A miracle is a perceptible interruption of the laws of nature, such that can be explained by divine intervention, and is sometimes associated with a miracle-worker. Many folktales, religious texts, and people claim various events they refer to as miraculous. People in different cultures have substantially different definitions of the word miracle. Even within a specific religion there is often more than one of the term. Sometimes the term miracle may refer to the action of a supernatural being that is not a god. Thus, the term divine intervention, by contrast, would refer specifically to the direct involvement of a deity.

In casual usage, miracle may also refer to any statistically unlikely but beneficial event, such as the survival of a natural disaster, or even that regarded as wonderful regardless of its likelihood, such as birth. Other miracles might be survival of a terminal illness, escaping a life threatening situation or beating the odds.

In this view, a miracle is a violation of normal laws of nature by some supernatural entity or unknown, outside force. Some scientist-theologians like Polkinghorne suggest that miracles are not violations of the laws of nature but exploration of a new regime of physical experience.

The logic behind an event being deemed a miracle varies significantly. Often a religious text, such as the Bible or Quran, states that a miracle occurred, and believers accept this as a fact. However, C.S. Lewis noted that one cannot believe a miracle occurred if one had already drawn a conclusion in one’s mind that miracles are not possible at all. He cites the example of a woman he knew who had seen a ghost and had discounted her experience, claiming it to be some sort of hallucination.

Many conservative religious believers hold that in the absence of a plausible, parsimonious scientific theory, the best explanation for these events is that they were performed by a supernatural being, and cite this as evidence for the existence of a god or gods. Some adherents of monotheistic religions assert that miracles, if established, are evidence for the existence of an omnipotent, omniscient, and benevolent God.

Followers of the Indian gurus Sathya Sai Baba and Swami Premananda claim that they routinely perform miracles. The dominant view among skeptics is that these are predominantly sleight of hand or elaborate magic tricks.

Some modern religious groups claim ongoing occurrence of miraculous events. While some miracles have been proven to be fraudulent, others such as the Paschal Fire in Jerusalem have not proven susceptible to analysis. Some groups are far more cautious about proclaiming apparent miracles genuine than others, although official sanction, or the lack thereof, rarely has much effect on popular belief.

Dream interpretation is the process of assigning meaning to dreams. In many of the ancient societies, including Egypt and Greece, dreaming was considered a supernatural communication or a means of divine intervention, whose message could be unravelled by those with certain powers. In modern times, various schools of psychology have offered theories about the meaning of dreams.

The ancient Greeks constructed temples they called Asclepieions, where sick people were sent to be cured. It was believed that cures would be effected through divine grace by incubating dreams within the confines of the temple. Dreams were also considered prophetic or omens of particular significance. In ancient Egypt, priests also acted as dream interpreters. Joseph and Daniel are recorded as having interpreted dreams sent from God, and indeed the Bible describes many incidents of dreams as divine revelation. Hieroglyphics depicting dreams and their interpretations are evident. Dreams have been held in considerable importance through history by most cultures.

Dream interpretation was taken up as part of psychoanalysis at the end of the 19th century; the perceived, manifest content of a dream is analyzed to reveal its latent meaning to the psyche of the dreamer. One of the seminal works on the subject is The Interpretation of Dreams by Sigmund Freud.

In 1953, Calvin S. Hall developed a theory of dreams in which dreaming is considered to be a cognitive process. Hall argued that a dream was simply a thought or sequence of thoughts that occurred during sleep, and that dream images are visual representations of personal conceptions. For example, if one dreams of being attacked by friends, this may be a manifestation of fear of friendship; a more complicated example, which requires a cultural metaphor, is that a cat within a dream symbolizes a need to use one’s intuition. For English speakers, it may suggest that the dreamer must recognize that there is “more than one way to skin a cat”, or in other words, more than one way to do something.

In the 1970s, Ann Faraday and others helped bring dream interpretation into the mainstream by publishing books on do-it-yourself dream interpretation and forming groups to share and analyze dreams. Faraday focused on the application of dreams to situations occurring in one’s life. For instance, some dreams are warnings of something about to happen – e.g. a dream of failing an examination, if one is a student, may be a literal warning of unpreparedness. Outside of such context, it could relate to failing some other kind of test. Or it could even have a “punny” nature, e.g. that one has failed to examine some aspect of his life adequately.

Faraday noted that “one finding has emerged pretty firmly from modern research, namely that the majority of dreams seem in some way to reflect things that have preoccupied our minds during the previous day or two.”

Exploding head syndrome is a condition that causes the sufferer to occasionally experience a tremendously loud noise as originating from within his or her own head, usually described as the sound of an explosion, roar, waves crashing against rocks, loud voices or screams or a ringing noise.

This noise usually occurs within an hour or two of falling asleep, but is not the result of a dream and can happen while awake as well. Perceived as extremely loud, the sound is usually not accompanied by pain. Attacks appear to change in number over time, with several attacks occurring in a space of days or weeks followed by months of remission.

Sufferers often feel a sense of fear and anxiety after an attack, accompanied by elevated heart rate. Attacks are also often accompanied by perceived flashes of light (when perceived on their own, known as a “visual sleep start”) or difficulty in breathing. It is not thought to be dangerous, although it is sometimes distressing to experience.

The cause of the exploding head syndrome is not known, though some physicians have reported a correlation with stress or extreme fatigue. The condition may develop at any time during life and women suffer from it slightly more often than men. Attacks can be one-time events, or can recur.

The mechanism is also not known, though possibilities have been suggested. One is that it may be the result of a sudden movement of a middle ear component or of the eustachian tube. Another is that it may be the result of a form of minor seizure in the temporal lobe where the nerve cells for hearing are located. Electroencephalograms recorded during actual attacks show unusual activity only in some sufferers, and have ruled out epileptic seizures as a cause.

This syndrome can also cause the sufferer to feel an extreme rush or adrenaline kick going through his or her head, sometimes multiple times. In most cases, it occurs when they are in a state between asleep and awake. Some sufferers report familiarisation with the subsequent fear or panic element such that they no longer consciously experience it.

Symptoms may be resolved spontaneously over time. It may be helpful to reassure the patient that this symptom is harmless. Clomipramine has been used in three patients, who experienced immediate relief from this condition.

Fluorescence is a luminescence that is mostly found as an optical phenomenon. The term fluorescence was coined by George Gabriel Stokes in a 1852 paper. The name was given as a description of the essence of the mineral fluorite, composed of calcium fluoride, which gave a visible emission when illuminated with UV radiation.

The common fluorescent tube relies on fluorescence. Inside the glass tube is a partial vacuum and a small amount of mercury. An electric discharge in the tube causes the mercury atoms to emit light. The emitted light is in the ultraviolet range, is invisible, and is harmful to most living organisms. The tube is lined with a coating of a fluorescent material, called the phosphor, which absorbs the ultraviolet and re-emits visible light.

All plants, algae, and cyanobacteria are naturally fluorescent, since chlorophyll a is fluorescent. Some flowers also contain other more visibly fluorescent pigments like betaxanthins, increasing visibility to pollinators.

Plants have also been genetically modified to fluoresce. There are many types of green fluorescent proteins that absorb and emit at different wavelengths. This enables the production of many differently labeled fluorescent molecules in a single plant.

Plant fluorescence is being found to be highly useful for the University of Florida and the NASA staff. These individuals are working together to learn more about the planet Mars. These scientists and engineers have chosen the Arabidopsis mustard plant to go to Mars, for many reasons.

Reporter genes have been added to this plant to glow for different environmental stressors. These stressors include temperature, drought, disease, metal content in the soil and peroxides. Each stressor will glow at a different wavelength that will be monitored. By doing such an experiment more will be learned about the environment on Mars in order to modify plant life to be able to survive there.

Crude oil (petroleum) fluoresces in a range of colors, from dull brown for heavy oils and tars through to bright yellowish and bluish white for very light oils and condensates. This phenomenon is used in oil exploration drilling to identify very small amounts of oil in drill cuttings and core samples.

The dream argument is the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion should not be fully trusted, and therefore any state that is dependent on our senses should at the very least be carefully examined and rigorously tested to determine if it is in fact reality.

While people dream, they usually do not realize they are dreaming. This has led philosophers to wonder whether one could actually be dreaming constantly, instead of being in waking reality (or at least that one can’t be certain that he or she is not dreaming). Having received serious attention in René Descartes’ Meditations on First Philosophy, the dream argument has become one of the most popular skeptical hypotheses.

Dreaming provides a springboard for those who question whether our own reality may be an illusion. The ability of the brain to trick itself into believing a neuronally generated world is the real world means at least one variety of simulated reality is a common, even nightly event.

Those who argue that the world is not simulated must concede that the mind, at least the sleeping mind, is not itself an entirely reliable mechanism for attempting to differentiate reality from illusion.

This could be seen as a challenge to those who claim a simulated reality requires highly advanced scientific technology, since, if dreaming really is a form of virtual reality, the only apparatus needed to construct a simulated reality capable of fooling the unconscious mind is a human brain.

In Lewis Carroll’s Through the Looking-Glass, Alice finds the Red King asleep in the grass. Tweedledum and Tweedledee tell her that the Red King is dreaming about her, and that if he were to wake up she would “go out—bang!—just like a candle.”