If Spacetime Were a Superfluid, Would It Unify Physics—or Is the Theory All Wet? - Scientific American

If Spacetime Were a Superfluid, Would It Unify Physics—or Is the Theory All Wet? - Scientific American: If it is true that spacetime is a superfluid and that photons of different energies travel at different speeds or dissipate over time, that means relativity does not hold in all situations. One of the main tenets of relativity, the Lorentz invariance, states that the speed of light is unchanging, regardless of an observer’s frame of reference. “The possibility that spacetime as we know it emerges from something that violates relativity is a fairly radical one,” Jacobson says. It does, however, clear a potential pathway toward rectifying some of the problems that arise when trying to combine relativity and quantum mechanics. “Violating relativity would open up the possibility of eliminating infinite quantities that arise in present theory and which seem to some unlikely to be physically correct.”

Physicists Discover Geometry Underlying Particle Physics | Simons Foundation

Physicists Discover Geometry Underlying Particle Physics | Simons Foundation: The amplituhedron looks like an intricate, multifaceted jewel in higher dimensions. Encoded in its volume are the most basic features of reality that can be calculated, “scattering amplitudes,” which represent the likelihood that a certain set of particles will turn into certain other particles upon colliding.

Fairly Simple Math Could Bridge Quantum Mechanics and General Relativity

Fairly Simple Math Could Bridge Quantum Mechanics and General Relativity: The analysis does not model gravity explicitly, and so is not an attempt to formulate a theory of ‘quantum gravity’ that brings general relativity and quantum mechanics under one umbrella. Instead... their work might provide a simplified framework for understanding the effects of gravity on quantum particles, as well as describing other situations in which the spaces that quantum particles move in can radically alter, such as in condensed-matter-physics experiments...
Wilczek and his co-authors set up a hypothetical system with a single quantum particle moving along a wire that abruptly splits into two. The stripped-down scenario is effectively the one-dimensional version of an encounter with ripped space-time, which occurs when the topology of a space changes radically. The theorists concentrate on what happens at the endpoints of the wire — setting the ‘boundary conditions’ for the before and after states of the quantum wave associated with the particle. They then show that the wave can evolve continuously without facing any disruptions as the boundary conditions shift from one geometry to the other, incompatible one.

The surprise theory of everything

The surprise theory of everything: The question is whether we can express the whole of physics simply by enumerating possible and impossible processes in a given situation. This is very different from how physics is usually phrased, in both the classical and quantum regimes, in terms of states of systems and equations that describe how those states change in time. The blind alleys down which the standard approach can lead are easiest to understand in classical physics, where the dynamical equations we derive allow a whole host of processes that patently do not occur - the ones we have to conjure up the laws of thermodynamics expressly to forbid, such as dye molecules reclumping spontaneously in water...

Apply this logic more generally, and time ceases to exist as an independent, fundamental entity, but one whose flow is determined purely in terms of allowed and disallowed processes. With it go problems such as that I alluded to earlier, of why the universe started in a state of low entropy. If states and their dynamical evolution over time cease to be the question, then anything that does not break any transformational rules becomes a valid answer.

Topology: The Secret Ingredient In The Latest Theory of Everything

Topology: The Secret Ingredient In The Latest Theory of Everything: Today, Wen combines topology, symmetry and quantum mechanics in a new theory that predicts the existence of new states of matter, unifies various puzzling phenomena in solid state physics and allows the creation artificial vacuums populated with artificial photons and electrons...

Xiao-Gang Wen's approach is to explore the properties of matter when the topological links between particles become much more general and complex. He generalises these links, thinking of them as strings that can connect many  particles together. In fact, he considers the way many strings can form net-like structures that have their own emergent properties...
That makes string nets a kind of "quantum ether" through which electromagnetic waves travel. That's a big claim.

One weird theory could make anti-gravity and faster-than-light travel possible

One weird theory could make anti-gravity and faster-than-light travel possible: Heim Theory was originated by Burkhard Heim, a German physicist, in the mid-twentieth century. It was attempted as a way to reconcile the two pillars of physics, quantum theory and general relativity. It takes what's currently the only way out, between the two theories - extra dimensions...
Heim's goal was to find ways to convert between all kinds of energy, and in adding two dimensions to his calculations he was able to equate, at least in theory, gravitational energy and electromagnetism.

About time: Countdown to the theory of everything - New Scientist - New Scientist

About time: Countdown to the theory of everything: Carlo Rovelli, a physicist at the Centre for Theoretical Physics in Marseilles, France, has rewritten the rules of quantum mechanics so that they make no reference to time (New Scientist, 19 January 2008, p 26).

"For me, the solution to the problem is that at the fundamental level of nature there is no time at all," Rovelli says. In his view, quantum mechanics does not have to describe how physical systems evolve in time but only how they evolve relative to other systems, such as observers or measuring devices. "Physics is not about 'how does the moon move through the sky in time?' but rather 'how does the moon move in the sky with respect to the sun?'," he says. "Time is in our mind, not in the basic physical reality."

Distant light hints at size of space-time grains - space - 07 July 2011 - New Scientist

Distant light hints at size of space-time grains: terrestrial telescopes... have seen low-energy photons from a gamma-ray burst (GRB) arriving before their high-energy counterparts. While this could be due to delays in emission at the source, it could also be caused by the interaction of photons with the structure of space-time...
Now a team has used data from the Integral satellite, run by the European Space Agency (ESA), to study an entirely different effect: the polarisation of light of different energies from a GRB...
this puts an important limit on the size of the grains of space-time. According to an ESA press release, it means they must be smaller than 10-48 metres, many orders of magnitude smaller than the Planck length of 10-35 metres, the universe's smallest length scale...

Observations: Garrett Lisi Responds to Criticism of his Proposed Unified Theory of Physics

Observations: Garrett Lisi Responds to Criticism of his Proposed Unified Theory of Physics:  Distler's colleagues also wrote a letter to the editor of Scientific American decrying the lack of parity violation. This fact would seem very damning for E8 Theory, but it is simply not true. The structure of gravity and the Standard Model along with one generation of fermions (including their parity-violating interactions) does fit in E8, as I described explicitly in a recent paper. In their misleading argument, Distler and Garibaldi make unnecessary assumptions about how the embedding needs to happen, and then prove it can't happen that way -- a "straw man" argument.

A Geometric Theory of Everything: Scientific American

A Geometric Theory of Everything: Scientific American

Gravity eases its pull

Gravity eases its pull: "'My research shows conclusively that charge is affected by gravity, and that it tends to make the charge weaker as you proceed to smaller distances. This is unexpected because in the complete absence of gravity the charge gets larger as the distance decreases.'"

Why the early universe was free of charge - space - 04 November 2010 - New Scientist

Why the early universe was free of charge: In 2006, Wilczek and Sean Robinson, both at the Massachusetts Institute of Technology, showed that the electromagnetic force also weakens at higher energies, but only in the presence of gravity, which is neglected in the standard model (Physical Review Letters, DOI: 10.1103/PhysRevLett.96.231601). Others punched holes in their calculations, however, and so the idea remained controversial. "We tried to do it without going through the heavy formal mathematics," Wilczek says.

Now David Toms of Newcastle University in the UK has redone the calculations more rigorously and come up with the same conclusions. In the presence of gravity, electric charge - a barometer of the strength of the electromagnetic force - tends to go to zero as energies rise (Nature, DOI: 10.1038/nature09506). "With no gravity, the electric charge gets bigger [with higher energies]," says Toms. "Gravity changes the picture."

Rummaging for a Final Theory: Can a 1960s Approach Unify Gravity with the Rest of Physics?: Scientific American

Rummaging for a Final Theory: Can a 1960s Approach Unify Gravity with the Rest of Physics?: Scientific American: "Not everyone shares this optimism. Skip Garibaldi, a mathematician at Emory University, says that E8-inspired nostalgia is misguided. Working with physicist Jacques Distler of the University of Texas at Austin, Garibaldi has shown that Lisi’s theory predicts the existence of unwanted particles, whose interactions are the mirror image of regular fermions. Such particles would most likely have already exerted a noticeable effect on known particles, Garibaldi argues. “There is no way to shove gravity inside E8 without also predicting something that has nearly been ruled out by experiment,” he says.

Lisi, who posted the latest version of his theory on the Internet in June and presented it at the meeting, concedes that mirror fermions are an issue but adds that E8 theory is a work in progress and that mirror fermions could have evaded notice if they are heavier than commonly thought. They could even show up in the Large Hadron Collider, he says."

The imperfect universe: Goodbye, theory of everything

Could belief in a physical theory that unifies the secrets of the material world - a "hidden code" of nature - be the scientific equivalent of the religious belief in oneness held by the billions who go to churches, mosques and synagogues every day?

http://www.newscientist.com/article/mg20627591.200-the-imperfect-universe-goodbye-theory-of-everything.html