Fundamentals II - The Unseen Universe (Examples)

Some examples of the 'empirical' classification presented in our past post are given below. Not all phenomena are observable as we see. Many of them are non-observable and cannot be sensed in any way.

Observable and cyclic: 

• Conspicuous astronomical events: apparent movement of celestial bodies, eclipses of the sun, moon, tides - rise and fall of sea level; 
• Seasonal ocurrrences: change of color of leaves in the beginning of autumn, the menstrual cycle;

Observable and noncyclic:

A large category of natural ocurrences such as:

• Weather and climate: storms, lightning, hurricanes; 
• Life (biology): an interesting example are bat´s sounds at the threshold of what can be heard by humans (below 20KHz). Most of bat´s interaction with the environment is ultrasonic and, therefore (according to our nomenclature) 'invisible' (non-audible), almost all life occurrences are noncyclic and shows a strong cause and effect link; 
• Geology: vulcanic eruptions (including geysers) and earthquakes. Other geological occurrences are too slow to be witnessed during the human life interval; 
• Astronomy: the sudden appearance of a bright supernova (ex. SN1987A); 
• Medicine: many symptons are observables and are related to (nonobservable) causes. 

Nonobservale, Visible and Cyclic

• Astronomy: the observation through a telescope of Jupiter´s moons transits or eclipses; 
• Biology: observation  of the cyclic cell division through microscopes; 

Nonobservable, Visible and noncyclic

• Astronomy: observation of solar prominences. Interesting enough, solar prominences are observable only during total solar eclipses.In normal conditions, the sun bright photosphere outshines their appearance that can only be observed with the use of special equipments. In general, all nonperiodic astronomical events (such as supernavas in distant galaxies) share the same features; 
• Biology: observation though microscope of all types of nonperiodic biological phenomena; 
• General: low amplitude sound effects: throught the use of amplifiers, unhearble sounds can become hearable; 
• Medical techniques: Positron emission tomography. A remarkable example of something hidden (observable body structures) that can become visible through a PET scan device. 

Nonobservable, invisible and cyclic

Radioastronomy:radio waves of periodic pulsars can become audible using radio telescopes.

Nonobservable, invisible and noncyclic

• Thermophysics, optics: Schlieren imaging reveals very small changes in the refraction index of transparent media.  Thermal plumes rising from human bodies can not be seen in any way, but are visible throught Schlieren imaging tecniques  (intervening medium). The technique also allows the visualization of sound waves; 
• Radio: all sorts of electromagnetic phenomena can become audible using a radio. The range of frequencies is very wide; 
• Astronomy: X-ray, infrared, Ultraviolet astronomy revealing an universe we are totally blind to; 
• Astrophysics and Cosmology: ~74% of what exists in the universe is invisible (and nonobservable), the so called dark energy. Dark matter is the term used to describe another special matter state that respond for 22% of what exist.The remaining 4% is made up of atoms and, therefore, matter of our ordinary knowledge. 

How do we know about the existence of non-observable, invisible and sporadic events ? The secret lies in the theories or rational structures that provide ways to experimentally access them.

Fundamentals I - The Unseen Universe

For centuries, people were unaware of the invisible, that in Nature there are hidden things out of reach of our common senses. The progress of science has unveil a new Universe formed by phenomena that will never be disclosed by these senses alone. 

However, they become tangible through a transducer or special media. The role of these media is to be  intermediaries between the phenomena and our senses.

Classification of natural phenomena

The universe contains many strata of different phenomena. Some of them are cyclic occurrences while others are sporadic. Many phenomena were discovered with the progress of science, but quite a few of them are accessible to ordinary observation (the so called human senses). 

Instead of categorizing natural occurences in broad areas (physics, biology etc), one can divide them  according to their accessibility to our senses. We suggest to classify nature´s event by the following definitions:

• Observable phenomena: occurrences that are directly acessible. This is the group that shape our immediate neighborhood from which we extract our life experiences. An 'observable' is a group of events that are acessible to the human senses withoutthe use of any intervening medium. According to such definition, the eclipses of Jupiter´s moons are not observable because we need telescopes to observe them;
• Non-observable phenomena: the immense majority of natural ocurrences belong to this class. These are phenomena that can not be sensed and, therefore, are unable to influence our experiences of life in a direct way. They can be divided into 2 categories: 

                      i) visible phenomena.
                      ii) invisible phenomena.

Visible occurrences are events that can be sensed with the help of magnifying or amplifying instruments. A good example is the use of telescopes to look at distant and faint objects, or the use of microscopes to observe microbes and cells. Invisible phenomena are unobservable events that can´t be made visible through an amplifying equipment, but that can be sensed by a human using a special type of intervening medium. (an example is a radio which transforms electromagnetic radiation in sound waves).

Cyclic and noncyclic phenomena

Another dimension of our phenomenological description is the frequency of occurrence. One can also divide natural phenomena in cyclic and noncyclic occurrences. Cyclic phenomena are events that repeat themselves periodically. Noncyclic natural phenomena are sporadic events.

The frequecy of occurrence is an important aspect for the correct evaluation from the point of view of Science because scientist will have difficulty in providing theories for noncyclic and extremely rare events. Science prefers cyclic phenomena because, for them, it is considerably easier to find a cause (frequent effects are well correlated with repeatable causes), which is the first step toward buiding a satisfactory theory.

In summary, events in Nature can be classified according to their frequency of ocurrence:

• Cyclic: periodic ocurrences
• Non-cyclic: non periodic phenenoma. There is no well determined rate or frequency.

Extremely rare phenomena may be cyclic or noncyclic as it is reasonable to expect. It is also expected that cyclic occurrence will be linked to cyclic causes. 

Particularly intriguing are non-observable, invisible and non-periodic phenomena. Event periodicity is an important feature in the study of whatever phenomena, since nobody will be willing to accept as real an occurrence that only happens once or even a couple of times. Extremelly rare events are therefore the hardest ones to study and are at the threshold of scientific inquiry just as the non-observable and and invisible ones.

An image of the night sky at 4.85 GHz revealing structures that are both non-observable and invisible according to our definition. Image Credits: National Radio Astronomy Observatory.

In the next post, we will discuss some examples.