【推荐1】Scientists at the California Institute of Technology (Caltech) have reported evidence that Mars was warmer and wetter long ago than it is today. The Caltech scientists say they have directly established the temperature of Mars four billion years ago. At least, they established the surface temperature on part of the planet at that time. The researchers say it is the first such evidence to be discovered and presented.

The Caltech scientists say carbonate minerals formed on Mars at about eighteen degrees Celsius. They reached the finding after studying a meteorite that had its beginnings near the Martian surface.

Today, the average temperature on Mars is sixty-three degrees below zero Celsius.The finding was reported on the website of the National Academy of Sciences. Caltech Assistant Professor Woody Fischer helped to prepare the report. He says eighteen degrees Celsius is not especially cold or hot. He says this makes the finding extremely interesting. Knowing the temperature can give scientists an idea of the climate on Mars long ago. It can also help them decide whether the planet had liquid water. Spacecraft orbiting Mars have shown what appear to be rivers, lakebeds and mineral deposits. These pictures suggest that, at one time, water did flow there. Mars Rover vehicles and other spacecraft have confirmed the information.

Caltech Geology Professor John Eiler was another writer of the report. He says knowing the temperature of Mars from long ago provides valuable information. It shows that early in the planet's history, at least part of Mars could support a climate like that of Earth.

The meteorite the scientists examined is one of the oldest known rocks in the world. It is called the Allan Hills meteorite. Its name came from the place in Antarctica where it was found in 1984. The meteorite is believed to have blown loose from the Mars' surface when another space rock struck its "home."

【推荐3】Time has always been of great interest to scientist…

Theory 1: According to Caltech cosmologist (宇宙学家) Dr Sean Carroll, the flow of time from past to future may be the symptom of our Universe having emerged from another universe that existed before the Big Bang and then gave birth to our own. Theory 2: In 1967, two American theorists came up with an equation describing the quantum (量子) state of the whole Universe. Known as the Wheeler-DeWitt equation, it includes many key features of the universe, such as its size. But one aspect is absent: time. Some theorists believe this implies that time only exists in our minds. Theory 3: According to theorist Prof Lee Smolin at the Perimeter Institute, Canada, the existence of life in the Universe is the result of the laws of physics evolving to their current state over an unlimited number of previous universes. If true, this means that our very existence is proof that time does exist. Theory 4: In 2009, physicists at the universities of Bristol and Cambridge showed that the passing of time revealed by, say, the cooling of a cup of tea, may be due to quantum effect called ‘entanglement’. This involves the particles (粒子) in the team interacting with their surroundings, being bound together and becoming harder to distinguish from each other—a one-way process that requires the forward progression of time to occur. Theory 5: Dark energy, the mysterious anti-gravitational force that drives the expansion of the Universe, may be linked to the existence of the arrow of time. Last year, two cosmologists at the Yerevan Physics Institute showed that dark energy leads to the growth of entropy, a measure of disorder, in the Universe.