But they are not solving the fundamental problem: gravity. We invented ways to neutralize electromagnetism (any electrical wire is wrapped in a substance that neutralizes electricity) but we never defeated gravity.

Today we shoot rockets into space by using an explosion, the same concept used in gasoline-powered cars. First of all, it is a dangerous system: many astronauts died during take-off. Second, the speed has to be slow because otherwise we die, and, if it is safe, then it is too slow for the lifespan of human beings: we cannot even visit the Solar System in a human lifetime. Third, even if you find a way to have humans survive a speed of 1/10th the speed of light, the the amount of fuel that you need to travel to the nearest star (Alpha Centauri) is about the size of the Sun. In 1996 NASA launched a project called Breakthrough Physics Propulsion Program to find alternative ways to travel in outer space. The project failed, but the manager, Marc Millis, in 2006 founded the Tau Zero Foundation that is still active.

We are stuck on the surface of the Earth because we don't know how to neutralize gravity. Musk and Bezos need to talk with astrophysicists and particle physicists.

Another possibility is to use the energy released by matter-antimatter collisions. When matter and antimatter collide, they emit high-energy photons. In 1953 Eugen Sanger, one of the solitary heroes that i like, imagined that these matter-antimatter reactions could power a starship. Sanger was not an idiot because in the 1940s (before the first satellite!) he and his wife Irene Bredt invented a kind of spacecraft (called "Silbervogel") that worked exactly like the Space Shuttle that NASA designed in 1977. Sanger calculated a lot of facts about the photon-propelled spaceship in his "Handbook of Astronautical Engineering" (1961), which is a fascinating book. Poul Anderson's science-fiction novel "Harvest the Fire" (1995) features a matter-antimatter rocket. In 2011 Friedwardt Winterberg resurrected Sanger's idea, but it is too soon to say if it can work. Dragan Hajdukovic at CERN in Switzerland is planning an experiment to prove that matter and antimatter "repulse" each other if kept apart (if they don't disintegrate each other).

And, talking of science-fiction books, Arthur Clarke's "Songs of Distant Earth" (1958) features a spaceship that uses vacuum energy, an energy predicted by Quantum Mechanics that pervades the whole universe, and it is therefore virtually infinite. Great physicists like Andrei Sakharov in 1968 and Harold Puthoff in 1989 have written about a possible connection between the vacuum and gravity.

A space elevator is featured in Arthur Clarke's novel "The Fountains of Paradise" (1979). In 1895 a Russian scientist, Konstantin Tsiolkovsky, planned a space elevator that would take spacecrafts outside the Earth's atmosphere. In 1959 another Russian scientist, Yuri Artsutanov, resurrected his idea. In those days the problem was the weight of the spacecraft, but today nanotechnology is developing carbon nanotubes that are strong and lightweight, so a space elevator might become feasible. Bradley Edwards at NASA has been working on a space elevator and published the book "The Space Elevator" (2003) and in 2014 Google X began the design of a space elevator. In 2014 another Russian scientist, Yuri Rezunkov at the Institute of Optoelectronic Instrument Engineering, invented a way to use lasers for additional acceleration.

Philip Lubin, an astrophysicist at UC Santa Barbara, has a more practical idea: build a very light spacecraft and use lasers to propel it. He calculated that one could travel to Mars in three days. NASA's Voyager 1 spacecraft took 36 years to exit our solar system, a journey of about 0.0005 light years. The nearest star, Alpha Centauri, is 4.4 light years away. With the existing technology it is unlikely that human civilization will ever reach the nearest star. And that's just one of the billions of stars in our galaxy, which is just one of the billions of galaxies in the universe. Pretty depressing. Russian billionaire Yuri Milner likes Lubin's alternative idea, and in 2016 he launched the Breakthrough Starshot project to send tiny 20-gram spacecrafts to Alpha Centauri. He set up the Starshot organization on Sand Hill Road in Menlo Park (better known for the venture capitalists who fuel Silicon Valley's bubbles). Starshot wants to solve the problem of gravity by using a flock of tiny spaceships propelled by 10 million lasers spread over a square km of land. Then the journey to Alpha Centauri would take "only" 20 years. The project is headed by former NASA Ames executive Pete Worden, with British cosmologist Stephen Hawking and Facebook's founder Mark Zuckerberg as board members, and a cast of advisors that includes UC Berkeley's astrophysicist Saul Perlmutter, Harvard's astronomer Avi Loeb, Institute for Advanced Study's mathematician Freeman Dyson, and of course Philip Lubin. Harvard scientist Zachary Manchester had crowdfunded a similar project in 2011, launching a large number of very small satellites from a 3U CubeSat in 2014; but he didn't have Milner's financial power and his experiment has not been successful.

I joke that maybe some day we will be able to build a digital clone of you. Then we can just send a spaceship to a distant star with a computer and a 3D Printer. When the spaceship arrives at its destination, the computer runs the file of you and the 3D printer prints the clone of you. And then a voice tells you "You have arrived at your destination" like the smartphone app Waze does.

NASA, founded in 1958, is the oldest and most famous of space agencies. It was created a few months after the Soviet Union successfully launched the first artificial satellite, the Sputnik. That event came as a shock to the West: how could the Soviet Union pass the West in space technology? The technological leadership would remain Soviet until 1961, when Yuri Gagarin became the first astronaut. Then the USA found a simple motivation to start the "space race": beating the Soviet Union. The president of the USA, John Kennedy, set out a plan to put a man on the Moon and NASA got all the funding that it needed. In 1969 that mission was accomplished. The USA beat the Soviet Union. For us in the West this was psychologically important because we thought that our democracies were good the Soviet Union was evil, so it was important to prove that "good" wins over "evil". In reality the scientists of the two sides always behaved more like friends than enemies. In fact, every year our scientists celebrate April 12 (the day that the first Soviet astronaut Gagarin left the Earth) but we don't always celebrate July 20 (the day that the USA landed on the Moon).

Secretely, i think that NASA and their Soviet rivals liked each other: as long as one existed, the other one was getting top attention from the politicians of its country. "We can't let the Soviet Union beat us in space" was a good excuse to get money to carry out research. The truth is that space exploration had no military value in those days, and even today it has very limited value beyond the communications satellites. In other words: we have to thank the Cold War for all the progress of the 1960s, 1970s and 1980s in space technology. In 1991 the Soviet Union collapsed and suddenly the USA lost interest in the "space race". NASA has tried several arguments to justify its programs, but the US public has lost interest and the USA doesn't have the money that it used to have.

NASA is still useful for scientific missions, sometimes paid by other agencies and other countries, but today those missions can be carried out by robots: we don't need to send humans in space. Unmanned missions are much cheaper than manned missions, and we don't risk losing lives. Not many would admit it publicly, but most politicians have tacitly decided that there is no reason for sending humans into space: let the robots do the job. That feeling is shared by many scientists. A legendary astronomer, James Van Allen, wrote an article in 2004 arguing that human spaceflight was not "justifiable".

Boom is a startup that is building a supersonic passenger plane that will fly at twice the speed of sound. It would be the first supersonic passenger plane since the Concorde was retired. The trip from New York to London will take only 3.5 hours, and San Francisco to Beijing a little over 5 hours.

Flying cars have been featured extensively in science-fiction movies, but nobody has been able to make them. In 2013 Terrafugia announced plans for a flying car, and it estimates that it will fly a prototype by 2018. Skycar is another flying-car prototype. In 2016 China's EHang 184, which technically is an autonomous quadcopter, was demonstrated: it can carry a single passenger for 23 minutes at a maximum speed of 100 km/h.

Then there are E-volo's Volocopter VC200 in Germany and Chris Malloy's Hoverbike in Britain.

My feeling is that we still need to defy gravity. Anything that uses "fuel" to fly is dangerous, heavy and slow. I don't want these things to fly over my house.

But the revolution started in 1962 with the first commercial satellite, Telstar, developed by AT&T's Bell Labs in collaboration with France and Britain. A few days later the USA, France and Britain enjoyed the first live transatlantic broadcast, that showed two live pictures, side by side, each coming from a different continent: the Statue of Liberty and the Eiffel Tower. Since then we got use to the phrase "Live via satellite!" A few weeks later the world experienced the first effect of instant communications: the US president John Kennedy denied that the US was about to devaluate the dollar, and the markets in Europe reacted immediately. That's the world in which we live today, but it wasn't that way before 1962. The power of seeing something live on television totally changed our perception of distant events. Before 1962 a videotape was shipped by airplane to another country and sometimes showed on television days after the event had taken place. People already knew what had happened when they watched the video on their television set. The Telstar was the big news of 1962: a one-meter object that was orbiting around the Earth and sending us signals from outer space. (By the way, younger people say that the Telstar looks like a soccer ball: no, it's the soccer ball that was redesigned to look like the Telstar!)

The Telstar circled the Earth every two and a half hours. This was during the Cold War with the Soviet Union, so the Telstar was designed to serve only the USA and Western Europe. Because of its slow speed, it was in the right position only for about 20 minutes each day, so the USA and Western Europe only had 20 minutes to communicate "live via satellite". In the summer of 1963 the USA launched the first "geosynchronous" communications satellite, the Syncom 2, designed by the legendary engineer Harold Rosen at Hughes in Los Angeles: "geosynchronous" means that the satellite always stays in the same position when viewed from us, i.e. that it can broadcast 24 hours a day, not just 20 minutes. Now it was really possible to broadcast an entire TV program across the Atlantic, from the USA to Western Europe and viceversa. Now it was really possible to have long-distance telephone calls: on the 23rd of August the US president, Kennedy, telephoned Nigeria's prime minister. TV journalism was born. Ironically, the first transatlantic TV broadcast was the assassination and the funeral of president Kennedy. In August 1964 the Olympic Games of Tokyo were broadcast live to the USA. An international organization (initially called IGO but then Itelsat) was created to serve the Western World and Japan. Its first satellite, nicknamed "Early Bird", was launched in 1965. Twenty years later that organization started a humanitarian program to provide free access to satellites for civilian projects: Project SHARE (Satellites for Health and Rural Education). One of the first beneficiaries was China's National Television University, that began broadcasting via satellite to millions of students, the biggest educational program in the history of the world. In May 1984 the first full-time international satellite TV channel started to broadcast live: Japan's NHK. Before the Telstar there were only 300 international telephone circuits in the world, and there was no transatlantic television. Now there are more than one million international satellite circuits and more than 12,000 satellite TV channels.

Another important milestone was 1972, when the USA started deploying the Global Positioning System (GPS). This was another military project that today is used by every smartphone in the world. Can you imagine your life without navigation software on your smartphone?

The demand for live communications is increasing every year, but the costs have remained high. The GPS III satellite costs $500 million to build, and it currently costs $300 million to launch a satellite, so the total cost is $1 billion. We take for granted that Internet on board airplanes will be normal in a few years, but someone has to invent a way to make satellites cheaper and increase the amount of communications that they can handle.

Our satellites are still using radio frequencies but we use laser communications (optical fibers) over the cables that connect cities and continents. Lasers can transmit data 100 times faster than radio. Users who live far from the hubs of fiber-optic cables are actually using satellite communications (i.e. radio, slow and unreliable). Ships and airplanes are also providing Internet via satellite, which, again, means radio communications. Japan experimented with laser satellite communications in 1994 and the European agency ESA did the same in 2001. NASA Ames in Silicon Valley experimented with laser communications in 2013 when it broadcast from the Moon: the Lunar Laser Communications Demonstration (LLCD). In the short term, laser satellite communications will be useful to provide Internet to ships, airplanes and remote villages. In the long term it will be essential if we want to transmit video streams from other planets.

The process of miniaturization is finally beginning to bring down the cost of satellites. We can build smaller satellites. But to launch them into orbit we still need the big expensive rockets of the old days. Today there are very few companies that can take your satellite into space, no matter how small and light your satellite is. Those companies shoot a big rocket and carry several satellites at the same time so that several customers can share the cost. It is a little bit like putting your satellite on a bus. The "bus" drops your satellite in the neighborhood where you wanted it, but not in the exact spot.

The cost of launching a satellite is largely proportional to its weight. This fact was painfully clear to Jordi Puig-Suari of California's Polytechnic State University and Robert Twiggs of Stanford University. In 1999 they developed the CubeSat specifications to invent a new generation of very small satellites.

A CubeSat is a small satellite made of simple electronic components. The original proposal was for these "nanosats" to have a size of exactly one cubic liter. In 2013 a company based in Virginia, Orbital Sciences, launched 29 satellites, and Kosmotras, based in Russia, launched 32 satellites. In 2014 Orbital sent an additional 33 satellites up to the International Space Station. These CubeSats were built by Planet Labs, founded in San Francisco by former NASA scientists. Another San Francisco-based startup, Nanosatisfi (now renamed Spire), founded by graduates of France's International Space University who had also been NASA interns, worked on affordable satellites (nicknamed "ArduSats") based on an open-source platform.

Rocket Lab, founded by Peter Beck in Los Angeles, has designed its Electron rocket to send small satellites into orbit around the Earth, and is building its own launch pad in New Zealand.

Google has spent more than $28 billion on more than 160 companies since 2001, so it wasn't really surprising that it also ventured into the sky. It acquired Skybox Imaging, that is planning to launch an army of mini-satellites so that some day we will be able to see any spot on Earth.

In 2016 NASA tested another idea. Bigelow Aerospace was founded in Las Vegas by another billionaire, Robert Bigelow, to serve the market of "space tourists": rich people who will want to spend a weekend in a space hotel orbiting the Earth. Bigelow has been struggling to survive because space travel is still too expensive. Now Bigelow is reinventing itself thanks to a NASA invention that NASA did not develop: the inflatable habitat TransHab of 2000. This is a module that inflates like a balloon: it is very compact and light to launch, but then inflates ten time when it reaches its destination. Bigelow renamed it BEAM (Bigelow Expandable Activity Module) and in 2016 SpaceX carried BEAM to the International Space Station, where the "balloon" expanded and transformed into an additional room. It took seven hours for the astronaut on the ISS to inflate the BEAM, but in the future it may take just minutes. Bigelow has plans to put in orbit by 2020 a commercial space station for space tourists; but first we need SpaceX's Dragon V2, that is planned for 2017.

Tensegrity is going to play a role in these space adventures. The idea first came to the artist Kenneth Snelson in 1948, but the word was coined by the architect Buckminster Fuller who wanted to describe structures that are in perfect equilibrium and can adapt to change. The simplest example of tensegrity is... you. We are the product of evolution, that designed the best best possible structure to live in our environment. A tensegrity structure seems to violate the laws of physics because it is only subject to its own internal forces. It does not require energy from the outside in order to adapt to changes. For example, a tensegrity structure automatically changes shape from gravity to zero-gravity. Scientists like to say that it generates its own gravitational force around it while at the same time it generates an anti-gravitational force against the rest of the world, so it perfectly isolates itself from external forces. Tensegrity can be used to design cheap and quick structures in space; and it can be used to design the robots that will work on those structures. The BEST Lab (Berkeley Emergent Space Tensegrities) is a collaboration between Alice Agogino at UC Berkeley and Vytas Sunspiral at NASA Ames to develop tensegrity robots for planetary exploration.

The "intelligence" of the drone depends on the autopilot. The autopilot was first demonstrated in 1914 by Elmer and Zula Sperry at a conference in Paris. The autopilots of World War II simply kept the airplane flying straight. After the war the same system was used in civilian airplanes so that the pilot can take a rest. In 1947 a military airplane completed a transatlantic flight, including takeoff and landing, completely under the control of an autopilot. Now the autopilot has become much more sophisticated: it can follow the whole route and maintain the optimal altitude. Any airplane has become a robot.

In 2002 the CIA used a Predator drone to kill someone: it was the first time that humans used a robot (in this case a flying robot) to kill a specific person. It happened during the war in Afghanistan and the target was Osama bin Laden (for the record, they killed an innocent tall man who happened to look like Osama bin Laden). Since then the USA has used drones at an increasing rate. There is a lot of discussion in the USA whether this is right or wrong, and what the success rate is (in other words: how many innocents are we killing?) The psychological advantage of military drones cannot be denied. Konrad Lorenz wrote in his book "On Aggression" that humans are much more likely to kill with technology that acts at a distance, so that we don't see the enemy that we kill. The same fact is the subject of Dave Grossman's book "On Killing" (1995) that documents the behavior of soldiers. A drone is commanded by a human being, who is obeying orders given by other human beings, based on data collected by devices and computers built by human beings and running software written by human beings: if the drone kills an innocent, who is responsible? However, drones are still been used mainly for surveillance, rarely for killing.

Today's consumer drones are a completely different thing, in my opinion. This is another case in which a community of hobbyists "hijacks" a military invention. The origin of the modern drone goes back to the studies by Seymour Papert at the MIT Media Lab. Papert wanted to use computers to teach children mathematics and creativity in general. He wrote an influential book titled "Mindstorms - Children, Computers, and Powerful Ideas" (1980). In 1998 one of his students, Fred Martin, developed the MIT Programmable Brick, a set of hardware and software parts to build robots. Lego immediately understood the potential of this kit and marketed it as the Lego Mindstorms, a series of kits that allow children to build programmable robots. In 2007 Chris Anderson, the editor-in-chief of Wired magazine, built his first drone at home using parts from one of these Lego kits. Anderson realized the potential of what he had done and founded DIYDrones.com, which is now the largest open-source community for drone hobbyists. Anderson met a 19-year-old kid from Mexico, Jordi Munoz, who had built an autopilot using parts of a videogame remote, and in 2009 they decided to found 3D Robotics to make drones. 3D Robotics and the Swiss research institute ETH launched the Pixhawk, an open-source autopilot platform. This was not the first open-source autopilot system: Paparazzi started in 2003 at ENAC, France's National School of Civilian Aviation. Another one is PX4, started in 2009 at ETH. In 2014 the Linux Foundation founded a more general open-source project, called Dronecode, with founding members such as 3D Robotics and Baidu. AeroQuad and ArduCopter are open-source hardware and software projects based on Arduino for building quadcopters.

The most influential result so far of these open-source projects is probably the "universal autopilot", ArduPilot Mega (APM), which then evolved into Pixhawk. The power of these open-source projects is always amazing: in 2016 an average amateur can use the DIYDrones resources to build with less than $1,000 a drone that has the same functionalities of the $140 million Global Hawk drone that was used by the US military over Afghanistan. This is another case in which 1. hobbyists beat government and 2. the big corporations "missed the train".

The main use of small cheap drones is just for individual and family fun, but Hollywood uses them as platforms for videocameras and some national parks use them to monitor wildlife.

There are now dozens of other companies making drone technology for the "hobbyist" market, including Hoverfly, DJI Innovations, MikroKopter, and 3D Robotics. Camera drones, such as the Chinese-made DJI Phantom and the French-made Parrot AR Drone, rapidly became common toys. Nixie is a small camera-equipped drone that can be worn as a wrist band.

An innovative drone was invened at EPFL in Switzerland: Gimball, a small ultralight insect-like flying spheroid that doesn't have sensors. Instead, it can bounce off walls and obstacles.

An EPFL spinoff, Flyability, builds drones for industrial exploration, to explore places that are too difficult or too dangerous for humans.

We tend to think of a drone as an individual entity, separated and isolated from other drones. But in 2008 Raffaello D'Andrea at ETH in Switzerland had the idea to create drones that need to collaborate in order to achieve a goal. "Collaborate" in this case means "cooperate to build a higher-level drone. The goal consists in flying. The individual drones don't fly, but, when they assemble in the proper structure, they become a flying drone. This self-assembly flying robot is called Distribution Flight Array.

If drones have to become a serious market, not just weekend toys, they need to expand the range of potential applications. For example, Jonathan Downey's Airware in San Francisco is building an operating system for drones. This software will make drones programmable for use by corporations.

Drone companies are starting with small drones and then will try to move into bigger (and more useful) drones, maybe also to transport passengers. Airbus has a laboratory in Silicon Valley called A3 that is doing the opposite: Airbus makes airplanes, and today's airplanes are basically robots that fly by themselves. Airbus knows how to build "autonomous flying vehicles" because that's its job. Their project Vahana has all the components that they need to deliver not only a flying car but a driver-less flying car.