Nick Cook – A Ramble Through an Oxford Author's Imagination and Inspiration: Stephen Hawking

Solar sails used for propelling space ships across the vast distances of space have always been a firm favourite of science fiction stories. I first heard of the concept back in the 1970s in Larry Niven and Jerry Pournelle’s book, The Mote in God's Eye. Also, concept images frequently adorned the pages of the science and science fiction magazines back then, such as in the wonderful OMNI (sadly no longer in print).

In September 2016, this technology will take a significant step forward, when a tiny spacecraft, Prox-1, will hitch a ride onboard the new SpaceX orbital lifter, the Falcon Heavy. And this will be a very important moment for the future of space exploration.

Once Prox-1 has achieved orbit, it will eject a rather special CubeSat spacecraft, LightSail2, a little larger than a loaf of bread, into space. From this tiny ship, once the instruction to deploy has been received, a solar sail, 4.5 microns thick (far thinner than a rubbish bag), will start to unfurl. Once it has been fully extended to its full 32 square metres size, it will start to capture packets of photons from the sun on its reflective surface, converting their momentum to thrust and pushing LightSail2 gently forward.

Image credit: NASA

The LightSail 2 is the work of The Planetary Society, a nonprofit group raising funding through Kickstarter campaigns. The group's stated aim is to engage and empower people around the world, in the advancement of space science and exploration. In 2015 they deployed LightSail 1 which hitched a ride onboard an Atlas V rocket. Although the craft didn’t reach a high enough altitude for solar sailing, its deployment sequence was successfully tested. LightSail 2, picks up where its predecessor left off, and once sailing with the power of the sun's captured photons, ground-based lasers will measure the effect of sunlight on the sails. Its solar sail should also be highly visible from Earth and The Planetary Society intend to organise public viewings.

Compared to chemical rockets, solar sails enjoy a distinct advantage. Unlike the short burst of thrust of a rocket, solar sails deliver continual thrust, ultimately achieving a far higher speed than their chemical rocket cousins. And without the need to carry huge amounts of fuel, this makes them a particularly interesting propulsion system for interstellar travel.

Image credit: NASA

NASA isn’t being left out either and is experimenting with a variant of solar sail technology. They have started testing the Heliopause Electrostatic Rapid Transit System, or HERTS for short. This is an E-Sail that uses charged wires covering an area of 219 football pitches, to electrostatically push the protons in the sun’s solar winds to create propulsion. The intention is to use this craft for travel across the solar system. By comparison, Voyager 1, launched in 1977, took 35 years to reach interstellar space. If the tests all proceed to plan, a HERTS based craft should be able to do the same journey in around twelve years, a third of the time.

Image credit: Breakthrough Starshot Initiative

Solar sails also hit the news again this week with the announcement that Stephen Hawkin has signed his name to the Breakthrough Starshot Initiative. This project has announced a significant $100 million research fund to investigate the creation of a fleet of tiny nanocraft, the size of postage stamps, and packing the sort of processing power that we find in the average smartphone today. These craft, being propelled by lasers, will head out of our solar system towards our neighbouring star, Alpha Centauri, at up to 20 percent of the speed of light. Travelling at this velocity they should make the 4 light-year journey to Alpha Centauri in about twenty years, taking snapshots all the way during their long voyage and beaming their images back home. Can you begin to imagine the excitement when that fleet of tiny nanocraft finally arrives in our nearest neighbour's system?

Although there is ongoing research into esoteric drive systems like the EmDrive, the technology for solar sails exists today. The Breakthrough Starshot Initiative has a very real chance of sending a probe using this technology, out across the vast distances of space to visit our interstellar neighbours. And with that, and the other current space developments, including in reusable rocketry, it really does feel like we are entering a new era in space exploration. And that can only be a wonderful thing for our future as a species.

Article header image credit: The Planetary Society

Photo credit: NASA's Marshall Space Flight Center via Visual Hunt / CC BY-NC-ND

“Reality can be beaten with enough imagination.”

– Mark Twain

In previous articles I've mentioned parallel realities that various theories point toward, but if they really do exist is there some way you could travel between them?

As it happens we may be in luck. In 1935 Albert Einstein and Nathan Rosen working together on the theory of gravity, came me out with the esoteric concept of a wormhole. To explain the principle of what this is, if you think of our universe as a flat plane and another reality on a plane below it, the wormhole is an effectively a tunnel that can directly link these otherwise separate realities. Now before you get too excited at the idea of an intergalactic tunnel between parallel dimensions, there are some serious technical problems that need to be addressed.

Also, it isn’t only Einstein and Rosen who have theorised about the existence of wormholes. They crop up in quantum mechanics (the study of the very small) and scientists like Stephen Hawking have proposed that we are actually surrounded by them. Now before you started glancing nervously around worried that you may be about to be sucked into a parallel reality, let me reassure you. These sort of wormholes are infinitesimally small, tinier than even atoms, constantly forming in something called quantum foam, to link different places and even different times, before disappearing again. Now obviously these tunnels are far too small for a human to pass through (you can stop looking nervously over your shoulder now), but some scientists believe it might be possible to expand one so we could.

Another idea is that we could build huge wormhole generators in space. If the entrance was placed near the Earth, the exit could be placed next to far off stars, allowing a spaceship entering to be instantly transported to the far flung point. Alternatively, if the exit was in the same place but at a different time, it would allow instant time travel between the two gates for our space ship.

So how could we build ourselves a viable machine to create a traversable wormhole that remains stable?

The first issue is that the wormholes are inherently unstable, try to pass through one and you are going to ripped apart when they collapse. So how could we prevent this? The answer is we need to use something that hasn’t been discovered yet and it’s been labelled negative energy. With this magic missing ingredient we could keep the walls open. Simple!

The second serious hurdle to overcome is to that to get anywhere close to a useable wormhole, an incredible amount of energy is required. How much? We are talking the power of harnessed stars. That’s quite a power bill.

So unfortunately for now in practical terms creating useable wormholes seems a way off. In the meantime we’ll just have to rely on science fiction to fire our imaginations about the possibilities of travel between parallel realities and time travel.

This excellent short video with Michio Kaku and narrated by no less than Morgan Freeman, explains wormholes further.