Lost and Wanted(57)

“But can you surf them?” Roxy asked.

Terrence smiled.

“I think it would be more like them surfing you,” Neel said, “if that makes any sense.”

“It doesn’t,” Roxy said. “You should always let Helen explain.”

“I’ve been reading about spacetime,” Terrence said.

“In Helen’s books?” Neel asked politely.

I knew what Neel thought of my books. They weren’t inaccurate; it was just that there was no reason to write them.

Terrence shook his head. “An author named Robert Lanza. He says that time is just a human invention, and so there’s no real past, present, and future. Everything is just nows. So even after your body dies, your consciousness is just in another now. Einstein said that, too.”

    “I think Einstein said just the opposite,” Neel said. He had a way of jumping in and correcting people, as if he expected they would also take pleasure in being contradicted, as soon as they realized he was right. “He believed that the universe has an objective reality that scientists study. A lot of people say he was religious—God doesn’t play dice, and all that—but his notion of God was really just physics. He thought there was a sublime order in the way the universe is arranged, and he was awed and inspired by that. But he thought the idea that we outlive our physical body was ridiculous.”

Terrence was looking at Neel in a way that worried me. I realized that I wanted them to like each other, maybe because of how much I cared what each of them thought of me.

“I think Terrence is talking about a version of the anthropic principle—an explanation for why our part of the universe is so perfectly calibrated to support human life.” I addressed this to Dan and Roxy, since Neel obviously knew what the anthropic principle was, and I didn’t want Terrence to think I was talking down to him.

“Philosophy,” Neel said, “not science.”

“Lots of scientists you respect embrace it.”

“Yes, okay,” Neel said. “But that’s a very weak form of the anthropic principle—Penrose’s or Susskind’s. Not a biologist like Lanza who writes scientific best sellers, and fancies himself another Einstein. No offense, Helen.”

“None taken. I don’t fancy myself another Einstein.”

Neel smiled. “I meant the best sellers.”

“Only one of them was on the best-seller list. For about ten minutes.”

“Go back to the black holes,” Dan said. “What happens when they crash into each other?”

Roxy nodded. “Yes, please.”

Dan winked at her. “I used to go for moo shu pork with these two guys all the time, so I had to learn how to distract them. Otherwise they’re at each other’s throats.”

Neel picked up two olives from the bowl on the table, and moved them along two ellipses, one clockwise, the other counterclockwise, getting closer and closer to each other with each rotation. “The black holes are inspiraling, like this. They’re attracted by each other’s enormous gravity, and also pushed apart by angular momentum, and so they circle each other for centuries, getting just a tiny fraction closer with each rotation. Finally they come together with the most terrific noise you can imagine.” He smashed the olives together, then popped them into his mouth. “If you think of the energy of the sun, and then multiply that by a billion trillion, that’s how much energy is released—more than anything since the Big Bang. But it’s released as sound, not light. If it were possible for a human being to be close enough, we could actually hear the sound. The combined black hole is still wildly spinning after it comes together. It releases wave after wave of energy as it goes around—each one slightly less powerful than the last. The sound becomes quieter and quieter, like a bell.” Neel drew the wave in the air with his right hand, its amplitude diminishing as it got more distant from the source: “That’s the ringdown.”

    “That was pretty good,” I told him. “You should write a best seller.”

“That’s why for most of the twentieth century, we thought we’d never be able to measure a gravitational wave,” Neel said, ignoring me. “Finally we have machines sensitive enough to do it. You can translate that incredibly quiet vibration to an audible register, and the computer spits out an actual, billion-year-old sound: a rising tone—we call it a ‘chirp.’?”

For the first time, Terrence looked astonished. “This thing with the black holes happened a billion years ago?”

Neel nodded happily. “And now our detectors can hear it.”

“What’s the point?”

I didn’t know whether this was a challenge or not. Terrence’s way of talking was so casual, so Californian, that it was sometimes hard to tell.

“Ah,” said Roxy. “Now we’re getting to it.”

Neel took a drink from a bottle, some fancy microbrew. “It’s less about a practical application than it is learning more about the universe. Combining our data with data from traditional, light-based astronomy.”

    Terrence looked skeptical.

“Scientists have been dreaming of finding these waves—hearing them, I should say—for a hundred years.”

“You never know, though,” I said. “Lasers came out of pure physics. Not to mention MRI machines, the microwave, and a lot of today’s encryption technology.” I wasn’t sure if I was defending Neel, or my profession in general, but it was important to me that Terrence understand that what we did had real-world applications.