Posted on 01/20/2006 8:09:35 PM PST by strategofr
BERKELEY – University of California, Berkeley, physicists can now tune in to and hear normally inaudible quantum vibrations, called quantum whistles, enabling them to build very sensitive detectors of rotation or very precise gyroscopes. Quantum whistle Hear the synchronized vibrations from a chorus of more than 4,000 nano-whistles, created when physicists pushed superfluid helium-4 though an array of nanometer-sized holes. Note that the pitch drops as the pressure drops.
A quantum whistle is a peculiar characteristic of supercold condensed fluids, in this case superfluid helium-4, which vibrate when you try to push them through a tiny hole. Richard Packard, professor of physics at UC Berkeley, and graduate student Emile Hoskinson knew that many other researchers had failed to produce a quantum whistle by pushing helium-4 through a tiny aperture, which must be no bigger than a few tens of nanometers across - the size of the smallest viruses and about 1,000 times smaller than the diameter of a human hair.
To their surprise, however, a chorus of thousands of nano-whistles produced a wail loud enough to hear. This is the first demonstration of whistling in superfluid helium-4. According to Packard and Hoskinson, the purity of the tone may lead to the development of rotation sensors that are sufficiently sensitive to be used for Earth science, seismology and inertial navigation.
"You could measure rotational signals from an earthquake or build more precise gyroscopes for submarines," Packard speculated.
Four years ago, Packard and his coworkers built and successfully tested a gyroscope based on quantum whistling in superfluid helium-3. But that required cooling the device to a few thousandths of a degree above absolute zero, a highly specialized and time-consuming process. Because the new phenomenon exists at 2 Kelvin - a temperature achievable with off-the-shelf cryo-coolers - the proposed sensors also will be user-friendly to scientists unfamiliar with cryogenic technology. A temperature of 2 Kelvin is the equivalent of minus 456 degrees Fahrenheit.
"Because these oscillations appear in helium-4 at a temperature 2,000 times higher than in superfluid helium-3, it may be possible to build sensitive rotation sensors using much simpler technology than previously believed," the researchers wrote in a brief communication appearing in the Jan 27 issue of the journal Nature.
Packard noted that sensitive rotation or spin detectors could have application in numerous fields, from geodesy, which charts changes in the spin and wobble of the Earth, to navigation, where gyroscopes are used to guide ships. Though little is now know about the rotational signals from earthquakes, having a sensitive rotation detector might reveal new and interesting phenomena.
Quantum whistling is analogous to a phenomenon in another macroscopic quantum system, a superconductor, which develops an oscillating current when a voltage is applied across a non-conducting gap. Nobel Laureates Philip Anderson, Brian Josephson and Richard Feynman predicted in 1962 that the same would happen in superfluids. In the case of superfluids, however, a pressure difference across a tiny hole would cause a vibration in the superfluid at a frequency - the Josephson frequency - that increases as the pressure increases. The fact that the fluid oscillates back and forth through the hole rather than flows from the high-pressure side to the low-pressure side, as a normal liquid would, is one of the many weird aspects of quantum systems like superfluids.
Eight years ago, Packard and fellow UC Berkeley physicist Seamus Davis, now at Cornell University, heard such vibrations when pushing superfluid helium-3 through a similar array of 4,225 holes, each 100 nanometers across. Though no simple feat - it took them 10 years to make their experiment whistle, working at one thousandth of a degree Kelvin - it's theoretically easier than with helium-4.
For helium-4 to whistle, physicists predicted that the holes either had to be much smaller, pushing the limits of today's technology, or the temperature had to be within a few hundred thousandths of a degree of the temperature at which helium-4 becomes a superfluid, that is, 2 Kelvin. While working with an array of holes 70 nanometers across, essentially testing the apparatus with helium-4 before using it to conduct a helium-3 experiment, Hoskinson was surprised when he put on earphones and heard the characteristic slide whistle sound as the pitch dropped with the pressure in the device.
"Predictions on where the Josephson oscillations would occur put them much closer to the transition temperature than I could hope to go," Hoskinson said. "The fact that I could detect the oscillations with the set-up I had was amazing in itself, and something we're very interested in exploring."
He and Packard calculated that the tones were due to a different mechanism, phase slippage, than that producing the whistle in helium-3, though it follows the same relationship between frequency and driving pressure. Phase slippage shouldn't have produced a pure tone at all. The vibrations at the holes should shift randomly and get lost in the noise. Even if phase slippage did produce a constant tone in a single hole, the whistles from the array of 4,225 holes should have been out of phase and the resulting sound less than 100 times louder than that from a single hole.
Apparently, Packard said, the vibrating holes somehow achieved synchrony, like crickets chirping in unison on a summer evening, amplifying the sound 4,000 times higher - loud enough to be heard above the background noise of the experiment.
"For 40 years, people have been trying to see something like this, but it has always been with single apertures," Hoskinson said. "Maybe it's true that you don't get coherent oscillations with a single aperture, but somehow, with an array of apertures, the noise is suppressed and you hear a coherent whistle."
"There was no reason to expect that. I still think it's amazing," Packard added.
The research by Packard, Hoskinson and post-doctoral fellow Thomas Haard is supported by the National Science Foundation and by the National Aeronautics and Space Administration.
strategofr wrote:
Warning! Kids: don't try this at home!
---Thanks for posting this fun tech article! I wish i was that smart so i could try cool stuff like that at home, but i'm just your average bear!
"---Thanks for posting this fun tech article! "
Welcome.
"Quantum whistle alert!"
:)
"A temperature of 2 Kelvin is the equivalent of minus [sic] 456 degrees Fahrenheit."
You'd think a University press office could manage to realize that "minus" is a verb while "negative" is an adjective. Or, as one of my math profs used to taunt me when I slipped up: "what's 'minus' number? I have no idea what that is...."
What am I to say, "It's really cool!"
Science PING
This public service announcement will run for about ten pings or until whenever I get bored posting it. :)
|
PING!
Does anyone here know why helium 3 is more a far more important isotope than helium 4?
It's a lot smaller than He4
I believe that it is the smallest gas particle, period.
(Hydrogen needs to be H2 to be stable. A single He atom is stable--noble gas thing--and He three is smaller than He four. Both asre smaller than H2)
I used a SIRU on one of my spacecraft. :-)
"The HRG uses a thin-walled quartz shell that is energized by an electrical field to produce an imperceptible vibration pattern within itself. This pattern is electrically sensed and used to determine the gyro's output parameters. The vibration is so minute that it creates virtually no internal stress and fatigue effects, leading to its unmatched reliability. Northrop Grumman is the exclusive producer of HRGs, which to date have accumulated more than 4,500,000 hours of operation in over 50 systems in space without a mission failure. "
http://www.irconnect.com/noc/press/pages/news_releases.mhtml?d=67278
How much is worth an additional 2 Kelvins compared to Helium-3? Is that such a great breakthrough?
That's an American thing. I grew up with 'minus two degrees centrigrade', etc.
I doubt most people would agree it's more important, but near 0 K it has very different properties, because it's a fermion (spin 1/2) rather than a boson like He-4. It's also got an NMR signal, which He-4 does not have, so you can use it, e.g., to image lungs.
It's horribly rare and expensive, though; the best source of it is radioactive decay of the tritium in thermonuclear weapons.
"University press office"
You are right. It is the phraseology of a not-really-literate person. Unfortunately, the steep decline in literacy is seeping into every crack and crevass. I am appalled by various things I read in the Wall Street Journal (not counting political things here), including things parallel to your comment as well as routine, frequent errors in the explication of technical and scientific facts. Sloppiness and laziness---both in use of language and in thinking. The two go together. The product of a creativity-based, rule-shy learning experience.
"I believe that it is the smallest gas particle, period.
(Hydrogen needs to be H2 to be stable. A single He atom is stable--noble gas thing--and He three is smaller than He four. Both asre smaller than H2)"
Fascinating. Could you please explain why adding helium atoms makes it smaller?
"The vibration is so minute that it creates virtually no internal stress and fatigue effects, leading to its unmatched reliability."
too cool.
"How much is worth an additional 2 Kelvins compared to Helium-3? Is that such a great breakthrough?"
yes. you need to turn your thinking upside down. the one is a few thousandths of a degree above 0 Kelvin---which is no motion at all. the other is 2° above zero Kelvin. that means the one is many hundreds of times further from zero Kelvin than the other. To look at it another way, I guess those last couple degrees to absolute zero are "a real doozy".
Nou doubt about that. 2K is really frickin' cold, but quite doable.
0.002K is a thousand times colder, and many thousands of times more difficult to pull off.
Yep - a 1 liter bottle of ~100psi He3 is roughly $2000.
Not adding atoms...this is hard to do without the HTML skills needed to do sufixes. So let's do this the non-HTML way:
He3 is one atom of Helium with 3 electrons in orbit around a single nucleus. He4 is one atom of Helium with 4 electrons in orbit. H is one atom of Hydrogen, with one electron in orbit. H2 is two atoms of hydrogen, bound as a molecule. The distance between their nuclii is much greater than the diameter of a single He3 or He4 atom.
Sorry for the mix up!
You need to travel overseas once in a while.
Um, lets try again.
He3 is an atom of Helium with two protons, one neutron and two electrons.
He4 is an atom of Helium with two protons, two neutrons and two electrons.
The 5 spin 1/2 particles of He3 give it fermion-like properties while the 6 spin 1/2 particles of He4 give it boson-like properties.
In addition, the lower mass of He3 also makes it act quite different than He4.
Darn good science writing in this article!
Ya beat me to it. :-)
Nobody can say why. Physicists can say how. It isn't adding He atoms, though, but nuclear particles.
Perhaps we should form a Science Posting Police Club?
LOL
THE STANDARD MODEL:
The best description of how matter and energy interact (sans gravity) is called “The Standard Model” It describes the organization of all of the particles and how they interact. The elementary particles are divided into two families called quarks and leptons. Each family consists of six particles and three of each of the particles in each group are acted on by a force carrier.
Quarks: Six called, up charm, top, down, strange, and bottom. All six quarks are acted upon by gluons and photons. This is because all of them carry electromagnetic charge (u,c,t have a charge of +2/3 e, while d,s,b have a charge of -1/3 e), and all of them carry a color charge. There are three kinds of color charge, which are commonly written as red, green and blue. Every quark in the universe has one of these charges. Each flavor of quark can have any color charge. The Up, charm, and top use the gluon for their force carrier. The Down, strange, and bottom use the photon for their force carrier.
Note: Super geek alert #1:
Because there is one kind of EM charge, there is one photon, but since there are three kinds of color charge, there are eight gluons. Gluons themselves carry both a color charge and an anti-color charge, so you'd think that there would be nine gluons, but the combination red-antired + blue-antiblue + green-antigreen is colorless, so if you define a red-antired gluon and a blue-antiblue gluon, a green-antigreen gluon can be described as a superposition of the other two. Only eight gluons are needed to span the color space.
Leptons: Six called: e neutrino, u neutrino, t neutrino, electron, muon, and tau. All quarks and leptons couple to both W and Z bosons. A “W”, for example, transforms an electron to an electron neutrino, or a t-quark to a b-quark. The E neutrino, u neutrino, and t neutrino use the W boson for their force carrier. The Electron, muon, and tau use the Z boson for their force carrier.
Gravity is not included in the standard model, however it is believed that is exchange force is a graviton.
THE FOUR FUNDEMENTAL FORCES OF NATURE:
Strong force
Weak force
Electromagnetism (EM)
Gravity
All of the fundamental forces are considered Exchange Forces. In other words the force involves an exchange of one or more particles.
The exchange particles are as follows:
Strong– The pion (and others)
Note: Super geek alert #2:
The pion does mediate the inter-nucleon force. That force isn't fundamental, however. The fundamental force is the inter-quark force that binds the quarks into hadrons (such as protons, neutrons and pions), and that is what we usually mean by the strong force, nowadays. The force between hadrons is a residual color dipole interaction that is analogous to the Van der Waals force in electromagnetism.
Lets explore this a bit further:
First, lets take a look at Van der Waals Forces:
Atom and molecules are attracted to each other by two classes of bonds. The Intramolecular bond and the Intermolecular bond.
The Intermolecular bond is divided into these categories; Van der Waals Forces, Hydrogen Bonds, and molecule-ion attractions.
The Intramolecular bond (which are much stronger than the Intermolecular bond) is divided into these categories; Ionic bonding, covalent bonding, and metallic bonds.
We will only concentrate on the Van der Waals Forces.
Van der Waals Forces arise from the interaction of the electrons and nuclei of electrically neutral atoms and molecules. How is this possible if these are considered electrically neutral I hear you ask. What is going on here is that the electrons and nuclei of atoms and molecules (for this description: from here out called particles) are not at rest, but are in a constant motion. Since this is the case, there arises an electrical imbalance (called an instantaneous dipole [another term is a temporary polarity]) in this electrically neutral particle. Two “particles” in this dipole state will attract. Also this dipole action in one particle can cause a dipole in an adjoining (nearby) particle. So the dipole-dipole attraction is what is known as Van der Waals Forces. If these “particles” kinetic energies are low enough (and close enough together), the repeated actions of the instantaneous dipoles will keep them attracted together.
One of the interesting things about this that the more electrons are in play the greater the Van der Waals Force. This is why the noble gas Krypton liquefies at a higher temperature than the noble gas Neon.
Back to the Standard Model.
A brief background: How does a nucleus stay together when it is packed with positively charged protons? Since “like” charges repel, you would think that the nucleus would fly apart. The force that keeps this from happening is the Strong Force. One of the things that was discovered is that the mass of any nucleus is always less than the sum of the individual particles (called nucleons) that make it up. The difference (residual) is due to the “Binding Energy” of the nucleus. This binding energy is directly related to the strength of the strong force. "Binding energy" is a negative energy. If the mass of a nucleus were always less than any sum of its potential components, then it would always take energy to split a nucleus.
This is true for any nucleus below iron. For nuclei above iron, the binding energy becomes less and less; the strong nuclear force creates stable minima in which very heavy nuclei can exist, but these are but local minima sitting high on the electromagnetic hill. A uranium nucleus is heavier than thorium plus helium.
So just what is this Strong Force anyway? The Strong force has an effect on quarks, anti quarks and gluons. Oh my, another term, QUARKS! After much research, it was discovered that the protons and neutrons in the nucleus were made up of smaller particles called quarks. It turned out that two types of quarks were needed to “produce” a proton or a neutron. However, there are six types of quarks in normal matter. The strong force binds these quarks together to form a family of particles called hadrons which include both protons and neutrons.
To simplify this discussion, quarks have a “color charge” (red, green, and blue). BTW, this was a convenient way of describing the charge, it is not referring to color as we commonly use it). Like colors repel and unlike colors attract. There are also antiquarks. If it is a quark/antiquark (same color) it is called a meson. If it’s between quarks it is called a baryon (protons and neutrons fall in this category). Here is the rub, baryonic particles can exist if their total color is neutral (colorless); i.e. have a red green and blue charge altogether. Both mesons and baryons are "colorless" with respect to the outside world. In baryons red + blue + green = colorless. In mesons, for example, red + anti-red (or, if you like, red - red) = colorless.
Without getting into too much more detail, quarks can interact, changing color, etc. so long as the total charge is conserved.
The quark interactions are cause by exchanging particles called gluons. There are eight kinds of gluons each having a specific “color” charge. The symmetry group of Quantum Chromodynamics is SU(3). In the minimal representation of SU(3), there are three generators...the color charges. In the non-minimal representation, there are 3²-1 generators...the eight gluons! This was spookily mirrored by Murray Gell-Mann's original (1964) quark theory, which also exploited the SU(3) symmetry. Only this time, the minimal representation was the three light quark flavors (up, down, strange), and the non-minimal representation was Gell-Mann's famous Eightfold Way, which correctly(!) predicted the properties of all the light hadrons, including some that had not yet been discovered.]
So back to the original paragraph: Neutral (all three colors) hadrons (which include protons and neutrons) can interact with the strong force similarly to the way atoms an molecules react via the Van der Waals forces.
Electromagnetic (EM) – The photon
Weak – The W and Z
Gravity – The graviton
So to sum this up:
The Strong Force:
It is a force that holds the nucleus together against the repulsion of the Protons. It is not an inverse square force like EM and has a very short range. It is the strongest of the fundamental forces.
The Weak Force:
The weak force is the force that induces beta decay via interaction with neutrinos. A star uses the weak force to “burn” (nuclear fusion). Three processes we observe are proton-to proton fusion, helium fusion, and the carbon cycle. Here is an example of proton-to-proton fusion, which is the process our own sun uses: (two protons fuse -> via neutrino interaction one of the protons transmutes to a neutron to form deuterium -> combines with another proton to form a helium nuclei -> two helium nuclei fuse releasing alpha particles and two protons). The weak force is also necessary for the formation of the elements above iron. Due to the curve of binding energy (iron has the most tightly bound nucleus), nuclear forces within a star cannot form any element above iron in the periodic table. So it is believed that all higher elements were formed in the vast energies of supernovae. In this explosion large fluxes of energetic neutrons are produced which produce the heavier elements by nuclei bombardment. This process could not take place without neutrino involvement and the weak force.
Electromagnetism:
The electromagnetic force is the forces between charges (Coulomb’ Law) and the magnetic force which both are describe within the Lorentz Force Law. Electric and magnetic forces are manifestations of the exchange of photons. A photon is a quantum particle of light (electromagnetic radiation). This particle has a zero rest mass The relativistic mass of a photon is also zero. Gravity couples to energy density, which is typically dominated by mass. But even in Newtonian gravity, massless light particles will bend in a gravitational field (the trajectory of a test particle doesn't depend on mass). The speed of light in a vacuum is a constant and is unobtainable by baryonic matter due to the lorentz transformation. Electromagnetism obeys the “inverse square law”.
Gravity:
Gravity is the weakest of the forces and also obeys the inverse square law. The force is only attractive and is a force between any two masses. Gravity is what holds and forms the large scale structures of the universe such as galaxies
Note: Super geek alert #3:
We can test the effect of gravitational waves on orbiting bodies under general relativity (GR). Not with the Earth and sun: any effect there is vanishingly small. Instead, we use binary pulsars, which are systems with two neutron stars revolving about a common center of gravity. We can measure the timing of such systems to a very high degree of accuracy, and the fact is, such systems are unstable! We can measure the distance between two gravitationally bound pulsars to within inches(!), and watch the orbits decay in real time. The decay is caused by gravitational waves, and the GR prediction is confirmed to many decimal places. If the speed of gravitational waves were grossly off, or if they didn't exist somehow, we'd see it.
Note: Physicist edited this for me adding many technical bits to make it more complete. However, any mistakes I take as entirely my own.
ARRGGGG!@%#%# Why is my red font color coming out green?
Green's a nice color too. I wouldn't worry about it!
(I have no idea. The source code has FF0000 as the color, which should be red.)
We produce tritium in great abundance w/cold fusion(LENR)which as you know decays to He3 in a 12.5 yr 1/2 life. This is why the DOE is(reluctantly)taking CFR seriously again after the hot fusioneers in the DOE have fought it tooth and nail for 15 years(fear of losing their federal funding). The tritium in their H-nucs decays and tritium is no longer produced by US reactors. As you know, the single neutron in the He3 nucleus means it has a nuclear magnetic moment. Thus 2 He3 atoms orbit around each other(bosing if you will)in the fluxions of a type II superconductor, much like 2 cooper pair electrons in su-co. Now, if you had a ring of Type II superconductor w/He3 atoms suffusing it, you can input energy so that the orbiting He3 atoms get further and further apart, forming sausage-shaped orbits in the fluxions. Take it all the way : 1/2 of the He3 atoms are moving CW and 1/2 CCW in the ring. You've created a Bohr Radius atom at a macroscopic scale. Then polar vise to squeeze it down and you've created the wave galaxy at the core of a fermion, composed of 3 quarks, a big DUD(neutron's wave galaxy). 3 new(balanced)charges appear(-1/3,+2/3,-1/3)wherein the -1/3 charges are in the ring-rim and the +2/3 charge is somewhere in the central probability bubble. You contain that +2/3 charge in an electrostatic chamber and WA-LA : your basic, disc shaped UFO. By moving that central +2/3 charge you move the whole ring. Got it?
In my browser, this
post looks red. Did you use hex
or the text word 'red'
in your font command
to change the color? I use
text almost always . . .
There's smaller yet. See blacklightpower.com
Punishment for impure thoughts....
No, it's captiousness. I've always said "minus", and I can't recall being corrected. "Minus" is the name of the symbol "-", a minus sign. "Negative" is fine, of course, but not more correct.
Shouldn't it come out white, since you've already included green and blue? :-)
Figured it out. Word 2000 quotes don't work with HTML. Once I used wordpad and replaced all the quotes, it came out fine on a test web page on my desktop.
THE STANDARD MODEL:
(Thunderous applause).
Thanks! :-)
I have not forgotten the post on solar spectra and stellar temperature for you. Will be done this weekend. :-)
Yeeeee-HAWWWWWWWW!!!!
Now, does anyone know how to post integral equations in HTML?
Works for me!
That's a very nice definition.
Yes, you've got standard physics down fairly well, are you ready for the next leap in understanding? Time(kinetic energy) and gravity(weight) are but over running matter wave force, in newtons. Physicists talk of the collapse of the wave function. What that means is that W>P which is deceleration which is weight. The relavent formulas are t=dKE=m=(W not=to P)and not-t=PE=M=(W=P). Can you think of a time event that is NOT a kinetic energy event? Heisenberg's delta Momentum term in the HUP is an oxymoron. "delta" means the rate of change of something, Momentum means no change of state; thus "delta Momentum" means, literally, "rate of change of no change of state"... Take Newton's First Law : an object will continue moving in a straight line(W=P Momentum state)until an external force(W>P or W<P)is impressed upon it. You see then the mistake that Heisenberg/Planck/DeLa Place made in stating that Momentum is a determinant of energy(the quantum area h), instead it's a RESULT of W=P(balance of the wave-particle duality). Einstein's "rest mass" is the complimentary oxymoron. Once you get past these earlier mistakes you can then understand the true importance of MATTER WAVES, a full HALF of your physical existence.
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