You pick up your phone and stare at it. The screen unlocks at once. But it won't do that for anyone else. The phone knows who you are. It recognizes（识别）the shape of your face. Welcome to the world of the latest iPhone. It comes with a feature called Face ID.

Your face isn't the only characteristic you can use as a password. Many smartphones already accept fingerprint recognition. Other safely systems check the shape of the ear, patterns in the eye, or the way a person walks. All of these characteristics, called biometrics（生物识别技术）, are unusual enough to identify someone.

People like using biometrics for safely because they're easy. You can't misplace or forget your own face. They're also usually very safe. It's hard to copy another person's body parts. But it's not impossible!

And the face may be one of the easiest body parts to copy. Most teens post plenty of photos online. These could probably help someone hack into（入侵）a safety system. In 2016, researchers at the University of North Carolina collected available Facebook photos. They used them to build 3D models of faces. Then they showed these fake faces to five different facial recognition systems. Four out of five let the cheater（骗子）in. （Face ID wasn't part of the test.）

Once a biometric password has been stolen, you can't easily change it. You can't get a new face! There's one more thing of Face ID that worries experts. It would be easy for someone else to hold your phone in front of your face to unlock it. For example, an angry sister or brother might do this to hack into your accounts.

Some people won't worry about all that. It's just so cool to use Face ID. As for me, I am always glad to use the new technology as long as it can make our lives easier and better. What do you think? Is it a good thing to you?

Every now and then you may see news of satellites (卫星) sent into space. On Feb 21st, 2022, for example, US company SpaceX took 46 satellites into space. On Feb 27th, 2022, China sent 22 satellites into space. Why do we need so many satellites? What do they do out there?

Until now, there are more than 4,000 active satellites moving around the earth. Satellites can do a lot of work.

Before satellites, TV signals (信号) didn’t go very far because mountains or tall buildings would stop them. Phone calls to faraway places were also a big problem. But with satellites, TV signals and phone calls can be sent to a satellite and then back down to different places on the earth. SpaceX’s Starlink Project is trying to go further. It plans to use satellites to provide Internet in the future.

Satellites can also provide information about clouds, sea, land and ice. They help scientists do research such as knowing about changes in weather. Satellites help people find natural disasters like wild fires by closely watching them. Farmers can use satellite pictures to decide the best time to water their fields.

Some satellites fly near other planets. They may look for water on Mars or take close-up (特写) pictures of other planets. In 2020, the video website (网站) Bilibili sent a satellite into space. Its job is to look at other planets and share the pictures and videos with Bilibili’s users.

Like any other machines, satellites do not last forever. When they die, they burn up (烧毁) or become space rubbish. The rubbish in space will hit each other or other satellites and cause more serious problems. So rubbish trucks (卡车) may help. In fact, scientists have invented rubbish trucks. Clear Space-l is one of them. Dr. Luc Piguet, the manager of the company Clear Space, will tell you how it works.

It’s the weekend, and you decide to visit your grandma who lives alone. When you arrive, however, you realize that she has another visitor, and you hear through the door the two of them laughing. You walk in and find that the visitor, sitting across the dining table from your grandma, is a laughing robot. It’s laughing at your grandma’s joke.

Such a robot is something that a team of scientists at Kyoto University in Japan are working toward. They are teaching a robot named Erica how to laugh while talking to a human.

“We think that one of the important abilities of robots is empathy (共鸣),” said Dr. KojiInoue, the leader of the team. “So we decided that one way a robot can empathize with users is to share their laughter.”

Erica’s development began with recording different human laughter. The scientists recorded more than 80 conversations. Then they studied the conversations and put the laughter in these conversations into different groups. Next, they trained Erica to learn the characteristics of each group of laughter in order to show them correctly in different situations.

Although the scientists have made some encouraging progress, they said that we are not able to have a natural talk with Erica as we have with a friend now. But then wait a few years, and you may find your own self at that dining table, telling jokes to a robot named Erica.