A pair of physicists discovered a new kind of fusion that occurs between quarks – and they were so concerned with its power they almost didn't publish the results. It could have been the dawning of a new subatomic age. But as they've explored the idea they've discovered there are limits to its potential that we can be both disappointed by and thankful for all at once.
The discovery of this
highly energetic form of fusion between quarks comes with limits that make it
an unlikely candidate for any kind of fuel source of the future. But it
also means we won't see it become the next generation of nuclear weapon.
"I must admit that
when I first realised that such a reaction was possible, I was scared,"
Marek Karliner of Tel Aviv University toldRafi Letzter at Live Science. "But, luckily, it is a one-trick
pony."
For over a century, we've
understood that the particles making up the nucleus of an atom are held in
place by an impressive amount of energy. Splitting them apart in an
act called nuclear fission can release some of this energy. Joining them
together under what's called fusion can potentially release even more energy.
Both have benevolent and
offensive applications as power sources and devastatingly dangerous weapons, so
Karliner and his colleague Jonathan L. Rosner can't be blamed for taking the
time to triple check their sums.
Rather than rearranging
protons and neutrons, the pair investigated the smaller particles inside them –
called quarks – rearranging in a similar way. Quarks come in a variety
of flavours with different masses and odd sounding names: up, down,
charm, strange, top, and bottom.
Quarks can bond with one
another in groups of three called baryons. The baryon Xi cc++, for instance, is
made of two charm quarks and one up quark, which is a lot heavier than the up
and down quarks you'll find in protons and neutrons.
The conversion of mass to
energy (thanks,
Einstein!) is where fission and fusion power come from, so comparing the
energy in atomic energy to this new subatomic process gives us a sense of how
much power is lurking inside.
If we take deuterium
(proton plus a neutron) and add energy to squish it against some tritium
(proton plus two neutrons), it will scramble to make helium (two protons and
two neutrons). That last neutron runs from the scene of the crime. For your
effort, you get 17.6 megaelectron volts and an H-bomb. Karliner and Letzter
ultimately calculated the fusing of the charm quarks in the recent LHC
discovery would release 12 megaelectron volts. Not bad for two itty-bitty
particles.
But if we were using
another pair of heavy quarks? Bottom quarks, for example? That becomes an
astonishing 138 megaelectron volts. We'd like to imagine this caused the
physicists to tap wildly at their calculator screens.
Given such impressive
energy output, our first reaction would be jubilation at a new way to produce
copious amounts of energy from a small handful of materials. Followed by images
of mushroom clouds. But, as it turns out,
neither will happen.
Unlike atoms, bottom quarks
can't be shoved into a flask and packed into a shell. They exist for something
in the order of a picosecond following atomic wrecks inside particle
accelerators, before transforming into the much lighter up quark.
That leaves quark bombs and
quark fusion drives to science fiction authors, and, thankfully, well out of
the hands of rogue nations and terrorist cells. But while we lament or
relax, depending on perspective, it's an amazing insight into the nature of
mass and energy and how things always get weirder at the quantum scale.
Updated version of the previous article.
This research was published
in Nature.
Via Sciencealert