My feet itched; they were too close to a nova. I had other priorities at that point. I stopped thinking and ran.

We bundled into the flitter; I let the buttlebot lift us off, and stored the Xeelee flower carefully in a locker.

The lift was bumpy: high winds in the stratosphere. A spectacular aurora shivered over us. “Squeem, are you sure you’ve done your sums right?”

“There is an inherent uncertainty in the behavior of novae,” the Squeem replied reassuringly. We reached orbit; the main ship swam towards us. “After all,” the Squeem lectured on, “a nova is by definition an instability. However I am confident we have at least five minutes before—”

At once, three events.

The moons blazed with light.

The Squeem shut up.

The main ship turned from a nearby cylinder into an arrow of light, pointing at the safety of the stars.

“Five minutes? You dumb fish.”

The buttlebot worked the controls frantically, unable to comprehend the abrupt departure of the Squeem. The nova had come ahead of schedule; the twin moons reflected its sick glory. We were still over the dark side of the planet, over which screamed a wind that came straight from the furnaces of a medieval hell. On the day side, half the atmosphere must already have been blasted away.

The flitter was a flimsy toy. I estimated we had about ten minutes to sunrise.

My recollection of the first five of those minutes is not clear. I do not pretend to be a strong man. I remember an image of the walls of the flitter peeling back like burnt flesh, the soft interior scoured out…

Leaving one object, one remnant, spinning in a cloud of metal droplets.

I realized I had an idea.

I grabbed the Xeelee flower from its locker, and wasted a few more seconds staring at it. The only substance within a million miles capable — maybe — of resisting the nova, and it was the size of my palm. I had to grow it, and fast. But how?

My brain chugged on. Right. One way. But would there be time? The flower’s activating base came off, and went into a suit pocket.

The buttlebot was still at the controls, trying to complete its rendezvous with a vanished ship. If there’d been time, I might have found this touching; as things were, I knocked it aside and began entering an emergency sequence. My thinking was fuzzy, my gloved fingers clumsy, and it took three tries to get it right. You can imagine the effect on my composure.

Now I had about a minute to get to the back of the vessel. I snapped closed my visor and de-cycled the airlock. I failed to observe the mandatory safety routines, thus voiding the manufacturer’s guarantees. The buttlebot clucked nervously about the cabin.

Clutching the Xeelee flower, I pulled into space and set off one-handed.

I couldn’t help looking down at the stricken planet. Around the curve of the world, the air rushing from the day side was gathering into a cyclone to end all cyclones; clouds swarmed like maggots, fleeing the boiling oceans. A vicious light spread over the horizon.

Followed by the confused buttlebot, I made it to the reactor dump hatch. In about thirty seconds, the safety procedure I had set up should funnel all the flitter’s residual fusion energy out through the hatch into space, in one mighty squirt. Except, the energy pulse wasn’t going to reach free space; it would all hit the Xeelee flower, which I was going to fix into place over the hatch.

Right. Fix it. With what? I fumbled in my suit pockets for tape. A piece of string. Chewing gum. My mind emptied. The buttlebot scuttled past, intent on some vital task.

I grabbed it, and wrapped the flower in one of its pseudopodia. “Listen,” I screamed at it, “stay right here. Got it? Hold it for five seconds, please, that’s all I ask.”

No more time. I scrambled to the far side of the flitter.

Five seconds isn’t long. But that five seconds was long enough for me to notice the brightening of the encroaching horizon. Long enough to note that I was gambling my life on a few more or less unfounded assumptions about the Xeelee flower.

It had to be a hundred percent efficient; if it couldn’t absorb all that was about to be thrown at it, then it would evaporate like dew. It had to grow exponentially, with the rate of growth area increasing with the area grown already. Otherwise it couldn’t grow fast enough to save me as planned.

I also had plenty of time to wonder if the buttlebot had got bored—

There was a flash. I peered around the flitter’s flank.

It had worked. The flower had blossomed in the fusion light into an umbrella-sized dish, maybe just big enough for the hard rain that was going to fall.

The flower tumbled slowly away from the now-derelict flitter, as did the buttlebot, sadly waving the melted stump of one pseudopod. I kicked it out of the way, and pushed into space. The heat at my back was knife-sharp.

I reached the flower and curled into a ball behind it. The light flooded closer, beading the edge of my improvised shield. I imagined the nova’s lethal energy thudding into the material, condensing into harmless sheets of Xeelee construction material. My suit ought to protect me from the nasty heavy particles which would follow. It was well made, based on Xeelee material, naturally… I began to think I might live through this.

I waited for dawn. The buttlebot tumbled by, head over heels. It squirmed helplessly, highlights dazzling in the nova rise.

At the last moment I reached out and pulled it in with me. It was the stupidest thing I have ever done.

The nova blazed.

The flitter burst into a shower of metal rain. The skin of the planet below wrinkled, like a tomato in steam.

And that buttlebot and I rode our Xeelee flower, like surfers on a wave.

It took about twelve hours. At the end of that time, I found I could relax without dying.

I slept.

I woke briefly, dry-mouthed, muscles like wood. The buttlebot clung to my leg like a child to a doll.

We drifted through space. The flower rotated slowly, half-filling my field of view. Its petaled shadow swept over the wasted planet. It must already have been a mile across, and still growing.

What a spectacle. I slept some more.

The recycling system of my suit was designed for a couple of eight-hour EVA shifts. The Squeem did not return from their haven, light years distant, for four days.

I did a lot of thinking in that time. For instance, about the interesting bodily functions I could perform into the Squeem’s tank. And also about the flower.

It grew almost visibly, drinking in the sunlight. Its growth was exponential; the more it grew, the more capacity it had for further growth — I did some woolly arithmetic. How big could it grow?

Start with, say, a square mile of construction material. I made educated guesses about its surface density. Suppose it gets from the nova and surrounding stars about what the Earth receives from the Sun — something over a thousand watts a square yard. Assume total efficiency of conversion: mass equals energy over cee squared.

That gave it a doubling time of fifteen years. I dreamed of numbers: one, two, four, eight, sixteen… It was already too big to handle. It would be the size of the Earth after a couple of centuries, the size of Sol a little later.

Give it a thousand years and you could wrap up the Galaxy like a birthday present. Doubling series grow fast. And no one knew how to cut Xeelee construction material.

The Universe waltzed around me; I stroked the placid buttlebot. My tongue was like leather; the failing recycling system of my suit left a taste I didn’t want to think about.

I went over my figures. Of course, the growing flower’s power supply would actually be patchy, and before long the edge would be spreading at something close to the speed of light. But it would still reach an immense size. And the Xeelee hadn’t shown much interest in natural laws in the past. We drifted into its already monstrous eclipse; the buttlebot snuggled closer.