"'SI0."
"Well, listen."
Alex strained his ears for half a silent minute. Insect chirps, a feeble rustle of wind, a few distant bird cries. "Maybe. A little."
"Well, I hear it," Buzzard said, with satisfaction. "Most people can't. Martha can't. But that's the Taos Hum."
"What's that?"
"Real low, kind of a wobbling sound... about thirty to eighty hertz. Twenty hertz is about as low as human hearing can go." He spread his arms. "Sourceless, like it's all around you, all around the horizon. Like an old-fashioned motor, or a fuel-burning generator. You can only hear it when it's really quiet."
"I thought it was the solar rack."
"Solar racks don't hum," Buzzard told him. "They hiss a little, sometimes...
"Well, what is it?"
"They call it the Taos Hum, 'cause the first reports came out of New Mexico about fifty years ago," Buzzard said. "That was when the first real greenhouse effects starting kicking in... . Taos, Santa Fe, Albuquerque...hen parts of Florida. Y'know, Jerry was born in Los Alamos. That's where Jerry grew up. He can hear The Hum."
"I still don't understand what it is, Boswell."
"Nobody knows," Buzzard said simply. "Jerry's got some theories. But The Hum doesn't show up on instruments. You can't pick up The Hum with any microphone."
Alex scratched his stubbled chin. "How d'you know it's really real, then?"
Buzzard shrugged. "What do you mean, 'real'? The Hum drives people nuts, sometimes. Is that real enough for ya? Maybe it's not a real sound. Maybe it's some disturbance inside the ear, some kind of resonant power harmonic off the bottom of the ionosphere, or something.
Some people can hear the northern lights, they say; they hear 'em sort of hiss and sparkle when the curtains move. There's no explanation for that, either. There's a lot we don't understand about weather." Buzzard clutched the lump of blackened metal on the leather thong around his neck. "A lot, man."
They stared silently at the western horizon for a lQng moment. "I'm sending the 'thopters out to scan those towers," Buzzard said. "They're gonna break the cap by noontime."
"You don't happen to have a spare pair of those shades, do you?" Alex said. "This glare is killing me."
"Naw," Buzzard said, turning back toward the truck. "But I got some spare virching goggles. I can put you under 'em and patch you in to the 'thopters. Let's go."
They returned to the truck, where Martha was remotely wrapped in flight. Buzzard rummaged in a tool kit, then produced a pair of calipers. He measured the distance between the pupils of Alex's eyeballs, then loaded the parameters into a laptop. He pulled spare goggles and phones from their dustproof plastic wrap and sterilized them with a swab. "Can't be too careful with virching equipment," he remarked. "People get pinkeye, swimmer~s ear... in the city arcades, you can get head lice!"
"I got no chair," Alex pointed Out.
"Sit on some bubblepak."
Alex fetched his bubblepak mat and sat on it, sweating. There was a faint hot wind from the southeast, and he couldn't call it damp, exactly, but something about it was suffocating him.
A lanky mosquito had landed unnoticed on Martha's virch-blinded arm and was filling its belly with blood. Alex thought of reaching over to swat it, then changed his mind. Martha probably wouldn't take a swat on the arm all that well.
"Here ya go," Buzzard said, handing him the goggles. "Telepresence is kind of special, okay? You can get some real somatic disturbance, 'cause there's no body sensation to go with the movement. Especially since you won't be controlling the flight. You'll just be riding shotgun with me and Martha, kinda looking over our wings, right?"
"Right, I get it."
"If you start getting virch-sick, just close your eyes tight till you feel better. And for Christ's sake, don't puke on the equipment."
"Right, I get it, no problem!" Alex said. He hadn't actually thrown up during his ultralight experience. On the contrary: he'd coughed up about a pint of blue goo from the pit of his lungs, then passed out from oxygen hyperventilation. He thought it was wiser not to mention this. If they thought it was merely vomit, so much the better.
Alex slipped the goggles on and stared at two tiny television screens, a thumb's width from the surface of his eyes. They were input-free and cybernetic blue, and the display had seen some hard use; the left one had a light pepper sprinkling of dead black pixels. He felt sweat beading on his goggle-smothered eyelids.
"Ready?" came Buzzard's voice from the distant limbo of the real world. "I'm gonna leave the earphones off awhile so we can talk easier.
"Yeah, okay."
"Remember, this is going to be a little disorienting."
"Would you just shut up and do it, man? You people kill me!"
White light snapped onto his face. He was halfway up the sky, and flying.
Alex immediately lost his balance, pitched over backward, and thunked the back of his head onto the hard plastic of the truck's rear tire.
Eyes wide, he squirmed on his back with his shoulders and heels and flung out both his arms to embrace the drifting sky. He felt both his arms fall to the bubblepak with distant thuds, like severed butcher's meat.
He was now soaring gut-first through space. The ground felt beautifully solid beneath his back, as if the whole weight of the planet was behind him and shoving. The outline of distant clouds shimmered slightly, a hallucinatory perceptual crawl. Computational effects; when he looked very closely, he could see tiny dandruff flakes of pixel sweeping in swift little avalanches over the variants in color and light intensity.
"Wow," he muttered. "This is it. Mega, mega heavy . .
Instinctively, he tried to move his head and gaze around himself. There was no tracking inside the goggles. The scene before him stayed rock steady, welded to his face. He was nothing but eyeball, a numbed carcass of amputated everything. He was body-free.
He heard the squeak of the lawn chair as Buzzard settled into his own rig. "You're on Jesse now," Buzzard said. "I'll switch you onto Kelly."
The scene blinked off and on again, flinging him electronically from machine to machine, like a soundless hammer blow between the eyes.
"We're gonna climb now," Buzzard announced. The machine began flapping soundlessly, with slow wrenching dips in the imagery.
"We want to get up to the cap," Buzzard said. "That's where the action is right now."
"Gimme those headphones," Alex demanded, stretching out one arm. "I'll put 'em over just one ear."
Buzzard handed him the headphone rig and Alex adjusted it by feel. The earphones had a little attached mouth mike, a foam blob on a bent plastic stick. Under his fumbling blind fingers, Alex's head felt unexpectedly huge and ungainly. His head felt like somebody else's head, like a big throw pillow upholstered in scalp.
With his ears secured beneath the pads of the earphones, Alex suddenly felt The Hum again, buzzing and tickling at the edge of his perception. The Hum was flowing right through him, some creepy rumbling transaction between the rim of outer space and planetary magma currents deep below. He strained his ears-but the harder he tried to hear The Hum, the less there was to perceive. Alex decided that it was safer not to believe in The Hum. He pulled the pad off his left ear. No more Hum. Good.
Then he began to hear the keening wind of the heights. "We got ourselves a storm situation," Buzzard announced, with satisfaction. "What we got, is two air masses m a scrap. You listening, Alex?"
"Yeah."
"That line of cloud dead ahead, that's the cutting edge of some damp hot air off the Gulf. It's wedging up a front of hot dry air coming off New Mexico. That dry air aloft- we're coming into that right now-that's the cap. Right now it's suckin' steam off the tops of those cumulus towers and strippin' 'em off flat."
Alex understood this. He was gazing down across the tops of clouds, approaching them unsteadily on flapping digital wings. The climbing, bubbling sides of the heap were the normal cauliflower lumps, but the flattened tops of the towers looked truly extraordinary: great rippling plazas of turbulent vapor that were being simultaneously boiled and beaten.