Hihihihi, totul e zadarnicie...

It's confirmed: Matter is merely vacuum fluctuations

* 19:00 20 November 2008 by Stephen Battersby
* For similar stories, visit the Quantum World Topic Guide

Matter is built on flaky foundations. Physicists have now confirmed
that the apparently substantial stuff is actually no more than
fluctuations in the quantum vacuum.

The researchers simulated the frantic activity that goes on inside
protons and neutrons. These particles provide almost all the mass of
ordinary matter.

Each proton (or neutron) is made of three quarks - but the individual
masses of these quarks only add up to about 1% of the proton's mass.
So what accounts for the rest of it?

Theory says it is created by the force that binds quarks together,
called the strong nuclear force. In quantum terms, the strong force is
carried by a field of virtual particles called gluons, randomly
popping into existence and disappearing again. The energy of these
vacuum fluctuations has to be included in the total mass of the proton
and neutron.

But it has taken decades to work out the actual numbers. The strong
force is described by the equations of quantum chromodynamics, or QCD,
which are too difficult to solve in most cases.

So physicists have developed a method called lattice QCD, which models
smooth space and time as a grid of separate points. This pixellated
approach allows the complexities of the strong force to be simulated
approximately by computer.
Gnarly calculation

Until recently, lattice QCD calculations concentrated on the virtual
gluons, and ignored another important component of the vacuum: pairs
of virtual quarks and antiquarks.

Quark-antiquark pairs can pop up and momentarily transform a proton
into a different, more exotic particle. In fact, the true proton is
the sum of all these possibilities going on at once.

Virtual quarks make the calculations much more complicated, involving
a matrix of more than 10,000 trillion numbers, says Stephan Dürr of
the John von Neumann Institute for Computing in Jülich, Germany, who
led the team.

"There is no computer on Earth that could possibly store such a big
matrix in its memory," Dürr told New Scientist, "so some trickery goes
into evaluating it."
Crunch time

Several groups have been working out ways to handle these technical
problems, and five years ago a team led by Christine Davies of the
University of Glasgow, UK, managed to calculate the mass of an exotic
particle called the B_c meson.

That particle contains only two quarks, making it simpler to simulate
than the three-quark proton. To tackle protons and neutrons, Dürr's
team used more than a year of time on the parallel computer network at
Jülich, which can handle 200 teraflops - or 200 trillion arithmetical
calculations per second.

Even so, they had to tailor their code to use the network efficiently.
"We spent an enormous effort to make sure our code would make optimum
use of the machine," says Dürr.

Without the quarks, earlier simulations got the proton mass wrong by
about 10%. With them, Dürr gets a figure within 2% of the value
measured by experiments.
Higgs field

Although physicists expected theory to match experiment eventually, it
is an important landmark. "The great thing is it shows that you can
get close to experiments," says Davies. "Now we know that lattice QCD
works, we want to make accurate calculations of particle properties,
not just mass."

That will allow physicists to test QCD, and look for effects beyond
known physics. For now, Dürr's calculation shows that QCD describes
quark-based particles accurately, and tells us that most of our mass
comes from virtual quarks and gluons fizzing away in the quantum
vacuum.

The Higgs field is also thought to make a small contribution, giving
mass to individual quarks as well as to electrons and some other
particles. The Higgs field creates mass out of the quantum vacuum too,
in the form of virtual Higgs bosons. So if the LHC confirms that the
Higgs exists, it will mean all reality is virtual.
.

Relevant Pages

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