Category Archives: Media Hunt #5

Angers Bridge


Angers Bridge was a suspension bridge that collapsed in France in 1850.  Soldiers were marching over the bridge in unison.  This caused the bridge to resonate, and eventually collapse.  Since then, when soldiers march across a bridge they are instructed to break their step.  This ensures that the bridge does not begin to vibrate, resonate, and fail.

This is a video of the opening of the Millenium Bridge in 2000.  People walking across the bridge caused lateral resonance.  The bridge did not fall, but they closed it for about two years after this walk to fix the problem.


Media Hunt #5: Chaos in Encryption


This rather annoyingly soundtracked video deals with nonlinear optics, an important “ingredient” in the chaos used in encryption.  Watching the video, one can see a demo similar to the demos we’ve done in class; two waves, with bars at the top that adjust frequency and change in the offset for each wave.  The mismatched waves form a second-harmonic generation (a resultant wave), which is very useful in the creation of lasers and the like.  Because of the nonlinearity of the system, the laser created with the given wave has variable frequency, which is used to alter signals and encrypt them with greater security.

Encoding/Decoding Process

This video shows a project in which they took the lasers and transmitted the audio waves.  The speaker is the transmitter and the light waves enter the receiver.  This is like the first picture on the article “Chaotic Optical Communications” where the carrier message is shown in the middle.  I also found many other examples similar to this of projects using different receivers and transmitters.

Optical Fibers

To encrypt messages using chaotic fluctuations in the intensity of a laser one must first be able to transmit information using lasers.  This is possible using optical fibers, which are hair-thin strands of glass through which pulses of light can be sent over long distances.  A beam of light that enters the fiber on one end is subject to total internal reflection, meaning that no light escapes until it reaches the other end of the fiber.  Thus, an optical signal transmitted on one end can be received in the same form on the other end.  The signal is modulated into varying intensities of light so that when the pulses of light reach the receiver the signal can be converted back into its original form.  Optical communication is favored over earlier forms of communication because the signals travel at the speed of light and are therefore faster than the signals sent using earlier technologies. 

The video below shows footage of Charles Kao, one of the pioneering researchers in optical fiber communications, in his laboratory in 1966.  If nothing else, the video demonstrates how thin the optical fibers are.  The video also mentions that many people were skeptical that such technology could become useful because at that time light was prone to escape the fibers and data was often lost in transmission.  These problems were corrected and fiber optics have became a fundamental part of the world’s communication network.  In fact, Kao was awarded the Nobel Prize in physics last year for his work on fiber optics.

Though this does not deal directly with chaos or encryption, it does help to illustrate the type of communication to which the chaotic encryption techniques described in the readings would be applied.

National Geo: A World in Chaos

This video shows what would happen if the moon shifted. In class we talked about the time researchers think chaos will occur, and this video seems to think around 1.5 billion years- much longer than 4 or 30 million we explored in our reading. The video explores the implications of the moon making a chaotic shift, thus causing the water to move away from the equator and destroying the agriculture of a lot of the world by changing the climate. This video has kind of a dooming tone, saying chaos is coming it’s just a matter of when, but it is still cool to think about how another factor could induce chaos in the solar system.

Chaos and Encryption

This image comes from a senior design project by Laney Williams at the University of North Texas.  In this project, she followed several different methods of using chaos to encrypt signals.  First was a circuit using a series of amplifiers that generated a chaotic output.  She then moved to a complex set of Matlab code to simulate a hardware application.  Finally, the system was implemented on a DSP, or Digital Signal Processing board. The top signal is the original audio waveform, the middle shows it mixed with a chaotic carrier, and the bottom shows the output signal, with the chaos subtracted.

The original paper can be found here:

Lasers, Encryption, and Chaos

A new technique in ensuring the security of data is encryption by lasers.  Data is converted into an optical signal.  Once in an optic form, the data is fed through a laser whose naturally occurring chaos has been heightened.  Now comes the confusing part: chaos synchronization.  Basically, a second laser receives the data that the first laser sent.  By knowing the chaos of the original laser the data can be extracted by subtracting the original laser’s beam from the receiving laser’s beam.  According to the article, scientists still are not entirely sure how this works, but it does!  This technique has been used to send data over 120 kilometers of fiber optic cable at a speed of about one gigabyte per second.  People are still performing many tests to see if this method of encryption is up to the standards of current methods, but it is predicted that this technique could being in large use within the next five years.

Surprisingly, there are no videos or pictures of lasers encrypting some data, so the hyperlink for the article is at the top of this post.

The Missing Universe

The stability of the universe is an ongoing debate between physicists. A major factor of this debate is the presence of hidden matter and energy, such as Dark Matter and Dark Energy. As mentioned in the video, visible matter is only 5% of the calculated total mass of the universe. The remaining mass is 23% dark matter and 72% dark energy. With the vast majority of the universe is not yet discovered or understood, it’s hard to say whether the universe is stable or not.

There were many interesting topics discussed in this video. It was posted Oct. 25, 2010, so all the information is relevant. The possibility of ‘anti-planets’ reminds me of many comic book plots, but it makes sense given the theory that an equal amount of matter and antimatter were created during the Big Bang.  Looking deep in the Earth for particles not blocked by the atmosphere is an idea that I would not have thought of

Birth of the Solar System

This video explores how chaotic conditions created the universe.  It explains the possible creation of the sun from an explosion of a larger star.  This video suggests that our universe was created from mulitple very violent explosions.  The big bang theory is discussed and how a large part of the matter in the universe possibly came from that single explosion.  There is however evidence that shows that a majority of the elements in the periodic table did not come from the big bang and that is an issue that is being further explored by scientists.

Chaos in Solar System Orbits

The video shows computer simulations of the solar system focusing on the orbits of the planets. There are multiple different simulations in the video that represent the number of different possible outcomes in which the orbits may evolve. It states that the gravitational effects of the planets can affect the other planets and cause unpredictable changes. This is very similar to the claim made in the reading where Peterson says “resonances destroy predictability.” Due to the interactions of the planets it is difficult to truly know how the solar system will evolve in the future. However, many researchers have come up with multiple possibilities. The video also shows the possible outcome of the orbits of the inner planets becoming catastrophic causing the Earth and Venus to collide. This was also mentioned in the reading, but both clearly state that the likelihood of that happening is very small. In fact, Peterson states that Laskar wrote that just because different orbits are possible does not necessarily  mean that this result will happen at all.

The Expanding Universe

Simply, the clearest, most well-explained description of a theory of this magnitude I’ve every seen. Click back to part 1 to see an explanation of how the universe was created. Part 1 looks at how the Heisenberg Uncertainty Principle and a sensitivity to initial conditions led to the creation of the universe. This part looks, instead, at the growth of the universe. Again, as with the Coast of Great Britain, it is interesting to look at distance as a function of other variables. For most practical purposes we assume that 10m is 10m, but this video turns that idea on its head. Worth the 8 minutes!

orbital chaos leads to planet collision

In “Celestial Disharmonies” the idea of orbital chaos was discussed.  Astronomers learned that even the planets show sensitivity to initial conditions, and if one planetary orbit is slightly changed, it has dramatic effects on the rest of the planets.  Even though these computer simulations show that the solar system is chaotic and that after a while all the planets will be moving around randomly, we have seen our solar system in the same stable state for billions of years.  Actually, when physicists calculated the Lyapunov time for our solar system it revealed that our solar system should have moved into chaos many years ago.  Perhaps this chaos that computer programs predict does not exist in our solar system or perhaps it just does not exist at such a large scale as to make the planets leave their orbits.  This video, however, does believe that in 3 million years the planets will begin moving chaotically and eventually crash.