Ever since I can remember the major roadblock to progress in physics has been the inability to develop a quantum theory of gravity. Of the four forces that appear to govern our universe, three, the electromagnetic force and the strong and weak nuclear forces, are explained in terms of quantum field theory (QFT). The fourth force, gravity, is explained in terms of general relativity (GR).

Most physicists believe that QFT is more fundamental than GR so it should be possible to "quantize" GR. For more than 8 decades physicists struggled to produce a quantum theory of gravity with no success.

But maybe, just maybe, Petr Horava at the University of California, Berkeley has cracked it

See: Splitting Time from Space—New Quantum Theory Topples Einstein's Spacetime, Scientific American, December 2009.

http://www.scientificamerican.com/article.cfm?id=splitting-time-from-space

If the reports are correct Horava gravity explains everything that GR explains plus a few things it can't. As added bonuses Horava gravity may:

--Dispense with the need to invoke so far undetected "dark matter" to explain why rapidly rotating galaxies do not fly apart; and

--Explain the acceleration of the expansion of the universe without the need to invoke dark energy

Horava gravity may also provide additional insights into the big bang.

If Horava is correct and time and space become "unstitched" at very high energies it lends some credence to string theories that require 10 dimensions of which 6 are curled up so tightly we don’t notice them.

Looks like VERY exciting times for physics. This MAY just be the paradigm shift we need to move beyond GR.

Steven.
Bugger! I was just beginning to get my head around the dark matter. Now that, is a Zionist plot to be sure (joke) :-)

Seriously even the author says that the theory isn't complete. Consequently I tend towards Sparrows comments.

I'm inclined to wait untill there is more proofs given especially given the abandoned theory from the Scientist from Cern.

Either way not being a physicist, or a theoretical mathematician etc I'll have to rely on others.

Not withstanding this it is an interesting idea and it will be interesting times.I do understand the significance of this theory if not the detail.

Examinator,

I certainly do not claim to be able to follow Horava's maths myself. But I find his idea intriguing.

I grew up in the paradigm that space and time are inextricably entwined. It's one of the very first things a budding physicist learns. The idea that the linkage could be broken at sufficiently high energies puts a whole new perspective on things.

In a way it's logical. GR assumes a differentiable space-time manifold. But if there really is a shortest length (the Planck length) and a shortest time (the Planck time) then at very high energies space and time become "foamy". They are fractal and no derivative can be defined. Therefore one of the assumptions underpinning GR falls away.

So far so uncontroversial. I haven't said anything that hasn't been known for decades.

But to the best of my knowledge Horava is the first person to come up with a theory that uncouples space and time without leading to ridiculous answers.

Very interesting reading, but didn't understand any of it.
Long time between a major break through.
Interesting photo shots.

Is this supposed to impress anyone?
I personally don’t believe in black holes , am conversant with relativity and am having a lot of difficulty accepting quantum physics at this moment , let alone its time concept.
The problem with physics is it’s just too easy to be wrong. That duality in physics exits is the answer to most problems and there are very few if any rules that apply across the board. However if you’re interested try this link and improve your physical concepts.
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

stevenlmeyer,

First, thanks for calling our attention to the article about the Horava-Lifshitz model of gravity. It is indeed hard to know what it is all about without access (and understanding of) Horava’s original paper in Phys. Rev. D 79 (January 2009).

Certainly the article by Lee Smolin “Loop Quantum Gravity- A Physics Theory Shatters Space and Time” (SciAmer, January 2004) that you seem to refer to - c.f. “if there really is a shortest length (the Planck length) and a shortest time (the Planck time)” - is more illuminating, and hopefully something similarly comprehensible even for non-physicists will eventually appear also about Horava’s model. Of course, Horava does not “topple” Einstein, the same as Einstein did not “topple” Newton.

Where I would recommend more caution is when you conclude that “no derivative can be defined”. The derivative is defined as a mathematical concept, that happens to be relevant to many physical theories (including Einstein’s) that model time (and space) locally as intervals of the real line (of the Euclidean space). On the other, hand Smolin (and others) suggests a discrete modelling of space-time, and you are probably right that Horava’s approach is compatible - if not more - with that.

If it were so then we could say that not a movie fools our senses by presenting a sequence of still pictures so fast that we perceive them as a real movement, but on the contrary, our senses fool us by presenting the sequence of still pictures (reality consisting of discrete events) as smooth movements allowing us to mathematically model (and explore) them using real numbers and differential calculus.

As students we used to speculate on how differently an extraterrestrial civilisation would perceive the physical world if they developed sophisticated discrete mathematics (and computers, I cann add today) without (or before) arriving at the concept of infinitesimals and the calculus.