An ancient subatomic signature extends across the universe. It seems
that some subatomic particles, invisible and untouchable effects of the
very creation of reality, might exist simultaneously across all of
space. We’re honestly surprised people who say science is boring don’t
spontaneously combust from the foolishness of their statements.
“Relic” neutrinos, like the relic photons that make up the cosmic
microwave background, are leftovers from the hot, dense early universe
that prevailed 13.7 billion years ago. But over the lifetime of the
cosmos, these relic neutrinos have been stretched out by the expansion
of the universe, enlarging the range in which each neutrino can exist.
Of course there’s a little bit of physics involved when you talk
about particles pouring out of the beginning of time. Neutrinos are
tiny, almost undetectable neutral particles which stream through pretty
much everything, ever. Over one hundred trillion have passed through
you while reading this sentence. Most of those came from nuclear
reactions, but a blast wave of neutrinos were also released shortly
after the big bang and are, we presume, still going strong.
“We’re
talking maybe up to roughly ten billion light-years” for each neutrino,
said study co-author George Fuller of the University of California, San
Diego. “That’s nearly on the order of the size of the observable
universe.” These oldest of the subatomic particles might each encompass
a space larger than thousands of galaxies, new simulations suggest.
While trying to calculate masses for neutrinos, Fuller and his
student Chad Kishimoto found that, as the universe has expanded, the
fabric of space-time has been tugging at ancient neutrinos, stretching
the particles’ ranges over vast distances.
Such large ranges can
remain intact, the scientists suggest in the May 22 issue of Physical
Review Letters, since neutrinos pass right through most of the
universe’s matter. The big question is whether gravity—say, the pull
from an entire galaxy—can force a meganeutrino to collapse down to a
single location.
“Quantum mechanics was intended to describe the
universe on the smallest of scales, and now here we’re talking about
how it works on the largest scales in the universe,” Kishimoto said.
“We’re talking about physics that hasn’t been explored before.”
According
to physicist Adrian Lee at the University of California, Berkeley, who
was not part of the study team, “gravity is a real frontier these days
that we don’t really understand. “These neutrinos could be a path to
something deeper in our understanding with gravity.”
Although
they should be extraordinarily common in the universe, the relic
neutrinos now have only about one ten-billionth of the energy of
neutrinos generated by the sun. “This makes relic neutrinos near
impossible to detect directly, at least with anything one could build
on Earth,” study co-author Fuller said.
Still, the fact that
there are so many relic neutrinos means that together they likely exert
a significant gravitational pull—”enough to be important for how the
universe as a whole behaves,” Fuller added. “So by looking at the
growth of structures in the universe,” Fuller said, “you might be able
to detect relic neutrinos indirectly by their gravity.”
The
second part of this crash-course in cosmologically relevant physics is
quantum theory. Particles can be “spread out” as a wavefunction - a
representation of possible states - until they’re observed and the wave
collapses into a single fact. While that explanation is so
horrifically simplified it would make a quantum scientists eyes bleed,
it’s good enough for now. The wavefunction of relic neutrinos from the
big bang is on the length scale of the universe itself. They literally
are sort of everywhere, because the only thing which can “observe” them
is gigantic black holes or galaxies.
It’s astonishing stuff, not
just for the cosmo-experts but the casual fan. Because even trying to
wrap your mind around such concepts is like a gym for your brain, and a
booster for your sense of awe.
Posted by Luke McKinney with Casey Kazan.
http://www.newscientist.com/article/mg20227115.800-stretched-neutrinos-could-span-the-universe.html?DCMP=OTC-rss&nsref=cosmology
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000102000020201303000001&idtype=cvips&gifs=yes.
http://physicalsciences.ucsd.edu/news/archives/archive_detail.php?clip_id=381
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