Smell (Olfaction)

Our sense of smell is probably our “oldest” sensory system – it has a very long evolutionary history.

The basic process is called olfaction, and a simplified breakdown of the process looks like this:

  1. Chemical molecules floating in the air enter the nose
  2. The molecules are dissolve in mucous within a membrane called the olfactory epithelium (this is an important safety step since the olfactory tract is a direct path to the brain)
  3. The olfactory receptor cells interact with particular chemicals
  4. The olfactory tract transmits signals to several brain areas such: the olfactory cortex, hippocampus, amygdala, and hypothalamus

It’s that “interact with particular chemicals” that we haven’t completely figured out. No one knows exactly what causes olfactory receptors to react. Until recently the science suggested that a chemical molecule’s shape fit into specific receptors (there are about 400 different types, as compared to four for vision – 3 cones and one rod, and five for taste). But new evidence has been uncovered that suggest a quantum connection, and it can be demonstrated by looking at the smell of almond.

The Quantum factor
Benzaldehyde (the smell in almonds) and Cyanide smell the same to us, but the molecules are completely different in size and shape – which creates some doubt about the concept of molecule’s shape fitting into specific receptors as the soul method for detecting a scent. So what do Benzaldehyde and Cyanide have in common? Both molecules vibrate at the same frequency. This conjecture has been demonstrated repeatedly with other chemicals (see Luca Turin’s TED Talk, The science of scent).

The conclusion is astounding, our olfactory system is listening to molecules … we are hearing smells … our olfactory system is a nanoscale spectroscope that may also be detecting electron tunneling … we are detecting quantum state information. Reference notes on Quantum perception.

Emotions, memory and smell
Smells often bring back memories associated with an object or specific event. The reason has to do with how the brain processes scent information. When the olfactory transmits signals to the brain those signals are not only processed by the olfactory cortex, but also the hippocampus, amygdala, and hypothalamus, and the limbic system, which is involved with emotional behavior and memory.

Smell also has an important part in how we taste food -I’ll talk about that tomorrow.

Phereomones
The ancient Greeks knew that scent was a factor in sexual attraction for some animals, then during the 20th century pheromones were discovered in moths. We now know that many insects and animals use pheromones, but science has been unable to detect pheromones in humans.

Additional interesting facts about scent

  • Humans have about 400 types of olfactory receptors (and about 40 million total. In comparison, a German Shepherd dog as about 2 billion).
  • Smells can vary from person to person when there are issues with olfactory receptors types (compare just three eye cone cells in anomaly causing color blindness).
  • Humans are, for some reason, very sensitive to the smell of green bell pepper – capable to detecting the smell at only 0.5 parts per trillion.
  • Anosmia is the loss of the sense of smell. It’s usually caused by a nasal condition, virus, brain injury, or age. In addition, some people are born without a sense of smell.

Web Application
We are again left with only the possibility of future applications in virtual reality, but designers are already pushing ahead in other areas. One obvious example is that any good chief knows that the visual appearance of food enhances the enjoyment of a meal. Additional thoughts can be found in Jinsop Lee’s TED Talk, Design for all 5 senses.

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Quantum perception

The physics and biological mechanics of vision are astounding – I find it amazing that we can see at all. A Photon of light is very small (measured by the width of its wavelength). For example, the wavelength of green light is about 500 nanometers, or about two thousandths of a millimeter. That begs the question: why don’t photons just go right though us? Lets look at the problem with an explanation of why photons can pass through glass:

“Particles can pass though objects. For example, right now there are 100 billion solar neutrinos per second passing through every square centimeter of your body. The neutrinos are particles that only have VERY weak interactions with the matter that our bodies are made of so almost all of them pass through without interacting. So, in general, there is no problem with particles passing through matter if they do not interact with the matter – there is lots of space between the nuclei of atoms.

Now light particles, photons, are packets of electromagnetic radiation and the electric fields and magnetic fields can interact with charged particles. Thus photons cannot penetrate through metal because the free electrons that make metals conductors will easily interact with and absorb the photons immediately.

However the electrons in glass are tightly bound to atoms so they are not free to move like the electrons in a metal and therefore they do not absorb the photons. … If the energy of the photon happened to equal the difference between a bound electrons energy level and another unoccupied electron energy level, then the photon would get absorbed by causing the electron to transition between those energy levels.  However, there are no such energy levels available in glass for visible light photons.  On the other hand, ultraviolet photons do get absorbed because there are available energy levels at the energies of those photons.”

– Frank Heile, Physicist

This helps us better understand some of the properties of our eye lens and our retina. But what does happen when a photon strikes the retina and stimulates a rod or cone?

First, it’s important to know that only 1 to 3 percent of photons actually reach a photoreceptor cell – there’s a lot of light that we don’t see and probably the only reason we are able to detect light hinges on:

  1. the number of photons passing into the eye (as many as 10^14 photons per second) and
  2. the massive number of cone and rod cells (120 million rod cells and 6 million cone cells).

When photons “hit” a molecule (on a cone or rod) it raises an electron to a higher level (the molecule absorbs photons in the electrons on the surface, transforming the energy into density vibration). Once stimulated our photoreceptor cells convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell’s membrane potential. The process happens at the atomic level an our photoreceptors are capable of detecting a single photon of light. Astronauts have reported seeing other colors such as yellow and pale green lights that were determined to be cosmic rays (gamma and x rays less than the diameter of an atom).

But some stimuli may be happening at an ever-smaller scale. Physicists now believe that the human eye is capable of detecting quantum effects.[1] To date I know of no direct experiments with humans that prove that conjecture, but there is evidence from experiments with European Robins that does.

It’s long been thought that birds navigate using Earth’s magnetic fields (which is very weak, too weak to detect), Experiments indicated that the robin’s magnetic detection is in the eye – the robin’s chemical compass can see the state of quantum entanglement of photons (which are more likely at magnetic north), the direct observation, by an eye of a quantum state. See: The Secrets of Quantum Physics: Einstein’s Nightmare, Physicist Jim Al-Khalili  [2]

That Darn Cat
There is a line of thought called Biocentrism that posits our perception is creates the universe. This argument is based on a concept expressed in the Schrodinger’s Cat thought experiment.

“A cat imagined as being enclosed in a box with a radioactive source and a poison that will be released when the source (unpredictably) emits radiation, the cat being considered (according to quantum mechanics) to be simultaneously both dead and alive until the box is opened and the cat observed.”

Biocentrism says that the quantum nature of matter sets up a universe where our perception actually creates the universe we experience. But the concept goes further, suggesting that time is an illusion, and that we are living all of our possible decisions/perceptions at the same “moment.”

I’ll revisit this line of thought in the next article, which covers the olfactory system.

Web Application

None known, but isn’t it interesting?

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