Below, I have copied in a few of their list, with some of the
accompanying explanation. I think it would be useful to discuss some of these in
the context of Rosennean Complexity. For example, # 5,9, and 7 (which come after
#6, below!) can easily be explained by principles of relational causality.
There's no need to conjure up "dark matter" and "dark energy"....
Sheesh!
Judith
6 Viking's methane
JULY 20, 1976. Gilbert Levin is on the edge of his seat. Millions of
kilometers away on Mars, the Viking landers have scooped up some soil and mixed
it with carbon-14-labeled nutrients. The mission's scientists have all agreed
that if Levin's instruments on board the landers detect emissions of
carbon-14-containing methane from the soil, then there must be life on
Mars.
Viking reports a positive result. Something is ingesting the nutrients,
metabolizing them, and then belching out gas laced with carbon-14.
5 Dark matter
TAKE our best understanding of gravity, apply it to the way galaxies
spin, and you'll quickly see the problem: the galaxies should be falling apart.
Galactic matter orbits around a central point because its mutual gravitational
attraction creates centripetal forces. But there is not enough mass in the
galaxies to produce the observed spin.
Vera Rubin, an astronomer working at the Carnegie Institution's
department of terrestrial magnetism in Washington DC, spotted this anomaly in
the late 1970s. The best response from physicists was to suggest there is more
stuff out there than we can see. The trouble was, nobody could explain what this
"dark matter" was.
And they still can't. Although researchers have made many suggestions
about what kind of particles might make up dark matter, there is no consensus.
It's an embarrassing hole in our understanding. Astronomical observations
suggest that dark matter must make up about 90 per cent of the mass in the
universe, yet we are astonishingly ignorant what that 90 per cent is.
Maybe we can't work out what dark matter is because it doesn't actually
exist. That's certainly the way Rubin would like it to turn out. "If I could
have my pick, I would like to learn that Newton's laws must be modified in order
to correctly describe gravitational interactions at large distances," she says.
"That's more appealing than a universe filled with a new kind of sub-nuclear
particle."
9 Dark energy
IT IS one of the most famous, and most embarrassing,
problems in physics. In 1998, astronomers discovered that the universe is
expanding at ever faster speeds. It's an effect still searching for a cause -
until then, everyone thought the universe's expansion was slowing down after the
big bang. "Theorists are still floundering around, looking for a sensible
explanation," says cosmologist Katherine Freese of the University of Michigan,
Ann Arbor. "We're all hoping that upcoming observations of supernovae, of
clusters of galaxies and so on will give us more clues."
One suggestion is that some property of empty space is
responsible - cosmologists call it dark energy. But all attempts to pin it down
have fallen woefully short. It's also possible that Einstein's theory of general
relativity may need to be tweaked when applied to the very largest scales of the
universe. "The field is still wide open," Freese says.
7 Tetraneutrons
FOUR years ago, a particle accelerator in France detected
six particles that should not exist. They are called tetraneutrons: four
neutrons that are bound together in a way that defies the laws of
physics.
Francisco Miguel Marquès and colleagues at the Ganil
accelerator in Caen are now gearing up to do it again. If they succeed, these
clusters may oblige us to rethink the forces that hold atomic nuclei
together.
The team fired beryllium nuclei at a small carbon target and
analyzed the debris that shot into surrounding particle detectors. They expected
to see evidence for four separate neutrons hitting their detectors. Instead the
Ganil team found just one flash of light in one detector. And the energy of this
flash suggested that four neutrons were arriving together at the detector. Of
course, their finding could have been an accident: four neutrons might just have
arrived in the same place at the same time by coincidence. But that's
ridiculously improbable.
Not as improbable as tetraneutrons, some might say, because
in the standard model of particle physics tetraneutrons simply can't exist.
According to the Pauli exclusion principle, not even two protons or neutrons in
the same system can have identical quantum properties. In fact, the strong
nuclear force that would hold them together is tuned in such a way that it can't
even hold two lone neutrons together, let alone four. Marquès and his team were
so bemused by their result that they buried the data in a research paper that
was ostensibly about the possibility of finding tetraneutrons in the future
(Physical Review C, vol 65, p 44006).
And there are still more compelling reasons to doubt the
existence of tetraneutrons. If you tweak the laws of physics to allow four
neutrons to bind together, all kinds of chaos ensues (Journal of Physics G, vol
29, L9). It would mean that the mix of elements formed after the big bang was
inconsistent with what we now observe and, even worse, the elements formed would
have quickly become far too heavy for the cosmos to cope. "Maybe the universe
would have collapsed before it had any chance to expand," says Natalia
Timofeyuk, a theorist at the University of Surrey in Guildford,
UK.
There are, however, a couple of holes in this reasoning.
Established theory does allow the tetraneutron to exist - though only as a
ridiculously short-lived particle. "This could be a reason for four neutrons
hitting the Ganil detectors simultaneously," Timofeyuk says. And there is other
evidence that supports the idea of matter composed of multiple neutrons: neutron
stars. These bodies, which contain an enormous number of bound neutrons, suggest
that as yet unexplained forces come into play when neutrons gather en
masse.
12 Not-so-constant constants
IN 1997 astronomer John Webb and his team at the University
of New South Wales in Sydney analyzed the light reaching Earth from distant
quasars. On its 12-billion-year journey, the light had passed through
interstellar clouds of metals such as iron, nickel and chromium, and the
researchers found these atoms had absorbed some of the photons of quasar light -
but not the ones they were expecting.
If the observations are correct, the only vaguely reasonable
explanation is that a constant of physics called the fine structure constant, or
alpha, had a different value at the time the light passed through the
clouds.
But that's heresy. Alpha is an extremely important constant
that determines how light interacts with matter - and it shouldn't be able to
change. Its value depends on, among other things, the charge on the electron,
the speed of light and Planck's constant. Could one of these really have
changed?
No one in physics wanted to believe the measurements. Webb
and his team have been trying for years to find an error in their results. But
so far they have failed.
Webb's are not the only results that suggest something is
missing from our understanding of alpha. A recent analysis of the only known
natural nuclear reactor, which was active nearly 2 billion years ago at what is
now Oklo in Gabon, also suggests something about light's interaction with matter
has changed.
The ratio of certain radioactive isotopes produced within
such a reactor depends on alpha, and so looking at the fission products left
behind in the ground at Oklo provides a way to work out the value of the
constant at the time of their formation. Using this method, Steve Lamoreaux and
his colleagues at the Los Alamos National Laboratory in New Mexico suggest that
alpha may have decreased by more than 4 per cent since Oklo started up (Physical
Review D, vol 69, p 121701).
There are gainsayers who still dispute any change in alpha.
Patrick Petitjean, an astronomer at the Institute of Astrophysics in Paris, led
a team that analyzed quasar light picked up by the Very Large Telescope (VLT) in
Chile and found no evidence that alpha has changed. But Webb, who is now looking
at the VLT measurements, says that they require a more complex analysis than
Petitjean's team has carried out. Webb's group is working on that now, and may
be in a position to declare the anomaly resolved - or not - later this
year.
"It's difficult to say how long it's going to take," says
team member Michael Murphy of the University of Cambridge. "The more we look at
these new data, the more difficulties we see." But whatever the answer, the work
will still be valuable. An analysis of the way light passes through distant
molecular clouds will reveal more about how the elements were produced early in
the universe's history.
The placebo effect
DON'T try this at home. Several times a day, for several
days, you induce pain in someone. You control the pain with morphine until the
final day of the experiment, when you replace the morphine with saline solution.
Guess what? The saline takes the pain away.
This is the placebo effect: somehow, sometimes, a whole lot of nothing
can be very powerful. Except it's not quite nothing. When Fabrizio Benedetti of
the University of Turin in Italy carried out the above experiment, he added a
final twist by adding naloxone, a drug that blocks the effects of morphine, to
the saline. The shocking result? The pain-relieving power of saline solution
disappeared.
So what is going on? Doctors have known about the placebo effect for
decades, and the naloxone result seems to show that the placebo effect is
somehow biochemical. But apart from that, we simply don't know.
Benedetti has since shown that a saline placebo can also reduce tremors
and muscle stiffness in people with Parkinson's disease (Nature Neuroscience,
vol 7, p 587). He and his team measured the activity of neurons in the patients'
brains as they administered the saline. They found that individual neurons in
the subthalamic nucleus (a common target for surgical attempts to relieve
Parkinson's symptoms) began to fire less often when the saline was given, and
with fewer "bursts" of firing - another feature associated with Parkinson's. The
neuron activity decreased at the same time as the symptoms improved: the saline
was definitely doing something.
We have a lot to learn about what is happening here, Benedetti says, but
one thing is clear: the mind can affect the body's biochemistry. "The
relationship between expectation and therapeutic outcome is a wonderful model to
understand mind-body interaction," he says. Researchers now need to identify
when and where placebo works. There may be diseases in which it has no effect.
There may be a common mechanism in different illnesses. As yet, we just don't
know.