World’s Highest Energy Particles (and No Black Hole Apocalypse)

Seven TRILLION electron volts! (7,000,000,000,000 eV) Or, 7 teraelectron volts. (7 TeV) Holy bug-zapper, Batman, that sounds like a lotta juice! If only we could bottle it, that would be one great “alternative” source of energy.

Hold on, cowboy! We’re talking electrons, here. You know how small those things are, right? Fact is, one mosquito buzzing around your head represents about 1 TeV of kinetic energy, so we’re looking at 7 flying mosquitoes’ worth of energy. Doesn’t sound like much, but it was enough to get scientists at the European Organization for Nuclear Research (CERN) all a-tizzy last month.

Aerial view of Large Hadron Collider, with location of tunnel drawn on

Some of you may remember that I posted a couple months ago about CERN’s Large Hadron Collider (LHC) on — actually, more than 570 ft. beneath — the French-Swiss border. Well, this was part of the experiments that particle physicists have been planning for the $9.4 billion particle accelerator. They were able to get two beams of protons up to 3.5 TeV each and ram them together! (Boys will be boys! Of course, there are girls involved, too, so, um,… nevermind.) A new world record for man-made particle collisions!

The 17-mile tunnel through which the collider loops is supercooled with liquid helium to just a couple degrees over absolute zero, making it “the coldest place in the universe”. There are two beam pipes that mostly run parallel, each containing a proton beam, which travel in opposite directions around the ring. More than 1600 powerful, superconducting magnets — recently repaired after electrical overheating caused major damage back in Sept. 2008 — keep the beams focused and “on track”, as it were. By altering the magnetic forces slightly, the two beams can be forced to cross at four intersection points and, hopefully, cause at least a few of the billions of protons to collide. Half a dozen detectors — two general purpose and four specialized — are set up at these points to, er, detect the various types of energy, forces, matter, & antimatter that are generated by the collisions.

Attempts earlier in the day experienced problems with the beams, so they had to “dump” the protons and inject fresh ones to create two new beams. But, on March 30 at 13:06 Central European Summer Time (CEST), the first successful collision was achieved, and scientists tuned in worldwide cheered enthusiastically.

“It’s a great day to be a particle physicist,” said CERN Director General Rolf Heuer. “A lot of people have waited a long time for this moment, but their patience and dedication is starting to pay dividends.”

Inside the Large Hadron Collider (LHC) -- notice the little man standing near the bottom

Now, they can begin studying this latest batch of data from the somewhat-controversial LHC project. The hope is to start getting some answers about things such as the origins of the universe, the nature of matter-antimatter asymmetry, supersymmetry, maybe even the elusive “God particle” (aka Higgs boson). The previous record for similar attempts was 2.36 TeV, but it was insufficient to mimic the desired conditions from the moments following the Big Bang. (Next, they plan to double the output to 14 TeV! But, not before 2013.)

Nature does it all the time with cosmic rays (and with higher energy) but this is the first time this is done in Laboratory!” tweeted one scientist.

You may also remember from my earlier post that some people who heard of the planned experiments warned of the mini black holes that could be generated and the apocalyptic results. But, as you may have noticed, such fears were (so far) unfounded, because, well, we’re still here.

With these record-shattering collision energies, the LHC experiments are propelled into a vast region to explore, and the hunt begins for dark matter, new forces, new dimensions and the Higgs boson,” said ATLAS collaboration spokesperson, Fabiola Gianotti. “The fact that the experiments have published papers already on the basis of last year’s data bodes very well for this first physics run.”

Sounds very promising, and I’m intrigued by what exciting discoveries lie just over the horizon. (For more quotes and more info on the experiments scheduled, check out this ScienceDaily article and related ones.)

A Black Hole in Your Backyard?: That Could Really Suck!

What would you think of having a black hole in your backyard? Well, not your actual backyard — but here on Earth. How about just a tiny one? Even if you aren’t scientifically-minded, you might remember black holes from watching programs like ‘Cosmos’ or sci-fi movies like, well, ‘The Black Hole’ (1979, but about to be “reimagined”) or ‘Event Horizon’ (1997). And you know they’re scary. (The black holes, that is. Maybe the movies, too.)

Black Hole concept drawing by NASA

Einstein theorized that space & time are warped by mass & energy, giving the effect known as “gravity”. If enough mass or energy gets forced into a sufficiently small space, the gravity becomes so strong that nothing can escape — even light disappears inside. Thus, a “black hole”. This usually happens when a hugely massive star collapses in on itself due to its own gravity. (I won’t go into details, don’t worry.) But, it’s really the ratio of mass (and/or energy) to the volume of space it’s being compressed into that matters. (No pun intended.) So, physicists of the past few decades have theorized that colliding just two microscopic particles (e.g., protons) can cause a very tiny black hole, as long as the energy was above a fundamental limit called the “Planck energy”. Or, put another way, the minimum mass required for a black hole is believed to be around the “Planck mass”, at which point general relativity “breaks down” in the face of quantum physics.

So far, however, no such collisions have been detected in nature and no particle accelerator has been able to produce the necessary conditions. Enter, the recently completed Large Hadron Collider (LHC) — a 17-miles long, elliptical tunnel under the French-Swiss border, where various experiments in high-energy physics will be performed to study areas of particle physics, quantum physics, supersymmetry, and perhaps answer some questions about the origins & structure of the universe. Among other results, particle physicists are hopeful that they will finally be able to produce mini black holes. But, not everybody thinks this is a good idea. You might remember some hoo-ha over the past couple of years over the LHC project. Despite physicists’ assurances to the contrary, some doomsayers claimed that these manmade black holes could very well proceed to suck the Earth and everything in the vicinity into them. Bye-bye Earth; so long human race! Some even petitioned the UN to stop the project.

Now, as I said, the ability to create these tiny black holes has all been speculation. Early modeling seemed to indicate it was possible, but it has since been acknowledged that certain assumptions in those calculations may have skewed the results. But, researchers from the University of British Columbia and Princeton University have just produced new simulations that gives a lot more weight to what was before just a hypothesis. “For simplicity and to make the simulations generic, they modeled the two particles as hypothetical objects known as boson stars, which are similar to models that describe stars as spheres of fluid. Using hundreds of computers, Choptuik and Pretorius calculated the gravitational interactions between the colliding particles and found that a black hole does form if the two particles collide with a total energy of about one-third of the Planck energy, slightly lower than the energy predicted by hoop conjecture, as they report in a paper in press at Physical Review Letters.”

Of course, they still don’t know if they can create mini black holes with the LHC. “The Planck energy is a quintillion times higher than the LHC’s maximum. So the only way the LHC might make black holes is if, instead of being three dimensional, space actually has more dimensions that are curled into little loops too small to be detected except in a high-energy particle collision. Predicted by certain theories [e.g., brane theory and superstring theory], those extra dimensions might effectively lower the Planck energy by a huge factor.”

“Waitaminute!”, you might be saying. “Why is this a good thing, if it puts us all in mortal danger?” As the physicists will tell you, black holes emit what is called “Hawking radiation”, which means they are losing mass. They shrink, or “evaporate”. For reasons I won’t get into, smaller black holes actually emit more Hawking radiation. Since the mini black holes in question would be extremely small to begin with, they would also disperse extremely quickly. For example, a black hole roughly the mass of a car would disappear in a nanosecond — not enough time to do any damage, unless perhaps you were standing unprotected nearby. Of course, once you get down to the quantum level, quantum gravitation effects could hypothetically make such a small black hole stable. Fortunately, there is no evidence to support this hypothesis (for now).

OK, it’s still a little disconcerting, but I’m not worried. In fact, I’m looking forward to what discoveries and new theories develop from the LHC experiments. Cool stuff!

UPDATE 4/22/2010:  Here’s a follow-up post.