Claude Sammut, a professor of computer science and engineering at the University of New South Wales in Australia, said it would soon be possible for robots to defeat the stars of the future.

For many years, Mr. Sammut has been a member of a project called RoboCup, where robots have been programmed to learn how to play football and compete against others in a football match.

As he explains, the robots are having difficulty in learning how to control the ball and move the ball on their own, but he is still full of confidence that one day in the future they will show the same skills as Wayne Rooney, who is one of the best football players in the world.

Mr. Sammut also said, “In 1968, John McCarthy and Donald Michie made a bet with David Levy, who was then the chess champion in Scotland, that within 10 years a computer program would be able to beat him. It took a little bit longer than 10 years nearly 30 years but eventually such programs came into being.

In the same spirit of a grand challenge, RoboCup aims to develop a team of robots that can defeat the world soccer champion team by the year 2050. To achieve this, or come even closer to the ambition, the robots will have to be able to sense and act in completely unstructured environments. This will require major advances in perception (感知), decision making, learning and cooperative behaviors. Considering robots are integrated hardware and software systems, great advances will also be needed in sensors (传感器), energy storage, and materials.”

Jellyfish (水母) are badly named. They are neither a fish nor made of jelly. Instead, their bodies are made up of 95% water and 5% solid matter. They have been in existence for at least half a billion years. Therefore, they are older than dinosaurs. Surprisingly, they don’t have a brain, a heart, or lungs. You may wonder how they can possibly survive without these vital organs, but everything is for the best. They don’t have lungs because their skin is so thin that they can absorb oxygen through it. They don’t need a heart to pump blood because they don’t have any. And they have a nerve net — which is sensitive to touch — below their outer skin. They respond to the changes in their environment using signals from the nerve net, so they don’t need a brain to process complex thoughts.

Their variety is nearly endless. Most of them are umbrella-shaped and have tentacles (触角). Some jellyfish have very long tentacles. However, they never get tangled (缠结) up or sting (蜇) themselves. That’s because the tentacles are very slippery and will only sting other animals. Most jellyfish have little or no vision, but they can discover light and ocean currents, which helps them to find their way and move. A few species can also recognize color and have a 360-degree view of their environment.

Jellyfish come in all sizes, from 0.5 millimeters to the giant Nomura’s jellyfish, which can measure up to two meters in diameter and weigh over 200 kilograms. While jellyfish are beautiful, they can also be dangerous. Some jellyfish toxins (毒素) can be deadly to humans, such as those from the box jellyfish and the Australian Irukandji, but deaths are relatively rare given the number of jellyfish-sting victims every year. In any case, it’s better to stay out of the way of any jellyfish you may see! You can go swimming with dolphins, but you definitely want to think twice before swimming with jellyfish.

The memory of elephants is the stuff of lore (传说), and now it seems they can recall the smell of a relative even after a decade apart.

When Franziska Hörner at the University of Wuppertal in Germany and her colleagues heard about planned reunions between two mother-daughter pairs at zoos in Germany, the took advantage of the chance to test the elephants’ memories. One pair had been separated for two years, while the other had spent 12 years apart.

Hörner collected faecal (排泄物的) samples from these African elephants and others at German zoos, hauling the stinking 10-to-15-kilogram samples around in her tiny car.

Her team presented these samples one at a time to the four elephants in advance of their reunions with family members. When they encountered faeces from unrelated elephants, cither those in the same zoo or unfamiliar animals, they sniffed and walked away.

But when presented with a sample from the mother or daughter they were due to be reunited with, the female elephants repeatedly sniffed the samples and showed a variety of reactions, from making sounds to flapping their ears.

Such reactions may be linked to positive emotions, the researchers say. “That was amazing and really intense,” says Hörner. “We were sure they do remember, and they know exactly what they are smelling there.”

The sample size was small, but it would be cruel to do similar tests on elephants that weren’t being reunited, says Hörner.

“I am not surprised that elephants have memories, especially in social contexts, that last a long time,” says Joshua Plotnik at Hunter College in New York, who wasn’t involved with the work. Elephants live in groups that split up and come back together over long periods of time.

But Plotnik says the experiment may not be a true test of memory. There may be scent cues (线索，提示) common to all relatives that can trigger recognition not linked to memory, he says, and presenting the elephants with other smells would help make sense of their responses.