times.”
Mac leaned closer. “So someone could travel from here to a totally different place and time?”
“In theory, but—”
“What if there were wormholes large enough to walk through?” Mac leaned in, gripping the edge of the desk.
David grinned. “What? Just chilling, ready to open like an automatic grocery store door?”
Mac looked away, frowning. “Well, no, not exactly. I just thought there might be places…”
“I doubt it. If there were, people would have done it already, don’t you think?”
She nodded. “Yeah, they would have.”
David now had the same patient and kind look she had seen him use with his students. “But there aren’t. Wormholes are smaller than atoms.”
“But they could exist. I mean, it’s not entirely impossible.” Mac shrugged nonchalantly, which was far from how she was feeling.
“Not impossible—but implausible, yes.”
Mac must have looked disappointed because David’s attitude shifted. “Look, I’m not saying they exist, because they don’t. But if there were human-sized wormholes, there would need to be some sort of energy present, enough to propel someone from one place and time to another. And, of course, they couldn’t go any faster than the speed of light.”
“Light? Like the sun?”
David’s tone became very deliberate, as if he were trying not to sound condescending. “Yeah, the sun emits light.”
“And energy? Like solar energy?”
“Yeah, solar energy is a thing.” David’s brow furrowed. His mouth twitched as though he wanted to smirk, but he kept it in check.
Mac’s face lit up. “The sun. It has something to do with the sun.”
David’s eyes narrowed. “What does?”
Mac pulled herself from her thoughts and looked at him. “Oh. Nothing. Just a book I was reading.”
“What book?”
Her eyes darted away as she searched for an answer. “Can’t remember.”
David’s whole demeanor relaxed. “If I’d known you like sci-fi, well, I’ve got some books you would love.”
Before he went on, Mac held up her hand. “No. That’s okay. I’ve got a stack of books at home waiting to be read. I don’t need any more, really. But thank you.” She shook her head slowly. “So time travel’s possible.”
“In theory. But no one has tried it—not seriously. Nor will they.”
“Why not?”
“Think about it. If you were a brilliant scientist, how crazy would you sound just asking for funding? And then, who would grant it? Time travel research? Game over. Career crash and burn.”
“I guess it would sound pretty crazy.”
David’s smiled faded as he caught something in Mac’s expression. “Hey, are you okay?”
She shrugged casually. “Yeah.”
David looked toward the door.
“But what if it had already happened?” Mac was serious. “What if someone had done it?”
He met her gaze for a moment and then grinned. “Well, that would be freaking awesome.” He laughed. “From the looks of those tests I’m grading, I’m pretty sure my students have time traveled to back before I ever taught them.” He stood up. “Well, I’d better get going. Those papers won’t grade themselves.”
David rose and turned to leave, but Mac barely reacted, still fixed on a thought.
“Well, like I said, I’ll be leaving now.” With a chuckle, David tapped his fist as though it were a mic. “Is this thing on?”
A smile bloomed on Mac’s face. “I’m sorry. I was thinking.”
“Yeah, I could tell. I’m intuitive like that. Look, Mac, what’s this all about?”
She thought for an instant about telling him, but the next moment she said, “Just curious.”
David narrowed his eyes but said nothing.
Mac let out a breath and stood up to follow him to the door. “I’d better let you get back to work.”
When he got to the closed door, he turned and extended his hand. He shook her hand and said in a falsetto voice, “I’ve had a lovely evening.”
Mac laughed and shoved his shoulder as he opened the