Shiv Raatri is the time when Shiv takes a rest. Shiv rests for one 'Prahar' (three hours) of the night. This 'Prahar' is referred to as the Shiv Raatri. When Lord Shiv takes rest, the function of 'Shiv Tattwa' (Shiv Principle) ceases, ie Lord Shiv goes into a meditative state. Shiv's meditative state is the time when he is engrossed in his own spiritual practice. During that time, the 'Shiv Tattwa' does not accept any Tamo Gun (most base of the 3 elements in us are Sattwa, Rajas and Tamas) or any Halaahal (venom churned from the ocean) coming from the Universe. As a result, the ratio of halahal or the pressure of the negative energies increases. For protection from this pressure, things like 'Bilva Patra', white flowers, 'Rudraaksh' beads etc are offered to Shiv. These things attract the 'Shiv Tattwa' from the atmosphere, thus providing protection from the increasing effect of the negative energies.

The Earth is a gross object. Gross objects have very low velocities, means they require more time to cover a specific distance in space. Gods on the other hand, are subtle hence they are capable of traversing space within a few seconds. That is why one year on the Earth is equivalent to just one day of Heaven.

Science in the Worship of Shiv on Mahaa Shiv Raatri

The Functions of the 'Shiv Pindee'
(1) Emitting waves of Knowledge, Devotion and renunciation Predominantly 'Sattwa' waves of knowledge, 'Rajas' waves of devotion and 'Tamaa' waves of Renunciation (Vairaagya) are emitted by the 'Shiv Pindee'.  During Mahaa Shiv Raatri, the emission increases by 30 percent.
(2) Emission of subtle vibrations of Chaitanya, bliss and peace - The 'Shiv Pindee' emits subtle vibrations of Chaitanya, bliss and peace. During the Mahaa Shiv Ratri, the emission increases by 25 percent. This helps purify the subtle-body of one who worships the Shiv Pindee on this day. The 'Sun' or the 'Moon' channels in the body get activated as per necessity. The capacity to absorb the Sattwa Gun and Chaitanya also increases. Due to the presence of the unmanifest Shiv principle in the Shiv Pindee and the vibrations of peace emitted,the Shiv Pindee remains cool and the mind too experiences peace. Worship of Shiv Pindee with devotion, activates the dormant Shiv principle. An offering of puffed rice and milk reaches Shiv in the subtle form.
(3) Receiving the 'Taarak or Maarak Tattwa (element)' as required - There is a confluence of the manifest and the unmanifest elements along with the 'Taarak and Maarak Tattwa' in the Shiv Pindee. (Taarak = Savior; Maarak = Destroyer). That is how worshipers receive the required element. The temperature of the Shiv Pindee increases due to the emission of the Maarak Tattwa and there one experiences bliss. Similarly, when the Taarak tTattwa is emitted, the temperature drops and one experiences peace and bliss.
(4)  Bilva Patra (Bel leaves) - Bilva Patra contains 2% Shiv Tattwa. By offering Bilva Patra to the Shiv Pindeei on Mahaa Shiv Raatri, the manifest Shiv Tattwa near the stalk of the Bilva Patra gets activated. Due to this, waves of Chaitanya as well as Shiv Tattwa are emitted by the Bilva Patra. The Bilva Patra attracts 20% of the Shiv Tattwa present in the Shiv Pindee towards itself. By immersing this Bilva Patra in water or by placing it in grains, the Shiv Tattwa present in the Bilva Patra is transmitted to them. The Shiv Tattwa in the Bilva Patra is activated to a larger extent on Mondays when it transmits 10% of the Shiv Tattwa and Saattwikataa. On other days only 1% of the Shiv Tattwa is activated in the Bilva Patra.
(5) Bilvaarchan - Offering Bilva Patra to the Shiv Pindee and chanting the Mantra "Om Namah Shivaaya" with each offering is known as Bilvaarchan. Continue offering the Bilva Patra until the Pindee is completely covered. Offer the Bilva Patra from the lower part of the Pindee. By starting from the feet of the idol, more benefit is derived and then the idol can be covered completely. Chanting on Mahaa Shiv Raatri 'Om Namah Shivaaya'. Om represents an unmanifest state beyond the 3 Gun (elements of Sattwa, Rajas and Tamas). We bow to Shiv, from whom Om was created.

What Does the Word 'Shiv' mean?

(1)The word Shiv has been derived by reversing the letters of the word "Vash". "Vash" means to enlighten; thus the one who enlightens is Shiv. He remains radiant and also illuminates the universe.
(2) He is the auspicious and prosperity - bestowing principle.

Some Unique Attributes of Shiv

(1) Physical Attributes
--Gangaa : Just as the Sun is the focal point of the solar system and the soul that of the body, the focal point of divine consciousness (Chaitanya) in every object and pure particles (Pavitrakaa) is "ga-aum". The flow from which "ga-aum" originates is "gan gaha" = Gangaa. Ga-aum flows from Shiva's head. This is called the descent of the Gangaa from Shiv's head. Since the river Gangaa has a fraction of the principle of the spiritual Ganga, no matter how polluted it becomes, its purity is perpetually retained. Hence, when compared to any other water in the world, the water from the Gangaa is the purest. This is realized not only by those who can perceive the subtle dimension but also by scientific researchers.
--Moon : Shiv adorns the Chandra (Moon) on his forehead. The point where the three frequencies - affection (Mamataa), mercifulness (Kshamaa -Sheelataa) and motherly love (Vaatsalya) originate is referred to as the Chandra (Moon). Thus, one can conclude that Chandramaa (the Moon principle) is the state in which the three attributes of affection, mercifulness and motherly love are present.
--Third eye : Shankar is three-eyed, ie he can perceive events of the past, present and future. According to the science of Yog the third eye means the Sushumnaa Naadee (channel).
--Serpent : One of the Names of Lord Shankar is Bhujang-pati Hari. Bhujang means a serpent or pure particles (Pavitrakaa), Pati means the nurturer and Hari means one with a garland around his neck. Thus  Bhujanga-pati Hari means the One who nurtures pure particles and wears them like a garland. Various serpents represent groups of pure particles. Though externally they appear like serpents, internally they are a kind of ladder. To make spiritual progress one has to climb up holding onto the tail of the serpent. Shankar adorns serpents at nine points on His body - one on the head, one around the neck, one on each arm, one on each wrist, one around the waist and one on each thigh. This implies that his body is comprised of pure particles or that serpents of pure particles play all over the body of Shankar who has the universe as His form.

2. Spiritual Attributes
--One performing severe austerities and the great Yogee Shiv is always seated in a Bandh or a Mudraa. His temperature rises due to heat generated by performing severe austerities; hence, he uses the Gangaa, the Moon and serpents which endow a cooling effect and lives on the snow-clad Kailaash mountain.
--Short tempered - If someone disturbs his meditation the radiance generated by spiritual practice will be suddenly expelled and whoever is in front of Him will not be able to tolerate it, and gets destroyed. This is referred to as being 'reduced to ashes by Shankar's opening of the third eye'.
--One who is willing to undergo any distress for the sake of imparting happiness to others. The poison generated during the churning of the celestial ocean (Samudra Manthan) was burning the entire Universe but no deity came forward to accept it. At that time Shiv drank that poison and saved the world from destruction.
--One who has both, deities and demons, as His worshippers - Neither did demons like Baanaasur, Raavan, etc worship Vishnu nor did Lord Vishnu bestow any boon upon any demon. However, they worshipped Shiv who blessed them.
--Master of the spirits - Since Shiv is the master of spirits, his worshippers are generally not possessed by them.
--Science in the idol - in the Human form - This represents the Brahm in the form of the word (Shabd Brahm). Alphabets consisting of the sounds of fifty-two basic letters and the forms of fourteen Maheshwar verses (Sootra) have generated from it. Later the universe was created from these.

2. Trident : represents the following - The three components - Sattwa, Rajas and Tamas. The root of creation, sustenance and dissolution Volition, knowledge and action.

3. Noose (Paash) : The noose represents the noose of time (Kalpaash) - (The rope in Lord Ganapati's hand too is the same).

Worship
--Application of holy ash (Bhasm) - Tripundra refers to the three horizontal lines of holy ash applied to the forehead. These lines symbolize spiritual knowledge, purity and penance (spiritual practice of Yog), so also they represent the three eyes of Shiv.
--Wearing a Rudraaksh - Wearing a Rudraaksh when worshipping Shiv is ideal. A Rudraaksh is reddish in color with yellow stripes and is flat like a fish. On one side it has a slight opening which appears like an open mouth. The Rudraaksha converts light frequencies of deities from the universe into sound frequencies in the body of humans and vice versa. As a result, humans can absorb frequencies of deities and thoughts can get converted into the language of deities.
--A genuine Rudraaksh - The Rudraaksh absorbs Sama (Sattwa) frequencies. Similarly Sama frequencies are emitted by its crests. A real Rudraaksh can be recognized by the vibrations felt by holding it in the hand. At that time the body absorbs the Sama frequencies emitted by the Rudraaksh. Nowadays, mostly Vikrutaaksh is sold as a Rudraaksh. This is the seed of a type of wild berry. Vikrutaaksh is used for sacrificial fires of Taantrik, black magic etc by sorcerers.
--Ritualistic worship of the Pindee - Only cold water and Bel is offered to Shankar's Pindee. Neither is it bathed with milk and Panchaamrit (a mixture of milk, curds, ghee, sugar and honey) nor offered turmeric, vermilion (Kumkum) or white consecrated rice (Akshat). Milk and clarified butter (ghee) symbolize sustenance while turmeric is an underground stem and represents fertility of the soil, that is creation. Vermilion is prepared from turmeric. Since Shiv is the deity of dissolution, substances such as milk, vermilion and turmeric are not used in his worship.
--Circumambulation - Pradakshinaa - When circum-ambulating, one should begin from the left side and continue till the channel of the Shaalunkaa, from where the water offered during the ritualistic bathing (Abhishek) flows. Without crossing it one should complete a circum-ambulation by moving in the reverse direction up to the other side of the channel. The flow of a Shaalunkaa is not crossed as it is the flow of energy which adversely affects the formation of semen and the five internal vital energies (Praan Vaayu).
--Chanting the Name of Shiv - 'Namah Shivaaya is Shiv's five-syllabled Mantra. The spiritual meaning of each of the five syllables is:
na = Foremost deity of all the regions (Lok)
ma = Bestower of supreme spiritual knowledge (Gyaan) and redeemer of the greatest of sins
shi = Benevolent, serene and responsible for initiation by Shiv
vaa = Symbolic of a bull as the vehicle and Vaasuki and Vaamaangee energy (Shakti)
ya = Auspicious abode of Supreme Bliss and Lord Shiv.
Hence, obeisance (Namaskaar) to these five syllables.