Starship Asterisk*

• To quickly summarize the preceding series on the quantum astronomy, in the first article (Quantum Astronomy: The Double Slit Experiment) we looked at the double-slit experiment and how it appears to indicate that a single particle of light (a photon) travels through two slits (apertures) to make an interference pattern, apparently being in two places at once, and yet still be detected as a small particle when it registers on a detector screen.
  
  In the second article (Quantum Astronomy: The Heisenberg Uncertainty Principle) we looked at the uncertainty principle which requires that certain pairs of measurable quantities (position and momentum, for example) cannot both be measured accurately simultaneously. Time and energy are another such set of "complimentary pairs" so that if one measures the energy of a particle really well, one cannot tell very accurately at what time the particle had that energy. This uncertainty principle can be manipulated—one might say that one can trade off one kind of information for another, as long as ignorance is conserved.
  
  In the third article (Quantum Astronomy: Knowability and Unknowability in the Universe) we noted that waves associated with particles in quantum physics are waves of probability (not waves like ocean waves, although they do share many characteristics). So what one can know or cannot know about, for example, which path a photon took to a detector, actually determines what one will detect—for example whether an interference pattern is detected or not. If one cannot tell which path a photon took to a detector, one can get interference, but not otherwise.
  
  And finally, in the fourth article (Quantum Astronomy: A Cosmic-Scale Double-Slit Experiment), we discussed doing a cosmic-scale double-slit experiment, first proposed by John Wheeler of Princeton University, where a decision about which path a photon takes around a gravitational lens (a galaxy aligned so it can bend light from a more distance quasar) can be decided long after—even billions of years after—the photon had supposedly already left the source and traveled along one path or the other. This was called the "cosmic-scale delayed-choice" experiment.
  
  Changing this experiment from a gedanken experiment to a performable experiment, (We) proposed that one might actually utilize the uncertainty principle itself to replace the trillions-of-miles-long fiber optics cable. This notion was based on the idea that, since knowability or unknowability is the important consideration (rather than actual distances involved), we proposed not so much to make the two paths a photon traveled equal, but rather to just render any difference in the length of the two paths unmeasureable (i.e., unknowable). We proposed that by knowing the energy of the photon very well (by using a narrow band radio filter, for example) that the time that the photon actually had that energy would be unknowable (since time is the complimentary pair of energy). So, if the unknowability in the time is unmeasureably longer than the delay time between the light paths of the gravitational lens itself, then the two paths are, essentially, "unmeasureably equal," and one cannot tell which path the photon took. If one persists in thinking classically, the photon can then be said to have taken both paths then. To put it in physics-ese, we have used the uncertainty principle as a quantum eraser — it erases the quantum nature of a photon, making it a probability wave again, which can "exist" (if probability wave can be said to exist) along both possible paths again.

Abstract: The measurement of the gravitational lens delay time between light paths has relied, to date, on the source having sufficient variability to allow photometric variations from each path to be compared. However, the delay times of many gravitational lenses cannot be measured because the intrinsic source amplitude variations are too small to be detectable. At the fundamental quantum mechanical level, such photometric “time stamps” allow which-path knowledge, removing the ability to obtain an interference pattern. However, if the two paths can be made effectively equal (zero time delay) then interference can occur. We describe an interferometric approach to measuring gravitational lens delay times using a “quantum-eraser/restorer” approach, whereby the light travel time along the two paths may be rendered unmeasurable. Energy and time being non-commuting observables, constraints on the photon energy in the energy-time uncertainty principle — via adjustments of the width of the radio bandpass — dictate the uncertainty of the time delay and therefore whether the “path taken” along one or the other gravitational lens geodesic is “knowable.” If one starts with interference, for example, which-path information returns when the bandpass is broadened (constraints on the energy are relaxed) to the point where the uncertainty principle allows a knowledge of the arrival time to better than the gravitational lens delay time itself, at which point the interference will disappear. We discuss the near-term feasibility of such measurements in light of current narrow-band radio detectors and known short time-delay gravitational lenses.

http://www.imdb.com/title/tt0049223/quotes wrote:
Memorable quotes for _Forbidden Planet_ (1956)

Chief Engineer Quinn: I'll bet any quantum mechanic in the service
would give the rest of his life to fool around with this gadget.

bystander wrote:Quantum Astronomy: Information in the Universe
Space.com - 2009 August 20

• To quickly summarize the preceding series on the quantum astronomy, in the first article (Quantum Astronomy: The Double Slit Experiment) we looked at the double-slit experiment and how it appears to indicate that a single particle of light (a photon) travels through two slits (apertures) to make an interference pattern, apparently being in two places at once, and yet still be detected as a small particle when it registers on a detector screen....

northstar wrote:What if the particle (photon) were actually two particles (on-photon and off-photon) whose energies interact with each other to create a wave, but with the two particles registering as one particle?

Qev wrote:

northstar wrote:What if the particle (photon) were actually two particles (on-photon and off-photon) whose energies interact with each other to create a wave, but with the two particles registering as one particle?

You still get interference fringes if you use three slits instead of two in the experiment...

northstar wrote:But could a composite particle explain the particle-wave dual nature?
How much work has been done to determine if the photon is a single entity?

http://en.wikipedia.org/wiki/Satyendra_Nath_Bose wrote:
<<Satyendra Nath Bose (1 January 1894 – 4 February 1974), FRS, was an Indian physicist, specializing in mathematical physics. He is best known for his work on quantum mechanics in the early 1920s, providing the foundation for Bose-Einstein statistics and the theory of the Bose-Einstein condensate. He is honoured as the namesake of the boson. Although more than one Nobel Prize was awarded for research related to the concepts of the boson, Bose-Einstein statistics and Bose-Einstein condensate—the latest being the 2001 Nobel Prize in Physics, which was given for advancing the theory of Bose-Einstein condensates—Bose himself was never awarded the Nobel Prize. Among his other talents, Bose spoke several languages and could also play the Esraj, a musical instrument similar to a violin.

While presenting a lecture at the University of Dhaka on the theory of radiation and the ultraviolet catastrophe, Bose intended to show his students that the contemporary theory was inadequate, because it predicted results not in accordance with experimental results. During this lecture, Bose committed an error in applying the theory, which unexpectedly gave a prediction that agreed with the experiment. The error was a simple mistake—similar to arguing that flipping two fair coins will produce two heads one-third of the time—that would appear obviously wrong to anyone with a basic understanding of statistics. However, the results it predicted agreed with experiment, and Bose realized it might not be a mistake at all. He for the first time took the position that the Maxwell-Boltzmann distribution would not be true for microscopic particles where fluctuations due to Heisenberg's uncertainty principle will be significant. Thus he stressed the probability of finding particles in the phase space, each state having volume h³, and discarding the distinct position and momentum of the particles.

Physics journals refused to publish Bose's paper. It was their contention that he had presented to them a simple mistake, and Bose's findings were ignored. Discouraged, he wrote to Albert Einstein, who immediately agreed with him. His theory finally achieved respect when Einstein sent his own paper in support of Bose's to Zeitschrift für Physik, asking that they be published together. This was done in 1924.

The reason Bose's "mistake" produced accurate results was that since photons are indistinguishable from each other, one cannot treat any two photons having equal energy as being two distinct identifiable photons. By analogy, if in an alternate universe coins were to behave like photons and other bosons, the probability of producing two heads would indeed be one-third (tail-head = head-tail). Bose's "error" is now called Bose-Einstein statistics. Einstein adopted the idea and extended it to atoms. This led to the prediction of the existence of phenomena which became known as Bose-Einstein condensate, a dense collection of bosons (which are particles with integer spin, named after Bose), which was proven to exist by experiment in 1995.>>

neufer wrote:

northstar wrote:But could a composite particle explain the particle-wave dual nature?
How much work has been done to determine if the photon is a single entity?

Satyendra Bose claimed that all photons are identical indistinguishable particles and
what the consequences of that condition would be. His theory has held up for 85 years.

http://en.wikipedia.org/wiki/Satyendra_Nath_Bose wrote:
<<Satyendra Nath Bose (1 January 1894 – 4 February 1974), FRS, was an Indian physicist, specializing in mathematical physics. He is best known for his work on quantum mechanics in the early 1920s, providing the foundation for Bose-Einstein statistics and the theory of the Bose-Einstein condensate. He is honoured as the namesake of the boson. Although more than one Nobel Prize was awarded for research related to the concepts of the boson, Bose-Einstein statistics and Bose-Einstein condensate—the latest being the 2001 Nobel Prize in Physics, which was given for advancing the theory of Bose-Einstein condensates—Bose himself was never awarded the Nobel Prize. Among his other talents, Bose spoke several languages and could also play the Esraj, a musical instrument similar to a violin.

While presenting a lecture at the University of Dhaka on the theory of radiation and the ultraviolet catastrophe, Bose intended to show his students that the contemporary theory was inadequate, because it predicted results not in accordance with experimental results. During this lecture, Bose committed an error in applying the theory, which unexpectedly gave a prediction that agreed with the experiment. The error was a simple mistake—similar to arguing that flipping two fair coins will produce two heads one-third of the time—that would appear obviously wrong to anyone with a basic understanding of statistics. However, the results it predicted agreed with experiment, and Bose realized it might not be a mistake at all. He for the first time took the position that the Maxwell-Boltzmann distribution would not be true for microscopic particles where fluctuations due to Heisenberg's uncertainty principle will be significant. Thus he stressed the probability of finding particles in the phase space, each state having volume h³, and discarding the distinct position and momentum of the particles.

Physics journals refused to publish Bose's paper. It was their contention that he had presented to them a simple mistake, and Bose's findings were ignored. Discouraged, he wrote to Albert Einstein, who immediately agreed with him. His theory finally achieved respect when Einstein sent his own paper in support of Bose's to Zeitschrift für Physik, asking that they be published together. This was done in 1924.

The reason Bose's "mistake" produced accurate results was that since photons are indistinguishable from each other, one cannot treat any two photons having equal energy as being two distinct identifiable photons. By analogy, if in an alternate universe coins were to behave like photons and other bosons, the probability of producing two heads would indeed be one-third (tail-head = head-tail). Bose's "error" is now called Bose-Einstein statistics. Einstein adopted the idea and extended it to atoms. This led to the prediction of the existence of phenomena which became known as Bose-Einstein condensate, a dense collection of bosons (which are particles with integer spin, named after Bose), which was proven to exist by experiment in 1995.>>

northstar wrote:But you didn't answer the question. It is entirely possible that a photon is composite. Photons and Electrons are at best only "believed" to be single point particles. I suggest that wave nature of the particle suggests in itself that that particle is composite, and that interaction between the parts of the particle create the wave. How many decades was an atomic nucleus beleived to be a single particle?

http://en.wikipedia.org/wiki/Anomalous_magnetic_dipole_moment wrote:
<<Composite particles often have a huge anomalous magnetic moment.

This is true for the proton, which is made up of charged quarks, and
the neutron, which has a magnetic moment even though it is electrically neutral.>>

http://en.wikipedia.org/wiki/Precision_tests_of_QED wrote:
<<As of February 2007, the best measurement of the anomalous magnetic dipole moment of the electron was made by Gabrielse et al. using a single electron caught in a Penning trap. The difference between the electron's cyclotron frequency and its spin precession frequency in a magnetic field is proportional to g−2. An extremely high precision measurement of the quantized energies of the cyclotron orbits, or Landau levels, of the electron, compared to the quantized energies of the electron's two possible spin orientations, gives a value for the electron's spin g-factor:

. g/2 = 1.001 159 652 180 85, a precision of better than one part in a trillion.

The current state-of-the-art theoretical calculation of the anomalous magnetic dipole moment of the electron includes QED diagrams with up to four loops. Combining this with the experimental measurement of g yields the most precise value of α:

α−1 = 137.035 999 070, a precision of better than a part in a billion. This uncertainty is ten times smaller than the nearest rival method involving atom-recoil measurements.>>

Aims.We study the distribution of fermionic dark matter at the center of galaxies using NFW, Moore and isothermal density profiles and show that dark matter becomes degenerate for particle masses of a few keV and for distances less than a few parsec from the center of our galaxy.
Methods: .A compact degenerate core forms after galaxy merging and boosts the growth of supermassive black holes at the center of galaxies.
Results: .To explain the galactic center black hole of mass of ~3.5 × 106~Mȯ and a supermassive black hole of ~3 × 109~Mȯ at a redshift of 6.41 in SDSS quasars, we require a degenerate core of mass between 3 × 103~Mȯ and 3.5 × 106~Mȯ. This constrains the mass of the dark matter particle between 0.6~keV and 82~keV. The lower limit on the dark matter mass is improved to 7 keV if exact solutions of Poisson's equation are used in the isothermal power law case. We argue that the constrained particle could be the long sought dark matter of the Universe that is interpreted here as a sterile neutrino.

northstar wrote:But could a composite particle explain the particle-wave dual nature? How much work has been done to determine if the photon is a single entity?

Chris Peterson wrote:

northstar wrote:But could a composite particle explain the particle-wave dual nature? How much work has been done to determine if the photon is a single entity?

There's nothing that needs explaining. The only problem is your lack of acceptance of any theory that can't be reduced to billiard-ball equivalence. As you've been told many times in the past, there's no requirement that the Universe operate in a way that seems intuitive to you. The only reason there is a "duality" is because some people don't understand quantum mechanics.

Photons are single entities- a fact that is supported by both theory and observation. All entities- single or multiple- show a statistical wave-like nature.

northstar wrote:Read Wikipedia if you don't beleive me, Chris O Priest of the false religion calling itself science. "It is believed..." they are single point entitities.

Chris Peterson wrote:

northstar wrote:Read Wikipedia if you don't beleive me, Chris O Priest of the false religion calling itself science. "It is believed..." they are single point entitities.

"Belief" is a tricky word, one that often leads to confusion when applied to scientific ideas. That sentence is shorthand for something like "the reason that scientists conclude photons are single point entities is that all theory and observation are consistent with that conclusion." The word "belief" in this context has nothing in common with the word "belief" as used to describe people's philosophical or religious opinions.

manamongzombies wrote:Sounds like there's been a man among zombies here at APOD. Watch out, Northstar, The zombies will undoutedly attempt to eat the man in polite little lukewarm bites .. but their teeth won't handle meat, so stay strong. Believe in the Northstar, Northstar .. it's light shines on.

bystander wrote:Quantum Astronomy: Information in the Universe
Space.com - 2009 August 20

Scientists are usually very friendly and happy to discuss new ideas, but when something is going into the refereed scientific literature, that is a whole 'nother story.

quantum physics is still redefining how we think of science and what we think the fundamental nature of reality may be

no classical interpretation of quantum physics is the correct one

And Einstein himself once wrote, "I have thought a hundred times as much about the quantum problems as I have about general relativity theory." We can relate. And you are also most welcome to join Einstein's "hundred times" club. [emphasis mine] You, too, may begin thinking of the universe, not so much in terms of material objects, but rather in terms of information. And as quantum measurement begins to leave the laboratory and extend throughout space I think we're all in for a lot of surprises. And a lot of fun too.