【推荐3】Advertising in mass media is powerful. Right ads help create demands of products, campaign for political candidates or ideas and historically, even start wars. Detailed files the social media Companies build for each user, however, make advertising even more powerful by enabling advertisers to tailor their messages to individuals. These files even include your family size and whether you buy a lot of beer.

Consequently, social media has greater abilities to expose people to ideas as fast as they’ll individually accept them. The same ticks that can commend products to just the right person or suggest something addictive just when someone is most fragile can also suggest an extreme Conspiracy (阴谋) theory just when he is ready to consider it.

It’s increasingly common for friends and family to find themselves on opposite sides about important political issues. Many recognize social media as part of the problem, but how are these powerful customized advertising techniques contributing to the divisive landscape?

One important part is that people associated with foreign governments, without admitting that, take extreme positions in social media posts with the deliberate goal of sparking division and conflict. These extreme posts take advantage of the social media algorithms (算法), which are designed to heighten engagement Meanwhile, people seeking to influence others put things to more and more extreme positions. The result is apparent. Rather than most people having balanced views with fewer people holding extreme views, fewer and fewer people are in the middle.

What can be done? Skepticism about social media recommendations matters. Keep on a more deliberate path to information and avoid just clicking on whatever is recommended. Second, consider supporting efforts to require social media platforms to offer users a choice of algorithms for recommendations. Most importantly, invest more time in interacting with friends and family off social media. Probably, you’ll be far off a constructed track toward extremes.

【推荐2】By 2035, NASA wants to land humans on Mars. But reaching the red planet, on average around 140 million miles away, will be difficult. Colder than Antarctica and with little to no oxygen, Mars is an unfriendly environment. Besides, the longer it takes astronauts to get there and the longer they stay, the more they are at risk.

That's why scientists are looking at ways to reduce trip time. Seattle-based company Ultra Safe Nuclear Technologies (USNC-TECH) has offered a solution: an NTP engine that could get humans from Earth to Mars in just three months. Such an engine takes advantage of nuclear technology. Currently, the shortest possible trip for an unmanned spacecraft is seven months, but a manned mission is expected to take at least nine months. Shorter missions would limit the astronauts exposure to space radiation, but there is still concern about the radiation sent out from the nuclear reactor inside the spacecraft. This would be mitigated through the rocket's design, which would help ease the scientists’ concern.

To protect people on the ground, the NTP spacecraft would not lift off directly from Earth, Jeff Sheehy, a NASA scientist, adds. Instead, a regular chemical rocket would carry it into orbit, and only then would it fire up its nuclear reactor. Once in orbit, it could do little harm, as heat radiation cannot move through a vacuum(真空). If disaster struck and the rocket’s reactor broke up, pieces would not land on Earth— or any other planet—for thousands of years. By that time, the radioactive substance would have ''naturally got to the point where it wasn’t dangerous anymore”.

Michael Eades, director of engineering at USNC-TECH, says that nuclear-powered rockets would be more powerful and twice as efficient as the chemical engines used today, meaning they could travel further and faster, while burning less fuel. "Nuclear-powered rockets will be key to opening up the solar system but it could be at least two decades before they are used widely,9, he says, adding that numerous demonstrations and tests would need to be carried out before an astronaut is sent to Mars in an NTP rocket.

【推荐3】These days, we wonder a lot about why social networks go bad, full of terrible behavior. But it’s equally illuminating (有启发性的) to ask about the ones that work well. These communities share one characteristic: They’re small. Generally they have only a few hundred members, or maybe a couple thousand if they’re really popular.

And smallness makes all the difference. First, these groups have a sense of cohesion (凝聚性). The members have joined specifically to talk to people with whom they share an enthusiasm. That creates a type of social glue, a context and a mutual respect that can’t exist on a highly public site like Twitter, where anyone can crash any public conversation.

More important, small groups typically have people who work to keep interactions polite. Sometimes this will be the organizer or an active, long-term participant. They’ll greet newcomers to make them feel welcome, draw out quiet people and solve conflict when they see it emerge. But what’s crucial is that these key members model good behavior, illustrating by example the community’s best standards. The internet thinkers Heather Gold, Kevin Marks and Deb Schultz put a name to this: “tummeling,” after the Yiddish “tummeler,” who keeps a party going.

None of these positive elements can exist in a massive, public social network, where millions of people can get into each other’s spaces. That’s why perhaps the single biggest problem facing social media is that our mainstream networks are too interested in scale. But scale breaks social relations.

Is there any way to approach this problem? I’ve never heard of any simple solution. Strict antitrust laws for the big networks would be useful, to encourage competition among networks. But this likely wouldn’t fully solve the problem of scale, since many users fancy scale too. Longing for massive, global audiences, they will crowd into whichever site offers the hugest. Many of the well-known solutions to social media might help, but all ignore the biggest problem of all: Bigness itself.