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The Dark Universe and Limitless Dark Energy
Posted on Wednesday, October 01, 2008 @ 20:59:23 UTC by vlad
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 By CambridgeBlog: Last week I explained what I argue to be the greatest theoretical challenge facing fundamental physics today; that the very concept of the spacetime continuum is flawed and in need of revision. This week I want to explain what I think is the very greatest challenge coming from the experimental and observational side. Science thrives on a dialogue between theory and experiment and when you put all this together you arrive, as I see it, at the most exciting time for theoretical physics for a century, perhaps even since the 17th century in terms of the expected level of shake-up.
The experiments and observations that I refer to do not relate to the Large Hardon Collider. While that should be interesting especially if they don’t find the Higgs particle … well the LHC is now broken for a few months and that gives us a chance to see what else is going on. What is going on is the possibility of testing physics at the Planck scale, i.e. at energies 10 million billion times greater than the LHC could ever produce. It’s a brand new field, hitherto considered by physicists completely impossible, called ‘quantum gravity phenomenology’.
Don’t worry, we won’t actually be producing energies that high on Earth in the near future, we will be turning to cosmology. But the energies available if we knew quantum gravity could be rather high. If you watch the SciFi Channel series Stargate Atlantis, the portal device is powered by a ‘zero point module’ that taps into the vacuum energy of completely empty space. I think it was Arthur C. Clarke who first brought this into fiction, but it was based on theoretical ideas at the time. One can give a simplistic estimate of this vacuum energy based on cutting off particle wavelengths at the ‘minimum wavelength’ of 10^33 cm and the size of the Universe. I do this in On Space and Time and it comes out naively as about 10^94 grams of mass-energy per cubic centimetre of empty space. To put this in perspective, this is about 10^88 (i.e.10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,000,000,000,000) times the energy consumption of the world in a year, in each cubic centimetre! You can think roughly of a kind of ’sea’ with the same density as Planck-scale quantum-black hole objects (as featured in my first post two weeks ago) perhaps making up the foam-like structure of spacetime which, at a distance, we see roughly as a continuum. But please don’t think take this too literally. This is more like a 'sea' of quantum fluctuations and may well be a theoretical artefact of the way we think about quantum mechanics...
More: http://www.scienceblog.com/cms/comment/reply/17482
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Tackling the big questions -- approaching a revolution in our understanding of gravit (Score: 1)
by vlad on Saturday, November 08, 2008 @ 16:18:18 UTC
(User Info | Send a Message) http://www.zpenergy.com | (PhysOrg.com) -- The way galaxies move through the cosmos has recently
begun to baffle scientists. Even when the gravitational theories of
Newton and Einstein are taken into account, the universe is expanding
and galaxies are rotating in ways that do not comply with our current
knowledge and predictions.
...In a separate study, Dr Padilla
will also explore the concept of degravitation — which suggests that
the vacuum energy could actually be huge, but just appears small when
observed on large scales as gravity becomes weaker...
“Whether we are excited by old
problems like how to model the interior geometry of a rotating star in
General Relativity, or newer ones like dark energy, there can be little
doubt that we seem to be approaching a revolution in our understanding
of gravity,” said Dr Padilla. “And it is not all speculation and theory
— experiment is catching up. When the Large Hadron Collider begins
producing results at CERN, there is a chance that black holes will form
in the accelerator and that extra dimensions will start to open up. It
sounds scary, but from a physicist's point of view it is enormously
exciting!”
Provided by University of Nottingham
Full article: http://www.physorg.com/news145113960.html [www.physorg.com]
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NEW LIMITS ON THE ORIGIN OF DARK MATTER (Score: 1)
by vlad on Tuesday, January 27, 2009 @ 21:13:19 UTC
(User Info | Send a Message) http://www.zpenergy.com | NEW LIMITS ON THE ORIGIN OF DARK MATTER, January 27
(PhysOrg.com) -- Determining the identity of dark matter, the mysterious stuff thought to make up the vast majority of matter in the universe, is one of the most fundamental challenges facing modern physics. Through theory and experiment, scientists have been gradually determining what dark matter probably isn't composed of, and now recent results from one collaboration have ruled out another possibility.
Full story at http://www.physorg.com/news152284387.html [www.physorg.com]
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Dark flow: Proof of another universe? (Score: 1)
by vlad on Saturday, January 24, 2009 @ 20:15:02 UTC
(User Info | Send a Message) http://www.zpenergy.com | FOR most of us the universe is unimaginably vast. But not for
cosmologists. They feel decidedly hemmed in. No matter how big they
build their telescopes, they can only see so far before hitting a wall.
Approximately 45 billion light years away lies the cosmic horizon, the
ultimate barrier because light beyond it not has not had time to reach
us.
So
here we are, stuck inside our patch of universe, wondering what lies
beyond and resigned to that fact we may never know. The best we can
hope for, through some combination of luck and vigilance, is to spot a
crack in the structure of things, a possible window to that hidden
place beyond the edge of the universe...
More: http://www.newscientist.com/article/ [www.newscientist.com]
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