravitational radiation (any gravitational deformation produces a gravity wave that travels outward at the speed of light). The sheet bends with the weight of the rock and ripples with the force of its plop onto the sheet.

But the certainty of classical physics breaks down at the quantum level. Nobody has ever discovered the supposed force-carrying particle for gravity, the graviton. This may be due to the incredibly small size a graviton is expected to have. Or it may be due to the fact that we have no real idea of just what gravity is to begin with.

In the famous Sidney Harris cartoon, a mathematician works out an equation on a blackboard and in the midst of the operators is the expression “THEN A MIRACLE OCCURS.” The caption of the cartoon has his colleague commenting: “I think you should be more explicit here in step two.”

A lot rides on “step two” when it comes to quantum gravity. There are attempts at explaining how the big bang happened -- or, rather, attempts to describe what conditions would be in place for there to have been a big bang – that depend upon an interpretation of gravity as being like all the other fundamental forces (that is, the electroweak and strong nuclear) but smaller. Way smaller. Only mighty at the tiniest levels conceivable.

Just how small can we conceive things to be?

Continuous time can’t be measured in units shorter than the time it would take a photon to cross the Planck length, a measurement twenty orders of magnitude littler than a proton in an atom. It comes out to about 10-24 second. And the first tick of this clock was the most important 10-24 second of all existence. According to some quantum cosmological theories, it was then that a quantum fluctuation produced a particle out of nothing. A special particle.

This is maybe not as strange as it sounds. Virtual particles are not merely a theoretical construction in quantum physics. They’ve been proved to exist. Naked space can and does “create” particles (always in twos with baryons, but singly with photons and the like), and with a blade of sufficient tininess – a blade with a sharpness approaching the Planck distance – these particles can be winnowed apart and teased into continued existence. See the Quantum Connection novels of Travis S. Taylor or my own Metaplanetary and upcoming Guardian of Night [Baen, February 2012] for some of the fun science fiction writers can have with such concepts.

But in the quantum fluctuation theory, this first virtual particle was different from your ordinary run-of-the-mill virtual particle. It had enormous mass and incredibly low entropy. It was, in fact, everything that is, held together at the moment of birth by the concerted action of the unified forces of nature. It couldn’t last long that way, however.

Tick.

Symmetry cracks. Gravity separates out first among all forces..

Tock.

Kaboom. Or Ka-bloom, maybe is the better expression.

The clock started, and the universe ran . . . downhill. It’s this presumption about the quality of quantum gravity – that it is essentially one with the other fundamental forces, merely the first portion of the original force of forces to break symmetry – that gets us to our current bleak state. But it is entirely a presumption because nobody has successfully worked out a theory of quantum gravity.

Not for lack of trying, of course.

John Wheeler’s “quantum foam” of wormholes, entangled, knotty loops, vortices of spinning Planck-sized cellular structures, and a bunch of other possible shapes and sizes, as well as so-far analogy-less mathematical constructions, have been proposed.

Perhaps the most famous of the quantum gravity conceptualizations at the moment are those of string theory. I won’t dig into the meat of those ideas here, but will note that with much of string theory predicting observable consequences and creating repeatable experiments has proved problematic. You can’t help but suspect that this is because string theory may turn out to be about as useful as medieval philosophical arguments for how many angels can dance on the head of a pin.

Show me an angel, and then we’ll talk about pins and dancing.

But what if there are no gravitons, no fundamental particles that are force carriers for gravity? Some recent theories describe gravity as an emergent property of the universe rather than a fork in the road one portion of existence took after the big bang. Gravity becomes something like thermodynamics, fluid dynamics or biology – a consequence rather than a cause.

The key to such theories is the attempt to stand the idea that gravity causes entropy on its head. Instead, entropy is itself a fundamental force and gravity is a product of this “entropic principle.” All of the laws of at least Newtonian physics can thus be derived from viewing the universe as relatively coarse-grained. Within certain areas you can treat all the different particles as if they were one and the same.

Take as an analogy a wooden kid’s block that is uniformly green on all six sides. This doesn’t mean that every molecule on the block’s surface is green. There may be some blues mixed in there. There may be some yellows. In fact, there may be no “real” green reflectors at all. Nevertheless the block appears green, and we can call it green and it will do “green block” things. The universe is lumpy and a lump often behaves uniformly for certain purposes.

So the idea is that gravity arises as a boundary effect when two or more such coarse regions interact. Think of a balloon. If we rub the outside of a latex balloon to make static electricity, the dust motes concentrate on that side due to the electrostatic charge on the exterior. But in the case of emergent gravity, the effect is inertial, occurs at a much larger scale (and doesn’t make that awful, cringe-inducing balloon squeak). In fact, say the emergent theorists, as a general rule we can state that entropy in the universe acts to separate and tease apart matter so that it maximizes itself, that is, that it maximizes the overall entropy. And that separation and destruction of coarseness, the propensity to smooth out the lumps, is what we experience as gravity.

An interesting part of this theory – and the part that may give us hope to avoid the heat death of everything – is that it treats gravity as pure information.

We can look at quantum phenomenon – especially the force carrying particles – as carriers of information about other particles, for example “normal” matter, say baryons like electrons and protons. In this view, the universe is in a sense a computer, and the discrete entities of quantum mechanics are its bits and bytes. The problem with this idea has been gravitons. As in, where are they? What are they? Do they behave like the other force-carriers, and exactly what kind of information do they carry? Nobody knows.

What if emergent gravity theory is right and there simply are no gravitons to begin with? Gravity would then be not a basic-unit bit or byte but a larger subroutine. This would make our conception of time emergent as well. What matters is the information contained in the universe, not its physical placement. And, through various mechanisms such as a black hole event horizon or, heck, even a perpetually traveling photon, information can be made to seem to last forever.

We might escape the end of time by essentially crawling into our own bellybuttons.

Or, to put it another way, entropy saves -- and makes incremental backups which we can stash in places we hope are removed from the hard drive. The hard drive? We know that’s going to crash. But so what? We’re information, baby.

Gravity? We don’t need no stinking gravity!

Yeah, right. First, I am queasy with the idea of existence becoming a mere backup to a dead reality. Don’t you get the sneaking suspicion that something is going to get lost along the way? I know I’ve never done a successful full restored from a back-up without something going missing. Furthermore, I’m not at all convinced that if the beauty and truth of existence becomes disembodied, generalized, and transmuted into a static form that anything that, er, matters about it will remain.

Second, it is very difficult to conceive of gravity as anything but a fundamental force. Granted, this is intuitional, and intuition can be very wrong. Yet extraordinary claims, such as emergent gravity, require extraordinary proof precisely because intuition is more often right than not – since it is but the sum total of our rules of thumbs derived from experience (plus, maybe, a dash of creativity and a jigger of single malt insanity). In any case, we should listen to intuition, absent any other evidence. And, like string theory, the predictable, observable consequences of emergent gravity theory do not seem apparent.

Furthermore, the inflection of gravity with entropy smells like a tautology, an A = A statement, as well. Finally, the conflation of information with physical forces in general has the feel of an analogy run wild. More specifically, it feels like it may be the psychological product of humanity in the current developed world sitting for hours in front of the glowing screens of our current dominant technology and getting stuck in information-age metaphors for everything.

Do we really live in an old laptop with a battery failing from being plugged into the a.c. current too long? Yuck.

Which sends us back to the tragedy of the dying universe again.

One recent escape hatch that seems more promising than a theory of emergent gravity is put forward by the mathematician and physicist Roger Penrose.

Penrose’s Cycles of Times is a unique book, the likes of which we seldom see these days: it’s written for the general reader but doesn’t soft pedal any of the complexity of thought (or math) that leads to the conclusions. If you’ll persevere to the end, you’ll love it – or at least feel like in completing it you’ve finished something like a mental marathon (although your final time may leave something to be desired. Mine did.).

In Cycles, Penrose proposes what he admits is a conjectural notion of universe formation. In his youth, he admits to having admired prettiness of the old steady state model of the universe, where matter is being born from quantum fluctuations and such, where the universe is expanding forever, and where the road goes ever on, as it were.

Then Penrose ran into Stephen Hawking and gave all that nonsense up.

Penrose makes an argument in Cycles for something with similarities to the old balanced beauty of the steady state while taking into account all the new stuff such as the steady-state-killing discovery of the cosmic background radiation and black holes. Penrose assumes that gravitons somehow exist on the quantum level and will be described sooner or later.

He argues that at the extreme end of things -- the heat death of the universe after all the black holes have evaporated and all that remains in existence are mass-less protons and gravitons -- the geometry of the universe will match the geometry necessarily in place at the time of the big bang. Time, things happening, low entropy flowing to high via the Second Law of Thermodynamics, all of which Penrose says are permutations of the same phenomenon, would lose expression in the dark after the long twilight.

The moment the last boson passes beyond the last causation possibility of any other particle, the big bang will have its freshly lined football field, or its empty chess board, if you prefer.

The game can begin again. The ball can bounce.

At least the necessary smooth geometric conditions would be in place for a big bang to occur. What’s more – and this is important to Penrose, who is queasy about theories that involve assumptions of unique conditions -- you don’t have to consider such initial, “pre” big-bang conditions to be unique, singular, or highly improbable. They are the outcome of the death of our universe, and of any universe.

And so we could be somewhere in the midst of an endless cycle of expanding and "bouncing" universes, in a kind of a amalgamation of the big bang and the steady state. Would the physical constants and laws have to be the same from universe to universe? I think Penrose would say as long as the laws of the new universe were scalable and could be mapped onto our own using the advanced mathematical version of saving in a different file format.

I am more cheered by Penrose’s idea for escape than by any of the others, but even Penrose admits that his is only an attempt to lay the groundwork for a new big bang at the end of our current universe. He’s doubtful that quantum fluctuations can produce such an event (he mainly finds the unique and random nature of such an event aesthetically displeasing, it seems) and he doesn’t know otherwise how the thing itself would happen.

At least with Penrose, we return to the notion of cycles of time. We get an elegant rhythm to being. The universe may be entirely deterministic and somewhat repetitive, but at least it isn’t doomed to fizzle and go away forever.

In Tom Godwin’s famous, melodramatic story, “The Cold Equations,” a young girl stows away on a rocket ship bringing emergency medicine to stop a plague on a distant planet. The ship has only enough fuel to take the weighty cargo and one human to its destination.

Millions of people are at risk. The ship requires a trained pilot. And if the stowaway remains, the ship, and its vital medical supply, will run out of fuel before it gets to its destination.

Even if you haven’t read the story, you can probably guess what happens. What, in the logic of the story, has to happen. Let’s just say it doesn’t have a happy ending.

Must we treat our hope for something other than frozen nothingness at the end of time as if it were that fresh-faced eighteen-year-old girl?

Contrary to the tenets of scientism, I don’t think that is the pickle in which we find ourselves.

Recall assumption #1: scientific law is deterministic or probabilistic for the entire cosmos and assumption #2: the current understanding of physics is more or less correct and we can extrapolate from it.

We’ve seen that as regards the ugly Heat Death rigmarole, assumption #2 is not merely uncertain, but wildly off the mark. Despite some intriguing suggestions, we are missing any understanding of gravity on a quantum level.

But what about assumption #1? Is not this the basis of science? Not at all.

Science may or may not have a basis in what we currently view as rational. Science does not even assume inductive logic. David Hume was right to throw it out as a certainty. What happens always trumps whatever has gone before.

This is enormously cheering.

Nobody knows what is going to happen.

There may be rules to this game of which we are unaware. In fact, I have a sneaking suspicion (you might even call it faith) that there are.

Heat death ain’t pretty. There’s no fun in it. No entertainment. No beauty. It just feels incomplete as a prediction and as an explanation for anything, like a song that cuts off before its proper conclusion. Why should this sense of incompleteness be any less meaningful than some presumption that science as we know it is necessarily done, finished, and that existence is ultimately kaput. Human aesthetic perception can be just as world-based as human sense of time. Why shouldn’t it be? A honed sense of beauty is a survival mechanism, too.

Anyway, I hope and expect that this universe will escape such a fate.

If I’m wrong and somebody shows me I’m wrong, then so be it. But so far nobody has.

As the philosopher William James puts it:

“When scientific and moral postulates war, and objective proof is not to be had, the only course is voluntary choice, for skepticism itself, if systematic, is also voluntary choice…Freedom's first deed should be to affirm itself. We ought not to hope for any other method of getting at the truth if indeterminism be a fact.”

In my case, the postulates are probably more aesthetic than moral. But if our universe’s fate to experience an ugly, wasting death is not predetermined, then who is to say we cannot find a way for it (and maybe even us as a species) to escape the coming fizzle? Who is to say we can’t make a solution for ourselves once we discover what gravity really might be on the small scale and what scientific truths even beyond some hoped-for grand unified field theory may exist and be out there for discovery? We should at least not go down without a fight.

And who knows, maybe gravity will be on our side in the end.

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