Tag Archives: grand unified theory

BigBang

Universal Amniotic Fluid

Another day, another physics paper describing the origin of the universe. This is no wonder. Since the development of general relativity and quantum mechanics — two mutually incompatible descriptions of our reality — theoreticians have been scurrying to come up with a grand theory, a rapprochement of sorts. This one describes the universe as a quantum fluid, perhaps made up of hypothesized gravitons.

From Nature Asia:

The prevailing model of cosmology, based on Einstein’s theory of general relativity, puts the universe at around 13.8 billion years old and suggests it originated from a “singularity” – an infinitely small and dense point – at the Big Bang.

 To understand what happened inside that tiny singularity, physicists must marry general relativity with quantum mechanics – the laws that govern small objects. Applying both of these disciplines has challenged physicists for decades. “The Big Bang singularity is the most serious problem of general relativity, because the laws of physics appear to break down there,” says Ahmed Farag Ali, a physicist at Zewail City of Science and Technology, Egypt.

 In an effort to bring together the laws of quantum mechanics and general relativity, and to solve the singularity puzzle, Ali and Saurya Das, a physicist at the University of Lethbridge in Alberta Canada, employed an equation that predicts the development of singularities in general relativity. That equation had been developed by Das’s former professor, Amal Kumar Raychaudhuri, when Das was an undergraduate student at Presidency University, in Kolkata, India, so Das was particularly familiar and fascinated by it.

 When Ali and Das made small quantum corrections to the Raychaudhuri equation, they realised it described a fluid, made up of small particles, that pervades space. Physicists have long believed that a quantum version of gravity would include a hypothetical particle, called the graviton, which generates the force of gravity. In their new model — which will appear in Physics Letters B in February — Ali and Das propose that such gravitons could form this fluid.

To understand the origin of the universe, they used this corrected equation to trace the behaviour of the fluid back through time. Surprisingly, they found that it did not converge into a singularity. Instead, the universe appears to have existed forever. Although it was smaller in the past, it never quite crunched down to nothing, says Das.

 “Our theory serves to complement Einstein’s general relativity, which is very successful at describing physics over large distances,” says Ali. “But physicists know that to describe short distances, quantum mechanics must be accommodated, and the quantum Raychaudhui equation is a big step towards that.”

The model could also help solve two other cosmic mysteries. In the late 1990s, astronomers discovered that the expansion of the universe is accelerating due the presence of a mysterious dark energy, the origin of which is not known. The model has the potential to explain it since the fluid creates a minor but constant outward force that expands space. “This is a happy offshoot of our work,” says Das.

 Astronomers also now know that most matter in the universe is in an invisible mysterious form called dark matter, only perceptible through its gravitational effect on visible matter such as stars. When Das and a colleague set the mass of the graviton in the model to a small level, they could make the density of their fluid match the universe’s observed density of dark matter, while also providing the right value for dark energy’s push.

Read the entire article here.

 

BigBang

The Universe of Numbers

There is no doubt that mathematics — some very complex — has been able to explain much of what we consider the universe. In reality, and perhaps surprisingly, only a small subset of equations is required to explain everything around us from the atoms and their constituents to the vast cosmos. Why is that? And, what is the fundamental relationship between mathematics and our current physical understanding of all things great and small?

From the New Scientist:

When Albert Einstein finally completed his general theory of relativity in 1916, he looked down at the equations and discovered an unexpected message: the universe is expanding.

Einstein didn’t believe the physical universe could shrink or grow, so he ignored what the equations were telling him. Thirteen years later, Edwin Hubble found clear evidence of the universe’s expansion. Einstein had missed the opportunity to make the most dramatic scientific prediction in history.

How did Einstein’s equations “know” that the universe was expanding when he did not? If mathematics is nothing more than a language we use to describe the world, an invention of the human brain, how can it possibly churn out anything beyond what we put in? “It is difficult to avoid the impression that a miracle confronts us here,” wrote physicist Eugene Wigner in his classic 1960 paper “The unreasonable effectiveness of mathematics in the natural sciences” (Communications on Pure and Applied Mathematics, vol 13, p 1).

The prescience of mathematics seems no less miraculous today. At the Large Hadron Collider at CERN, near Geneva, Switzerland, physicists recently observed the fingerprints of a particle that was arguably discovered 48 years ago lurking in the equations of particle physics.

How is it possible that mathematics “knows” about Higgs particles or any other feature of physical reality? “Maybe it’s because math is reality,” says physicist Brian Greene of Columbia University, New York. Perhaps if we dig deep enough, we would find that physical objects like tables and chairs are ultimately not made of particles or strings, but of numbers.

“These are very difficult issues,” says philosopher of science James Ladyman of the University of Bristol, UK, “but it might be less misleading to say that the universe is made of maths than to say it is made of matter.”

Difficult indeed. What does it mean to say that the universe is “made of mathematics”? An obvious starting point is to ask what mathematics is made of. The late physicist John Wheeler said that the “basis of all mathematics is 0 = 0”. All mathematical structures can be derived from something called “the empty set”, the set that contains no elements. Say this set corresponds to zero; you can then define the number 1 as the set that contains only the empty set, 2 as the set containing the sets corresponding to 0 and 1, and so on. Keep nesting the nothingness like invisible Russian dolls and eventually all of mathematics appears. Mathematician Ian Stewart of the University of Warwick, UK, calls this “the dreadful secret of mathematics: it’s all based on nothing” (New Scientist, 19 November 2011, p 44). Reality may come down to mathematics, but mathematics comes down to nothing at all.

That may be the ultimate clue to existence – after all, a universe made of nothing doesn’t require an explanation. Indeed, mathematical structures don’t seem to require a physical origin at all. “A dodecahedron was never created,” says Max Tegmark of the Massachusetts Institute of Technology. “To be created, something first has to not exist in space or time and then exist.” A dodecahedron doesn’t exist in space or time at all, he says – it exists independently of them. “Space and time themselves are contained within larger mathematical structures,” he adds. These structures just exist; they can’t be created or destroyed.

That raises a big question: why is the universe only made of some of the available mathematics? “There’s a lot of math out there,” Greene says. “Today only a tiny sliver of it has a realisation in the physical world. Pull any math book off the shelf and most of the equations in it don’t correspond to any physical object or physical process.”

It is true that seemingly arcane and unphysical mathematics does, sometimes, turn out to correspond to the real world. Imaginary numbers, for instance, were once considered totally deserving of their name, but are now used to describe the behaviour of elementary particles; non-Euclidean geometry eventually showed up as gravity. Even so, these phenomena represent a tiny slice of all the mathematics out there.

Not so fast, says Tegmark. “I believe that physical existence and mathematical existence are the same, so any structure that exists mathematically is also real,” he says.

So what about the mathematics our universe doesn’t use? “Other mathematical structures correspond to other universes,” Tegmark says. He calls this the “level 4 multiverse”, and it is far stranger than the multiverses that cosmologists often discuss. Their common-or-garden multiverses are governed by the same basic mathematical rules as our universe, but Tegmark’s level 4 multiverse operates with completely different mathematics.

All of this sounds bizarre, but the hypothesis that physical reality is fundamentally mathematical has passed every test. “If physics hits a roadblock at which point it turns out that it’s impossible to proceed, we might find that nature can’t be captured mathematically,” Tegmark says. “But it’s really remarkable that that hasn’t happened. Galileo said that the book of nature was written in the language of mathematics – and that was 400 years ago.”

Read the entire article here.

BigBang

The More Things Stay the Same, the More They Change?

[div class=attrib]From Scientific American:[end-div]

Some things never change. physicists call them the constants of nature. Such quantities as the velocity of light, c, Newton’s constant of gravitation, G, and the mass of the electron, me, are assumed to be the same at all places and times in the universe. They form the scaffolding around which the theories of physics are erected, and they define the fabric of our universe. Physics has progressed by making ever more accurate measurements of their values.

And yet, remarkably, no one has ever successfully predicted or explained any of the constants. Physicists have no idea why constants take the special numerical values that they do (given the choice of units). In SI units, c is 299,792,458; G is 6.673 × 10–11; and me is 9.10938188 × 10–31 —numbers that follow no discernible pattern. The only thread running through the values is that if many of them were even slightly different, complex atomic structures such as living beings would not be possible. The desire to explain the constants has been one of the driving forces behind efforts to develop a complete unified description of nature, or “theory of everything.” Physicists have hoped that such a theory would show that each of the constants of nature could have only one logically possible value. It would reveal an underlying order to the seeming arbitrariness of nature.

In recent years, however, the status of the constants has grown more muddied, not less. Researchers have found that the best candidate for a theory of everything, the variant of string theory called M-theory, is self-consistent only if the universe has more than four dimensions of space and time—as many as seven more. One  implication is that the constants we observe may not, in fact, be the truly fundamental ones. Those live in the full higher-dimensional space, and we see only their three-dimensional “shadows.”

Meanwhile physicists have also come to appreciate that the values of many of the constants may be the result of mere happenstance, acquired during random events and elementary particle processes early in the history of the universe. In fact, string theory allows for a vast number—10500 —of possible “worlds” with different self-consistent sets of laws and constants. So far researchers have no idea why our combination was selected. Continued study may reduce the number of logically possible worlds to one, but we have to remain open to the unnerving possibility that our known universe is but one of many—a part of a multiverse—and that different parts of the multiverse exhibit different solutions to the theory, our observed laws of nature being merely one edition of many systems of local bylaws.

No further explanation would then be possible for many of our numerical constants other than that they constitute a rare combination that permits consciousness to evolve. Our observable uni verse could be one of many isolated oases surrounded by an infinity of lifeless space—a surreal place where different forces of nature hold sway and particles such as electrons or structures such as carbon atoms and DNA molecules could be impossibilities. If you tried to venture into that outside world, you would cease to be.

Thus, string theory gives with the right hand and takes with the left. It was devised in part to explain the seemingly arbitrary values of the physical constants, and the basic equations of the theory contain few arbitrary parameters. Yet so far string theory offers no explanation for the observed values of the constants.

[div class=attrib]Read the entire article here.[end-div]

BigBang

A Theory of Everything? Nah

A peer-reviewed journal recently published a 100-page scientific paper describing a theory of everything that unifies quantum theory and relativity (a long sought-after goal) with the origin of life, evolution and cosmology. And, best of all the paper contains no mathematics.

The paper written by a faculty member at Case Western Reserve University raises interesting issues about the peer review process and the viral spread of information, whether it’s correct or not.

[div class=attrib]From Ars Technica:[end-div]

Physicists have been working for decades on a “theory of everything,” one that unites quantum mechanics and relativity. Apparently, they were being too modest. Yesterday saw publication of a press release claiming a biologist had just published a theory accounting for all of that—and handling the origin of life and the creation of the Moon in the bargain. Better yet, no math!

Where did such a crazy theory originate? In the mind of a biologist at a respected research institution, Case Western Reserve University Medical School. Amazingly, he managed to get his ideas published, then amplified by an official press release. At least two sites with poor editorial control then reposted the press release—verbatim—as a news story.

Gyres all the way down

The theory in question springs from the brain of one Erik Andrulis, a CWRU faculty member who has a number of earlier papers on fairly standard biochemistry. The new paper was accepted by an open access journal called Life, meaning that you can freely download a copy of its 105 pages if you’re so inclined. Apparently, the journal is peer-reviewed, which is a bit of a surprise; even accepting that the paper makes a purely theoretical proposal, it is nothing like science as I’ve ever seen it practiced.

The basic idea is that everything, from subatomic particles to living systems, is based on helical systems the author calls “gyres,” which transform matter, energy, and information. These transformations then determine the properties of various natural systems, living and otherwise. What are these gyres? It’s really hard to say; even Andrulis admits that they’re just “a straightforward and non-mathematical core model” (although he seems to think that’s a good thing). Just about everything can be derived from this core model; the author cites “major phenomena including, but not limited to, quantum gravity, phase transitions of water, why living systems are predominantly CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur), homochirality of sugars and amino acids, homeoviscous adaptation, triplet code, and DNA mutations.”

He’s serious about the “not limited to” part; one of the sections describes how gyres could cause the Moon to form.

Is this a viable theory of everything? The word “boson,” the particle that carries forces, isn’t in the text at all. “Quark” appears once—in the title of one of the 800 references. The only subatomic particle Andrulis describes is the electron; he skips from there straight up to oxygen. Enormous gaps exist everywhere one looks.

[div class=attrib]Read more here.[end-div]