Milky Way : Galactic Quadrant

The Milky Way is the galaxy that contains the Solar System.  It is a barred spiral galaxy containing 200-400 billion stars, with 100,000 light years in diameter, and 1,000 light years thick.  It is estimated to be about 13.2 billion years old, nearly as old as the Universe.

Edwin Hubble, in 1920s observed that the Milky Way is just one of around 200 billion galaxies in the observable universe.

Galactic Quadrant

A galactic quadrant refers to one of four circular sectors in the division of the Milky Way galaxy.

Ancient Mesopotamian formulae spoke of “the four corners of the universe” & ”the heaven’s four corners”;

Biblical Book of Jeremiah echoes this phraseology : “And upon Elam will I bring the four winds from the four quarters of heaven” ( Jeremiah 49:36 )

Galactic quadrants within fictional Star Trek are based around a meridian that runs from the center of the galaxy through Earth’s solar system. 

                                                

Real world :  

Sun as center                                       

Described using ordinals, as               

1^st galactic quadrant                              

2^nd galactic quadrant                         

3^rd galactic quadrant                          

4^th galactic quadrant                         

Star Trek :
Galactic Core as center

Designated by Greek letters, as
Gamma Quadrant   
Alpha Quadrant
Beta Quadrant
Delta Quadrant

Motion Sickness

Motion sickness or kinetosis, also known as travel sickness, is a condition in which a disagreement between visually perceived movement and the vestibular system’s sense of movement.  Depending on the cause it can also be referred to as seasickness, car sickness, airsickness, or simulation sickness.

Sopite syndrome is a neurological disorder that relates to prolonged periods of motion.  Symptoms includes dizziness, fatigue, and nausea.  If the motion causing nausea is not resolved, the sufferer will frequently vomit.  Unlike ordinary sickness, vomiting in motion sickness tends not to relieve the nausea.

About 33% of people are susceptible to motion sickness even in mild circumstances ; the remaining 66% are susceptible in more severe conditions.  Individual and animals without a functional vestibular system are immune to motion sickness.

Cause

The most common hypothesis for the cause of motion sickness is that it functions as a defense mechanism against neurotixins.  

When feeling motion but not seeing it, the vestibular system in inner ear transmits to the brain that it senses motion, but the eyes tell the brain that everything is still. 

As a result of the discordance, the brain will come to the conclusion that one of them is hallucinating and further conclude that the hallucination is due to poison ingestion.  The area postrema in the brain responded by inducing vomiting, to clear the supposed toxin.

Types

Motion sickness can be divided into 3 categories :

1. Motion is felt but not seen

In these cases, motion is sensed by the vestibular system and hence the motion is felt, but no motion or little motion is detected by the visual system,  e.g. car sickness, air sickness, sea sickness, centrifuges, spinning.

Reading a book, a map or interior or the car, which are motionless, in a moving car/airplane/boat tends to easily motion sickness.  While visual system sees the motionless objects ( book, map or interior of car/airplane/boat ), vestibular system senses motion, especially vehicle goes around corners or over hills, which cause the discordance. 

The effect may be lessened by looking outside of the vehicle.

Yet, there is little that can be seen outside of a window of an airplane due to the small windows. 

Travelers on sea crafts too find it difficult to visually detect motion even if they look outside of the boat, as water does not offer fixed point with which to visually judge motion.

When one spins and stops suddenly, fluid in the vestibular system continues to rotate, causing a sense of continued spinning while one’s visual system no longer detects motion.

2. Motion is seen but not felt

Motion is detected by visual system, but no motion or little motion is sensed by the vestibular system.  It is also referred to as Visually Induced Motion Sickness ( VIMS ), eg. motion sickness due to films / virtual reality, simulation sickness, space sickness.

This type of sickness occurs when watching films on especially large screen or 3D, or even TV.  Films or home videos shot by handheld camcorder without image stabilization technology tend to contribute to motion sickness. 

Playing computer or video games too will cause motion sickness.

3. Motion sickness that are seen and felt but do not correspond

When moving in a vehicle for a long time on a badly maintained road at a very slow speed, the visual and vestibular systems fail to correspond which cause motion sickness.  Vibration of vehicle give sense of severe motion to the vestibular system, but due to the slow speed the visual system doesn’t sense proportional amount of motion.

Prevention & Treatment

Motion sickness can be cured or prevented by :

- Look out of the window of the moving vehicle and gaze toward the horizon in the direction of travel.  This helps to reorient the inner sense of balance by providing a visual reaffirmation of motion

- In the night, or in a craft without windows, it is helpful to simply close one’s eyes, or take a nap.  This resolves the input conflict between the visual and vestibular system.  Napping also helps prevent psychogenic effects ( the effect of sickness being magnified by thinking about it ).

- Chewing gum, snacking or just chewing in general seems to reduce adverse effects of the conflicts between visual and vestibular systems.

- Fresh, cool air also relieve motion sickness slightly.  As does avoiding foul odours.

- Get plenty of rest.   Weariness and exhaustion may induce motion sickness.

- Avoid acidic, spicy or oily food.   Avoid caffeinated beverages and soft drinks.

- Drink plenty of water.  Do not skip meals.  Don’t over eat.

- Medications such as Dramamine ( dimenhydrinate ), Stugeron ( cinnarizine ), and Bonine ( meclozine )

Water

Systematic Naming

The accepted IUPAC name of water is oxidane (H₂O) or simply water.

The simplest and best systematic name of water is hydrogen oxide.

The polarized form of the water molecule, H⁺OH^-, is also called hydron hydroxide by IUPAC nomenclature.

Dihydrogen monoxide (DHMO) is an overly pedantic naming of water.  Other systematic names for water include hydroxic acid, hydroxylic acid, and hydrogen hydroxide. Both acid and alkali names exist for water because it is amphoteric (able to react both as an acid or an alkali). While these names are technically not incorrect, none of them are used widely.

Electrical Properties

Dipole

Water is 1 molecule of oxygen covalently bonded to 2 hydrogen atoms, forms an angle ( 104.5° ), with H at the tips and O at the vertex.

Since O has a higher electronegativity than H, the side of the molecule with O has a partial negative charge.  An object with such a charge difference is called a dipole.   The charge differences cause water molecules to be attracted to each other and to other polar molecules.  This attraction contributes to hydrogen bonding, and explains many of the properties of water, eg. universal solvent, pH, adhesion, cohesion, capillary action, electric conductivity…   

Hydrogen bonding

A water molecule can form a maximum of 4 hydrogen bonds, because it can accept 2 and donate 2 hydrogen atoms. 

In water local tetrahedral order due to the 4 hydrogen bonds gives rise to an open structure and 3-dimensional bonding network, resulting in the anomalous decrease of density when cooled below 4°C.

Hydrogen bonding is responsible for a number of water’s physical properties, eg. high melting point, high boiling points, large specific heat capacity, large specific heat of vaporization, surface tension & capillary waves, density …

Physical Properties

Taste & Odor

Water is a tasteless, odorless liquid at standard temperature and pressure.

Transparency

Water is transparent to visible light, near ultraviolet light, and far-red light, but it absorbs most ultraviolet light, infrared light and microwaves. 

Most photoreceptors and photosynthetic pigments utilize the portion of the light spectrum that is transmitted well through water.  Thus aquatic plants can live within the water because sunlight can reach them.

Colour

The very weak onset of absorption in the red end of the visible spectrum lends water its intrinsic blue hue.

Density

The density of water is approximately 1 gram per cm³.   Yet it is very inconsistent. 

Although it is dependent on its temperature, the relation is not consistent.  At high temperature, it is less dense.  When it cooled from room temperature, the density increases.  At approximately 4°C, pure water reaches its maximum density.   

Upon freezing, the density of water decreases by about 95%.  Thus, the less denser solid water will float on denser liquid form.   

The reason of this is the water molecule forming hexagonal Ice l_h formation.

These properties of water have important consequences in its role in the Earth’s ecosystem.  Water at 4°C will accumulate at the bottom of fresh water lakes. Ice will floats over the water surface, creating a blanket which prevent loss of heat of the liquid water beneath.  Thus it is unlikely a deep lake will freeze completely, thus help preserve aquatic life.

Surface Tension

Water has a high surface tension of 72.8 mN/m at room temperature, cause by the dipolar interactions, the highest of the non-metallic liquids.  

The effects of surface tension can be seen with ordinary water :

-         beading of water on  sorption-free surface ( non-adsorbent and non-absorbent, eg. polyethylene ).  Surface tension give water their near-spherical shape, because a sphere has the smallest possible surface are to volume ratio.

-         formation of drops.

-         flotation of object denser than water occurs when the object is non-wettable and its weight is small enough to be borne by the forces arising from surface tension.

-         separation of oil and water

-         tears of wine

-         emulsions are a type of solution in which droplets of oil suspended in water ( or vice versa ).

Capillary Action

Due to an interplay of the forces of adhesion and surface tension, water is able to flow against gravity where it spontaneously rises in a narrow space such as a thin tube, or in porous material such as paper or cloths.

Examples of capillary actions:

-         kerosene lamp’s wick

-         chromotography

-         water movement in plant’s xylem

Universal Solvent

Water is a good solvent.  Substances that dissolve in water includes : salts, sugars, acids, alkalis, some gases.

However, water cannot dissolve all substances, especially those that are non-polar or hydrophorbic in nature.

Electrical Conductivity

Pure water does not conduct electricity, thus an excellent insulator.  But there are no such pure that it is free of ions, even deionized water.  As water is such a good solvent, it  almost always has some solute dissolved in it. 

pH

Pure water is pH neutral, that is pH 7.0. 

But since there are no such pure water, as there are a lot of substances that dissolve easily in water.  It is thus, water’s pH is very dependent on dissolved chemicals and minerals, as does it changes over time.

Normally, water pH is < 7.0.   That explains metals rust upon contact with water.  Surface water are mostly acidic.

Water with pH > 7.0 is considered basic.  Sea water is basic in nature.

Water with pH > 8.5 is considered hard water.  Hard water contains high mineral content, especially Ca²⁺ and Mg²⁺.  Hard water is difficult to suds – difficult to produce soap bubbles.  It also forms deposits that clog plumbing.

High Boiling Point

Boiling point is when a substance reach a temperature at which the liquid state of the substance change to vapor, under atmospheric pressure.  Water has a high boiling point ( 100°C ) for its strong hydrogen bonding.  High boiling point means water is not easily vaporized by heat, thus a stable medium for living organism.

Specific Heat Capacity & Heat of Vaporization

Water has the 2^nd highest specific heat capacity of all known substances, after ammonia, as well as high heat of vaporization, both of which are a result of the extensive hydrogen bonding between its molecules.

Specific heat capacity is the amount of energy required to change a substance’s temperature by a given amount. 

Ice’s specific heat capacity at -10°C is about 2.05 J•g^-1•K^-1.

Steam’s specific heat capacity at 100°C is about 2.08 J•g^-1•K^-1.

Heat of vaporization refers to amount of energy required to transform a given quantity of a substance into a gas at a given pressure. 

Water’s heat of vaporization is 2257 kJ•kg^-1.

The high specific heat capacity and heat of vaporization of water help to moderate Earth’s climate by buffering large fluctuations in atmosphere temperature.