(MENAFN – The Conversation) In 1994, physicist Miguel Alcubierre proposed a radical technology that would allow movement faster than light: the warp drive, a hypothetical way to bypass the ultimate speed limit of the universe by folding the fabric reality.
It was an intriguing idea – even NASA studied it at the Eagleworks lab – but Alcubierre’s proposal contained problems that seemed insurmountable. Today, a recent article by American physicists Alexey Bobrick and Gianni Martire solved many of these problems and generated a lot of buzz.
But while Bobrick and Martire have managed to dramatically demystify warp technology, their work actually suggests that faster-than-light travel will remain out of reach for beings like us, at least for now.
There is, however, a silver lining: chain technology may have radical applications beyond space travel.
Across the universe?
The history of distortion training begins with Einstein’s crowning glory: general relativity. The equations of general relativity capture how space-time – the very fabric of reality – bends in response to the presence of matter and energy which, in turn, explains how matter and energy are moving.
General relativity imposes two constraints on interstellar travel. First, nothing can be accelerated beyond the speed of light (about 300,000 km per second). Even traveling at this breakneck speed, it would take us another four years to get to Proxima Centauri, the star closest to our Sun.
Second, the clock of a spacecraft traveling near the speed of light would slow down relative to a clock on Earth (this is called time dilation). Assuming a constant state of acceleration, this makes it possible to travel the stars. You can reach a distant star that is 150 light years away in its lifetime. The catch, however, is that when he returns, more than 300 years will have passed on Earth.
This is where Alcubierre came in. He argued that the mathematics of general relativity allowed for “ warping bubbles ” – regions where matter and energy were arranged in such a way as to bend the space-time past the bubble and extend it backwards in a way that allowed a “flat” area inside the bubble to travel faster than light.
Read more: Don’t stop me now! Superluminal journey into Einstein’s universe
To get an idea of what “flat” means in this context, note that spacetime is a bit like a rubber mat. The mat bends in the presence of matter and energy (think of putting a bowling ball on the mat). Gravity is nothing more than the tendency for objects to roll into the bumps created by things like stars and planets. A flat region is like a part of the carpet with nothing on it.
Such training would also avoid the unpleasant consequences of time dilation. One could potentially make a round trip to deep space and still be greeted by his nearest and dearest home.
A space-time quirk
How does Alcubierre’s device work? Here the discussion is often based on analogies, because the math is so complex.
Imagine a rug with a cup on it. You are on the mat and you want to get to the cup. You can move around on the mat or pull the mat towards you. The warp reader is like shooting space-time to bring your destination closer.
But analogies have their limits: a warp drive doesn’t really pull your destination towards you. It contracts space-time to shorten your path. There is just less carpet between you and the cup when you turn on the player.
Alcubierre’s suggestion, although mathematically rigorous, is difficult to understand on an intuitive level. The work of Bobrick and Martire will change all that.
Bobrick and Martire show that any distortion drive must be a shell of material in a state of constant motion, encompassing a flat region of spacetime. The energy of the shell changes the properties of the space-time region within.
It might not sound like a find, but until now, it wasn’t really clear what warp drives could be, physically speaking. Their work tells us that a chain drive is, somewhat surprisingly, like a car. A car is also a shell of energy (in the form of matter) that encloses a flat region of space-time. The difference is that getting in a car doesn’t make you age any faster. However, this is the sort of thing a distortion reader could do.
Using their simple description, Bobrick and Martire demonstrate a method for using Einstein’s equations of general relativity to find space-times that allow arrangements of matter and energy that would act as distortion bubbles. This gives us a mathematical key to finding and classifying chain technologies.
Their work manages to solve one of the fundamental problems of distortion drives. To balance the equations, Alcubierre’s device operates on “negative energy” – but we have yet to discover viable sources of negative energy in the real world.
A two-dimensional visualization of an Alcubierre reader. The expansion and contraction of the spacetime regions on opposite sides of the central flat region causes it to move. Applied physics
Worse, the negative energy needs of Alcubierre’s device are immense. By some estimates, all the energy in the known universe would be needed (although further work will reduce the number a bit).
Bobrick and Martire show that a warp drive can be made from positive energy (ie “normal” energy) or from a mixture of negative and positive energy. However, the energy needs would still be immense.
If Bobrick and Martire are right, then a warp drive is like any other moving object. It would be subject to the universal speed limit imposed by general relativity after all, and it would need some sort of conventional propulsion system to make it accelerate.
The news is getting worse. Many types of warp drive can only alter indoor space-time in one way: by slowing down the passenger’s clock in exactly the way that makes deep space travel a problem.
Bobrick and Martire show that some warp drives could travel faster than light, but only if they’re created at that speed already – which doesn’t help any ordinary human hoping for a bit of interstellar tourism.
The final game
Remember that a warp reader can change the region of flat spacetime that it encompasses. In particular, it can speed up or slow down a clock inside the reader.
Consider what it would mean to have such an item available. Want to put someone with a terminal illness on the ice? Stick them in a distortion reader and slow down their clocks. From their point of view, a few years will pass, while a hundred years will pass on Earth – enough time to find a cure.
Read more: The art and beauty of general relativity
Want to grow your crops overnight? Stick them into a chain drive and speed up the clock. A few days will pass for you, and a few weeks will pass for your seedlings.
There are even more exotic possibilities: by spinning space-time inside a reader, one may be able to produce a battery capable of holding enormous amounts of energy.
Traveling faster than light remains a distant dream. But the chain technology would be revolutionary in itself.
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