--- title: Why Interstellar Travel Has Suddenly Become a Realistic Goal description: Stephen Hawking is taking part in the Breakthrough Starshot Initiative, which uses light to propel a spacecraft into to explore stars. canonical: https://time.com/4292365/instellar-travel-reality/ author: TIME Staff article:opinion: false article:content_tier: free article:published_time: 2016-04-13T16:28:06.000Z article:modified_time: 2026-10-05T08:50:04.901Z article:section: Science og:title: Why Interstellar Travel Has Suddenly Become a Realistic Goal og:description: Thanks to Stephen Hawking and the Breakthrough Starshot initiative og:url: https://time.com/4292365/instellar-travel-reality/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt6f96883e8e1e3a5b/69888ef02dce0177199e8a2e/breakthrough-starshot-initiative-stephen-hawking.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 3000 og:image:height: 1688 og:image:alt: breakthrough-starshot-initiative-stephen-hawking og:type: article twitter:card: summary_large_image twitter:title: Why Interstellar Travel Has Suddenly Become a Realistic Goal twitter:description: Thanks to Stephen Hawking and the Breakthrough Starshot initiative twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt6f96883e8e1e3a5b/69888ef02dce0177199e8a2e/breakthrough-starshot-initiative-stephen-hawking.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Why Interstellar Travel Has Suddenly Become a Realistic Goal > Sponsored content. 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Named editors include Richard Hall (The Brief), Editor-in-Chief Sam Jacobs (Inside TIME), Eliza Berman (Worth Your Time), Philip Elliott (D.C. Brief), Justin Worland (Future Proof) and Harry Booth (In the Loop). Health Matters is written by TIME's health desk. #### How do I sign up for a TIME newsletter? Go to time.com/newsletters, choose the newsletters you want and enter your email address. There is no cost and no subscription requirement. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-network-2026q3/newsletters?i=796a5c3d-6ce3-44ca-818f-fb04c5a19d58&cr=time-nl-network-2026q3-v1) ## Video: Mapping The Stars: How to Get to the Nearest Star in Twenty Years [Watch (HLS stream): Mapping The Stars: How to Get to the Nearest Star in Twenty Years](https://cdn.jwplayer.com/manifests/oJiBtWvc.m3u8) (4:13)  _Published 2016-04-13. Philip Lubin, physics professor at The University of California, Santa Barbara, explains how sending laser-propelled probes into outer space can further mankind's exploration and knowledge about our universe._ by [TIME Staff](https://time.com/author/time-staff/) ## TIME Staff Apr 13, 2016 4:28 PM UTC by [TIME Staff](https://time.com/author/time-staff/) ## TIME Staff Apr 13, 2016 4:28 PM UTC It takes a bold person to declare that interstellar travel is now within our grasp. Physicist Stephen Hawking has shown that he is just that, taking part in the [Breakthrough Starshot initiative](http://www.breakthroughinitiatives.org/Initiative/3). The project has announced a $100 million research programme to investigate the technology of using light to propel spacecraft out of the solar system to explore neighbouring stars. For the first time in human history, interstellar travel is a realistic and achievable aspiration, and not just the playground of science fiction. So what has changed that makes interstellar travel achievable? First of all, clear expectations. This is not about a great big spaceship with a colony of astronauts travelling for generations to settle a planet around a distant star. Neither is it about faster-than-light travel, tunnelling through wormholes to arrive at the other side of the universe in an instant of time. This is about technology that already exists, or nearly exists, being applied in new and exciting ways. The technology is that of solar sails combined with the ability to miniaturise instruments. The [idea behind solar sails](http://www.esa.int/Education/Solar%5Fsails) is that the light that streams from the sun can be used to propel an object. Gradually, as the object is moved, it accelerates and builds up speed, eventually reaching values that are a significant fraction of the speed of light. So far, tests have been made on sails that are many metres across, carrying payloads of kilograms in weight. And [the technology works](http://www.nasa.gov/mission%5Fpages/tdm/solarsail/) – both the European Space Agency and NASA have developed systems that could be applied to spacecraft. To work efficiently, these sails need to be several metres across, just as a sail on a sea-going vessel needs to be a certain size to catch enough wind to push a ship forward. Miniaturisation of instruments has been a significant driver of space exploration ever since the launch of Sputnik, the first artificial satellite to orbit the Earth. The ideal instrument for a space mission has minimal mass and requires minimal power. These requirements led to the concept of [CubeSat](http://www.cubesat.org/), a tiny satellite where a standard platform has been developed onto which different instruments could be fitted. The entire satellite can also be launched by a variety of different vehicles. We can all appreciate the rate at which equipment is getting ever smaller – a quick glance at a smart phone, with its powerful camera, ability to record and store gigabytes-worth of sound and images shows where technology sits at the moment. There have been proposals to use a CubeSat to launch multiple tiny probes carrying instruments to the moon and to Mars. Breakthrough Starshot, though, will be a single microchip – a spacechip that is a spaceship (and vice versa!). The concept is to have individual microchips each propelled by a solar sail. Given that the sail is likely to be much, much bigger than the vessel – the spacechip is likely to be of the order of a centimetre long – there are practical as well as technological difficulties to overcome. But attaching the sail to the ship is probably one of the least serious potential problems. **Interstellar threats** Interplanetary and interstellar space are full of hazards for a tiny traveller. The two greatest hazards will be dust and radiation. Even though there have been great advances in production of thin but strong materials that would make appropriate solar sails, a dust grain travelling at speed could rip a sail apart. Also, microchips are very [sensitive to high doses of radiation](https://hps.org/publicinformation/ate/q11162.html) – and interstellar space is shot through by cosmic rays. While the chips are still within the solar system, how vulnerable will they be to changes in the solar wind? Once all the technological development has taken place, and the chips are launched – which might be sooner rather than later, if the Breakthrough Starshot initiative is successful – where will they go and what will they do when they get there? The idea is that they will travel to our nearest neighbour beyond our Solar System, Alpha Centauri, taking about 20 years to get there, travelling at a speed of about 60,000 km per second (or 135m miles per hour). This is not just an amazingly short time to travel a distance of 40 trillion km, it is also a reasonable length of time for a space mission to last – think of how long the Hubble Space Telescope has been operating and returning spectacular images. En route for Alpha Centauri, the chips will act as tourists – taking pictures, meeting the local inhabitants (planets? comets?), and looking at the scenery (such as more distant stars). These findings in themselves are probably sufficient scientific justification for the project. For example, we have never seen a star or a supernova from interstellar space – we are always looking through the lens of the solar system. Once the tiny travellers reach Alpha Centauri, the instruments will make measurements of a stellar system, giving us – again for the first time – a detailed insight into stars that are different from our own. They might even find planets and moons. We’ve had talk of surfing on [gravitational waves to travel in time](http://www.usnews.com/news/articles/2016-02-23/discovery-of-gravitational-waves-makes-time-travel-mathematically-possible) – which is still very much science fiction. Now, though, we are sailing in a solar wind, and interstellar travel is within our grasp. We might not yet be at the stage of interstellar travel for people, but being able to see what it is like to travel through interstellar space while still in the comfort of our own home is certainly a first step. _This_ [_article_](https://theconversation.com/why-sailing-to-the-stars-has-suddenly-become-a-realistic-goal-57762) _was originally published on_ [_The Conversation_](http://theconversation.com) ## Transcript Why do people explore? You know that's really a profoundly interesting question. We've looked at the sky for as long as we've been alive and we've dreamed in stories and in movies of traveling to the stars. Why? We want to see what's out there. The problem is that while we can go to the moon, and while we actually have it within our power to go to Mars, we don't have a well defined way to get out to the stars. So what we're proposing. Is precisely that. A well defined and logical way to go to stars. Not with humans, but with robotic hopes. I'm a professor in the physics department at the University of California at Santa Barbara. This department is one of the Top ten departments in the country in physics. We have a group in our department, the experimental cosmology group, that we started in 1987. And it's a very dynamic group. Some of those students are also focused on applications of directed energy systems. The main mission behind the experimental cosmology group is to advance science and advance directed energy studies and its application. There's an aircraft flying overhead that you hear. That aircraft can only fly about the speed of sound. But that's way too slow to explore the stars. If you were to maintain that same speed and wanted to go to the nearest star, it would take you more than five million Ten years in that aircraft. In our system, with the smallest probes it could take as little as 20 years. If we wanna get to Alpha Centauri in 20 years, we have to take our ideas and scale them down. And in order to do that, we've set up a vacuum chamber to simulate space conditions. [ MUSIC ] The energy system is basically Like a laser pointer. Take a laser or a flashlight, turn it on, you direct energy. That means can be used for many purposes. When it's taken to extremes, it can be used to deflect an asteroid coming into the Earth. It could be used to propel a spacecraft. In order to get to the future Sure when you take small steps, I like to think baby steps. Some of those include just laboratory measurements of the thrust that you can get from a [ UNKNOWN ] and Asterope. The thrust you get from building spacecraft. You scale that up to large guild directed energy systems like what we're proposing, that forest becomes significant. Theoretically the wafer spacecraft is actually four inches. Inches by four inches, almost as thin as your hair. And these probes would literally be a spacecraft on a chip. The propulsion system is the laser, which stays [ UNKNOWN ] on the moon nearby. You fire it And then it's gone. If we reduce the spacecraft to a wafer, which we have things like imaging sensors, cameras for looking at the stars for orientation, and then a laser communication system to communicate back to the Earth. But keep in mind the same system, this is a very important point, the same system is used not just to send out one probe, but to send out And are monochromes. It takes about 10 minutes to accelerate a wafer to 30 % of the speed of light. And that's it. You can send a hundred per day or more. You can send nearly 40000 per year. Once we have thousands of space crafts out in space, we can look at many things out in space that we've never been able. To explore before, such as the solar gravity events, Alpha Centauri, and the closest star. When we really begin to look at the issues of sending humanity into interstellar travel it becomes very different than the movies. We're not really the ideal creatures to be traveling. Really what we want is not necessarily. To spread our bodies throughout the universe but to spread the capability of replicating ourselves, our spirit, our inquiry, our biological subsystems. Obviously you're going to start out with critics and people that are going to question you. But then we can actually see people starting to like our idea more and more and Like coming to it and I think that's really special and that's where the optimism comes from. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/4292365/instellar-travel-reality/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/4292365/instellar-travel-reality/"},"headline":"Why Interstellar Travel Has Suddenly Become a Realistic Goal","datePublished":"2016-04-13T16:28:06.000Z","dateModified":"2026-10-05T08:50:04.901Z","description":"Thanks to Stephen Hawking and the Breakthrough Starshot initiative","url":"https://time.com/4292365/instellar-travel-reality/","keywords":["Space"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt6f96883e8e1e3a5b/69888ef02dce0177199e8a2e/breakthrough-starshot-initiative-stephen-hawking.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"TIME Staff","jobTitle":null,"url":"https://time.com/author/time-staff/"}],"articleSection":"Science","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt6f96883e8e1e3a5b/69888ef02dce0177199e8a2e/breakthrough-starshot-initiative-stephen-hawking.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"breakthrough-starshot-initiative-stephen-hawking","caption":"at One World Observatory on April 12, 2016 in New York City.","creditText":"Jemal Countess/Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/science/","name":"Science"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/space/","name":"Space"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/4292365/instellar-travel-reality/","name":"Why Interstellar Travel Has Suddenly Become a Realistic Goal"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"Project Announced to Explore Alpha Centauri","description":"Breakthrough Starshot is a project to discover life potential in Earth's closest star system.","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/nqbmYYve/poster.jpg?width=720","uploadDate":"2016-04-12T21:44:56.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/nqbmYYve.m3u8","embedUrl":"https://time.com/4292365/instellar-travel-reality/","duration":"PT1M3S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/4292365/instellar-travel-reality/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}},{"@context":"https://schema.org","@type":"VideoObject","name":"Mapping The Stars: How to Get to the Nearest Star in Twenty Years","description":"Philip Lubin, physics professor at The University of California, Santa Barbara, explains how sending laser-propelled probes into outer space can further mankind's exploration and knowledge about our universe.","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/oJiBtWvc/poster.jpg?width=720","uploadDate":"2016-04-13T15:27:44.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/oJiBtWvc.m3u8","embedUrl":"https://time.com/4292365/instellar-travel-reality/","duration":"PT4M13S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/4292365/instellar-travel-reality/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}}] ```