Most of us have never heard of this “Copernican Principle” that is apparently so popular in astrophysics. According to Wikipedia The Copernican principle insists that Earth is not in a central, specially favored position in the universe (or solar system). New York Times science blogger John Tierney examines the principle as part of the Doomsday argument.
Physicists at Oxford University, however, have released a paper that reaches the conclusion that we just might inhabit a ‘special’ region of the universe after all.
In the article Dark Energy: Is It Merely An Illusion?, the Oxford scientists theorize that we might instead inhabit a “huge void” in the universe where the density of matter is particularly low. This would tend to account for increasing expansion, which simply cannot be explained by the gravitational realities factored on the density of matter, on the assumption that the density is uniform throughout the universe.
The Oxford mavericks conclude that forthcoming tests of the Copernican principle should help sort the reality from the theories in the next few years.
As the LHC accelerator at CERN prepares to complete final whole-torus testing and “shoot the moon” with particles colliding at ~5TeV per beam, the report from the DZero experiment at Fermilab’s Tevatron is in – “Wiggly Higgly” (the so-called “God Particle” that imparts mass to matter) remains missing in action at 170GeV/c2.
The prediction that the Higgs boson would appear at 114GeV/c2 was ruled out in 2000, this experiment rules out the next best guess of mass for the exchange particle. This finding will tend to put more importance on findings expected from the higher energy levels at LHC over the next few years, though experimenters have long believed Higgs would be discovered at the lower Tevatron energies. That appears to have been ruled out too.
Higgs is probably the most famous component of the ‘Standard Model’ of physics to remain MIA after so much expense over so many years of seeking answers about the nature of nature. The Tevatron experiment did succeed in producing Z boson pairs, so researchers had maintained hope for Higgs at this level.
It took 600 physicists from 90 institutions in 18 countries to determine that Higgs is not present at 170GeV. Perhaps the LHC physicists will have better luck while they’re busy producing quark-gluon plasmas, mini black holes and other odd sub-sub-particles of interest. It’s scheduled to be fully up and running by October, so some answers should come soon!
Link:
Hunt for Elusive Higgs Boson Gets Boost
Researchers have recently discovered some new things about both our own planet’s core and our close encounters of the closest kind with extraterrestrial billard balls. Beginning here at home, geophysics researchers published a paper in Science reporting that Deep Earth Model Challenged by New Experiment.
Apparently the iron concentrated in the lower Earth mantle behaves quite differently than previous models predicted. Instead of finding a particular, thin “transition zone” at a certain depth where the temperature and pressure ‘flips’ the spin of electrons in Iron atoms to a paired state (a quantum effect that affects the density of the iron compounds), the experiments found a whole new region in the lower mantle where both high and low spin states coexist in the same crystal structure.
This continuous transition zone grew to a thickness of nearly 750 miles, comprising the entire region between the depths of 620 and 1,365 miles beneath the surface of the Earth.
Meanwhile, a team of planetary geologists reported in the PNAS journal that Extraterrestrial Impact is Likely Source of Sudden Ice Age Extinctions.
About 12,900 years ago wooly mammoths, giant sloths, saber-toothed cats, other giant animals and a condor with a 16-foot wingspan disappeared from the fossil record, as did evidence of human remains over entire swaths of North America.
They say that one or more comets or meteorites exploded over the earth or slammed into it, triggering catastrophic climate change. The culprit in this dramatic cooling of the period is apparently carbon, which I suppose we aren’t supposed to notice is the cited culprit today for predicted catastrophic climate change in precisely the opposite direction. Ah, well. It’s always something.
Farther away from our immediate neighborhood, researchers from Duke University and the University of Cambridge think they’ve come up with a way to determine if some black holes out there in the universe might not be black at all, but instead are running around indecently naked!
Some Black Holes May Not Be Black challenges the cosmic censorship hypothesis, which holds that singularities must be properly shielded from outside view by an “event horizon,” a region from which not even light can escape.
Researchers Arlie Petters of Duke and Marcus Werner of Cabridge used gravitational lensing to calculate whether a spinning black hole (those discovered and suspected do appear to spin, some at more than 1,000 revolutions a minute) could ever shed its event horizon to become naked. Surprisingly (to everyone), they can…
“In work supported by the National Science Foundation in the United States and the Science and Technology Facilities Council in the United Kingdom, the pair employed a finding that a black hole could be shed of its event horizon and become a naked singularity if its angular momentum – an effect of its spin – is greater than its mass.”
Sir Roger Penrose, who with Stephen Hawking developed the original singularity theorems derived from Einstein’s theory of general relativity, once remarked that “God abhors a naked singularity.” We humans might wonder why a naked gravity well would seem so indecent, but it seems that in close vicinity to such a phenomenon time would behave very strangely. Even Petters isn’t so sure he wants to meet a naked singularity…
“If you ask me whether I believe that naked singularities exist, I will tell you that I’m sitting on the fence,” said Petters. “In a sense, I hope they are not there. I would prefer to have covered-up black holes. But I’m still open-minded enough to entertain the ‘otherwise’ possibility.”
Maybe naked singularities are like pornography, we’ll know it if we see it. We can still hope this burlesque show stays far away from our cosmic neighborhood, where decent people live!
Links:
Deep Earth Model Challenged by New Experiment
Extraterrestrial Impact is Likely Source of Sudden Ice Age Extinctions
Some Black Holes May Not Be Black
Big astrophysics science news this week that a Big Chunk of the Universe Is Missing – Again. This requires a little background for understanding how it is our universe can be so adept at playing hide-and-seek.
As much as 96% of the mass necessary to account for how our universe is observed to be has been missing for a long time. The mass is necessary to explain the gravity that holds galaxies together, but all the atomic matter we can see in planets, comets, asteroids, assorted space junk, stars and galaxies accounts for just 4% of it. In 1974 astronomer Vera Rubin discovered that instead of following a Newtonian scheme where Mercury travels faster around the sun than Neptune does, almost all stars rotating around a galaxy’s center – at any distance – all travel at the same speed.
There had to be some ‘extra’ source of gravity working in galaxies, but there wasn’t nearly enough mass to account for this anomaly. The choice was between gravity being variable (unthinkable!) or the existence of a great deal of extra mass that we couldn’t see. Scientists jumped on that answer in defense of Newtonian/Einsteinian gravity and gifted us with “Dark Matter.”
They couldn’t come up with likely candidates enough to cover more than about 21% of the necessary extra mass, so they soon came up with some fudges for gravity itself – an “anti-gravity” force called Dark Energy where they could hide the anomalous data. They were up to 4% matter + 21% Dark Matter + 75% Dark Energy. Voilå! Universe explained.
That scientists had no real grasp on what Dark Matter and Dark Energy really are did not particularly upset them, and these have become consensus theory. There are some intriguing alternative theories out there, but none enjoy consensus status and are mostly considered somewhat ‘crackpot’ – aether theories, geometrical theories, and ‘hyper’ theories that include extra large dimensions are generally frowned upon even though some of them actually do attempt to describe the empirical observations without sacrificing 96% of reality to phantom agents.
In 2000, astrophysicists thought the missing matter might be in the form of gas or plasma in the intergalactic medium. Then in 2002 the Chandra space-based telescope seemed to confirm that theory when it discovered 7% of the missing universe.
By 2007 astronomers and astrophysicists were back on the trail, reporting that they’d found hundreds of ‘missing’ black holes hiding in galaxies billions of light years away. Which translates into a finding that billions of years ago there were hundreds of black holes in some galaxies…
“Active, supermassive black holes were everywhere in the early universe,” said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. “We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself.” Dickinson is a co-author of two new papers appearing in the Nov. 10 issue of the Astrophysical Journal.
Now the new research from the University of Alabama in Huntsville [UAH] informs us that we’re 20% light again even after the discoveries in 2002 and 2005 (and all those black holes discovered just last month). Turns out that a lot of those x-rays supposedly coming from the intergalactic clouds of hot gas are instead probably caused by electrons. Electrons are a lot smaller than atoms, with a lot less mass. Those rivers can’t hold the amount of mass previously attributed to them.
Well, they still have WIMPs [Weakly Interacting Massive Particles] as a candidate for missing matter. Problem with these theoretical beasties is that they’re even less interactive than neutrinos, so much more difficult to detect. In fact, nobody’s ever seen a WIMP or measured any Dark Energy. The term “Dark” in these cases means “We Don’t Know” what the heck it is, or even if it exists at all. But the standard models of how our universe works requires filling in huge (as in 90%) gaps with whatever sounds reasonable right now. The alternative – that our standard models are wrong – is too dire to contemplate.
So anyone interested in the stars – and that’s a lot of us, young and old – should try to keep current on the question of what the “missing” 90% of our universe might be, and where it could be hiding. It’s certainly an entertaining pastime, and never dull!
Links:
Dark Matter the Answer to the “Missing Universe?”
Astronomers Find Part of Universe’s Missing Matter
Galaxy Cluster Surveys May Help Explain “Dark Energy”