Think back to 2008, when the Large Hadron Collider (LHC) was about to be switched on for the first time. Remember all those “micro-black hole,” “spacetime-ripping,” “stranglet-creating” doomsday headlines?
Although much of the hype was complete nonsense, those pesky physicists are at it again; they want to build a laser so powerful that it will literally rip spacetime apart. (Keanu Reeves, over to you.)
The headlines write themselves.
What’s more, by giving spacetime a hernia, it is hoped that theorized “ghost particles” may spill from the fissure, providing evidence for the hypothesis that extra-dimensions exist and the vacuum of space isn’t a vacuum at all — it is in fact buzzing with virtual particles.
Such a laser could also help in understanding the nature of dark matter, the “missing” mass that is thought to pervade the entire observable Universe.
As we all know, all good megalomaniac plans for world domination start with lasers (not necessarily attached to sharks’ heads). But the lasers planned by the Extreme Light Infrastructure Ultra-High Field Facility, known as “ELI,” would concentrate 200 petawatts of power — that’s 100,000 times the world’s power production — and fire it at a single point for less than a trillionth of a second.
The combined power of 10 separate lasers would be focused down to a very small volume, creating conditions more extreme than in the center of our sun. It is hoped (yes, hoped) that this immense energy will punch a hole through the fabric of spacetime itself, heralding a new era of exotic physics discovery.
Needless to say, a novel means of energy collection would be needed to operate the facility, and their electricity bill will be gargantuan, so why start shooting holes through spacetime in the first place?
“We are taught to think of the vacuum as empty space, but it seems even a true vacuum is filled with pairs of (particles) that come into our universe for an extremely short time,” said Wolfgang Sandner, coordinator of the Laserlab Europe network and president of the German Physics Society.
“An extremely powerful laser should be able to pull these particles apart and keep them in existence for longer.”
In other words, the term “vacuum of space” is a misnomer. As is taught in degree-level physics, one of the bedrock theories of quantum dynamics is that space is anything but empty.
There is a buzz of energy throughout the Cosmos — whether that be in my atmosphere-rich office, the center of a star, or the frigid “void” between the galaxies. However, this “buzz” is rather exotic, like nothing we can physically experience.
In a nutshell, pairs of particles — particle/anti-particle pairs — are spontaneously created by the vacuum, “borrowing” energy from spacetime. However, these “virtual” (or “ghost”) particles must return their energy to the vacuum within a minuscule period of time. Within that time period, the pair will collide and annihilate, thus returning energy to the Universe.
So these virtual particles pop in and out of existence like ghosts… until something very massive, or very energetic, interferes with their annihilation dance.
One of the most famous, massive things that could interrupt them is a black hole.
As predicted by Stephen Hawking, black hole evaporation is caused by virtual particles. Right at a black hole’s event horizon — the point at which even light cannot escape the extreme gravitational warping of the black hole — virtual particles will pop in and out of existence as normal.
However, one of the pair of virtual particles may get sucked into the event horizon while the other is ejected. With no partner to annihilate with, the ejected particle keeps the borrowed energy all for itself, and becomes a real particle — like Pinocchio turning from a wooden toy into a real boy.
As this newly-real particle is ejected, it is effectively stealing energy (and therefore a tiny bit of mass) from the black hole — this effect is known as Hawking radiation. Over time, the black hole shrinks. Hawking radiation will therefore eventually cause black holes to fizz out of existence!
It is hoped that the ELI lasers will also be able to pull these particles apart — not to make them “real” (à la Hawking radiation) but to keep them around long enough so we can detect their existence.
“There are many challenges to be over come before we can do that, but it is mainly a matter of scaling up the technology we have so we can produce the powers needed,” added Sandner.
So, sensibly, prototype lasers are being built in the Czech Republic, Hungary and Romania in the hope of seeing them commissioned in 2015. The final decision on the location of the fully-functional ELI site will remain with the European Commission, and many European nations are bidding to be hosts of the $1.6 billion project.
“ELI is going to take us into an uncharted regime of physics. There could well be some surprises along the way,” said Thomas Heinzl, an associate professor of theoretical physics at Plymouth University.
Image credit: Ian O’Neill/Discovery News