From ``Ring'', by Stephen Baxter.

She had entered a new realm of matter.

Lieserl. Lieserl! I know you can hear me. I'm monitoring your feedback loops. Just listen to me. Your senses are overloaded; they are going to take time to adapt to this environment. That's why you're whited out. You're not designed for this, damn it. But your processors will soon be able to interpret the neutrino flux, the temperature and density gradients, even some of the g-mode patterns, and construct a sensorium for you. You'll be able to see again, Lieserl; just wait for the processors to cut in ...

The voice continued, buzzing in her ear like some insect. It seemed irrelevant, remote. In this mush of plasma, she couldn't even see her own body. She was suspended in isotropy and homogeneity -- the same everywhere, and in every direction. It was as if this plasma sea, this radiative zone, were some immense sensory-deprivation bath arranged for her benefit.

But she wasn't afraid. Her fear was gone now, washed away in the pearl-like light. The silence ...

Damn it, Lieserl, I'm not going to lose you now! Listen to my voice. You've gone in there to find dark matter, not lose your soul.

Lieserl, lost in the whiteness, allowed the still, small voice to whisper into her head.

She dreamed of photinos.

Dark matter was the best candidate for aging the Sun.

Dark matter comprised all but one hundredth of the mass of the Universe; the visible matter -- baryonic matter which made up stars, galaxies, people -- was a frosting, a thin scattering across a dark sea.

The effects of dark matter had been obvious long before a single particle of the stuff had been detected by human physicists. The Milky Way galaxy itself was embedded in a flattened disk of dark matter, a hundred times the mass of its visible components. The stars of the Milky Way didn't orbit its core, as they would in the absence of the dark matter; instead the galaxy turned s if it were a solid disc -- the illuminated disc was like an immense toy, embedded in dark glass.

According to the Standard Model there was a knot of cold, dark matter at the heart of the Sun -- perhaps at the heart of every star.

And so, Lieserl dreamed, perhaps it was dark matter, passing through fusing hydrogen like a dream of winter, which was causing the Sun to die,

Now, slowly, the isotropy bleached out of the world. There was a hint of color -- a pinkness, a greater warmth, its source lost in the clouds below her. At first she thought this must be some artifact of her own consciousness -- an illusion concocted by her starved senses. The shading was smooth, without feature save for its gradual deepening, from the zenith of her sky to its deepest red at the nadir beneath her feet. But it remained in place around her, objectively real, even as she moved her head. It was out there, and it was sufficient to restore structure to the world -- to give her a definite up and down.

She found herself sighing. She almost regretted the return of the external world; she could very quickly have grown accustomed to floating in nothingness.

Lieserl. Can you see that? What do you see?

``I see elephants playing basketball.''

Lieserl --

``I'm seeing the temperature gradient, aren't I?''

Yes. It's nice to have you back, girl.

The soft, cozy glow was the light of the fusion hell of the core, filtered through her babyish Virtual senses.

There was light here, she knew -- or, at least, there were photons: packets of X-ray energy working their way out from the core of the Sun where they were created in billions of fusion flashes. If Lieserl could have followed the path of a single photon, she would see it move in a random, zigzag way, bounding off charged particles as if in some subatomic game. The steps in the random walk -- traversed at the speed of light -- were, on average, less than an inch long.

The temperature gradient in this part of the Sun was tiny. But it was real, and it was just sufficient to encourage a few of the zigzagging photons to work their way outwards to the surface, rather than inwards. But the paths were long -- the average photon needed a thousand billion billion steps to reach the outer boundary of the radiative layer. The journey took ten million years -- and because the photons moved at the speed of light, wrapped over on themselves like immense lengths of crumpled ribbon.

Now, as other ``senses'' cut in, she started to make out more of the environment around her. Pressure and density gradients showed up in shades of blue and green, deepening in intensity toward the center, closely matching the temperature differentials. It was as if she were suspended inside some huge, three-dimensional diagram of the Sun's equation of state.

As if on cue, the predictions of the Standard Model of theoretical physics cut in, overlaying the pressure, temperature and density gradients like a mesh around her face. The divergences from the Standard Model were highlighted in glowing strands of wire.

There were still divergences from the Model, she saw. There were divergences everywhere. And they were even wider than before.

Dark matter and baryonic matter attracted each other gravitationally. Dark matter particles could interact with baryonic matter through other forces: but only feebly, and in conditions of the highest density -- such as the heart of stars. In Earthlike conditions, the worlds of baryonic and dark matter slid through and past each other, all but unaware, like colonies from different millennia.

This made dark matter hard to study. But after centuries of research, humans had succeeded in trapping a few of the elusive particles.

Dark matter was made up of sparticles -- ghostly mirror-images of the everyday particles of baryonic matter.

Images in what mirror? Lieserl wondered feebly. As she framed the question the answer assembled itself for her, but -- drifting as she was -- it was hard to tell if it came from the voice of Kevan Scholes, or from the forced-learning she'd endured as a child, or from the data stores contained within her wormhole.

Hard to tell, and harder to care.

The particle mirror was supersymmetry, the grand theory which had at last shown how the diverse forces of physics -- gravitational, electromagnetic, strong and weak nuclear -- were all aspects of a single, unified superforce. The superforce emerged at extremes of temperature and pressure, shimmering like a blade of some tempered metal in the hearts of supernovas, or during the first instants of the Big Bang itself. Away from these extremes of time and space, the superforce collapsed into its components, and the supersymmetry was broken.

Supersymmetry predicted that every baryonic particle should have a supersymmetry twin: a sparticle. The electron was paired with a selectron, the photon with the photino-- and so on.

The particular unified-theory called Spin (10) had, with time, become the standard. Lieserl rolled that around her tongue, a few times. Spin (10). A suitably absurd name for the secret of the Universe.

The divergence, of theory from observation, was immense-- and increased toward the center of the Sun.

``Kevan, it's way too hot out here.

We see it, Lieserl, he said wryly. For now we're just logging the data. Just as well you didn't pack your winter coat.

She looked within herself, at some of her subsidiary senses. ``And I'm already picking up some stray photino flux.''

Already? This far out from the center? Scholes sounded disturbed. Are you sure? As a star like the Sun swept along its path about the center of the galaxy -- through a huge, intangible sea of dark matter -- photinos fell into its pinprick gravity well, and clustered around its heart.

The photinos actually orbited the center of the Sun, swarming through its core around the geometric center like tiny, circling carrion-eaters, subatomic planets with orbital ``years'' lasting mere minutes. The photinos passed through fusing hydrogen as if it were a light mist...

Almost.

The chances of a photino interacting with particles of the plasma were remote -- but not zero. Once every orbit, a photino would scatter off a baryonic particle, perhaps a proton. The photino took some energy away from the proton. The gain in energy boosted the orbital speed of the photino, making it circle a little further out from the heart of the Sun.

Working this way, passing through the fusing hydrogen with its coagulated mass of trapped photons, the photinos were extremely efficient at transporting heat out from the center of the Sun.

According to the Standard Model, the temperature at the center should have been suppressed by a tenth, and the fusion heat energy smoothed out into the surrounding, cooler regions, making the central regions nearly isothermal -- at a uniform temperature. The core would be a little cooler than it should otherwise have been, and the surrounding material a little warmer.

... Just a little. According to the Standard Model.

Now, Lieserl studied the temperature contours around her and realized how far the reality diverged from the ancient, venerated theoretical image. The isothermal region stretched well beyond the fusion core -- far, far beyond the predictions of the Standard Model with its modest little knot of circling photinos.

``Kevan, there is much more heat being sucked out of the core than the Standard Model predicted. You do realize that there's no way the Model can be made to fit these observations.''

No. There was a silence, and Lieserl imagined Scholes sighing into his microphone. I guess this means goodbye to an old friend.

She allowed the contour forms of the Standard Model to lapse from her sensorium, leaving exposed the gradient curves of the physical properties of the medium around her. Without the spurious detail provided by the overlay of Standard-Model contours, the gradient curves seemed too smooth, deceptively featureless; she felt a remnant of her earlier deprived-sensorium tranquility return to her. There was no sense of motion, and no real sense of scale; it was like being inside overlaid clouds glowing pink and blue from some hidden neon source.

``Kevan. Am I still falling?''

You've reached your nominal depth now.

``Nominal. I hate that word.''

Sorry. You're still falling, but a lot more slowly; we want to be sure we can handle the energy gradients.

But she'd barely breached the surface of the plasma sea; eighty percent of the Sun's radius -- a full two light-second -- still lay beneath her.

And you're picking up some lateral drift, also. There are currents of some kind in there, Lieserl.

It was as if her Virtual senses were dark-adapting; now she could see more structure in the waxy temperature-map around her: pockets of higher temperature, slow, drifting currents. ``Right. I think I can see it. Convection cells?''

Maybe. Or some new phenomenon. Lieserl, you're picking up data they've never seen before, out here. This stuff is only minutes old; it's a little early to form hypotheses yet, even for the bright guys in Thoth.

I wish you could see the Interface -- out here, at the other end of your heat sink. Deep Solar plasma is just spewing out of it, pumping from every face; it's as if a small nova has gone off, right at the heart of the System. Lieserl, you may not believe this, but you're actually illuminating the photo-sphere. Why, I'll bet if we looked hard enough we'd find you were casting shadows from prominences.

She smiled.

I can hear you smiling, Lieserl. I'm smart like that. You enjoy being the hero, don't you?

``Maybe just a little.'' She let her smile broaden. I'm casting shadows onto the Sun. Not a bad monument.