Perfectly Justified Response

"Did you know the Earth formed through planetary accretion during the formation of the Solar System approximately four-point-five billion years ago?" These words greeted Nome as she stepped out into the basement laboratory, pulling her workplace-mandatory goggles on over her short brown hair. Wires and cables crisscrossed the room, taped to the floor or wall, and hung from the ceiling like technological vines.

"Uh, sure," she said. "Second grade, right between state capitals and long division. Why?"

Arkady turned to her and pulled her own goggles down so they hung off her neck. "It turns out that a ten-megaton bomb in the middle of that process is enough to blow it all apart."

"And, what, stop the planet from forming?"

"Yes. Unrelated thing: Nome, I need you to get me a bomb. Ten megatons or bigger. It'll have to be nuclear." Arkady brushed her long blond hair out of the way and pulled her goggles back up.

"So," said Nome, then she shouted. "So... stop welding!" When Arkady put down the blow torch, Nome continued. "So, what forming planetary body are we stopping? Where are we going?"

"We aren't. I'm sending this." Arkady gestured at a silvery, artichoke-like device behind her. It was the size of a backpack and covered with welding scars.

"What's that?" Nome asked. "It doesn't look like a spacecraft." She bent down to look under it. "And there's no room for a drive...." She stopped as Arkady mumbled something. "What?"

"I said, it's not a spacecraft, it's a time machine."

Nome stood up so fast she hit her head on one of the time-artichoke's more unfolded leaves. "Tell me you're not going to use this on our own planet."

Arkady rolled her eyes. "I'm not going to use this on our own planet," she mumbled as fast as possible. "Now will you get me my bomb?"

"Not until I believe you," she said. "Which is a long way off at this point."

"I could get my gullibility ray and speed it up," said Arkady.

"I hid it," said Nome. "Now talk."

Arkady pouted.

"No talk, no bomb," said Nome.

"Fine." Arkady snorted. "I'm just so sick of humanity I'm going to hit the reset button. Genocide? Bigotry? Hatred? Time to let another planet try generating the leading intelligence."

"You don't get to make that decision for the rest of us. And as your friend, I'm personally insulted you didn't ask me first."

"So skip my next birthday party. Bomb?"

"No bomb."

"Damn it!"

"You've never been this interested in Earth's considerable injustices before," said Nome. "Or even aware of them, as far as I know. What's the real reason?"

Arkady fiddled with her hair. "Petty revenge."

"Now that sounds believable. What happened?"

"Jeremy pissed me off. Said I couldn't calculate eleven-space tensors in less than half an hour." She scrunched up her face. "Everybody laughed."

"Dr. Bigger?" asked Nome. Arkady nodded. "Aw, that sucks, Arkady. I'm sorry."

"...Thanks."

"So, can we get past the overreaction to this insult that involves literally destroying the planet?"

"Yeah, I guess so. But you--"

"--can't destroy something before it exists? Oh, yeah, you're right, I'm convinced." She smiled at Arkady.

They both stood there, not looking at each other or the time-artichoke.

"So," said Nome, "can that thing take us back thirty years, or only entire eons?"

"Not people, just things, but sure. You have a reverse time capsule in mind?"

"While I'd love to see what happens if we send an iPhone back to my playground years, no. I just happen to know what middle school Dr. Bigger went to, and that he has a deathly and--to him--embarrassing fear of balloons."

Arkady smiled.