Now, a recentpaperby US-based physicists Alexey Bobrick and Gianni Martire has resolved many of those issues andgeneratedalotofbuzz.
There is, however, a silver lining: warp technology may have radical applications beyond space travel.
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The story of warp drives starts with Einsteins crowning achievement: general relativity.
General relativity places two constraints on interstellar travel.
First, nothing can be accelerated past the speed of light (around 300,000 km per second).
Assuming a constant state of acceleration, this makes it possible to travel the stars.
One can reach a distant star that is 150 light years away within ones lifetime.
The catch, however, is that upon ones return more than 300 years will have passed on Earth.
A new hope
This is where Alcubierre came in.
A flat region is like a part of the mat with nothing on it.
Such a drive would also avoid the uncomfortable consequences of time dilation.
A spacetime oddity
How does Alcubierres gear work?
Here discussion often relies on analogies, because the math is so complex.
Imagine a rug with a cup on it.
Youre on the rug and you want to get to the cup.
You could move across the rug, or tug the rug toward you.
The warp drive is like tugging on spacetime to bring your destination closer.
But analogies have their limits: a warp drive doesnt really drag your destination toward you.
It contracts spacetime to make your path shorter.
Theres just less rug between you and the cup when you switch the drive on.
Alcubierres suggestion, while mathematically rigorous, is difficult to understand at an intuitive level.
Bobrick and Martires work is set to change all that.
The energy of the shell modifies the properties of the spacetime region inside it.
Their work tells us that a warp drive is, somewhat surprisingly, like a car.
The difference is that getting inside a car does not make you age faster.
That, however, is the kind of thing a warp drive might do.
This gives us a mathematical key for finding and classifying warp technologies.
Their work manages to address one of the core problems for warp drives.
A two-dimensional visualization of an Alcubierre drive.
Expanding and contracting regions of spacetime on opposite sides of the central flat region cause it to move.
Credit: Applied Physics
Worse, the negative energy requirements of Alcubierres gadget are immense.
Bobrick and Martire show a warp drive could be made from positive energy (i.e.
normal energy) or from a mixture of negative and positive energy.
That said, the energy requirements would still be immense.
If Bobrick and Martire are right, then a warp drive is just like any other object in motion.
The news gets worse.
The end game
Remember that a warp drive can modify the region of flat spacetime it encloses.
It can, in particular, speed up or slow down a clock inside the drive.
Consider what it would mean to have such an object available.
Want to put someone with a terminal illness on ice?
Stick them in a warp drive and slow their clock down.
Want to grow your crops overnight?
Stick them in a warp drive and speed the clock up.
A few days will pass for you, and a few weeks will pass for your seedlings.
Faster-than-light travel remains a distant dream.
But warp technology would be revolutionary in its own right.
This article bySam Baron, Associate professor,Australian Catholic Universityis republished fromThe Conversationunder a Creative Commons license.
