This is another of those stories this week that so many people sent along that it went directly into the "finals cut" folder, because, as one can imagine, it prompts all sorts of high octane speculations. In brief, China is experimenting with extremely high energy lasers that, it is thought, might be a technique for creating lasers capable of breaking the symmetry of the vacuum - of the fabric of space-time itself, and thereby creating particles from mere light, and thereby taking another step toward direct access of the creative energies of the vacuum:
Now, if you're like me, when you read an article titled "Physicists are planning to build lasers so powerful they could rip apart empty space", you might be thinking "What could possibly go wrong?" Ripping apart empty space is no big deal, right? After all, the last time Someone did it was... er... well, the Big Bang. It would be a nifty capability to have lying around the workbench of your garage if, for example, you were Marduk and took it in your head to blow up a planet. How better to do that than rip apart the local latticework of space-time in which said planet is embedded with your
divine lightning bolts titanium-doped sapphire pulsed lasers?
Now of course, all this is pure speculation. The reality is a bit more prosaic:
The group's ambitions don't end there. This year, Li and colleagues intend to start building a 100-PW laser known as the Station of Extreme Light (SEL). By 2023, it could be flinging pulses into a chamber 20 meters underground, subjecting targets to extremes of temperature and pressure not normally found on Earth, a boon to astrophysicists and materials scientists alike. The laser could also power demonstrations of a new way to accelerate particles for use in medicine and high-energy physics. But most alluring, Li says, would be showing that light could tear electrons and their antimatter counterparts, positrons, from empty space—a phenomenon known as "breaking the vacuum." It would be a striking illustration that matter and energy are interchangeable, as Albert Einstein's famous E=mc2 equation states. Although nuclear weapons attest to the conversion of matter into immense amounts of heat and light, doing the reverse is not so easy. But Li says the SEL is up to the task. "That would be very exciting," he says. "It would mean you could generate something from nothing."
Oh, wait, the creation of particles and anti-particles isn't so prosaic at all, because if one could actually collect and sustain all that anti-matter somehow, one could produce "anti-matter reactors" which might have enough energy to ... oh, say... power NASA's and DARPA warp drive plans, or perhaps to build bombs utilizing the total annihilation reaction properties of matter/anti-matter reactions. (Hmmm... seems to me that I recall the late Dr. Tom Van Flandern speculating on such reactions as one possible mechanism for blowing up planets.) Indeed, such a capability would inevitably imply the God-like ability to locally engineer the properties of the vacuum.
But, again, I am speculating of course. How has the Chinese laser's extremely high energy been achieved?
To get to higher powers, scientists have turned to the time domain: packing the energy of a pulse into ever-shorter durations. One approach is to amplify the light in titanium-doped sapphire crystals, which produce light with a large spread of frequencies. In a mirrored laser chamber, those pulses bounce back and forth, and the individual frequency components can be made to cancel each other out over most of their pulse length, while reinforcing each other in a fleeting pulse just a few tens of femtoseconds long. Pump those pulses with a few hundred joules of energy and you get 10 PW of peak power. That's how the SULF and other sapphire-based lasers can break power records with equipment that fits in a large room and costs just tens of millions of dollars, whereas NIF costs $3.5 billion and needs a building 10 stories high that covers the area of three U.S. football fields. (Emphasis added)
(Oh wait, you mean, this really will fit into my garage?)
Not to worry, we're still along way from ripping apart the vacuum and achieving any sort of sustained anti-matter containment:
Once the laser builders summon the power, another challenge will loom: bringing the beams to a singularly tight focus. Many scientists care more about intensity—the power per unit area—than the total number of petawatts. Achieve a sharper focus, and the intensity goes up. If a 100-PW pulse can be focused to a spot measuring just 3 micrometers across, as Li is planning for the SEL, the intensity in that tiny area will be an astonishing 1024 watts per square centimeter (W/cm2)—some 25 orders of magnitude, or 10 trillion trillion times, more intense than the sunlight striking Earth.
Those intensities will open the possibility of breaking the vacuum. According to the theory of quantum electrodynamics (QED), which describes how electromagnetic fields interact with matter, the vacuum is not as empty as classical physics would have us believe. Over extremely short time scales, pairs of electrons and positrons, their antimatter counterparts, flicker into existence, born of quantum mechanical uncertainty. Because of their mutual attraction, they annihilate each another almost as soon as they form.
But a very intense laser could, in principle, separate the particles before they collide.... "This will be completely new physics," Sergeev says. He adds that the gamma ray photons would be energetic enough to push atomic nuclei into excited states, ushering in a new branch of physics known as "nuclear photonics"—the use of intense light to control nuclear processes.(Emphasis added)
So...hmmm... the very thing used to create particle/anti-particle pairs could conceivably be used to sustain their separation... and as a remote possibility, collect a bunch of them and (crawling way out onto the end of the twig of speculation), conceivably create whole molecules of "anti-elements"? Not to worry, that's centuries away, if even possible at all. After all, particle/anti-particle theory has been around for...er... mere decades and ... uhm... here we are talking about ripping the vacuum symmetry apart with powerful lasers only a few decades later.
Well... there you are. I started out trying to convince myself that there was nothing to worry about here. It's only a few particles, after all. All the other stuff is just wild and woolly end-of-the-twig speculation. Nothing-to-see-here, move along. But I'm curiously and massively uneasy about this, and cannot escape the image I have in my head of a National Enquirer headline: Scientists Admit Experiment Went Wrong: Alternative Universe Created... and Growing..."
There's always the "oops factor", folks.
See you on the flip side...