Chapter 239 Are You Serious?_3

For instance, [\hat{H}=\hat{H}_0 + \hat{H}_{\text{gravity}}]. Of course, this is only the simplest example, I hope it can be of some help with your question.

After finishing the email, Qiao Ze clicked the send button and then went on to read other emails. To his surprise, it hadn't been five minutes before his computer's Dou Dou pinged him that Edward Witten had replied to his email.

"Professor Qiao, you've finally replied to my email. That's great. If it's convenient, could we talk now? As you know, it's hard to thoroughly discuss a problem through letters. Face-to-face communication is the best way, and I wouldn't want to hide this from you, we can use whichever video communication tool you prefer."

Receiving a reply so quickly made Qiao Ze somewhat puzzled.

He glanced at the time—it was already three in the afternoon. Calculating the time difference, it should be the early hours of the morning in Princeton. Doesn't the other party need to sleep?