Technology
By Charles Arthur

The tension between privacy, security, sharing and impermanence will come to the fore in 2014.

The Edward Snowden revelations echoed loudest through the technology business, with companies including Google, Apple, Microsoft and Yahoo all implicated in the US National Security Agency's scooping up of huge amounts of data. That, of course, is their business - but it's generally with users' permission.

Privacy and security are becoming intertwined, though they're different. Privacy is about the right not to be overlooked; security is about the systems that ensure it.

Yet we're happy to sacrifice a form of privacy, our personal data, in return for clear benefits.

That's why systems like Google Now - which try to tell you useful information before you ask for it, such as delayed trains on your commute or hotels near your arrival points in a new city - are accepted.

We'd like computers to do such boring stuff but we don't want that shared with other people.

And what we do share is becoming more permanent and more transient. Facebook's growth continues and people commit more and more to it. Yet a younger generation is adopting services such as Snapchat, whose key feature is impermanence: you take a photo, send it, and within seconds of being viewed, it's gone.

That Snapchat was offered US$3 billion ($3.68 billion) by Facebook (it declined) shows how important it is becoming to leave no trace in the modern world.

The device on which all this privacy, security and sharing happens is increasingly, of course, the smartphone, of which more than a billion will be sold during the year. But is what we do on our mobile phone private? Is it secure? Apps give us the promise of privacy yet sometimes break it (some grab details without permission) and, when it comes to security, the hacking of phones by the NSA demonstrates that the battle doesn't end, it just moves to a new platform.

Science
By Robin McKie

On January 20, a tiny electronic chip inside Europe's Rosetta spacecraft is scheduled to flicker into life. The robot probe will by then be several hundred million kilometres from Earth, on course for Comet 67P/Churyumov-Gerasimenko.

Once its circuits, heaters and instruments have been brought to life, the probe will rendezvous with its target in August before landing a tiny craft, called Philae, in November.

Rosetta and Philae will stay with Comet 67P/CG over the next few months, studying the plumes of gas and vapour boiling from its surface as it sweeps past the sun.

The 840 million ($1700 million) project will be one of the most spectacular feats of space exploration ever planned and, if successful, will be a milestone for the European Space Agency.

The agency will also start taking data later in the year from its robot satellite Gaia, launched 10 days ago.

Carrying the biggest, most accurate camera constructed, Gaia will pinpoint more than a billion stars with unprecedented precision and create a 3D map of the Milky Way.

The billion-pixel camera will also help astronomers pinpoint planets orbiting stars elsewhere in our galaxy, and help their quest to detect dark energy, the mysterious force believed to be pushing the universe apart.

Also coming next year are a programme of commercial satellite launches and flights of European astronauts to the International Space Station, showing that Europe's ambition to become a major space power may soon be fulfilled.

Travel
By Joanne O'Connor

What's the good of having half a million apartments to browse on Airbnb if you're not sure where you want to go?

The growth of the "sharing economy" will continue to be one of the biggest travel stories of 2014.

Once seen as niche alternatives, accommodation sites such as Airbnb and Housetrip, car share service BlaBlaCar and dinner-party finder EatWith are moving swiftly into the mainstream and giving traditional hoteliers, car rental companies and restaurateurs sleepless nights.

Unable to compete with behemoths such as Tripadvisor and Airbnb, the new wave of travel startups will focus on offering a personalised service, in effect performing the role of the old-school travel agent.

After all, what's the good of having half a million apartments to browse on Airbnb if you're not sure where you want to go in the first place?

San Francisco-based Peek.com is typical of the new breed of startup, offering a selection of handpicked travel experiences in the US, London and Paris. Local personalities in each city are enlisted to suggest itineraries for their own "perfect day".

Mygola.com is another site that was created in response to a lack of decent online itineraries for independent travellers. Users can download a suggested itinerary, modify it and book the various components all in one place.

Taking this customisation process one step further, new apps from travel website Triposo provide recommendations for things to do and places to go in 200 countries, based on your location, the time of year, the weather and your personal preferences.

Even the "peer to peer" accommodation sector, where size has been everything so far, is showing signs of fragmentation and specialisation, with an increase in house-swap sites that target niche demographics, whether it be university graduates, families or retired people.

Berlin-based Roomsurfer.com uses algorithm technology to bring together travellers and like-minded hosts - online dating meets couch surfing, if you like.

Food
By Jay Rayner

At the dawn of the new year the global population will stand at just over 7.2 billion and rising. We are expected to hit 8 billion by 2024 and 9 billion not long after that. The imperative of feeding all those mouths remains, and the Global Forum for Food and Agriculture will hold its Empowering Agriculture summit in Berlin from January 16 to 18.

Likewise, the African Union has declared 2014 the year of agriculture and food security, and will debate the issues at its annual gathering in Addis Ababa at the end of January. It's likely similar discussions will be held in March at the Wheat Food Security summit in Mexico. This marks the centenary of the birth of Dr Norman Borlaug, the father of the green revolution that ushered in an explosion in agricultural yields in India and Pakistan from the 1960s.

But the key event in the food security diary is likely to be the United Nations Food and Agriculture Organisation's second international conference on nutrition in Rome in November.

Given that the first one took place in 1992, it's long overdue. Back then there were people who had enough to eat and a lot who didn't.

Now an explosion in the middle classes of the emerging economies has created a different narrative. There are still nearly a billion people with not enough to eat but there are also vast numbers consuming too much. Agricultural fixes alone will not secure the food supply; we must find a way to rebalance our consumption. This is the debate that will come to the fore in 2014.

- Observer