{"id":3587,"date":"2015-05-21T04:28:29","date_gmt":"2015-05-21T04:28:29","guid":{"rendered":"http:\/\/www.lifeandnews.com\/articles\/?p=3587"},"modified":"2016-08-25T02:40:59","modified_gmt":"2016-08-25T02:40:59","slug":"faster-than-light-travel-are-we-there-yet","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/faster-than-light-travel-are-we-there-yet\/","title":{"rendered":"Faster-than-light travel: are we there yet?"},"content":{"rendered":"

Robert Scherrer<\/a>, Vanderbilt University<\/a><\/em><\/p>\n

Long before the Empire struck back, before the United Federation of Planets federated, Isaac Asimov created Foundation<\/a>, the epic tale of the decline and fall of the Galactic Empire. Asimov\u2019s Empire comprised 25 million planets, knit together by sleek spaceships hurtling through the galaxy.<\/p>\n

And how did these spaceships cross the vast gulf between the stars? By jumping through hyperspace, of course, as Asimov himself explains in Foundation:<\/p>\n

Travel through ordinary space could proceed at no rate more rapid than that of ordinary light\u2026 and that would have meant years of travel between even the nearest of inhabited systems. Through hyper-space, that unimaginable region that was neither space nor time, matter nor energy, something nor nothing, one could traverse the length of the Galaxy in the interval between two neighboring instants of time.<\/p><\/blockquote>\n

What the heck is Asimov talking about? Did he know something about a secret theory of faster-than-light travel? Hardly. Asimov was participating in a grand science fiction tradition: when confronted with an immovable obstacle to your story, make something up.<\/p>\n

\"\"<\/a>
Nothing goes faster than light.<\/span>
\nBastian Hoppe<\/a>, CC BY-NC-ND<\/a><\/span><\/figcaption><\/figure>\n

You can\u2019t beat the speed of light<\/h2>\n

The problem is that as far as we know, faster-than-light travel is impossible, making galactic empires, federations, confederacies and any other cross-galaxy civilizations impossible. But that\u2019s so inconvenient<\/em>. To evade the cosmic speed limit science fiction has created \u201cwarp-drives,\u201d \u201chyperspace,\u201d \u201csubspace,\u201d and other tricks that have become so ingrained, fans of science fiction don\u2019t give them a second thought.<\/p>\n

Everyone knows what the Enterprise is doing when it does this:<\/p>\n

Warp drive, Mr Scott.<\/figcaption><\/figure>\n

Or when the Millennium Falcon does this:<\/p>\n

I\u2019m going to make the jump to light speed!<\/figcaption><\/figure>\n

Or when the Jupiter 2\u2026 actually the Robinson family tried to get to Alpha Centauri without any special effects:<\/p>\n

\"\"<\/a>
Good luck.<\/span>
\nLost in Space ‘The Derelict’<\/a><\/span><\/figcaption><\/figure>\n

No wonder they got lost in space.<\/p>\n

Light sets the cosmic speed limit<\/h2>\n

Why can\u2019t<\/em> we really exceed the speed of light? After all, people used to talk about a \u201csound barrier\u201d up until the barrier was broken. But the speed of light is a much tougher barrier to crack. When scientists developed the theory of light back in the 19th century, it came with a special puzzle: their theory seemed to show that every observer should measure the same speed for light, about 186,000 miles per second. But that means if you try to chase a beam of light, no matter how fast you move, the light beam will still fly away from you at 186,000 miles per second. And what\u2019s even more bizarre is that if you are moving at 99% of the speed of light, and your friend is standing still, both of you will see the light moving away at exactly the same speed.<\/p>\n

Many scientists back then didn\u2019t really believe this odd prediction, and the American physicist Albert Michelson (along with his collaborator Edward Morley) set out to measure how the speed of light would change due to the motion of the earth through space. But their famous Michelson-Morley experiment<\/a> found no change at all. The speed of light seemed to be the same regardless of whether they measured it in the same direction the earth was moving, or in some other direction \u2013 a rare example of a non-discovery that turned out to be more important than a discovery!<\/p>\n

Enter Einstein and relativity<\/h2>\n

Instead of trying to explain away this bizarreness, Albert Einstein embraced it. He built an entire theory, called special relativity<\/a>, around the idea that the speed of light is the same for everyone who measures it, no matter how fast they are moving in relation to the light. In order to accommodate this behavior for light, Einstein\u2019s theory predicted that time and space would have to stretch or contract as someone traveled with increasing speed. And out of special relativity popped a cosmic speed limit: nothing could ever exceed the speed of light.<\/p>\n

Relativity is a cornerstone of all of modern physics, and we have no reason to doubt it \u2013 no one has ever observed an object moving faster than light. There\u2019s actually a minor clarification necessary here: Einstein\u2019s speed limit is the speed of light in a vacuum<\/em>. Light slows down when it moves through a material like water or glass, and then it\u2019s perfectly possible to exceed this reduced speed of light \u2013 up to its speed in a vacuum, of course. Anything moving faster than light in water or glass produces the luminous equivalent of a sonic boom, called \u010cerenkov radiation. It\u2019s what gives underwater nuclear reactors their attractive blue glow.<\/p>\n

But about that warp drive\u2026<\/h2>\n

Of all of the attempts to wiggle out of Einstein\u2019s speed limit, probably the most plausible is theoretical physicist Miguel Alcubierre\u2019s \u201cwarp drive\u201d<\/a>. Alcubierre\u2019s proposal doesn\u2019t violate the cosmic speed limit \u2013 it goes around it. Try filling a greasy frying pan with water and then put a drop of soap into the pan. The grease will fly away to the sides of the pan.<\/p>\n

\"\"<\/a>
A visualization of a warp field. The ship rests in a bubble of unaltered space, while what\u2019s in front contracts and what\u2019s behind stretches.<\/span>
\nTrekky0623<\/a><\/span><\/figcaption><\/figure>\n

Alcubierre\u2019s warp drive does the same thing with space itself<\/em>. Alcubierre showed that by a suitable distribution of matter, you can shrink space in front of your spaceship and stretch it behind the spaceship, creating a small bubble around the ship that moves as fast as you like. Because space is contracting in front of the ship, the ship wouldn\u2019t officially be moving faster than the speed of light. In fact, the ship would actually be at rest relative to the warp bubble, and the people inside the ship wouldn\u2019t even feel any acceleration. Talk about a smooth ride!<\/p>\n

Everybody ready to say goodbye to our solar system? We\u2019ll have to violate the weak energy condition\u2026.<\/figcaption><\/figure>\n

There\u2019s just one tiny problem\u2026. Alcubierre\u2019s space warp can only be generated by violating something called the \u201cweak energy condition.\u201d Scientists can\u2019t prove that the weak energy condition is always true, but any violation would produce a lot of strange things, like negative energy densities, and possible wormholes<\/a> or time machines<\/a>. Cool \u2013 sign me up for that! But we\u2019ve never seen any actual violations of the weak energy condition. So the Alcubierre warp drive occupies a kind of physics twilight zone \u2013 not absolutely ruled out, but not very plausible, either.<\/p>\n

So how will humanity ever reach the stars? The door marked \u201cfaster-than-light travel\u201d has been slammed in our face and welded shut. We\u2019ll have to sneak in some other way. Get to work!<\/p>\n

\"The<\/p>\n

Robert Scherrer<\/a> is Professor and Chair of Physics and Astronomy at Vanderbilt University<\/a>.<\/p>\n

This article was originally published on The Conversation<\/a>.
\nRead the original article<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Robert Scherrer, Vanderbilt University Long before the Empire struck back, before the United Federation of Planets federated, Isaac Asimov created Foundation, the epic tale of the decline and fall of the Galactic Empire. Asimov\u2019s Empire comprised 25 million planets, knit together by sleek spaceships hurtling through the galaxy. And how did these spaceships cross the […]<\/p>\n","protected":false},"author":40,"featured_media":7250,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[118],"tags":[],"_links":{"self":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/3587"}],"collection":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/users\/40"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/comments?post=3587"}],"version-history":[{"count":2,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/3587\/revisions"}],"predecessor-version":[{"id":7251,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/3587\/revisions\/7251"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media\/7250"}],"wp:attachment":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media?parent=3587"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/categories?post=3587"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/tags?post=3587"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}