One way to do this is with lasers. Radiation is good at transporting energy from one place to another, especially over the vast distances of space. The spacecraft can then capture this energy and propel itself forward. This is the basic idea behind the Breakthrough Starshot project , which aims to design a spacecraft capable of reaching the nearest stars in a matter of decades.
In the simplest outline of this project, a giant laser on the order of gigawatts shoots at an Earth-orbiting spacecraft. That spacecraft has a large solar sail that is incredibly reflective.
The laser bounces off of that sail, giving momentum to the spacecraft. The thing is, a gigawatt laser only has the force of a heavy backpack. You didn't read that incorrectly.
If we were to shoot this laser at the spacecraft for about 10 minutes, in order to reach one-tenth the speed of light, the spacecraft can weigh no more than a gram. This is where the rubber meets the interstellar road when it comes to making spacecraft travel the required speeds. The laser itself, at gigawatts, is more powerful than any laser we've ever designed by many orders of magnitude.
To give you a sense of scale, gigawatts is the entire capacity of every single nuclear power plant operating in the United States combined. And the spacecraft, which has to have a mass no more than a paper clip, must include a camera, computer, power source, circuitry, a shell, an antenna for communicating back home and the entire lightsail itself.
That lightsail must be almost perfectly reflective. If it absorbs even a tiny fraction of that incoming laser radiation it will convert that energy to heat instead of momentum. At gigawatts, that means straight-up melting, which is generally considered not good for spacecraft. Space exploration is the future. It satisfies the human urge to explore and to travel, and in the years and decades to come it could even provide our species with new places to call home — especially relevant now, as Earth becomes increasingly crowded.
Extending our reach into space is also necessary for the advancement of science. Space telescopes like the Hubble Space Telescope and probes to the distant worlds of the Solar System are continually updating, and occasionally revolutionising, our understanding of astronomy and physics. But there are also some very practical reasons, such as mining asteroids for materials that are extremely rare here on Earth.
One example is the huge reserve of the chemical isotope helium-3 thought to be locked away in the soil on the surface of the Moon. This isotope is a potential fuel for future nuclear fusion reactors — power stations that tap into the same source of energy as the Sun. Unlike other fusion fuels, helium-3 gives off no hard-to-contain and deadly neutron radiation. However, for this to happen the first challenge to overcome is how to build a base on the Moon.
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Travel My Hometown In L. Subscriber Exclusive Content. Why are people so dang obsessed with Mars? How viruses shape our world. The era of greyhound racing in the U. See how people have imagined life on Mars through history. In theory, this approach does not contradict the laws of relativity since you are not moving faster than light in the space around you. Proxima Centauri here we come, right? The warp drive would require either negative mass — a theorized type of matter — or a ring of negative energy density to work.
Physicists have never observed negative mass, so that leaves negative energy as the only option. To create negative energy, a warp drive would use a huge amount of mass to create an imbalance between particles and antiparticles. For example, if an electron and an antielectron appear near the warp drive, one of the particles would get trapped by the mass and this results in an imbalance.
This imbalance results in negative energy density. But for a warp drive to generate enough negative energy, you would need a lot of matter. Alcubierre estimated that a warp drive with a meter bubble would require the mass of the entire visible universe.
In , physicist Chris Van Den Broeck showed that expanding the volume inside the bubble but keeping the surface area constant would reduce the energy requirements significantly , to just about the mass of the sun. A significant improvement, but still far beyond all practical possibilities.
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