Category Archives: Physics

Mass and length may not be fundamental properties of nature

Natalie Wolchover writes: Though galaxies look larger than atoms and elephants appear to outweigh ants, some physicists have begun to suspect that size differences are illusory. Perhaps the fundamental description of the universe does not include the concepts of “mass” and “length,” implying that at its core, nature lacks a sense of scale.

This little-explored idea, known as scale symmetry, constitutes a radical departure from long-standing assumptions about how elementary particles acquire their properties. But it has recently emerged as a common theme of numerous talks and papers by respected particle physicists. With their field stuck at a nasty impasse, the researchers have returned to the master equations that describe the known particles and their interactions, and are asking: What happens when you erase the terms in the equations having to do with mass and length?

Nature, at the deepest level, may not differentiate between scales. With scale symmetry, physicists start with a basic equation that sets forth a massless collection of particles, each a unique confluence of characteristics such as whether it is matter or antimatter and has positive or negative electric charge. As these particles attract and repel one another and the effects of their interactions cascade like dominoes through the calculations, scale symmetry “breaks,” and masses and lengths spontaneously arise.

Similar dynamical effects generate 99 percent of the mass in the visible universe. Protons and neutrons are amalgams — each one a trio of lightweight elementary particles called quarks. The energy used to hold these quarks together gives them a combined mass that is around 100 times more than the sum of the parts. “Most of the mass that we see is generated in this way, so we are interested in seeing if it’s possible to generate all mass in this way,” said Alberto Salvio, a particle physicist at the Autonomous University of Madrid and the co-author of a recent paper on a scale-symmetric theory of nature. [Continue reading…]

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Nothingness: From a childhood hallucination to the halls of theoretical physics

Alan Lightman writes: My most vivid encounter with Nothingness occurred in a remarkable experience I had as a child of 9 years old. It was a Sunday afternoon. I was standing alone in a bedroom of my home in Memphis Tennessee, gazing out the window at the empty street, listening to the faint sound of a train passing a great distance away, and suddenly I felt that I was looking at myself from outside my body. I was somewhere in the cosmos. For a brief few moments, I had the sensation of seeing my entire life, and indeed the life of the entire planet, as a brief flicker in a vast chasm of time, with an infinite span of time before my existence and an infinite span of time afterward. My fleeting sensation included infinite space. Without body or mind, I was somehow floating in the gargantuan stretch of space, far beyond the solar system and even the galaxy, space that stretched on and on and on. I felt myself to be a tiny speck, insignificant in a vast universe that cared nothing about me or any living beings and their little dots of existence, a universe that simply was. And I felt that everything I had experienced in my young life, the joy and the sadness, and everything that I would later experience, meant absolutely nothing in the grand scheme of things. It was a realization both liberating and terrifying at once. Then, the moment was over, and I was back in my body.

The strange hallucination lasted only a minute or so. I have never experienced it since. Although Nothingness would seem to exclude awareness along with the exclusion of everything else, awareness was part of that childhood experience, but not the usual awareness I would locate within the three pounds of gray matter in my head. It was a different kind of awareness. I am not religious, and I do not believe in the supernatural. I do not think for a minute that my mind actually left my body. But for a few moments I did experience a profound absence of the familiar surroundings and thoughts we create to anchor our lives. It was a kind of Nothingness.

To understand anything, as Aristotle argued, we must understand what it is not, and Nothingness is the ultimate opposition to any thing. To understand matter, said the ancient Greeks, we must understand the “void,” or the absence of matter. Indeed, in the fifth century B.C., Leucippus argued that without the void there could be no motion because there would be no empty spaces for matter to move into. According to Buddhism, to understand our ego we must understand the ego-free state of “emptiness,” called śūnyatā. To understand the civilizing effects of society, we must understand the behavior of human beings removed from society, as William Golding so powerfully explored in his novel Lord of the Flies.

Following Aristotle, let me say what Nothingness is not. It is not a unique and absolute condition. Nothingness means different things in different contexts. From the perspective of life, Nothingness might mean death. To a physicist, it might mean the complete absence of matter and energy (an impossibility, as we will see), or even the absence of time and space. To a lover, Nothingness might mean the absence of the beloved. To a parent, it might mean the absence of children. To a painter, the absence of color. To a reader, a world without books. To a person impassioned with empathy, emotional numbness. To a theologian or philosopher like Pascal, Nothingness meant the timeless and spaceless infinity known only by God. [Continue reading…]

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Earth’s magnetic field polarity could flip sooner than expected

Scientific American reports: Earth’s magnetic field, which protects the planet from huge blasts of deadly solar radiation, has been weakening over the past six months, according to data collected by a European Space Agency (ESA) satellite array called Swarm.

The biggest weak spots in the magnetic field — which extends 370,000 miles (600,000 kilometers) above the planet’s surface — have sprung up over the Western Hemisphere, while the field has strengthened over areas like the southern Indian Ocean, according to the magnetometers onboard the Swarm satellites — three separate satellites floating in tandem.

The scientists who conducted the study are still unsure why the magnetic field is weakening, but one likely reason is that Earth’s magnetic poles are getting ready to flip, said Rune Floberghagen, the ESA’s Swarm mission manager. In fact, the data suggest magnetic north is moving toward Siberia.

“Such a flip is not instantaneous, but would take many hundred if not a few thousand years,” Floberghagen told Live Science. “They have happened many times in the past.”

Scientists already know that magnetic north shifts. Once every few hundred thousand years the magnetic poles flip so that a compass would point south instead of north. While changes in magnetic field strength are part of this normal flipping cycle, data from Swarm have shown the field is starting to weaken faster than in the past. Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner. [Continue reading…]

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To understand turbulence we need the intuitive perspective of art

turbulence-leonardo

Philip Ball writes: When the German physicist Arnold Sommerfeld assigned his most brilliant student a subject for his doctoral thesis in 1923, he admitted that “I would not have proposed a topic of this difficulty to any of my other pupils.” Those others included such geniuses as Wolfgang Pauli and Hans Bethe, yet for Sommerfeld the only one who was up to the challenge of this subject was Werner Heisenberg.

Heisenberg went on to be a key founder of quantum theory and was awarded the 1932 Nobel Prize in physics. He developed one of the first mathematical descriptions of this new and revolutionary discipline, discovered the uncertainty principle, and together with Niels Bohr engineered the “Copenhagen interpretation” of quantum theory, to which many physicists still adhere today.

The subject of Heisenberg’s doctoral dissertation, however, wasn’t quantum physics. It was harder than that. The 59-page calculation that he submitted to the faculty of the University of Munich in 1923 was titled “On the stability and turbulence of fluid flow.”

Sommerfeld had been contacted by the Isar Company of Munich, which was contracted to prevent the Isar River from flooding by building up its banks. The company wanted to know at what point the river flow changed from being smooth (the technical term is “laminar”) to being turbulent, beset with eddies. That question requires some understanding of what turbulence is. Heisenberg’s work on the problem was impressive—he solved the mathematical equations of flow at the point of the laminar-to-turbulent change—and it stimulated ideas for decades afterward. But he didn’t really crack it—he couldn’t construct a comprehensive theory of turbulence.

Heisenberg was not given to modesty, but it seems he had no illusions about his achievements here. One popular story goes that he once said, “When I meet God, I am going to ask him two questions. Why relativity? And why turbulence? I really believe he will have an answer for the first.”

It is probably an apocryphal tale. The same remark has been attributed to at least one other person: The British mathematician and expert on fluid flow, Horace Lamb, is said to have hoped that God might enlighten him on quantum electrodynamics and turbulence, saying that “about the former I am rather optimistic.”

You get the point: turbulence, a ubiquitous and eminently practical problem in the real world, is frighteningly hard to understand. [Continue reading…]

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Physicists report finding reliable way to teleport data

The New York Times reports: Scientists in the Netherlands have moved a step closer to overriding one of Albert Einstein’s most famous objections to the implications of quantum mechanics, which he described as “spooky action at a distance.”

In a paper published on Thursday in the journal Science, physicists at the Kavli Institute of Nanoscience at the Delft University of Technology reported that they were able to reliably teleport information between two quantum bits separated by three meters, or about 10 feet.

Quantum teleportation is not the “Star Trek”-style movement of people or things; rather, it involves transferring so-called quantum information — in this case what is known as the spin state of an electron — from one place to another without moving the physical matter to which the information is attached.

Classical bits, the basic units of information in computing, can have only one of two values — either 0 or 1. But quantum bits, or qubits, can simultaneously describe many values. They hold out both the possibility of a new generation of faster computing systems and the ability to create completely secure communication networks.

Moreover, the scientists are now closer to definitively proving Einstein wrong in his early disbelief in the notion of entanglement, in which particles separated by light-years can still appear to remain connected, with the state of one particle instantaneously affecting the state of another. [Continue reading…]

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Have cosmologists lost their minds in the multiverse?

Luke Barnes and Geraint Lewis write: The recent BICEP2 observations – of swirls in the polarisation of the cosmic microwave background – have been proclaimed as many things, from evidence of the Big Bang and gravitational waves to something strange called the multiverse.

The multiverse theory is that our universe is but one of a vast, variegated ensemble of other universes. We don’t know how many pieces there are to the multiverse but estimates suggest there many be squillions of them.

But (if they exist) there has not been enough time since our cosmic beginning for light from these other universes to reach us. They are beyond our cosmic horizon and thus in principle unobservable.

How, then, can cosmologists say they have seen evidence of them?

Unobservable entities aren’t necessarily out-of-bounds for science. For example, protons and neutrons are made of subatomic particles called quarks. While they cannot be observed directly, their existence and properties are inferred from the way particles behave when smashed together.

But there is no such luxury with the multiverse. No signals from from other universes have or will ever bother our telescopes.

While there is some debate about what actually makes a scientific theory, we should at least ask if the multiverse theory is testable? Does it make predictions that we can test in a laboratory or with our telescopes? [Continue reading…]

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The beginning of everything — when our universe expanded faster than the speed of light

Space.com: Astronomers announced Monday (March 17) that they have discovered a telltale signature of gravitational waves in the cosmic microwave background radiation (CMB), the light left over from the universe’s birth 13.8 billion years ago.

The new results suggest that space-time really did expand at many times the speed of light in the first few tiny fractions of a second after the Big Bang, as predicted by the theory of cosmic inflation, researchers say.

That may seem impossible, since Albert Einstein’s theory of special relativity holds that nothing can travel faster than light. That rule, however, applies only to matter and information moving through space, not to the expansion of space-time itself. [Continue reading…]

Space.com: The new research also lends credence to the idea of a multiverse. This theory posits that, when the universe grew exponentially in the first tiny fraction of a second after the Big Bang, some parts of space-time expanded more quickly than others. This could have created “bubbles” of space-time that then developed into other universes. The known universe has its own laws of physics, while other universes could have different laws, according to the multiverse concept.

“It’s hard to build models of inflation that don’t lead to a multiverse,” Alan Guth, an MIT theoretical physicist unaffiliated with the new study, said during a news conference Monday. “It’s not impossible, so I think there’s still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking [the idea of a] multiverse seriously.” [Continue reading…]

Click “Read more” link to see a “Cosmic Inflation” infographic.
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In unseen worlds, science invariably crosses paths with fantasy

f13-iconPhilip Ball writes: For centuries, scientists studied light to comprehend the visible world. Why are things colored? What is a rainbow? How do our eyes work? And what is light itself? These are questions that preoccupied scientists and philosophers since the time of Aristotle, including Roger Bacon, Isaac Newton, Michael Faraday, Thomas Young, and James Clerk Maxwell.

But in the late 19th century all that changed, and it was largely Maxwell’s doing. This was the period in which the whole focus of physics — then still emerging as a distinct scientific discipline — shifted from the visible to the invisible. Light itself was instrumental to that change. Not only were the components of light invisible “fields,” but light was revealed as merely a small slice of a rainbow extending far into the unseen.

Physics has never looked back. Today its theories and concepts are concerned largely with invisible entities: not only unseen force fields and insensible rays but particles too small to see even with the most advanced microscopes. We now know that our everyday perception grants us access to only a tiny fraction of reality. Telescopes responding to radio waves, infrared radiation, and X-rays have vastly expanded our view of the universe, while electron microscopes, X-ray beams, and other fine probes of nature’s granularity have unveiled the microworld hidden beyond our visual acuity. Theories at the speculative forefront of physics flesh out this unseen universe with parallel worlds and with mysterious entities named for their very invisibility: dark matter and dark energy.

This move beyond the visible has become a fundamental part of science’s narrative. But it’s a more complicated shift than we often appreciate. Making sense of what is unseen — of what lies “beyond the light” — has a much longer history in human experience. Before science had the means to explore that realm, we had to make do with stories that became enshrined in myth and folklore. Those stories aren’t banished as science advances; they are simply reinvented. Scientists working at the forefront of the invisible will always be confronted with gaps in knowledge, understanding, and experimental capability. In the face of those limits, they draw unconsciously on the imagery of the old stories. This is a necessary part of science, and these stories can sometimes suggest genuinely productive scientific ideas. But the danger is that we will start to believe them at face value, mistaking them for theories.

A backward glance at the history of the invisible shows how the narratives and tropes of myth and folklore can stimulate science, while showing that the truth will probably turn out to be far stranger and more unexpected than these old stories can accommodate. [Continue reading…]

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Is the lopsided Universe telling us we need new theories?

a13-iconArs Technica reports: The Universe is incredibly regular. The variation of the cosmos’ temperature across the entire sky is tiny: a few millionths of a degree, no matter which direction you look. Yet the same light from the very early cosmos that reveals the Universe’s evenness also tells astronomers a great deal about the conditions that gave rise to irregularities like stars, galaxies, and (incidentally) us.

That light is the cosmic microwave background, and it provides some of the best knowledge we have about the structure, content, and history of the Universe. But it also contains a few mysteries: on very large scales, the cosmos seems to have a certain lopsidedness. That slight asymmetry is reflected in temperature fluctuations much larger than any galaxy, aligned on the sky in a pattern facetiously dubbed “the axis of evil.”

The lopsidedness is real, but cosmologists are divided over whether it reveals anything meaningful about the fundamental laws of physics. The fluctuations are sufficiently small that they could arise from random chance. We have just one observable Universe, but nobody sensible believes we can see all of it. With a sufficiently large cosmos beyond the reach of our telescopes, the rest of the Universe may balance the oddity that we can see, making it a minor, local variation.

However, if the asymmetry can’t be explained away so simply, it could indicate that some new physical mechanisms were at work in the early history of the Universe. As Amanda Yoho, a graduate student in cosmology at Case Western Reserve University, told Ars, “I think the alignments, in conjunction with all of the other large angle anomalies, must point to something we don’t know, whether that be new fundamental physics, unknown astrophysical or cosmological sources, or something else.” [Continue reading…]

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Stephen Hawking: ‘There are no black holes’

Nature reports: Most physicists foolhardy enough to write a paper claiming that “there are no black holes” — at least not in the sense we usually imagine — would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.

In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.

“There is no escape from a black hole in classical theory,” Hawking told Nature. Quantum theory, however, “enables energy and information to escape from a black hole”. A full explanation of the process, the physicist admits, would require a theory that successfully merges gravity with the other fundamental forces of nature. But that is a goal that has eluded physicists for nearly a century. “The correct treatment,” Hawking says, “remains a mystery.”

Hawking posted his paper on the arXiv preprint server on 22 January. He titled it, whimsically, ‘Information preservation and weather forecasting for black holes’, and it has yet to pass peer review. The paper was based on a talk he gave via Skype at a meeting at the Kavli Institute for Theoretical Physics in Santa Barbara, California, in August 2013 (watch video of the talk). [Continue reading…]

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A new theory about the origin of life

origin-life

Evolution explains how life changes, but it doesn’t explain how it came into existence. A young physicist at MIT has now come up with a mathematical formula which suggests that given the right set of conditions, the emergence of living forms is not merely possible; it almost seems inevitable.

Let there be light, shining on atoms, and there will eventually be life.

Quanta magazine: Why does life exist?

Popular hypotheses credit a primordial soup, a bolt of lightning and a colossal stroke of luck. But if a provocative new theory is correct, luck may have little to do with it. Instead, according to the physicist proposing the idea, the origin and subsequent evolution of life follow from the fundamental laws of nature and “should be as unsurprising as rocks rolling downhill.”

From the standpoint of physics, there is one essential difference between living things and inanimate clumps of carbon atoms: The former tend to be much better at capturing energy from their environment and dissipating that energy as heat. Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity. The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.

“You start with a random clump of atoms, and if you shine light on it for long enough, it should not be so surprising that you get a plant,” England said.

England’s theory is meant to underlie, rather than replace, Darwin’s theory of evolution by natural selection, which provides a powerful description of life at the level of genes and populations. “I am certainly not saying that Darwinian ideas are wrong,” he explained. “On the contrary, I am just saying that from the perspective of the physics, you might call Darwinian evolution a special case of a more general phenomenon.”

His idea, detailed in a recent paper and further elaborated in a talk he is delivering at universities around the world, has sparked controversy among his colleagues, who see it as either tenuous or a potential breakthrough, or both.

England has taken “a very brave and very important step,” said Alexander Grosberg, a professor of physics at New York University who has followed England’s work since its early stages. The “big hope” is that he has identified the underlying physical principle driving the origin and evolution of life, Grosberg said.

“Jeremy is just about the brightest young scientist I ever came across,” said Attila Szabo, a biophysicist in the Laboratory of Chemical Physics at the National Institutes of Health who corresponded with England about his theory after meeting him at a conference. “I was struck by the originality of the ideas.”

Others, such as Eugene Shakhnovich, a professor of chemistry, chemical biology and biophysics at Harvard University, are not convinced. “Jeremy’s ideas are interesting and potentially promising, but at this point are extremely speculative, especially as applied to life phenomena,” Shakhnovich said.

England’s theoretical results are generally considered valid. It is his interpretation — that his formula represents the driving force behind a class of phenomena in nature that includes life — that remains unproven. But already, there are ideas about how to test that interpretation in the lab. [Continue reading…]

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