A new space war

Last week China showed off her military power by shooting down an old Chinese satellite using a ballistic missile. I don’t think it is too difficult in the 21 century. All the reports I read from Chinese media cheer this event, and believe this test gives China tremendous political leverage to bargain with the US. However, the hawks in DC might very much appreciate Chinese government. A recent Wired article (Fanning Fears of a Space War) cited Hank Cooper, a former director of the Strategic Defense Initiative: "I hope the Chinese test will be a wake up call to people. I'd like to see us begin a serious anti-satellite program."

It is premature to see how practical this Chinese prototype missile will be in wartime, or how much risk China will take to destroy a US satellite. The US is still many decades ahead of China in space technology. The ripple generated by the missile might be favorable to China as they hoped. Maybe not.

Give aliens more time to find us

OK. In my earlier blog, I found an article says that we are highly likely the only advance civilization in the galaxy, otherwise we had been conquered by aliens. A new arXiv article says Aliens need a lot more time to find us (original paper). The author made an assumption that the alien spaceships travel at 1/10 of the speed of light. Each ship is capable of launching up to eight probes. It will take 10,000,000,000 years (3/4 the age of the universe) to explore just 0.4% of the galaxy. So be patient. Let's look at the sky waiting for our little green friends with no hurry. However, I have to say that assumption underestimates the alien technology, without challenging our known physical principles (e.g., speed of light, time machine…). How about the spaceships travel at 20%, or 99.9% of light speed? What if each ship can carry 32 or ten thousand probes, each sends off radio signals or more nanobots?