Could optical knots be a method of communicating with extra terrestrials?

http://physicsworld.com/cws/article/news/2013/oct/16/physicists-tie-light-into-knots

Physicists tie light into knots

Oct 16, 2013 20 comments

Trefoil knot of light

Fantastical knot-like structures of light could soon be created in the lab thanks to calculations made by physicists in the US, Poland and Spain. They have discovered a new family of solutions to Maxwell's equations that are knots of light that do not disperse or lose their specific topological properties as they propagate. The researchers say such knots, if made for real, could be used to trap atoms or create similar knots in plasmas or quantum fluids.

Identified by Hridesh Kedia at the University of Chicago, along with colleagues at the Polish Academy of Sciences in Warsaw and the Spanish National Research Council in Madrid, the new family of solutions to Maxwell's equations have field lines describing all "torus knots" and "links". Torus knots are those knots that can lie on the surface of a torus, whereas a link is a collection of such knots.

One solution involves magnetic-field lines that trace out a familiar "trefoil" knot around a torus that is aligned in the plane perpendicular to the direction of propagation of the light (see figure). As the light propagates, the knot is distorted but retains the topological property of being a trefoil knot. The electric-field lines have the same structure as the magnetic-field lines but are rotated about the propagation axis by an angle that depends upon the knot. Other solutions include cinquefoil knots and linked rings.

Knotty problem

Kedia and colleagues believe that these knots could be made in the lab using tightly focused Laguerre–Gaussian beams. These beams have been created and studied extensively because – unlike most other beams of light – they carry orbital angular momentum.

If these optical knots can be made in the lab, they could have a number of scientific applications. Physicists are already exploring how focussed Laguerre–Gaussian beams can be used to trap ultracold atoms and this latest theoretical development could lead to new ways of trapping them. Firing such knots into a plasma or quantum fluid could also result in knot-like entities propagating through those materials, thereby offering new ways of studying these states of matter.

Once the preserve of mathematicians, knot theory is playing an increasingly important role in how physicists describe the behaviour of physical systems, ranging from liquid crystals to superconductors. Most of these descriptions arise from numerical simulations of complex systems, rather than the exact solution of the equations describing the system of interest.

The research is described in Physical Review Letters.

About the author

Hamish Johnston is editor of physicsworld.com

Stellar and Planetary natural lasers recently discovered

It is exciting to hear the news that natural lasers have been found in solar coronas and planetary atmospheres.  In both cases the gain product remains small but it does hold promise of a technique to allow self replication of electromagnetic signals.

SCIENTISTS DISCOVER FIRST NATURAL LASER IN SPACE

http://www.nasa.gov/home/hqnews/1995/95-148.txt

MASERS, INTERSTELLAR AND CIRCUMSTELLAR

https://ned.ipac.caltech.edu/level5/ESSAYS/Deguchi/deguchi.html

Discovery of CO₂ Laser in Martian Atmosphere

http://laserstars.org/history/mars.html

User the solar corona as a laser (maser) pump amplifier

In discussions with Ken Tapping, an astrophysicist at Canada's National Research Council he points out that:

 "There are circumstances under which masering is possible in the solar atmosphere. These do not involve energy changes inside atoms but are do do with electron/magnetic field resonances.

On occasion we see short-lived, very intense, narrow-band and highly-circularly polarized bursts from solar flares. These are widely believed to be due to “electron/cyclotron masering”.

The picture starts off with a solar flare, which produces a population of high-energy, relativistic electrons. Some of these find their way into a bipolar magnetic loop, with both ends rooted in the photosphere. The electrons execute trapped motion, bouncing between the ends of the loop, where the structure tapers and the magnetic field strength increases.

If these particles have initially a wide distribution of pitch angles, those with high pitch angles (with a larger velocity component along the magnetic field lines) will tend to penetrate further down the throat of the loop, where the density of ambient plasma is higher.  There they have a much higher probability of hitting something. They get thermalized and scattered, so that after a few bounces the pitch angle distribution has a deficit of high pitch angle electrons; there are conical holes (loss cones) in the distribution. If the electron distribution is a high-energy beam, the pitch angle distribution of the electrons in the loop will not be initially isotropic. It can have a deficit of low-pitch angle electrons. After a few reflections and a loss cone has developed, the electron pitch angle distribution can become interesting. If the initial pitch angles are high enough, all the electrons will get deep enough in the solar atmosphere for them to be thermalized by collisions. This electron bombardment of that dense plasma makes X-rays we can detect as X-ray bursts. However, if part of the pitch angle distribution lies outside the loss cone we may end up with a narrow distribution of electron pitch angles right up against the loss-cone boundary.

The electrons are spiralling around the field lines at the cyclotron (or gyro frequency). A radio wave emitted at the cyclotron frequency can be amplified as it propagates. I tend to retreat into mathematics because some of this is hard to picture, especially in the relativistic case.  If you look at the equation for the absorption coefficient for radio waves going through a plasma, and plug in the sorts of conditions mentioned here, the absorption coefficient can be negative. That is, the waves are amplified as they pass through the plasma rather than attenuated. This is masering. However, this does not work for the fundamental frequency. Attenuation at the gyrofrequency is huge, due to other resonances, but not for the third or so harmonic. This still gets amplified and because it has a frequency well above the plasma or other frequencies at which the plasma has high attenuation, it radiates off into space and to Earth, where we can detect them.

If one wanted to produce these emissions on demand, one could do this by providing the high-energy electrons. A modulated stream of electrons could be used, since the emission damps very quickly due to energy loss by those electrons. However, this means we are modulating the power supply, which we have to provide. Alternatively, launching sausage or torsional wave modes in the flux tubes making up the loop would modulate the pitch angle, thus modulating the loss-cones. However, the modulation rate would then have to be low, because to the time these waves require to move to and fro in the loop. Sausage waves would be best because they damp rapidly.

It is true that masering provides an efficient amplification process, but in the solar case, the powering and modulation process would be hard to do efficiently. Since the mirroring depends essentially on the tapering of the magnetic loop, the cyclotron frequency varies along the tube, so the resonance conditions for waves at a given frequency will be met in only a small part of it.

There is another process that might be more interesting. It is less efficient but easier to drive from a low-energy source.

Once again we have a loop filled with high-energy electrons produced by a flare. In this case rather than producing synchrotron emission, they generate plasma oscillations. Imagine the electron being a surfer, but in this case he enters the scenario with high energy, which he give to the wave and not vice versa. Plasma waves fill the tube.

Plasma waves are not radio waves. You need some sort of mode conversion process to transform them. Much of the solar radio emission we observe is due to scattering of these waves off thermal ions, which is very low efficiency. However, if we launch whistlers (electron cyclotron waves ) along the field lines, they pass through a zone where they resonate with the plasma waves, converting them to radio waves with high efficiency.  More over, they get past the problem that radio waves with a frequency equal to the plasma frequency cannot propagate. The whistlers act like a mixer, producing radio emissions at the plasma frequency minus the whistler frequency and at the plasma frequency plus the whistler frequency.  The former cannot propagate and that sideband is suppressed, feeding its energy back into the conversion process and the upper sideband. Because this is at a frequency above the plasma frequency, it propagates off into space.

The really strong metre-wavelength bursts observed in solar noise storms might be produced by this process. They are intense, short-lived, narrow band, polarized, and that fits the bill.

An active region could be pumping electrons into such a magnetic loop for days.

Getting close enough to drive the whistler production could be a challenge. A pulsed particle accelerator could do it, or nuclear devices exploded in the right place."

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Quantum Entanglement Could Stretch Across Time

http://m.wired.com/wiredscience/2011/01/timelike-entanglement/

In the weird world of quantum physics, two linked particles can share a single fate, even when they’re miles apart.

Now, two physicists have mathematically described how this spooky effect, called entanglement, could also bind particles across time.

Orbital Angular Momentum – Bo Thide and Jan Bergman (SETI Talks)

Link to SETI Archive: seti.org On the extraction of all information embedded in radio siganls: Implications for SETI: A new idea for utilizing all of the information in photons for communication involves a little-know electromagnetic property: the photon’s orbital angular momentum (POAM). The communication and computer industries are actively looking at the possibilities. We will discuss current research and the implications for SETI.

http://ufo-tv.com/orbital-angular-momentum-bo-thide-and-jan-bergman-seti-talks

Want to leave a message for whatever comes next?

http://en.wikipedia.org/wiki/KEO

KEO
From Wikipedia, the free encyclopedia
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For the Cypriot company see KEO Ltd

KEO is a space time capsule which will be launched in 2010 or 2011[1] carrying messages from the citizens of present Earth to humanity 50,000 years from now, when it will reenter Earth's atmosphere.

The KEO project is supported by UNESCO (who voted it "Project of the 21st century"), Hutchison Whampoa and the European Space Agency, among other institutions. Its name is supposed to represent the three most frequently used sounds common to the most widely spoken languages today, [k], [e] and [o],[2] though this is in fact mistaken, as the most common sound is [a].[3]
Contents

* 1 Personal messages
* 2 Other contents
* 3 Technical aspects
* 4 Project history
* 5 Similar Projects
* 6 See also
* 7 Notes
* 8 References
* 9 External links

[edit] Personal messages

Every person is invited to write a message addressed to the future inhabitants—the deadline is December 31, 2009. Messages can be posted via the the project's website, or sent by postal mail. The organizers encourage everybody to gather messages from children, senior citizens and the illiterate so that every culture and demographic on Earth is represented. The satellite has enough capacity to carry a four-page message from each of the more than six billion inhabitants on the planet. Once the satellite is launched, the messages (with personal names removed) will be made freely available on the web.

[edit] Other contents

KEO will also carry a diamond that encases a drop of human blood chosen at random and samples of air, sea water and earth.[4] The DNA of the human genome will be engraved on one of the faces. The satellite will also carry an astronomical clock that shows the current rotation rates of several pulsars; photographs of people of all cultures; and "the contemporary Library of Alexandria", an encyclopaedic compendium of current human knowledge.

[edit] Technical aspects

The messages and library will be encoded in glass-made radiation-resistant DVDs. Symbolic instructions in several formats will show the future finders how to build a DVD reader.

The satellite itself is a hollow sphere 80 cm in diameter. The sphere is engraved with a map of Earth and surrounded by an aluminium layer, a thermal layer and several layers of titanium and other heavy materials intertwined with vacuum. The sphere is resistant to cosmic radiation, atmosphere re-entry, space junk impacts and so on. For its first few years in orbit, KEO will sport an artful pair of wings 10 meters across that will aid in its spotting from Earth. As the satellite enters the atmosphere, the thermal layer will produce an artificial aurora to give a signal of the satellite's re-entry. The passive satellite will not carry any communications or propulsion systems. It will be launched by an Ariane 5 rocket into an orbit 1,800 km high, an altitude that will bring it back to Earth in 500 centuries, the same amount of time that has elapsed since early humans started to draw in cavern walls.

The satellite has not been built and no contract has been tendered for its construction.

[edit] Project history

The KEO project was conceived in 1994 by French artist-scientist Jean-Marc Philippe, a pioneer of space art. Messages began to be collected, and an initial launch date was set for 2001. Technical feasibility demonstration and other various delays have moved the launch date to 2010 or 2011.

[edit] Similar Projects

Several previous spacecraft have included time capsules for humans (or aliens) in the far future. The Apollo 11 Lunar Module (now on the moon) includes a plaque showing the arrangement of the Earth's continents in 1969. The LAGEOS satellite (which will re-enter the atmosphere in 8.4 million years) contains a plaque showing the arrangement of the Earth's continents in the past, present, and future. Pioneer 10 and Pioneer 11 both contain plaques that give pictorial information about their time and place of origin. Most famously, the two Voyager spacecraft each contain a golden record that contains pictures and sounds of Earth, along with symbolic directions for playing the record and data detailing the location of Earth. The Pioneers and Voyagers have left the solar system for interstellar space.

[edit] See also

* Bracewell probe
* Crypt of Civilization
* Westinghouse Time Capsules

[edit] Notes

1. ^ Current launch date estimation
2. ^ Official FAQ page
3. ^ Ian Maddieson and Sandra Ferrari Disner, 1984, Patterns of Sounds. Cambridge University Press
4. ^ Edge Life Magazine, May 2003

[edit] References

* Bridges, Andrew (Jul. 31, 2000). KEO: The 50,000-Year Mission to Earth Space.com
* Stenger, Richard (Aug. 29, 2000). KEO time capsule could remain in orbit until 52001 AD CNN.com
* HowStuffWorks.com (Sept. 5, 2000). Time Capsule to Orbit Earth for 50,000 Years HowStuffWorks.com
* The Hindu Business Line (Aug. 29, 2002). Hutch brings space-time capsule project to India The Hindu Business Line
* ChennaiOnline.com (Sept. 4, 2002). KEO, a time capsule in space! ChennaiOnline.com
* The Digital Skyline (August 2003). A Message to the Future The Digital Skyline
* Ashraf, Syed Firdaus (Oct. 15, 2003). Once upon a time, 50,000 years ago... Rediff.com
* EUROPA (May. 28, 2004). New satellite carries hopes and dreams of humanity EUROPA

[edit] External links

Special Constellations that Nature would never produce

[I think Jaron's idea is very similar to my own that we need to build "galactic" pyramids and other artificial structures in space. But rather than moving stars and planets I think this can be done more practically by creating spatial spectral patterns that clearly would be the mark of intelligence. Using gravitational lensing as Raman amplifiers and optical circulators could possibly keep a signal radiating forever-- BSA]

A proposal to create special constellations that nature
would never produce

by Jaron Lanier

This month I seriously propose that we begin the process
of repositioning the sun and other nearby stars in order to send signals to aliens, and that we begin the search for signs that aliens might have done the same for our benefit.

Full article here:

http://discovermagazine.com/2008/feb/rearranging-stars-to-communicate-with-aliens