Tiona (a sequel to "Vaz") (15 page)

Weitzel frowned, “What if it’s like normal matter in outer space, where there is only a few molecules per cubic meter?”

She shrugged, “Then it accelerates those molecules close to light speed? They gain apparent mass and the action of accelerating those massive particles
still
drives the disc with an ‘equal and opposite reaction.’” She tilted her head curiously, “Of course we don’t
know
that that’s what’s happening. We just know that we
are
seeing a lot of thrust. Either there’s a lot of dark matter in this region of space, or the discs can generate a lot of thrust from very little dark matter.” She shrugged again, “Or, of course, maybe some completely different phenomenon is responsible for the thrust we’re measuring.”

Weitzel stared at Tiona for a minute; then turned to Eisner, “Can I borrow your rig for a while? Run some tests of my own?”

Eisner shrugged.

Tiona said, “I can let you have a pair of the membranes to work with, but it would sure be nice if you got your own current generator by the time the break is over. I’d like to keep doing my own studies.”

Eisner glanced at the current generator. “Of course. I can order my own, but are you saying you don’t need it right now?”

Tiona shook her head. “My dad has a couple in his lab. He’s really interested in this and we’re having a lot of fun working on it together so I’ll just be using his.”

Eisner and Weitzel quietly walked out together, each lost in his own thoughts. As they exited the building Weitzel turned to Eisner, “Her dad has a lab? What’s he do?”

Eisner shrugged, “I don’t know. She says he’s got a PhD in physics, but apparently he’s unemployed.” After a pause he resumed, “Obviously this isn’t for public consumption, but you should know—because it might affect some of your interactions with her—that they must have some significant financial problems.”

Weitzel frowned, “How did you come to find out about that?”

“One of the other grad students has seen her eating at the homeless shelter.” He put up a hand as if to fend off whatever Weitzel might say next, “We don’t think she’s homeless. Apparently you don’t have to be homeless to eat at the shelter, and Marlowe has seen her leaving the shelter after she has her dinner, but presumably she’s pretty low on funds if she has to eat there.”

“Oh… that’s sad. Let me know if there’s something I can do to help? Throw in a few bucks for some kind of an aid package?”

Eisner grunted, “I can’t think of a way to give her any money that wouldn’t be embarrassing. Besides, I told her about how you had some temporary paid work in your lab over the Christmas break and she didn’t want it.” He glanced at Weitzel to see how he took that; then continued, “To be honest, I found it a little frustrating. You know, that she’s accepting charity at the shelter, but won’t take on a little extra work to help her own financial situation?”

They walked a little further in silence; then Weitzel said, “Well, she’s a brilliant girl who probably has a good career in front of her. I hope she isn’t so far into debt that she can’t ever dig herself out.”

The two men went their separate ways.

***

When Tiona got home she found her father fidgeting in the kitchen, apparently making himself some lunch. “What did Dr. Weitzel think?” he asked.

Tiona shrugged, “He was pretty doubtful. However, he couldn’t think of an out and out proof that it
isn’t
dark matter. Neither he nor Dr. Eisner have been able to come up with a better explanation though.”

Lisanne came out of the pantry with a box of crackers. “It’s fun seeing the two of you working together, but what
are
you working on?”

Tiona looked at her dad, “You haven’t told her what we’re working on?”

Lisanne laughed, “You must be kidding. Your dad hardly ever talks about what he’s doing.”

Tiona frowned, “You’re keeping secrets from Mom?”

Vaz looked upset, but Lisanne came to his rescue. “It’s not that he’s keeping secrets, he just never thinks anyone else would be interested. Except, now of course, his daughter who’s getting a doctorate in physics.”

Vaz looked more upset, “But… usually you
don’t
want me to tell you what I’ve been doing!”

Lisanne giggled, “He’s got me dead to rights there. Sometimes I ask him about what he’s working on and before he gets very far into the description I’m completely bored and usually pretty cross eyed too.” She smiled fondly at him; then turned to Tiona. “However, I am interested in whatever it is you two have been working on together. I can tell you’re both pretty excited about it.”

“Well, we’ve got these membranes, that when you use them in pairs seem to accelerate dark matter from one to another…” Tiona went on to explain what they thought was going on and how they thought that the thrust might be useful for station keeping in satellites.

Lisanne frowned, “But if these discs are sucking dark matter in on one side and spraying it out on the other, why doesn’t the blast of dark matter coming out the other side knock things around? Surely you’d be able to see that happening?”

Tiona’s brow knit as she explained. “That’s one of the big issues with dark matter. It doesn’t really interact with normal matter so that’s why it’s so hard to detect. Dark matter can pass right through us without our even noticing it. Many think that untold billions of dark matter particles pass through you every second.”

“Wait, you’re saying that if one of your disks was making a jet of dark matter and I held it up to my hand here,” Lisanne held her hand up like a paddle, “that the jet of dark matter would just blow right through my hand without hurting it? Or pushing on it? Like I’m a ghost?”

Tiona nodded.

“But… how can it do that? Aren’t the… atoms or whatever of dark matter going to hit the atoms in my hand and bounce off?”

Tiona frowned again, “You know our atoms are mostly empty space, right? One analogy that’s made points out that if you blew up an atom to the size of the inside of St. Peter’s Cathedral in Rome, the nucleus of the atom would be the size of a grain of salt. So if particles of dark matter were similar in size, you can imagine how they would blow right through normal matter as long as they didn’t react electrically or magnetically or otherwise to the nucleus or the electrons.”

Lisanne stared at her daughter for a moment; then laughed again. “Well, I’m getting cross eyed again, but at least that analogy makes it a little bit easier to understand.”

Tiona made herself some lunch too and ate with her parents. Vaz was finished eating long before she was and immediately started fidgeting. He watched her eat and Tiona had the strong sensation that he wished she’d hurry up. Finally she said, “You don’t have to wait for me. You can head on back down to the lab and whatever you’ve been working on.”

He glanced up towards the basement door as if thinking about it, but then said, “No, I’ve got something interesting to show you.”

Tiona smiled at her mother, “Do you think mom would be interested in it?”

Vaz looked at Lisanne, considering the question as if it were extremely perplexing. “I don’t know,” he said dubiously, “maybe?”

Tiona smiled at Lisanne, “Well, what do you think Mom? You want to take a chance on coming down to look at something you only ‘might’ be interested in?”

Lisanne grinned back, “Sure.”

Once the dishes were put away, all three of them trooped down to the basement to see Vaz’s “something interesting.” As soon as they got down there, Tiona’s eyes were immediately drawn to a disc about a meter in diameter and a couple of inches thick that was sitting in the middle of the floor. It had a pole sticking up out of the middle of it that had some switches and buttons up near the top. “You built a big one?”

Vaz nodded eagerly. “I divided the surface of the big membranes on this disc up into partitions. Each section can be energized separately, but if they are all powered up it generates the same amount of thrust you would expect from a disc with a diameter of a meter.” He looked at Tiona to see if she grasped what he was saying.

“So… the fact that the individual sections aren’t actually circles doesn’t matter as long as they all work together to make a circle?”

“Yes! And, in fact if I vary the power to the different sections somewhat it still generates good thrust, but it tilts away from the one with the most power!”

“Oh! So you have control! It can tilt and fly around?”

“Yeah,” Vaz said sounding very satisfied and staring at the disc like a proud father would at a newborn child.

“Well let’s plug it in! I want to see it in action.”

Vaz blinked at her, as if surprised by her lack of perception. “It runs on batteries.”

Tiona turn to stare at it, “Where?” she began, then ran down. She turned to look at her father, “They’re between the top and bottom discs?”

Vaz nodded, “With the current generators and the control processors.”

Tiona turned back to look at the disc again, “Wait a minute, there isn’t room between the two surfaces of the disc for a current generator.” As soon as she said it, she saw their current generators still sitting there on the lab bench.

Vaz said, “
Those
current generators are big because they need to be adjustable. They can produce a lot of different frequencies and amplitudes, with various biases. I ordered some that just produce one gigahertz and modified their circuits for the bias. They’re much smaller.”

Tiona said musingly, “Processors?”

“Yeah, I put in a low level AI to control the current to the different sections so that it stays level. Unless you want it to go somewhere. Then the processor adjusts the current to tilt it the direction you want to go.”

“And you did all this in the past couple of days while I’ve been talking to Eisner and Weitzel?”

Vaz blinked, “Well, I ordered the current generators a few days ago when it looked like they might be cool things to have around. Then all I had to do was precipitate the membranes, modify the generator current and assemble it. I did almost all of it this morning.” He got a distant look, “Except for the precipitation yesterday.”

Tiona felt bemused by the way he described putting the project together like it was something very simple. “So, we have our own flying saucer, huh?”

Vaz frowned and turned to look at the disc, “You’re calling it a saucer because it’s round?”

“And it flies. You know, like in science fiction, where the aliens fly a saucer?”

Vaz looked a little confused, “Um, no, I don’t read science fiction. Why would they fly saucers?”

Tiona laughed, “Never mind. Let’s see this thing fly.”

“Okay,” Vaz said, walking over and stepping up on top of the disc.

He flipped a switch and Tiona heard a hum coming from the electronics. Just as she was thinking,
Wait, this thing can’t have enough power to…
it lifted off the floor a couple of inches.

Lisanne gave a little shriek and clapped her hands together in delight.

Astonished, Tiona watched the disc hovering there. As Vaz moved his weight around it shifted and wiggled a little bit, but seemed much more stable than Tiona would have expected. “What’s keeping it from skidding around? I mean, you’re standing there on a practically frictionless interface. You should be sliding around the room running into things!”

“I put some two inch discs all the way around the edge of this big disc,” Vaz said. “They push the big disc sideways when the AI energizes them. There are some infrared lasers on the bottom of the disc that lets the AI station-keep. One detects its altitude and the others detect motion like the lasers on the optical mice that people used to use to control their computers.” All of a sudden, the disc started sliding towards Tiona. It stopped before it hit her and Vaz said, “When you do want it to move, you push this little joystick,” he pointed to a little joystick on the top of the pole he was gripping, “and it shifts the current among the various disks so that you will slide that direction. The idea for the program came from me thinking of the old Segway two wheeled scooters.”

Tiona narrowed her eyes, “Wait a minute. How does this thing have enough power to lift you up and move you around on just batteries?”

Vaz shrugged, “Remember, energy storage was my old job at Querx? I developed quite a few systems for them. The A7 fuel cells that are in this disc store more power for their weight than any other battery in the world. They can put out twenty kilowatts for a little while.”

Lisanne asked, “Can it lift you higher, or can it
only
hover a few inches off the floor?”

Vaz said, “This scroll wheel adjusts the altitude.” As he said it he rolled the scroll wheel with a thumb and the disc lifted up high enough that Vaz had to bend his head down so that he didn’t hit the ceiling. Then he scrolled it back down until he was only a few inches off the floor again. “Until the tech is more mature, I don’t think it’s safe to be high enough that you’d get hurt if something failed.”

He flipped a switch. It settled to the floor as he stepped off.