Out of Nothing: An Emergent Universe

[Stormer0628]

Quantum Property Of Vacuum Finally Observed Thanks To Neutron Star

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Empty space is a lot less empty than you may expect, as it is inhabited by a flurry of virtual particles fluctuating in and out of existence. In the 1930s, it was predicted that when these particles are within an intense magnetic field, they interact with light in a very specific way. This phenomenon has finally been observed in nature.

An international team of researchers used the Very Large Telescope in Chile to observe light from the neutron star RX J1856.5-3754. In doing so, they witnessed how the light was affected by the strongly magnetized vacuum – an important test for quantum electrodynamics (QED), the theory that describes how light and matter interact.

“According to QED, a highly magnetized vacuum behaves as a prism for the propagation of light, an effect known as vacuum birefringence,” team leader Roberto Mignani, from INAF Milan and the University of Zielona Gora, said in a statement.

RX J1856.5-3754 is located about 400 light-years from Earth and has an inferred magnetic field of about 10 billion Gauss, about 20 billion times Earth’s own.

“This effect can be detected only in the presence of enormously strong magnetic fields, such as those around neutron stars," added co-author Roberto Turolla, from the University of Padua. "This shows, once more, that neutron stars are invaluable laboratories in which to study the fundamental laws of nature."

The observations, which will be published in the Monthly Notices of the Royal Astronomical Society and are available online, were only possible due to the incredible capabilities of the VLT. The telescope detected the relative dimness of the neutron star, allowing astronomers to observe the changes in light direction – known as polarization.

“This VLT study is the very first observational support for predictions of these kinds of QED effects arising in extremely strong magnetic fields,” remarked Silvia Zane of the Mullard Space Science Laboratory.

The analysis shows that the light from the star has a polarization degree of about 16 percent, which can only be explained by a strong interaction between the empty space around the star and its magnetic field.

"The high linear polarization that we measured with the VLT can’t be easily explained by our models unless the vacuum birefringence effects predicted by QED are included," adds Mignani.

Future telescopes, like the European Extremely Large Telescope, will be powerful enough to detect this effect around many other neutron stars, making these phenomenal objects a testing ground for extreme quantum mechanics effects.

SOURCE

 

[Stormer0628]

symmetry

Matter-Antimatter Symmetry: Why Are We Even Here?

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I think that this discovery of antimatter was perhaps the biggest jump of all the big jumps in physics in the 20th century
-Werner Heisenberg, Nobel Prize 1932​

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SUMMARY

• Antimatter research helps us understand the origin of our (matter) Universe
• By saying that we shouldn’t be here in the first place, antimatter research helps us see one of the most profound, most fundamental fact of our existence, as well as hopefully gain more appreciation of the mere fact that we exist.
• Medical applications of antimatter are of great interest

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While the interplay of inflation and quantum fluctuations gives us a fairly good picture of the emergence of the universe, there is a fact that is less understood, one that gives us one of the most profound mysteries directly connected to existence—not just of us humans, but of the whole lot of everything that we know of, like galaxies, planets, etc.—why are we here in the first place? No, the underlying question rests not on pseudophilosophical considerations, but purely relies on the laws of physics as we understand them: in physical terms, why do we even have matter, when all the laws of symmetry tell us that equal amounts of matter and antimatter are generated by quantum fluctuations, as also seen in all the particle accelerators? In other words, if the symmetry holds, we wouldn’t be here to reflect upon the issue altogether, because the universe should instead be just all photons, all radiation, all energy, no lumpy matter at all.

So why does the universe contain only matter? Why is there no antimatter in the universe if an equal amount of them is created with matter?

Is it because matter and antimatter have (slightly) different properties, for example in mass, charge, magnetic moment…?

Or Is it because matter and antimatter have different decay properties, described by the so-called CPT (charge-parity-time) violation…?

Recall that all fundamental particles have their own antiparticle counterparts. For example for every electron, proton, neutron, there is a corresponding positron, antiproton, and antineutron in the universe:

Over the years, a few propositions have been advanced. One of those came from renowned Russian (formerly Soviet Union) physicist, Andrei Sakharov...

Although CPT has been confirmed in laboratories, scientists are still looking at the exact mechanisms that produce it. Lately, they have turned their eyes on the Higgs field-boson, recently confirmed, as one responsible for the violation. Nevertheless, even if CPT mechanism came to be well understood, it may not be enough for the relatively large disparity in the matter-antimatter imbalance in the universe. It's believed the best explanation, whatever it would be or whoever comes up with it, would help usher in a new fundamental understanding of the universe....

Still, while all these are going on, matter-antimatter research has already produced technologies that benefit humanity...

 

[Stormer0628]

Verlinde's New Theory of Gravity Passes First Test
Press Release From: University of Leiden
Posted: Monday, December 12, 2016

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A team led by astronomer Margot Brouwer (Leiden Observatory, The Netherlands) has tested the new theory of theoretical physicist Erik Verlinde (University of Amsterdam) for the first time through the lensing effect of gravity. Brouwer and her team measured the distribution of gravity around more than 33,000 galaxies to put Verlinde’s prediction to the test. She concludes that Verlinde’s theory agrees well with the measured gravity distribution. The results have been accepted for publication in the British journal Monthly Notices of the Royal Astronomical Society.

The gravity of galaxies bends space, such that the light traveling through this space is bent, as through a lens. Background galaxies that are situated far behind a foreground galaxy (the lens), thereby seem slightly distorted. This effect can be measured in order to determine the distribution of gravity around a foreground galaxy. Astronomers have measured, however, that at distances up to a hundred times the radius of the galaxy, the force of gravity is much stronger than Einstein’s theory of gravity predicts. The existing theory only works when invisible particles, the so-called dark matter, are added.

Verlinde now claims that he not only explains the mechanism behind gravity with his alternative to Einstein’s theory, but also the origin of the mysterious extra gravity, which astronomers currently attribute to dark matter. Verlinde’s new theory predicts how much gravity there must be, based only on the mass of the visible matter.

Brouwer calculated Verlinde’s prediction for the gravity of 33,613 galaxies, based only on their visible mass. She compared this prediction to the distribution of gravity measured by gravitational lensing, in order to test Verlinde’s theory. Her conclusion is that his prediction agrees well with the observed gravity distribution, but she emphasizes that dark matter could also explain the extra gravitational force. However, the mass of the dark matter is a free parameter, which must be adjusted to the observation. Verlinde’s theory provides a direct prediction, without free parameters.

The new theory is currently only applicable to isolated, spherical and static systems, while the universe is dynamic and complex. Many observations cannot yet be explained by the new theory, so dark matter is still in the race. Brouwer: “The question now is how the theory develops, and how it can be further tested. But the result of this first test definitely looks interesting.”

The research is based on observations of GAMA (Galaxy And Mass Assembly) and KiDS (Kilo-Degree Survey), with scientists from the Netherlands (University of Leiden, University of Groningen), Germany, Scotland, England and Australia. The KiDS observations are performed with the Dutch OmegaCAM camera on ESO’s VLT Survey Telescope on Cerro Paranal in northern Chile.

==========================

Reference:
“First Test of Verlinde’s Theory of Emergent Gravity Using Weak Gravitational Lensing Measurements,” Margot M. Brouwer[1], Manus R. Visser[2], Andrej Dvornik[1], Henk Hoekstra[1], Konrad Kuijken[1], Edwin A. Valentijn[3], Maciej Bilicki[1], Chris Blake[4], Sarah Brough[5], Hugo Buddelmeijer[1], Thomas Erben[6], Catherine Heymans[7], Hendrik Hildebrandt[6], Benne W. Holwerda[1], Andrew M. Hopkins[5], Dominik Klaes[6], Jochen Liske[8], Jon Loveday[9], John McFarland[3], Reiko Nakajima[6], Cristóbal Sifón[1] & Edward N. Taylor[4], 2016, Monthly Notices of the Royal Astronomical Society .

[1] Leiden Observatory, Leiden University
[2] Institute for Theoretical Physics, University of Amsterdam
[3] Kapteyn Astronomical Institute, University of Groningen
[4] Centre for Astrophysics and Supercomputing, Swinburne University of Technology
[5] Australian Astronomical Observatory
[6] Argelander-Institut für Astronomie.
[7] SUPA, Institute for Astronomy, University of Edinburgh.
[8] Hamburger Sternwarte, Universität Hamburg
[9] Astronomy Centre, University of Sussex

source

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ADDITIONAL RESOURCES

 

[mirkocrocop]

Maganda ito ts..electrical engineer here from cebu.
Curious ako at interested about quantum mechanics.

 

[Stormer0628]

Maganda ito ts..electrical engineer here from cebu.
Curious ako at interested about quantum mechanics.

Great!

Ang main ideas ng thread are mostly derived from quantum mechanics, if you noticed. May konting diversion din sa ibang fields, like string theory and its subsets, like the holographic model by Juan Maldacena. Interesting times in the astronomical and physical sciences if one's into it.

 

[mirkocrocop]

Ang galing nyo po stormer, physicist po ba kayo?
Ako gusto ko sanang maging physicist kaso sa pagiging engineer bagsak ko.
Nasa science talaga ang gusto ko hilig ako magbasa ng article sa Live Science at manuod ng Vsauce at Veritasium.
Matagal kuna hinanap ang ganitong topic sa forum, hindi ako makasabay sa mga forum ng ibang bansa.

 

[Stormer0628]

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The black holes would be like the ones that helped us detect gravitational waves.

Earlier this year, after 100 years of searching for them, an international team of researchers detected the presence of gravitational waves for the first time, thanks to the collision of two massive black holes, providing proof for Einstein’s general theory of relativity.

Needless to say, it was a big deal, but two important questions remained: where did the two colliding black holes that created these gravitational ripples in space-time come from, and how did they get so massive?

Black holes form when a star runs out of fuel and collapses in on itself.

But for two black holes to end up so massive—they were both about 29 to 36 times the mass of our Sun—two stars must have existed that were even more gigantic, because by the time stars collapse into black holes, they've already lost most of their mass.

That's a problem, because it's thought that stars can't accumulate enough mass to make such massive black holes.

The issue is that when stars reach a size large enough to spawn such an epic black hole, they create so much energy that stellar winds rip most of their mass away, throwing it out into the Universe to be lost.

This leaves the star up to half the mass it once was - and not nearly big enough to produce a black hole of the size detected in the gravitational wave data.

So, how did two stars contain enough mass to form the two behemoth black holes? One idea is that they might have contained hardly any elements heavier than helium in their cores.

Heavier elements such as carbon, oxygen, and iron are all more likely to be blasted away by those stellar winds and be lost to space. So a star with hardly any metallic elements could potentially get to the sizes we're talking about - but is that the only option?

An international team of scientists has proposed another idea: magnetic fields.

The team, led by Véronique Petit from the Florida Institute of Technology, found evidence that a star could retain the amount of mass required to create the black holes if that they maintained vast magnetic fields roughly 10,000 timesmore powerful than the Sun’s.

The general idea here is that those powerful magnetic fields would surround the massive star and help catch much of that lost mass that is being swept into space and feed it back into the star, preserving its massiveness for an eventual collapse. In that way, its black hole could reach the sizes detected by the gravitational wave data.

"Strong surface magnetic fields also provide a powerful mechanism for modifying mass loss and rotation of massive stars," the team writes.
To test this hypothesis, they created a series of computer simulations to see how a gigantic star’s mass might change over time if a magnetic field of such magnitude was present.

In the end, they found that if they took a star that was about 80 times the mass of the Sun, covered it in strong magnetic fields, and waited for it to eventually collapse, the mass left at the end of the star’s life was way more than if there wasn't a magnetic field.

About 20 times the mass of the Sun, to be specific.

Based on this, the team says we need to consider the possibility that massive black holes might rely on extremely magnetic stars to form, though they also caution that proving this hypothesis will likely mean observing such an event happening in the Universe, which—as you can probably imagine—is no easy task.

"This is an interesting alternative hypothesis for how stars can end up holding onto more of their mass, so they can form such heavy black holes. [But], the mechanism is somewhat speculative," astrophysicist Vicky Kalogera from Northwestern University, who was not part of the study, told Science News.

But the good news is that the team’s hypothesis is definitely a step in the right direction if we ever hope to fully understand how the Universe was formed and how it continues to operate.

And now we have a new type of star to look for as the source of these huge black holes.

The team’s work was published in Monthly Notices of the Royal Astronomical Society.
source


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Ang galing nyo po stormer, physicist po ba kayo?
Ako gusto ko sanang maging physicist kaso sa pagiging engineer bagsak ko.
Nasa science talaga ang gusto ko hilig ako magbasa ng article sa Live Science at manuod ng Vsauce at Veritasium.
Matagal kuna hinanap ang ganitong topic sa forum, hindi ako makasabay sa mga forum ng ibang bansa.

Ako naman, looked up EE before settling with physics, yes.

Di ko alam aling schools sa Pinas aside from UP Diliman meron physics. Aling specific field ng science, and especially quantum physics, ang kursunada mo?

Aling mga forum kaya yun, tho di na rin ako masyado active sa labas. Exhausting ang discussion, haha.

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Now I know what's bugging back of my mind about Verlinde (video above): man takes some remarkable features of Travolta's

 

[Stormer0628]

Donnie Darko's Hidden Universe

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There is something about Donnie Darko that resonates with many like me who find the absence of uberdramatics and markedly understated acting overly discongruent with the earth-shaking scientific theories that the film espouses.

For those who have not seen the classic film that has garnered some cult following throughout the years, especially those who found fascination in the many-worlds interpretation of the universe—multiverse if you will—here's a chance to watch the remake.

Of course the Standard Inflationary Model of the Universe suggests a multiverse, although there are some scientists who have worked on models throwing the concept out altogether.

The following discusses the film remake in more detail:

Donnie Darko – reviewed by an astrophysicist

 

[Stormer0628]

einstein's general theory of relativity in hot seat after 100 years

A Well-Accepted Century-Old Einstein Scientific Theory In Peril
The discovery of gravitational waves will either corroborate Einstein's General Theory of Relativity, or refute it.​

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First, there was the Variable Light Theory — a testable theory that suggests the speed of light might not always have been the constant figure that we have all accepted as fact since Einstein’s General Relativity Theory came into the picture.

And now, with the discovery of gravitational waves, another challenge to Einstein’s theory is brewing. It’s actually quite ironic — on one end, it confirms Einstein’s prediction that merging of black holes produce ripples (gravitational waves) in space-time. But on the other end, it also shows that his theory is not consistent with what happens at a black hole’s event horizon — what’s referred to as the ‘point of no return’ or simply its boundary.

According to Einstein’s theory, anything that falls into a black hole (equivalent to crossing the event horizon) disappears completely and leaves no trace at all. That includes light, which is why it’s called a ‘black’ hole. In line with this, the event horizon will be completely invisible as well, and anything that crosses it will not even know it crossed anything. It will simply fall into what is practically an abyss of nothingness and cease to exist.

In contrast, quantum mechanics physicists believe that while matter that falls into a black hole gets completely swallowed by it, it will leave evidence of itself on the outside or the edge of the black hole. In this scenario, the event horizon will not be completely invisible. Rather, it will be like some kind of wall. It can either be a ring of high-energy matter that will burn up anything that passes through (firewall hypothesis), or a ring of low energy quantum particles that stores traces of everything it swallows up (Stephen Hawking’s ‘Soft Hair on Black Holes’ theory).

So which one is correct? No one really knows for sure. But now we might have better means to find out.

First discovered in February of this year, information from the Laser Interferometer Gravitational-Wave Observatory (LIGO) revealed the presence of ‘echoes’ that suggests a part of Einstein’s prediction was inaccurate – waves shouldn’t have been detected because isn’t a black hole supposed to make matter completely disappear? Interestingly, two other gravitational wave events were detected since then. And now the implications can’t simply be dismissed.

After poring through LIGO’s data, a team of physicists (Jahed Abedi, Niayesh Afshordi and Hannah Dykaar) are claiming that the gravitational waves they discovered could directly contradict Einstein – that his Theory of Relativity might not actually be ‘General’ but ‘Specific’. Why? Because it doesn’t hold up in extreme scenarios, specifically when it comes to black holes.

So far, the team’s findings have been published on arXiv.org. It’s only a beginning and would still require further studies and deeper investigation before being credible enough to be submitted for peer review. A lot can happen in between. The ‘echoes’ can just go away and simply be attributed to incorrect calculations. Or the echoes can be proven as real and existent, in which case, we might be looking at the dawn of a new age in physics.

source

LIGO black hole echoes hint at general-relativity breakdown

 

[Stormer0628]

understanding your universe

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First of all, don’t panic.

I’m going to try in this post to introduce you to quantum field theory, which is probably the deepest and most intimidating set of ideas in graduate-level theoretical physics. But I’ll try to make this introduction in the gentlest and most palatable way I can think of: with simple-minded pictures and essentially no math.

To set the stage for this first lesson in quantum field theory, let’s imagine, for a moment, that you are a five-year-old child. You, the child, are talking to an adult, who is giving you one of your first lessons in science. Science, says the adult, is mostly a process of figuring out what things are made of. Everything in the world is made from smaller pieces, and it can be exciting to find out what those pieces are and how they work. A car, for example, is made from metal pieces that fit together in specially-designed ways. A mountain is made from layers of rocks that were pushed up from inside the earth. The earth itself is made from layers of rock and liquid metal surrounded by water and air.

This is an intoxicating idea: everything is made from something.

So you, the five-year-old, start asking audacious and annoying questions. For example:

What are people made of?
People are made of muscles, bones, and organs.
Then what are the organs made of?
Organs are made of cells.
What are cells made of?
Cells are made of organelles.
What are organelles made of?
Organelles are made of proteins.
What are proteins made of?
Proteins are made of amino acids.
What are amino acids made of?
Amino acids are made of atoms.
What are atoms made of?
Atoms are made of protons, neutron, and electrons.
What are electrons made of?
Electrons are made from the electron field.
What is the electron field made of?
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And, sadly, here the game must come to an end, eight levels down. This is the hard limit of our scientific understanding. To the best of our present ability to perceive and to reason, the universe is made from fields and nothing else, and these fields are not made from any smaller components.

But it’s not quite right to say that fields are the most fundamental thing that we know of in nature. Because we know something that is in some sense even more basic: we know the rules that these fields have to obey. Our understanding of how to codify these rules came from a series of truly great triumphs in modern physics. And the greatest of these triumphs, as I see it, was quantum mechanics.

In this post I want to try and paint a picture of what it means to have a field that respects the laws of quantum mechanics. In a previous post, I introduced the idea of fields (and, in particular, the all-important electric field) by making an analogy with ripples on a pond or water spraying out from a hose. These images go surprisingly far in allowing one to understand how fields work, but they are ultimately limited in their correctness because the implied rules that govern them are completely classical. In order to really understand how nature works at its most basic level, one has to think about a field with quantum rules.

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The first step in creating a picture of a field is deciding how to imagine what the field is made of. Keep in mind, of course, that the following picture is mostly just an artistic device. The real fundamental fields of nature aren’t really made of physical things (as far as we can tell); physical things are made of them. But, as is common in science, the analogy is surprisingly instructive.

So let’s imagine, to start with, a ball at the end of a spring. Like so:

This is the object from which our quantum field will be constructed. Specifically, the field will be composed of an infinite, space-filling array of these ball-and-springs:

To keep things simple, let’s suppose that, for some reason, all the springs are constrained to bob only up and down, without twisting or bending side-to-side. In this case the array of springs can be called, using the jargon of physics, a scalar field. The word “scalar” just means a single number, as opposed to a set or an array of multiple numbers. So a scalar field is a field whose value at a particular point in space and time is characterized only by a single number. In this case, that number is the height of the ball at the point in question. (You may notice that what I described in the previous post was a vector field, since the field at any given point was characterized by a velocity, which has both a magnitude and a direction.)

In the picture above, the array of balls-and-springs is pretty uninteresting: each ball is either stationary or bobs up and down independently of all others. In order to make this array into a bona fide field, one needs to introduce some kind of coupling between the balls. So, let’s imagine adding little elastic bands between them:

Now we have something that we can legitimately call a field. (My quantum field theory book calls it a “mattress”.) If you disturb this field – say, by tapping on it at a particular location – then it will set off a wave of ball-and-spring oscillations that propagates across the field. These waves are, in fact, the particles of field theory. In other words, when we say that there is a particle in the field, we mean that there is a wave of oscillations propagating across it.

These particles (the oscillations of the field) have a number of properties that are probably familiar from the days when you just thought of particles as little points whizzing through empty space. For example, they have a well-defined propagation velocity, which is related to the weight of each of the balls and the tightness of the springs and elastic bands. This characteristic velocity is our analog of the “speed of light”. (More generally, the properties of the springs and masses define the relationship between the particle’s kinetic energy and its propagation velocity, like the KE=1/2mv[SUP]2[/SUP] of your high school physics class.) The properties of the springs also define the way in which particles interact with each other. If two particle-waves run into each other, they can scatter off each other in the same way that normal particles do.

(A technical note: the degree to which the particles in our field scatter upon colliding depends on how “ideal” the springs are. If the springs are perfectly described by Hooke’s law, which says that the restoring force acting on a given ball is linearly proportional to the spring’s displacement from equilibrium, then there will be no interaction whatsoever. For a field made of such perfectly Hookean springs, two particle-waves that run into each other will just go right through each other. But if there is any deviation from Hooke’s law, such that the springs get stiffer as they are stretched or compressed, then the particles will scatter off each other when they encounter one another.)

Finally, the particles of our field clearly exhibit “wave-particle duality” in a way that is easy to see without any philosophical hand-wringing. That is, our particles by definition are waves, and they can do things like interfere destructively with each other or diffract through a double slit.

All of this is very encouraging, but at this point our fictitious field lacks one very important feature of the real universe: the discreteness of matter. In the real world, all matter comes in discrete units: single electrons, single photons, single quarks, etc. But you may notice that for the spring field drawn above, one can make an excitation with completely arbitrary magnitude, by tapping on the field as gently or as violently as one wants. As a consequence, our (classical) field has no concept of a minimal piece of matter, or a smallest particle, and as such it cannot be a very good analogy to the actual fields of nature.

***​

To fix this problem, we need to consider that the individual constituents of the field – the balls mounted on springs – are themselves subject to the laws of quantum mechanics.

A full accounting of the laws of quantum mechanics can take some time, but for the present pictorial discussion, all you really need to know is that a quantum ball on a spring has two rules that it must follow. 1) It can never stop moving, but instead must be in a constant state of bobbing up and down. 2) The amplitude of the bobbing motion can only take certain discrete values:

This quantization of the ball’s oscillation has two important consequences. The first consequence is that, if you want to put energy into the field, you must put in at least one quantum. That is, you must give the field enough energy to kick at least one ball-and-spring into a higher oscillation state. Arbitrarily light disturbances of the field are no longer allowed. Unlike in the classical case, an extremely light tap on the field will produce literally zero propagating waves. The field will simply not accept energies below a certain threshold. Once you tap the field hard enough, however, a particle is created, and this particle can propagate stably through the field.

This discrete unit of energy that the field can accept is what we call the rest mass energy of particles in a field. It is the fundamental amount of energy that must be added to the field in order to create a particle. This is, in fact, how to think about Einstein’s famous equation E=mc[SUP]2[/SUP] in a field theory context. When we say that a fundamental particle is heavy (large mass m), it means that a lot of energy has to be put into the field in order to create it. A light particle, on the other hand, requires only a little bit of energy.

(By the way, this why physicists build huge particle accelerators whenever they want to study exotic heavy particles. If you want to create something heavy like the Higgs boson, you have to hit the Higgs field with a sufficiently large (and sufficiently concentrated) burst of energy to give the field the necessary one quantum of energy.)

The other big implication of imposing quantum rules on the ball-and-spring motion is that it changes pretty dramatically the meaning of empty space. Normally, empty space, or vacuum, is defined as the state where no particles are around. For a classical field, that would be the state where all the ball-and-springs are stationary and the field is flat. Something like this:

But in a quantum field, the ball-and-springs can never be stationary: they are always moving, even when no one has added enough energy to the field to create a particle. This means that what we call vacuum is really a noisy and densely energetic surface:

This random motion (called vacuum fluctuations) has a number of fascinating and eminently noticeable influences on the particles that propagate through the vacuum. To name a few, it gives rise to the Casimir effect (an attraction between parallel surfaces, caused by vacuum fluctuations pushing them together) and the Lamb shift (a shift in the energy of atomic orbits, caused by the electron getting buffeted by the vacuum).

In the jargon of field theory, physicists often say that “virtual particles” can briefly and spontaneously appear from the vacuum and then disappear again, even when no one has put enough energy into the field to create a real particle. But what they really mean is that the vacuum itself has random and indelible fluctuations, and sometimes their influence can be felt by the way they kick around real particles.

That, in essence, is a quantum field: the stuff out of which everything is made. It’s a boiling sea of random fluctuations, on top of which you can create quantized propagating waves that we call particles.

I only wish, as a primarily visual thinker, that the usual introduction to quantum field theory didn’t look quite so much like this. Because behind the equations of QFT there really is a tremendous amount of imagination, and a great deal of wonder.

SOURCE

 

[Stormer0628]

2016 science review

GRAVITATIONAL WAVES:
A LOOK BACK AT THE BIGGEST SCIENTIFIC STORY OF 2016​

Scientists detected ripples in space time called gravitational waves for the first time last year, almost 100 years after Einstein first predicted them.

It was, and still is, a huge deal, because now we have an entirely new way to study the Universe—and by most accounts, it was the biggest science story of 2016. But what you didn't read in all those articles and headlines was how absolutely absurd the entire process of detecting those gravitational waves really was.

Gravitational waves were very, very hard to find—so hard, in fact, it took the world's second largest vacuum, the smoothest mirrors on the planet, a laser so powerful it could fry your head instantly, and decades of research to even begin to have a chance of proving they exist. Check it out:

 

[Stormer0628]

the universe: ultimate reality

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We've arranged a civilization in which most crucial elements profoundly depend on science and technology. We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster…. Sooner or later, this combustible mixture of ignorance and power is going to blow up in our faces.
– C. Sagan, The Demon-Haunted World: Science as a Candle in the Dark (Random House, New York, 1995), p. 26

Particle states are never observable—they are an idealization which leads to a plethora of misunderstandings about what is going on in quantum field theory. The theory is about fields and their local excitations. That is all there is to it.
– M. Redhead, “More ado about nothing,” Foundations of Physics 25 (1), 123-137 (1995):

In quantum field theory, the primary elements of reality are not individual particles, but underlying fields. Thus, for example, all electrons are but excitations of an underlying field, the electron field, which fills all space and time.
– F. Wilczek, "Mass Without Mass I: Most of Matter," Physics Today 52 (11), 11-13 (1999)

Just as there is an electromagnetic field whose energy and momentum come in tiny bundles called photons, so there is an electron field whose energy and momentum and electric charge are found in the bundles we call electrons, and likewise for every species of elementary particles. The basic ingredients of nature are fields; particles are derivative phenomena.
– S. Weinberg, Facing Up: Science and its Cultural Adversaries (Harvard University Press, Cambridge, MA, 2001)​

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We frequently hear the complaint that quantum physics is a difficult subject, one that seemingly forces us to divorce our knowledge of the deep, ultimate, underlying reality with common-sense everyday reality as we know it. But this does not need to be the case: if we accept the idea that fields rather than particles are the fundamental essence of reality, we remove the anomalies that we associate with quantum physics. Experiment and theory imply unbounded fields, not bounded particles, are fundamental. Particles are epiphenomena arising from fields. Can you wrap your head around those statements?

For starters, the field for an electron is the electron; each electron extends over both slits in the 2-slit experiment and spreads over the entire pattern; and quantum physics is about interactions of microscopic systems with the macroscopic world rather than just about measurements. It's important to clarify this issue because textbooks still teach a particles- and measurement-oriented interpretation that contributes to bewilderment among students and pseudoscience among the public.

In more ways than one, part of the blame could be traced to the way we are trapped by the mindset put in place long ago by Democritus in his particle-based interpretation of the atom. Newton started to doubt this, but hardly voiced his ideas in public. It took Faraday and Maxwell to set things straight by recognizing the primacy of fields over particles, once serious scientists started to cast serious suspicion over the idea of the ether. The quandary persists because even famous scientists like Feynman holds on to the central tenet of a particle-based reality. And lacking better persuasion, the media, schools, and pseudo-thinkers perpetuate the confusing state of affairs.

Physicists are schizophrenic about fields and particles. At the high-energy end, most quantum field theorists agree for good reasons that relativistic quantum physics is about fields and that electrons, photons, and so forth are merely excitations (waves) in the fundamental fields. But at the low-energy end, most nonrelativistic quantum physics (NRQP) education and popular talk is about particles. Working physicists, teachers, and NRQP textbooks treat electrons, photons, protons, atoms, etc. as particles that exhibit paradoxical behavior. Yet NRQP is the nonrelativistic limit of the broader relativistic theory, namely QFTs that for all the world appear to be about fields. If QFT is about fields, how can its restriction to nonrelativistic phenomena be about particles? Do infinitely extended fields turn into bounded particles as the energy drops?

As an example of the field/particle confusion, the 2-slit experiment is often considered paradoxical—it is a paradox if one assumes that the universe is made of particles. For Richard Feynman, this paradox was unavoidable. Feynman was a particles guy. As Frank Wilczek puts it, "uniquely (so far as I know) among physicists of high stature, Feynman hoped to remove field-particle dualism by getting rid of the fields." As a preface to his lecture about this experiment, Feynman advised his students,

Do not take the lecture too seriously, feeling that you really have to understand in terms of some model what I am going to describe, but just relax and enjoy it. I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself, if you can possibly avoid it, "But how can it be like that?" because you will get "down the drain," into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that. ​

Faraday and Maxwell created one of history's most telling changes in our physical worldview: the change from particles to fields. As Albert Einstein put it, “Before Maxwell, Physical Reality … was thought of as consisting in material particles…. Since Maxwell's time, Physical Reality has been thought of as represented by continuous fields…, and not capable of any mechanical interpretation. This change in the conception of Reality is the most profound and the most fruitful that physics has experienced since the time of Newton.”

As the preceding quotation shows, Einstein supported a "fields are all there is" view of classical (but not necessarily quantum) physics. He put the final logical touch on classical fields in his 1905 paper proposing the special theory of relativity, where he wrote "The introduction of a 'luminiferous' ether will prove to be superfluous." For Einstein, there was no material ether to support light waves. Instead, the "medium" for light was space itself. That is, for Einstein, fields are states or conditions of space. This is the modern view. The implication of special relativity (SR) that energy has inertia further reinforces both Einstein's rejection of the ether and the significance of fields. Since fields have energy, they have inertia and should be considered "substance like" themselves rather than simply states of some substance such as ether.

Quantized Matter Fields
QFT puts matter on the same all-fields footing as radiation. In fact, it's a general principle of all QFTs that fields are all there is. For example the Standard Model, perhaps the most successful scientific theory of all time, is a QFT. But if fields are all there is, where do electrons and atoms come from? QFT's answer is that they are field quanta, but quanta of matter fields rather than quanta of force fields.

Thus the quantum theory of electromagnetic radiation is a reformulation of classical electromagnetic theory to account for quantization--the "bundling" of radiation into discrete quanta. It remains, like the classical theory, a field theory.

For over three decades, the Standard Model--a QFT--has been our best theory of the microscopic world. It's clear from the structure of QFTs that they actually are field theories, not particle theories in disguise.

Quantum fields have one particle-like property that classical fields don't have: they are made of countable quanta. Thus quanta cannot partly vanish but must (like particles) be entirely and instantly created or destroyed. Quanta carry energy and momenta and can thus "hit like a particle." Following three centuries of particle-oriented Newtonian physics, it's no wonder that it took most of the 20th century to come to grips with the field nature of quantum physics.

"Fields are all there is" should be understood literally. For example, it's a common misconception to imagine a tiny particle imbedded somewhere in the Schroedinger field. There is no particle. An electron is its field.

The Two-Slit Experiment Is Rid of Anomaly Under Pure Field Interpretation
How does one quantum get information as to how many slits are open? If a quantum is a field that is extended over both slits, there's no problem. But could a particle coming through just one slit obtain this information by detecting physical forces from the other, relatively distant, slit? The effect is the same for photons and electrons, and the experiment has been done with neutrons, atoms, and many molecular types, making it difficult to imagine gravitational, EM, or nuclear forces causing such a long-distance force effect. What more direct evidence could there be that a quantum is an extended field? Thus we cannot explain the extended patterns by assuming each quantum is a particle, but we can explain the patterns by assuming each quantum is a field.

THE QUANTUM VACUUM
Because it has energy and nonvanishing expectation values, the QFT vacuum is embarrassing for particle interpretations. If one believes particles to be the basic reality, then what is it that has this energy and these values in the state that has no particles? Because it is the source of empirically verified phenomena such as the Lamb shift, the Casimir effect, and the electron's anomalous magnetic moment, this "state that has no particles" is hard to ignore.

Both theory and experiment demonstrate that the quantized EM field can never be sharply (with probability one) zero, but rather that there must exist, at every spatial point, at least a randomly fluctuating "vacuum field" having no quanta. Again, a quantized field is equivalent to a set of oscillators. An actual mechanical oscillator cannot be at rest in its ground state because this would violate the uncertainty principle

THE UNRUH EFFECT
QFT predicts that an accelerating observer in vacuum sees quanta that are not there for an inertial observer of the same vacuum. More concretely, consider Mort who moves at constant velocity in Minkowski space-time, and Velma who is uniformly accelerating (i.e. her acceleration is unchanging relative to her instantaneous inertial rest frame). If Mort finds himself in the quantum vacuum, Velma finds herself bathed in quanta--her “particle” detector clicks. Quantitatively, she observes a thermal bath of photons having the Planck radiation spectrum. This prediction might be testable in high energy hadronic collisions, and for electrons in storage rings. In fact it appears to have been verified years ago in the Sokolov-Ternov effect.

The Unruh effect lies at the intersection of QFT, SR, and general relativity. Combined with the equivalence principle of general relativity, it entails that strong gravitational fields create thermal radiation. This is most pronounced near the event horizon of a black hole, where a stationary (relative to the event horizon) Velma sees a thermal bath of particles that then fall into the black hole, but some of which can, under the right circumstances, escape as Hawking radiation. The Unruh effect is counterintuitive for a particle ontology, as it seems to show that the particle concept is observer-dependent. If particles form the basic reality, how can they be present for the accelerating Velma but absent for the nonaccelerating Mort who observes the same space-time region? But if fields are basic, things fall into place: Both experience the same field, but Velma's acceleration promotes Mort's vacuum fluctuations to the level of thermal fluctuations. The same field is present for both observers, but an accelerated observer views it differently.

Single-Quantum Nonlocality
Nonlocality is pervasive, arguably the characteristic quantum phenomenon. It would be surprising, then, if it were merely an "emergent" property possessed by two or more quanta but not by a single quantum.

Single-photon nonlocality was first described in detail by Tan et. al. in 1991. But nonlocality normally involves two entangled quantum entities. With just one photon, what was there to entangle with? If photons are field mode excitations, the answer is natural: the entanglement was between two quantized field modes, with one of the modes happening to be in the vacuum state. Like all fields, each mode fills space, making nonlocality between modes more intuitive than nonlocality between particles: If a space-filling mode were to instantly change states, the process would obviously be nonlocal. This highlights the importance of thinking of quantum phenomena in terms of fields.

CONCLUSION
Overwhelming agreement in theory and experiments are grounds to conclude that all the fundamental constituents of quantum physics are fields rather than particles.

Textbooks need to reflect that fields, not particles, form our most fundamental description of nature.

It's not only an academic matter. This confusion has huge real-life implications. In a world that cries out for general scientific literacy, quantum-inspired pseudoscience has become dangerous to science and society. What the Bleep Do We Know, a popular 2004 film, won several film awards and grossed millions of dollars; it's central tenet is that we create our own reality through consciousness and quantum mechanics. It features physicists saying things like "The material world around us is nothing but possible movements of consciousness," it purports to show how thoughts change the structure of ice crystals, and it interviews a 35,000 year-old spirit "channeled" by a psychic. "Quantum mysticism" ostensibly provides a basis for mind-over-matter claims from ESP to alternative medicine, and provides intellectual support for the postmodern assertion that science has no claim on objective reality. According to the popular television physician Deepak Chopra, "quantum healing" can cure all our ills by the application of mental power. Chopra's book Ageless Body, Timeless Mind, a New York Times Bestseller that sold over two million copies worldwide, is subtitled The Quantum Alternative to Growing Old. Quantum Enigma, a highly advertised book from Oxford University Press that's used as a textbook in liberal arts physics courses at the University of California and elsewhere, bears the sub-title Physics Encounters Consciousness. It's indeed scandalous when librarians and book store managers wonder whether to shelve a book under "quantum physics," "religion," or "new age."

But What to Make of the Macroworld?
Macroscopic "particles" are nothing but bound bundles of excited fields (particles=waves).

The reason that large, complicated things like yourself can exist is that the particles (waves) that comprise you are not free. They exist in bound states of multiple particles that are held together by inter-particle forces. These forces bind the particles, which would otherwise freely propagate in straight lines, into stable orbits around each other. The middle school picture of these stable orbits is something like a planet orbiting around a sun. But the grown-up picture looks much more like a standing wave. Such standing waves are made of the same stuff as propagating waves, but they are just pulled into confined spaces by external forces.

 

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Empty space is never empty....

And watch out for scientists at the University of Konstanz, Germany: for some years now, they have been doing something with the nothingness of space and always come out with some award-winning works in the process.

In their latest tinkering with the nothingness of space, they've created what amounts to traffic with virtual particles, and the experiment promises to be of important use in the hunt for more gravitational waves, something that has caught the fancy of people lately with headline-grabbing results—twice. The work of these scientists from Konstanz, however, promises to populate gravitational wave detection by a few factor.

Traffic could be visualized as jam-packed at the front, with lesser cars incoming at the tail-end. Using light pulses, the scientists managed to squeeze virtual particles with high density at one part, while making the other end with less density. The result is equivalent to redistribution of vacuum fluctuations. The trick they used is astonishing as it is weird.

Again, these so-called “virtual” particles have a real effect on the universe. For instance, the virtual particles cause a ghostlike but measurable force, called Casimir force, that pushes two mirrors together in a vacuum. And the appearance of virtual particles on the edge of a black hole is what causes Hawking radiation.

Like dogs snapping at the wheels of a passing car, virtual particles also worry the edges of passing photons. This interaction slightly muddles the photon’s shape, distorting it from a perfect sine wave to something a bit fuzzier.

In October 2015, Alfred Leitenstorfer and a University of Konstanz team made one of the first direct detections of virtual particles by mapping out this photon fuzziness.

Leitenstorfer’s team have actually managed to manipulate that fuzziness, decreasing it in some locations along the light wave and increasing it in others.

The result is a so-called “squeezed light” wave—one that’s very noisy in some parts, but extremely quiet in others. The quiet regions are even quieter than the Uncertainty Principle would say is possible—a feature that could make for incredibly precise measuring instruments.

The experiment was based on a technique physicists have used since the 1980s to probe one pulse of light with another by firing them into a special crystal.

Via the crystal, the two light pulses interact, slightly changing the way the shorter “probe” pulse oscillates. In effect, the probe pulse “feels” the wiggle of the other, longer, light wave.

By changing the timing of the two pulses, and repeating a few million times, Leitenstorfer’s team mapped out the wiggle of light—and so measure its noise at different positions. So far, this is just what the team achieved in 2015.

Incredibly, this time around, the team used the intensity of the probe pulse to disturb the vacuum itself, causing a build-up of virtual particles in some regions and a depletion in others.

The virtual particles, so rearranged, interact differently with the longer light wave. In built up pockets they make the light wave noisier while in the depleted regions the light wave is quieter.

In a perspective piece for Nature, Marco Bellini, a physicist in the extreme light group at the Italian National Institute of Optics, points out that selecting these “quiet moments” could lead to gravitational wave detectors working in “a new regime of exceptional precision and sensitivity.”

Bottom line: manipulating nothingness will help us listen out for even fainter rumbles of black holes colliding a billion light years distant. How about that for something out of nothing?

The new experimental approach to quantum electrodynamics is only the third method to study the quantum state of light. Now fundamental questions arise: what exactly is the quantum character of light? What actually is a photon? Concerning the last question, that much is clear to the Konstanz physicists: instead of a quantized packet of energy, it is rather a measure for the local quantum statistics of electromagnetic fields in spacetime [see previous post: There Are No Particles, There Are Only Waves.]

 

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Perpetual motion without energy. You frequently hear them in fringe science, not mainstream. Not anymore.

NOW researchers have finally created time crystals—strange crystals whose atomic structure repeats not just in space, but also in time, putting them in perpetual motion without energy.

They have reported in detail how to make and measure these bizarre crystals—and two independent teams of scientists claim they've actually created time crystals in the lab based off this blueprint, confirming the existence of an entirely new form of matter.

The discovery might sound pretty abstract, but it heralds in a whole new era in physics—for decades we've been studying matter that's defined as being "in equilibrium," such as metals and insulators.

But it's been predicted that there are many more strange types of matter out there in the Universe that aren't in equilibrium that we haven't even begun to look into, including time crystals. And now we know they're real.

The fact that we now have the first example of non-equilibrium matter could lead to breakthroughs in our understanding of the world around us, as well as new technology such as quantum computing.

"This is a new phase of matter, period, but it is also really cool because it is one of the first examples of non-equilibrium matter," said lead researcher Norman Yao from the University of California, Berkeley.

"For the last half-century, we have been exploring equilibrium matter, like metals and insulators. We are just now starting to explore a whole new landscape of non-equilibrium matter."

First predicted by Nobel-Prize winning theoretical physicist Frank Wilczek back in 2012, time crystals are structures that appear to have movement even at their lowest energy state, known as a ground state.

Usually when a material is in ground state, also known as the zero-point energy of a system, it means movement should theoretically be impossible, because that would require it to expend energy.

But Wilczek predicted that this might not actually be the case for time crystals.

Normal crystals have an atomic structure that repeats in space—just like the carbon lattice of a diamond. But, just like a ruby or a diamond, they're motionless because they're in equilibrium in their ground state.

But time crystals have a structure that repeats in time, not just in space. And it keep oscillating in its ground state.

Imagine it like jelly—when you tap it, it repeatedly jiggles. The same thing happens in time crystals, but the big difference here is that the motion occurs without any energy.

A time crystal is like constantly oscillating jelly in its natural, ground state, and that's what makes it a whole new form of matter - non-equilibrium matter. It's incapable of sitting still.

But it's one thing to predict these time crystals exist, it's another entirely to make them, which is where the new study comes in.

Yao and his team have now come up with a detailed blueprint that describes exactly how to make and measure the properties of a time crystal, and even predict what the various phases surrounding the time crystals should be - which means they've mapped out the equivalent of the solid, liquid, and gas phases for the new form of matter.

 

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Like water these days, hydrogen is proving to be a strange animal indeed: not only does it give us an idea about the fundamental properties of the early universe, but it also makes up a critical part of life as we know it. Now add this: it's also managed to become a metal, and this could usher mankind into virtual new age. How? And how did it happen?

By subjecting molecular hydrogen, a gas, to ungodly pressures higher than those found at the Earth’s core, that's how it happened, and Harvard researchers were the ones who have accomplished the impossible this time, turning the lightest element into a metal. This is now the rarest and possibly the most expensive material on the planet. This may soon change as metal hydrogen moves from the stuff of alchemy to a critical resource in mankind’s quest of becoming an interstellar species.

The new material was created by Isaac Silvera, the Thomas D. Cabot Professor of the Natural Sciences, and post-doctoral fellow Ranga Dias. For over a hundred years scientists knew that it was theoretically possible to turn hydrogen into a metal if you compress it under the right condition but no one was able to prove it until recently.

“This is the holy grail of high-pressure physics,” Silvera said. “It’s the first-ever sample of metallic hydrogen on Earth, so when you’re looking at it, you’re looking at something that’s never existed before.... It’s a very fundamental and transformative discovery.​

A tiny hydrogen sample was squeezed with a pressure of 495 gigapascals, or more than 71.7 million pounds-per-square-inch. The sample was also chilled to just above absolute zero. At such a tremendous strain, the molecular hydrogen breaks down and the dissociative elements turn into atomic hydrogen, which is a metal. When the researchers stopped the experiment, everyone was dumbstruck when they saw their sample was shining!

Findings were reported in the journal Science.

What makes metallic hydrogen so interesting is the fact that it may be meta-stable, as reported by some models. In other words, once you lift the immense pressure that went into birthing the metal, the hydrogen will stay a metal. It’s akin to how graphite under immense heat and pressure turns into a diamond and remains in this configuration even after said heat and pressure is removed.

What makes metallic hydrogen so interesting is the fact that it may be meta-stable, as reported by some models. In other words, once you lift the immense pressure that went into birthing the metal, the hydrogen will stay a metal. It’s akin to how graphite under immense heat and pressure turns into a diamond and remains in this configuration even after said heat and pressure is removed.

This feature has excited a lot of people, both in science and industry. That’s because metallic hydrogen has a couple of very appealing features. It’s predicted that metallic hydrogen could act as a superconductor at room temperatures, allowing electricity to flow through it with zero loss. Right now, as much as 15 percent of all the electricity we generate is lost down power lines.

It’s in transportation, however, that metallic hydrogen could be revolutionary. Its superconductive properties could make high-speed trains that use magnetic levitation a common sight. If used as a fuel, metallic hydrogen would be four times more powerful than the best propellant at our disposal today.

“It takes a tremendous amount of energy to make metallic hydrogen,” Professor Silvera said.

“And if you convert it back to molecular hydrogen, all that energy is released, so it would make it the most powerful rocket propellant known to man, and could revolutionize rocketry. That would easily allow you to explore the outer planets.”​

Bear in mind that Silvera has been trying to create metallic hydrogen for 45 years.

"The hydrogen went from being transparent, to non-transparent and black, and suddenly it became lustrous," he explained. "We could actually see it become a metal." Imagine how his face had looked that very moment.

 

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Has Dogma Derailed the Search for Dark Matter?
by Pavel Kroupa, University of Bonn

A Hubble composite image shows a ring of ‘dark matter’ in the galaxy cluster Cl 0024+17.
Courtesy NASA, ESA, M.J. Jee and H. Ford. (Credit: Johns Hopkins University)​

ACCORDING TO mainstream researchers, the vast majority of the matter in the Universe is invisible: it consists of dark-matter particles that do not interact with radiation and cannot be seen through any telescope. The case for dark matter is regarded as so overwhelming that its existence is often reported as fact. Lately, though, cracks of doubt have started to appear. In July, the LUX experiment in South Dakota came up empty in its search for dark particles – the latest failure in a planet-wide, decades-long effort to find them. Some cosmic surveys also suggest that dark particles cannot be there, which is especially confounding since astronomical observations were the original impetus for the dark-matter hypothesis.

The issues at stake are huge. Acceptance of dark matter has influenced scientific thinking about the birth of the Universe, the evolution of galaxies and black holes, and the fundamental laws of physics. Yet even within academic circles, there is a lot of confusion about dark matter, with evidence and interpretation often conflated in misleading and unproductive ways.

The modern argument for dark matter begins with the assumption that the Universe is described by Albert Einstein’s field equation of general relativity, and that Newtonian gravitation (that is, gravity as we measure it on Earth) is valid in all places at all times. It further assumes that all the matter in the Universe was produced at the Big Bang. Simulations based on that scenario make specific predictions about how quickly cosmic structures form, and also about the motions of galaxies and stars within galaxies. When compared with observations, those simulations indicate that gravitational effects in the real world must be stronger than can be accounted for by the matter we know. Dark matter provides the additional gravitational pull to bring model and reality broadly into alignment. Researchers now routinely take this model – Einstein plus dark matter, often called the ‘null hypothesis’ – as their starting point and then perform detailed calculations of galactic systems to test it.

This is how I stumbled into the field in the late 1990s. I was studying the dynamics of small satellite galaxies as they orbit our galaxy, the Milky Way. From observation, we expected that these satellite galaxies must contain a lot of dark matter, from 10 to 1,000 times as much as their visible, normal matter. During my calculations, I made a perplexing discovery. My simulations produced satellite galaxies that look much like the ones actually observed, but they contained no dark matter. It seemed that observers had made wrong assumptions about the way the stars move within the satellite galaxies; dark matter was not required to explain their structures.

I published these results and quickly learned what it meant to not follow the mainstream. Despite the critiques I received, I followed up on these results some years later and uncovered another major inconsistency. The known satellite galaxies of the Milky Way are distributed in a vast polar disk running perpendicular to the orientation of our galaxy. But dark-matter dominated models predict that primordial dwarf galaxies should have fallen into the Milky Way from random directions, so should follow a spheroidal distribution. This finding set off a major debate, with the mainstream researchers arguing that this disk of satellites does not really exist; that it is not significant; or that it cannot be used to test models.

Meanwhile, astronomers kept identifying new dwarf satellite galaxies that made the disk structure even more pronounced. Rodrigo Ibata at Strasbourg Observatory showed that our neighbouring galaxy, Andromeda, has an even more pronounced disk of satellite galaxies. My team at the University of Bonn then found that the disks of satellites around Andromeda and the Milky Way appear to be aligned, and that the whole structure of our Local Group of galaxies is highly symmetrical. Ibata and his team subsequently confirmed that the observed distribution of matter does not match dark-matter predictions out to distances of 24 million light years.

More problems: when a dwarf galaxy with a dark-matter halo passes through the dark-matter halo of a large galaxy, the dark-matter halos should absorb the energy of motion such that the dwarf galaxy would fall to the centre of the large galaxy, somewhat like a marble dropped in honey. This is a well-studied process known as dynamical friction but it is not evident in the astronomical data, suggesting that the expected dark-matter haloes do not exist. Most recently, Stacy McGaugh at Case Western Reserve University in Ohio and his team documented that the pattern of rotation in spiral galaxies seems to precisely follow the pattern of the visible matter alone, posing yet another challenge to the null hypothesis.

In light of these findings, I argue that the null hypothesis must be discarded. What can it be replaced with? The first step is that we need to revisit the validity of Newton’s universal law of gravitation. Starting in the 1980s, Mordehai Milgrom at the Weizmann Institute in Israel showed that a small generalisation of Newton’s laws can yield the observed dynamics of matter in galaxies and in galaxy clusters without dark matter. This approach is broadly known as MOND (MOdified Newtonian Dynamics). Milgrom’s correction allows gravitational attraction to fall off with distance more slowly than expected (rather than falling off with the square of distance as per Newton) when the local gravitational acceleration falls below an extremely low threshold. This threshold could be linked to other cosmological properties such as the ‘dark energy’ that accounts for the accelerating expansion of the Universe.

These links suggest a deeper fundamental theory of space, time and matter, which has not yet been formulated. Few researchers have pursued such an alternative hypothesis, partly because it seems to question the validity of general relativity. However, this need not be the case; additional physical effects related to the quantum physics of empty space and to the nature of mass might be playing a role. MOND also faces its own challenges, both observational and theoretical. Its biggest drawback is that MOND is not yet well-anchored to general relativity. Because of the prevailing dark-matter dogma, few scientists dare to build on Milgrom’s ideas. Young researchers risk not getting a job; senior researchers face losing out on grants.

Together with Benoit Famaey in Strasbourg, my small group in Bonn is moving ahead anyway. Yes, we are being punished by not being granted some research money, but in our computers we are discovering a universe full of galaxies that look just like the real things – and this is awfully exciting. MOND could be the next great advance in gravitational research, building on the work of Newton and Einstein. This year’s detection of gravitational waves allows exciting new possibilities. Those waves have travelled cosmological distances, and so have passed through regions where Milgrom’s low-threshold effect should be significant. Gravitational wave studies will provide the kind of data needed to refine our ideas about MOND, and to explore cosmological thinking outside the constraints of dogma.

SOURCE

This article was originally published at Aeon and has been republished under Creative Commons.

NOTE: Another alternative to MOND, is of course Verlinde's take on the matter, discussed HERE

 

[nhile101]

Does the Emergence of the Universe Require a Creator?

http://www.symbianize.com/attachment.php?attachmentid=1159397&stc=1
In a word: no.
So, if a Creator is not needed for the universe to begin (or life, for that matter),
then what is left for them to create?​

SUMMARY:

• The key: if you have a natural mechanism that pretty much shows you how matter and everything else is created, then what is left to do is to find the evidence that it is in fact the very source of the universe itself.
• This natural mechanism, the spontaneous creation or annihilation of matter via quantum fluctuations, exists now and presumably for all eternity, in every pocket of the universe, or the larger cosmos if you consider the plausibility of a multiverse. And this mechanism could be verified by any experiment, which itself is relatively easy to set up. You might have heard of the Casimir experiment—the setup would be approximately the same.
• The relic microwave background radiation (CMB) is that evidence: the latest CMB data actually allows us to peer within the first trillionth of a second of the first moments—beyond the 300,000 years previous limit—of the emergence of the universe. What CMB represents—what are seen—within those moments are the quantum fluctuations that made all the universe possible. The universe itself is just those quantum fluctuations, magnified to the resolution of the current age of the universe. It bears repeating: what we now see as the universe is just the enlarged, magnified picture of the quantum fluctuations within the first trillionth of a second in the age of the universe.
• Quantum fluctuations are initial conditions: you cannot peer—or there is nothing more to see—further beyond it. They represent the ultimate beginning of what we know as our universe. Of us.
• “ABSOLUTE NOTHING” does not exist; it is a misleading mental construct resulting from the limited capabilities of our sensory organs. This is the reason our universe’s local version of space is sometimes called “false vacuum.”
• If our sensory organs were not limited, we would see a panoply of quantum fields permeating our immediate surroundings and beyond to all the parts of the universe. It means there is no “nothing” per se; rather, there has in fact always been something in the universe from the very beginning
• These fields include electroweak fields, strong nuclear force fields, gravity fields, the Higgs boson field, among many others
• Beyond these fields, quantum fluctuations produce pairs of particles and antiparticles.
• In the observed universe today, these particles and antiparticles always annihilate each other and leave behind radiations
• In the vicinity of black holes, however, pairs of particles and antiparticles do no always have time to annihilate one another because the black hole’s intense gravity absorbs one of the pair before it could reach the other one
• In the same way in the earliest time of the inflationary period, the ripping apart of space, which is faster than the speed of light, also makes it impossible for any pair to reach and annihilate one another
• The leftover particles from the initial inflationary conditions became what we know as matter and the rest of the structures of the universe—from planets, galaxies, superclusters, to the cosmic web with its cosmic filaments connecting all the structures of the universe
• The unique density signatures reflecting the original distribution of the first particles are now magnified in the cosmic microwave background revealed by the latest Planck space missions
• You can remove anything in the universe but you cannot do it with quantum fluctuations: they will persist no matter what you do. Which means: primordial quantum fluctuations are initial conditions. Like radioactive decay or quantum tunneling, they are not caused by any preceding event.
• BONUS: knowing these latest bits of information about the relationship of Inflation Theory and primordial quantum fluctuations will enable you to play around with bumbling astrophysicists (at YouTube, for example) who remain unaware of these latest developments in the field.

This post is worth hitting the thanks button!!!
It's pretty rare talaga to us Filipino folks to talk about Physics and even more rare to talk about the history of the universe...
and I know exactly why. (NOT because Filipinos don't care, per se; and NOT because Filipinos are not bright enough to tackle this particular subject [Filipinos are next to Koreans pagdating sa intelligence])

Kung hindi lang naging baldado si Stephen Hawking, I was wondering how far we, human beings, get to achieve the information about the building blocks of Reality.
hmmm, String theory is quite a dead end atm...

TS,

Sino bang mga Physicist malapit sa puso mo?

I do adore Brian Greene, I like the way he explains things, hindi ka mabo-bore.
Leonard Susskind, he's remarkable man but pang graduate school na yung mga paraan ng paglelecture nya, LOL!
Of course Michio Kaku, awesome guy kaso he's kind of a sore looser, (I'll tell you a story later, hehehe)

- - - Updated - - -

Has Dogma Derailed the Search for Dark Matter?
by Pavel Kroupa, University of Bonn


http://www.symbianize.com/attachment.php?attachmentid=1181016&stc=1
A Hubble composite image shows a ring of ‘dark matter’ in the galaxy cluster Cl 0024+17.
Courtesy NASA, ESA, M.J. Jee and H. Ford. (Credit: Johns Hopkins University)​

SOURCE

This article was originally published at Aeon and has been republished under Creative Commons.[/SIZE]

NOTE: Another alternative to MOND, is of course Verlinde's take on the matter, discussed HERE

This image would be the Hubble Ultra Deep Field or not?

 

[Stormer0628]

This post is worth hitting the thanks button!!!
It's pretty rare talaga to us Filipino folks to talk about Physics and even more rare to talk about the history of the universe...
and I know exactly why. (NOT because Filipinos don't care, per se; and NOT because Filipinos are not bright enough to tackle this particular subject [Filipinos are next to Koreans pagdating sa intelligence])

Thanks, man. It makes posting these things about science topics worthwhile for like-minded people.

Kung hindi lang naging baldado si Stephen Hawking, I was wondering how far we, human beings, get to achieve the information about the building blocks of Reality.

Given his condition, it's even a wonder he's still at it after having just turned 75 recently. He is a gift to humanity. A great communicator, even with his condition. I would upload his mind to a computer if it were possible.

hmmm, String theory is quite a dead end atm...

String theory has come under intense criticisms for some time now. Curiously, though, it's making some sort of "revival" these days, not only in the form of the holographic principle by Maldacena, but it's been shown to be such an effective tool in unexpected disciplines. For example:

Taming Superconductors With String Theory
The Strange Second Life of String Theory
String Theory with Other Disciplines
Why Humanity Absolutely Needs String Theory

TS,

Sino bang mga Physicist malapit sa puso mo?

I do adore Brian Greene, I like the way he explains things, hindi ka mabo-bore.
Leonard Susskind, he's remarkable man but pang graduate school na yung mga paraan ng paglelecture nya, LOL!
Of course Michio Kaku, awesome guy kaso he's kind of a sore looser, (I'll tell you a story later, hehehe)

Among the popular scientists, Brian Greene stands out for being a good communicator, like Hawking.

I admire Paul Dirac, for his deep intuition. He's right up there with the best of the best for me. Who would have thought of his sea of negative particles and the antiparticles, now so fundamental to our understanding of reality and the universe?

Louis de Broglie, John Stewart Bell, David Bohm, for giving us a deeper understanding of quantum physics outside of the Copenhagen Interpretation.

Edward Witten: just pure genius. And of course the original founders of string theory, Kaluza and Klein.

Guth, for his Inflation Theory. Too bad for the Russian counterpart who also was into it even before Guth, though.

Many others, really, but these names easily come to mind.

Hm, ano kaya yan tungkol kay Kaku, hehe.

- - - Updated - - -

This image would be the Hubble Ultra Deep Field or not?

I should think so, but I couldn't find the detailed description of this specific material from NASA/ESA.

 

[nhile101]

Thanks, man. It makes posting these things about science topics worthwhile for like-minded people.


Given his condition, it's even a wonder he's still at it after having just turned 75 recently. He is a gift to humanity. A great communicator, even with his condition. I would upload his mind to a computer if it were possible.


String theory has come under intense criticisms for some time now. Curiously, though, it's making some sort of "revival" these days, not only in the form of the holographic principle by Maldacena, but it's been shown to be such an effective tool in unexpected disciplines. For example:

Taming Superconductors With String Theory
The Strange Second Life of String Theory
String Theory with Other Disciplines
Why Humanity Absolutely Needs String Theory



Among the popular scientists, Brian Greene stands out for being a good communicator, like Hawking.

I admire Paul Dirac, for his deep intuition. He's right up there with the best of the best for me. Who would have thought of his sea of negative particles and the antiparticles, now so fundamental to our understanding of reality and the universe?

Louis de Broglie, John Stewart Bell, David Bohm, for giving us a deeper understanding of quantum physics outside of the Copenhagen Interpretation.

Edward Witten: just pure genius. And of course the original founders of string theory, Kaluza and Klein.

Guth, for his Inflation Theory. Too bad for the Russian counterpart who also was into it even before Guth, though.

Many others, really, but these names easily come to mind.

Hm, ano kaya yan tungkol kay Kaku, hehe.

- - - Updated - - -




I should think so, but I couldn't find the detailed description of this specific material from NASA/ESA.

Hehe! Witten... I remembered him as the one who figured out the math that unified the string theory equations from diff. theorists then later came up with the M-theory.
and his voice is just weird, hehehe. or just too disproportionate to his body size....

About Kaku...I'm a big fan of Big Bang Theory sitcom and also a follower of Dr. Kaku's official facebook fun page, and so, few years back, I posted an inquiry about the string theory after watching an episode of BBT.
(don't mind "they're" s/b "their" instead)
View attachment 302809


and Instead of answering my inquiry, he created a new video in his Big Think/youtube page




https://www.youtube.com/watch?v=vue8jsLqPbo


He could've been offended is some way. Lol! He's a witty guy but also a man who looses his "cool" so easily.

 

[Stormer0628]

Hehe! Witten... I remembered him as the one who figured out the math that unified the string theory equations from diff. theorists then later came up with the M-theory.
and his voice is just weird, hehehe. or just too disproportionate to his body size....

About Kaku...I'm a big fan of Big Bang Theory sitcom and also a follower of Dr. Kaku's official facebook fun page, and so, few years back, I posted an inquiry about the string theory after watching an episode of BBT.
(don't mind "they're" s/b "their" instead)
View attachment 1181473


and Instead of answering my inquiry, he created a new video in his Big Think/youtube page




https://www.youtube.com/watch?v=vue8jsLqPbo


He could've been offended is some way. Lol! He's a witty guy but also a man who looses his "cool" so easily.

lol, perhaps Witten has this issue in his voice box. I haven't really seen any of his videos, just the papers.

About Kaku ... well, he's a strange guy. But considering his Oriental background, I could not blame him going the way he's gone now; at least he still has the sense to let his audience know of the speculative nature of a few of his works. Heck, even Penrose is going that offbeat way lately! Hehe

One of the current scientists that I like, Sean Carroll, has previously touched on the backlash about string theory, and explains clearly why critics are missing the point. It's found here.