Saturn (土星) has beautiful rings. Of planets in the solar system, Saturn’s rings are the biggest and brightest. According to scientists, however, these rings will one day disappear completely.

How did Saturn get its rings in the first place? Scientists have no sure answer. But there’s a popular theory (理论): Some comets (彗星) or small planets ran into Saturn’s moons (卫星). Saturn had at least 60 moons. And this left behind a large number of ice and rock pieces. These pieces were different in size. Some were as small as grains of sand, Others were as large as houses.

These small pieces began to travel around Saturn. Saturn’s gravity (引力) pulled them towards it. At the same time, the speed of their orbit (轨道) tried to throw them into space. Over time, these pieces of ice and rock formed rings around Saturn.

A new study, however, suggests that Saturn’s gravity is winning. About ten tons of “ring matter” is falling into Saturn every second. If this continues, the planet’s ring system will disappear completely in 100 million to 300 million years time. According to scientists, Saturn’s rings are between 10 million and 100 million years old. “We’re lucky to be able to see Saturn’s huge ring system,” one of the scientists said, “Some of the planets in the solar system only have very thin rings today. Perhaps we just missed out on seeing their huge ring systems!”

Have you heard of parallel universes? Some scientists believe that there might be other universes right alongside ours. Our universe may be just a part of a tree of universes that are all there at the same time—only in different states of time with different pasts and different futures.

What does this mean? It means there is a different “you” in these parallel universes. You might be a Hollywood star in one of them!

In parallel universes, there may be completely different physical laws (物理法则). World wars might have different results. Really, humans themselves might have become extinct (灭绝的) in certain parallel universes!

The idea of parallel universes dates back to 1954. Hugh Everett Ⅲ, a Princeton University student in the United States, developed the idea that parallel universes—exactly like and related to our universe—are there. However, many physicists and astronomers say that this theory can’t be tested, so it’s not really a theory at all.

But since then, the idea has shown up in comic books, television and movies. Shows like Star Trek and Doctor Who use the idea to develop their stories.

Parallel universes might not only be there in the movies. If their stories are true, some people might have already experienced other realities.

First covered by newspapers in 1952, Cornelio Closa, a schoolboy from the Philippines, kept disappearing right in front of his friends and family. Sometimes disappearing for days, he would somehow disappear from his locked family home and crowded school classroom.

While such stories may sound crazy, even the known universe is far older and larger than we are. So, who’s to say that one day we won’t learn to cross dimensions (维)?

We have seen lots of science fiction movies about aliens (外星人). People travel to stars and even fight with aliens in the movies. But are there real aliens in the universe (宇宙)? Most of us think it is impossible, just like fairy tales. But the answer of some scientists is yes. So they have been searching for aliens in outer space for many years. They hope to find life signs of aliens.

Some scientists are used to using radio telescopes (望远镜) to search for aliens in space. In order to find aliens, they have worked hard for over half a century, but so far they have found nothing. Then some scientists guessed aliens might not want to connect us, but aliens could answer our messages. So some scientists sent radio signals into the universe. They hope one day they would be picked up by alien technology. These scientists want to prove (证明) that we are not alone in the universe.

But what should we do if the “alien phone” rings one day? Should we answer it? Stephen Hawking, the famous physicist, thught it could be dangerous to connect aliens. He said that the main purpose of aliens’ visit to the earth could be searching for our resources (资源). But other scientists think we have no need to worry. David Morrison, a NASA scientist, said, “If an alien radio signal reaches the earth from a planet thousands of light-years away, then they almost surely have solved all the problems we still have including the short of resources. Maybe they are much smarter than us, but why do they want to hurt us? I think we can try to connect them.”