Scientists in Argentina have created the world's first cow with two human genes that will enable it to produce human-like milk.

    Genetic engineering was used to introduce the "mothers' milk" genes into the animal before birth, according to the National Institute of Agribusiness Technology in Buenos Aires.

    As an adult, the cloned cow "will produce milk that is similar to that of humans", which will prove "a development of great importance for the nutrition of infants(婴儿)," said the institute. "The cloned cow, named Rosita ISA, is the first in the world with two human genes that contain the proteins present in human milk," said the statement.

    In April, scientists in China published details of research showing that they had created dairy cows which produced milk containing proteins found in human breast milk. But the Argentine team said the Chinese only introduced one human gene, while their research involved two, meaning the milk will more closely resemble that of humans.

    "Our goal was to raise the nutrition value of cows' milk by adding two human genes, which do good to the immune system of infants," said Adrian Mutto, from the National University of San Martin which worked with the institute.

    Cristina Kirchner, President of Argentina, said that the scientific institute made all Argentines proud. She also said that she had refused the "honour" of having the cow named after her. "They came to tell me that the name is Cristina, but what woman would like to have a cow named after her? It appeared to me to be more proper to call it Rosita."

    Brian Greene, a professor of physics and mathematics at Columbia University, has created an online science education platform. He tries to "build a bridge" with things you know about, and then "bring you across that bridge to the strange place of modern physics".

    Recently I had a chance to ask Greene about wormholes (a hole which some scientists think might exist, connecting parts of space and time that are not usually connected), time travel and other mysteries of the universe. I asked him a million-dollar question: What if I went through a worm-hole and prevented my parents from meeting? "Most of us believe that the universe makes sense," Greene said. Although there are several interesting theories about time travel, he added, the laws of physics would probably prevent something so illogical from taking place. The good news is that the time paradox (悖论) is open for future physicists to solve.

    When asked how physics could become more exciting for kids, Greene said that books by Stephen Weinberg, Leonard Susskind, and other physicists," make it a great time for people who want to learn about big ideas but aren't yet ready, perhaps, to learn maths".

    When I pointed out that some students still might find physics boring, Greene said that the key is to teach them about things that are strange." The basic stuff is important," Greene said." But I think it's really important to also describe the more modern ideas, things like black holes and the Big Bang. If kids have those ideas in mind, then at least some of them will be excited to learn all the details."

    Greene has followed Albert Einstein's lead in trying to solve the mysteries of the universe. Now he wants kids to do the same. As Greene said, physics is "not just a matter of solving problems in an exam". It's about experimenting, showing an interest in strange phenomena (现象)—and having fun!

I will never forget the day.

The old man stood there, .