FROM COLOURFUL CRYSTALS that 'harmonise auras' to research groups studying 'unexplained' phenomena such as Bigfoot, crank science is everywhere. Some of it has gone mainstream, such as homeopathy, the treatment of ills with solutions so dilute they have no active ingredients. Another is astrology, the study of how the movements of the stars and the planets dictate our personalities and daily affairs.

Most present themselves with a peppering of real science, or at least sciencey sounding jargon. Their purveyors, too, come decorated with the trappings of science.

Historically, faith healers and shamans would adorn themselves in spiritual symbols such as masks, amulets and perhaps the odd chicken's foot. Today, many still peddle snake oil, but often disguise themselves with surgical gloves and white coats. With a little bit of window dressing, the supernatural becomes the scientific.

Pseudosciences may sound harmless, but don't be fooled, says James Randi, a former magician turned professional sceptic, based in Fort Lauderdale, USA. "Any misinformation or misrepresentation, particularly if it appears in the guise of science or other genuine sources, can be, and often is, damaging," he says. "We need to receive dependable data in order to design, alter and direct our lives."

But for anyone caring to scratch the surface, says Randi, the frauds are easy to detect. Real science searches for the truth through rigorous methods; it strives to leave no questions unanswered; it provides solid evidence any other researcher can reproduce. Criticism and questioning is encouraged and constantly leads to an evolution of science in the face of new evidence.

Paranormal and alternative practices, such as channelling the dead and homeopathy, disregard the scientific method, cherry pick data that support their cause and promote claims that are difficult to test. Such practices distort our view of the world and remain tightly closed to scrutiny.

While purporting to be part of the scientific spectrum, and therefore trustworthy, pseudosciences also often claim to be beyond explanation by science, warding off criticism with descriptions of the mystical, the otherworldly or the divine. But, as sceptics are fond of saying, "Before we say something is out of this world, we should first make sure it's really not in this world." Let's take a quick tour of claims that are not quite as they seem.

1. ALIEN ABDUCTIONS

EACH YEAR THOUSANDS of new reports are made by people claiming to have experienced a 'close encounter of the fourth kind' (an alien abduction). This type was not included in the original scale developed by astrophysicist J. Allen Hynek, a scientific adviser to UFO studies by the U.S. Air Force and popularised by the 1977 Steven Spielberg film Close Encounters of the Third Kind.

Under the Hynek scale, the first kind is seeing something strange - odd lights and bizarre aerial objects. The second is experiencing physical effects in conjunction with a sighting, such as heat, radiation, paralysis or interference with car engines, TV or radio reception. The third type is seeing 'animate beings' associated with the other two phenomena.

Over several years, Hynek tried to bring a scientific eye to the study of unidentified flying objects, but was never able to satisfy himself that they had an extraterrestrial origin. He did note that a minority claimed to not only have seen aliens but to have been abducted by them.

According to an Associated Press poll in 2007, 14% of Americans say they have seen a UFO - that's about 43 million people. A small minority report being abducted by extraterrestrials (usually taken aboard spacecraft and examined) - though another 1991 poll estimated the figure could be as high as 3.7 million people who think they have been taken.

If you think that's a tad high, the non-profit organisation International Community for Alien Research will dispute you: it claims empirical studies show that "as many as one billion humans … have been abducted by hyperdimensional, amphibian-reptilian [civilisations]," according to director Joe Montaldo.

Abductees are not just an American phenomenon. "I was visited one night in my bedroom, in what I now know to be a typical abduction event," says Steve Smith (not his real name), of Sydney, Australia, who claims to have been taken to an alien spacecraft. "What happened to me is exactly how other people, who I've never even met, describe it," he says. "I woke up to the feel of eyes on me, a humming sort of sound, and then all of a sudden I was out my window … I couldn't move."

Like many 'abductees', Smith claims to have spoken to his captors with his mind and - after being weighed and measured - was returned safely to his bed. His experience is strikingly similar to countless reports collated in the works of 'ufologists', the people who make it their business to track and report UFO sightings and the more rare alien abductions. The same motifs often arise: strange sounds, lights and shapes; feelings of immobilisation; sensations of flying and falling; recollections of telepathic communication and being experimented upon.

But for all the years of research, ostensibly millions of alien visits and bountiful literature, the ufologists and abduction therapists (yes, they really exist) can only offer anecdotal evidence.

When pressed for proof, many insist hard evidence is found in the wreckage of alien craft that have come to Earth, but which have been locked away and classified by clandestine government agencies. Although explanations involving alien experimentation and a dash of government conspiracy are exciting, the evidence points in quite a different direction.

A simple and tidy explanation for the abductee phenomenon would be that people are merely telling tall tales about their experiences for fame or fortune, says Randi.

But it's not such an open and shut case. Often, abduction accounts "are examples of real, established, recognised delusions," he says. "A lot of these folks are genuinely, honestly and sincerely misled by their impressions of being attacked, molested or even taken away by mystical beings of varying sorts."

The fact that many descriptions are "unusually realistic and emotionally intense" suggests that there is something behind them, says neuropsychiatrist Christopher French, with Goldsmiths College, University of London, England.

"Very few people who have seriously examined this issue [of alien abductions] believe that the claimants are all lying, though inevitably there will always be one or two hoaxers," he says. "The vast majority of claimants appear to be sincere. Of course, that doesn't mean that the claims themselves are true."

Like many researchers studying the phenomenon, French cites the most likely explanation to be sleep paralysis - where the muscles become paralysed during REM sleep. Sleep paralysis occurs in healthy adults, though most of us wouldn't know it.

Rarely, though, people can become aware during a bout of paralysis, he says, which "can be a very frightening experience". A few people experience sleep paralysis in association with other symptoms, "including visual and auditory hallucinations," he says. These might account for many of the lights, sounds and other oddities experienced.

Sufferers may also experience "a strong sense of presence," adds French. "It is not uncommon, nor unsurprising, for people to report feeling intense fear during the experience."

And because sleep paralysis not widely known, but tales of alien abduction are pervasive, they're more likely to think they've had a terrifying alien or spiritual encounter than an unpleasant physiological experience.

But while sleep paralysis may account for a large part of the abduction puzzle, it doesn't wholly complete it. This is where the pseudoscience of 'repressed memory' comes in. Ufologists argue that aliens erase much of abductees' memories of the events, says French. "Many then recommend that the [abductees] undergo hypnotic regression, in the mistaken belief that hypnosis provides a magical key to unlock hidden memories."

Whether or not we can actually repress memories and later retrieve them remains an open question, but experiments have shown the power of suggestion can be used very effectively to create false memories. An oft-cited example is the scenario in which a person is fed a list of connotative words such as "sew" and "stitch" - and later recalls the words including the word "needle", which wasn't on the list.

"All of the experimental evidence shows that memories 'retrieved' using hypnosis can often be based entirely upon fantasy, expectation and bits and pieces of real memories. It is thus that false memories for entire episodes of alien abductions are formed," says French.

2. CROP CIRCLES

YOU'VE PROBABLY SEEN PICTURES: those flattened-out patterns that have appeared in great numbers in fields of crops since the 1980s. 'Cereologists' are the self-appointed researchers who have made studying the origins and meanings of crop circles an art form.

As crackpots go, cereologists are the cream of the crop, so to speak. Many of them are genuine academics who have spent years studying crop circles and even formed their own research groups.

If nothing else, they are a dedicated group trying their hardest to collate solid proof for their beliefs. But they are forever turning a blind eye to evidence that counters the alien origin of crop art. The irrefutable evidence, of course, is that crop circles are hoaxes, perpetrated by pranksters, artists and children, says Randi.

"It's hard enough to conceive why intergalactic aliens would opt to write in grain fields rather than public parks or on a piece of paper," he says, but even harder to understand why this pseudoscience persists.

Randi points to the adventures of Doug Bower and Dave Chorely, who came forward in the early 1990s to admit they were behind the original crop circles that kicked off the craze in Britain, their first and most famous example being a simple circle on a hill in Hampshire that drew the eyes of the world.

They even demonstrated for television how they made the large circles, using only planks of wood and string. Other pranksters, who jumped on the bandwagon following Bower and Chorely's lead, have since come forward, and a quick search on YouTube reveals reams of videos documenting their efforts.

Another nail in the coffin is an infamous video filmed near Oliver Castle, Ireland, showing balls of light apparently creating a circle. Once upheld as irrefutable evidence of an alien origin to the circles, the production company behind the video have since declared it a fake, and shown how the footage was doctored.

In short, the evidence that crop circles are bogus is plentiful, and the methods to create them are shown to be easily reproducible. Yet cereologists persist, ignoring evidence that doesn't aid their cause. Crop circles are simply too large and too complex to have been made in this way, claim researchers such as Eltjo Haselhoff author of The Deepening Complexity of Crop Circles.

Others argue that while some circles are hoaxes, many are genuine. They've even generated some rather wacky proof to back their claims. The late English astronomer Gerald Hawkins, for example, undertook a mathematical analysis of crop circles, studying their proportions to deduce geometric ratios.

These he saw to be integers, which corresponded with the white keys of a piano. When played, Hawkins said, the compositions associated with 'genuine' circles produced a pleasing sound, while those made by pranksters did not.

But not all crop circle research is so blatantly 'out there'. Take the BLT Research Team based in Massachusetts, USA. The world's largest crop circle research organisation, it claims to conduct tests using the scientific method. "Over 90% of many thousands of these tests [have] revealed a most interesting biophysical anomaly," in crops growing in circles, they say, describing how some seeds in crop circles grow "at up to five times the normal rate."

But "there isn't any data presented to substantiate the claims made," says David Guest, an agricultural scientist and plant pathologist at the University of Sydney who reviewed some of the BLT team's studies. "I want to see the actual evidence, but the data isn't there - so the reader has to take their word for it. That's not the way science works, of course."

The "complex atmospheric plasma energy system" that the researchers claim is responsible for enhancing the growth and resilience of older crops sounds impressive, Guest says. "But again, without evidence there's not much I can say, other than they are obviously passionate, but it looks like this passion leads them to the explanations they want in the absence of any reproducible data."

Whatever their position on the causes of crop circles, most agree that there is a rich history surrounding the idea of crop circles. For cereologists, the fact that ancient folklore tells "stories about fairies and elves seen dancing in the fields and leaving circles of trodden grass," stands as evidence to the fact the circles are real, claims one of many similar websites.

Believers also point to a woodcutting pamphlet more than 300 years old, "The Mowing Devil", which they claim depicts the Devil mowing a field in a circular pattern in history's earliest representation of the phenomenon.

But for Randi, this is just fallacious reasoning, often used in crank science - they are attempting to draw credibility from longstanding histories, disregarding their origins as fables and superstitions. Put simply, we always have - and always will - want to believe in the fantastic. In fact, many scientists believe we are even programmed to do so.

In 2006, Bruce Hood, an experimental psychologist from Britain's University of Bristol claimed that evolution had led to the human brain being hardwired to be open to supernatural beliefs. "Humans are born with brains designed to make sense of the world, and that sometimes leads to beliefs that go beyond any natural explanation," he says. "We are inclined from the start to think that there are unseen patterns, forces and essences inhabiting the world."

As the late Carl Sagan, astrophysicist and author points out in his book, The Demon Haunted World: Science as a Candle in the Dark, we have a long history of being 'visited'. But testimony to the fact that these strange encounters are anything but otherworldly is that these visitors have changed with the time and cultural reference frame.

Historically, people were visited by devils, demons and other creatures that emerged from the underground. Today, in the age of science fiction and space travel, we are visited by aliens from above.

Similarly, crop circles themselves have changed over time. At first they appeared as plain shapes; later, coinciding with the popularity of fractal geometry, they took on more geometric forms; today, in the computer age, many appear characteristically digitised. And perhaps the next trend, starting to draw media attention now, are circles made in ice.

3. PSYCHIC SURGERY

PEOPLE WITH PSYCHIC POWERS claim to be able to do a number of things - from seeing the past and predicting the future, to communicating with the dead.

In the 1970s and '80s celebrity 'psychic' Uri Geller used the awesome powers of his mind to bend spoons. Logical explanations abound for these parlour tricks. And while Geller and others might merely amuse and entertain, there are others who claim to put their psychic abilities to more disturbing uses.

So-called psychic surgeons purport to be able to treat serious medical conditions. Some do this simply by transferring positive energy (sometimes referred to as 'external Qi Gong energy') through touch and manipulation, while others - the most spectacular and theatrical practitioners - appear to delve into bodies with their bare hands and the power of their minds, root around and yank out 'bad energy', diseased tissue, blood clots, tumours and other nasties.

Patients miraculously feel no pain, are left with no physical evidence that the extreme procedure has taken place, and remain curiously immune to post-operative infections. No ailment is beyond curing, psychic surgeons claim.

Cancer, paraplegia, blindness -all can be fixed (the later alleviated simply by removing the eyeballs and giving them a good clean). Toothache? You're in luck: there are psychic dentists too. They'll even take a 'spiritual X-ray', which involves something along the lines of holding a sheet of white paper over the patient to pinpoint the problem areas.

However, according to Randi, psychic surgery is a classic example of quackery at work. One giveaway, he says, is the "free use of scientific terms, such as 'quantum' and 'vibrations', incorrectly and quite out of context." Several articles on alternative therapy attempt to explain psychic surgery in terms of modern physics, most popularly with chaos and quantum theory. One popularly cited explanation reads:

"The healers form strong etheric force or energy in their hands through intense concentration. This energy penetrates matter at the cellular or even sub-atomic levels where matter and energy are interchangeable. After the accumulation of etheric forces, the magnetic cohesive energy is separated through unpolarisation. And then after the operation, the cells go back to their former appearance."

That's a lot of sciencey-sounding words, but little of it makes sense.

The website of another psychic surgeon reads: "The concept of vibration may lead us to an understanding of the principles underlying psychic surgery, because we already know that the same material, vibrating at different rates, can exist in vastly different forms. Water, for example, can be a solid, a liquid or a gas."

This is a scientific fact used in an unrelated context. It's a typical example of how crank science uses genuine science to appear convincing.

Other times psychic surgeons attempt to shut out legitimate scientific inquiry. To do this, "claimants freely ascribe their findings and practices to divine inspiration," says Randi. Much like shamans or healers in pre-industrial societies, some practitioners claim to be vessels through which healing spirits operate.

Alex Orbito, one of the world's most infamous psychic surgeons once explained: "When my spiritual mind is attuned to the higher intelligence which is the Holy Spirit of God, my hands emit an energy which is more powerful than the physical constitution of the human cells, so that they merely give way to the more powerful force."

How can scientists and sceptics counter this? We don't have to, says Randi, we only need to be able to provide a simpler, more reasonable answer, and science will be on our side. The humdrum explanation is that psychic surgery is elaborate fakery.

Former practitioners have come forward to demonstrate the practiced hand gestures, fake blood and chicken innards they've used.

A 1979 study in medical journal The Lancet described tests after the psychic surgery on a man with kidney stones. X rays revealed his kidney stones to be unchanged and the blood spilled to be animal blood.

There are numerous similar studies, and indeed a number of psychic surgeons have been indicted for fraud, including Orbito, who was arrested in Canada in 2005 (the charges were dropped.)

Other psychic surgeons have been caught redhanded with the tools of their trickery, such as Gary Magno, arrested in 1986 in Phoenix, Arizona, with vials of red fluids and packets of meat.

Though it may seem like an amusing farce, psychic surgery can be dangerous. People believe they have treated a problem when they haven't. Not only does the practice waste time and money, says the U.S. National Council Against Health Fraud, but it "causes psychological harm [and] … may cause needless death by keeping people from timely, effective health care."

4. HOMEOPATHY

DESPITE ALL THE EVIDENCE to refute it, homeopathymaintains popular appeal. Among its fans are Britain's Prince Charles and some of the Hollywood elite. It's a multi-million dollar industry worldwide and remedies based on it can be in most health food stores and pharmacies.

In some countries, such as China and Brazil, the remedies are even part of mainstream medical care, and in Australia, many health insurers will help pay for homeopathic treatments.

Despite all of this, homeopathy is a medically unproven (many would say disproven) treatment, based on a set of laws concocted in the 18th century by German physician Samuel Hahnemann.

Back then, when leeches and bloodletting were all the rage, it's easy to imagine the appeal of the gentler approach of homeopathy. But today, it's hard to fathom why a practice with little logical foundation holds such appeal.

The basic idea of homeopathy is that 'like cures like': so, for example, a dose of coffee typically results in feelings of alertness, but it is used in homeopathic medicine to treat insomnia. Through a process called 'proving', homeopaths take a substance (an extract of a plant or a mineral), and give it to a test group of healthy people.

Whatever the symptoms they observe in those people - which could be anything from hives to bad dreams - are the symptoms that the preparation is then used to treat. Another pillar of homeopathy is the 'law of infinitesimals', which holds that the healing power of that substance will be made more potent the greater its dilution.

In fact, a typical homeopathic remedy is diluted to the point that it contains far less than one part per million of the original preparation.

One common dilution, '30C', is prepared with one part active ingredient in 1060 parts water (by way of example a trillion or a million, million is 1012). As keen observers will note, this is well past the dilution limit of any mixture, as measured by Avogadro's number, meaning there's little chance of any ingredient being left in the water.

Or as British physician, sceptic and newspaper columnist Ben Goldacre puts it: "a conventional homeopathic preparation is diluted so much that it's roughly one molecule in a sphere of water the size of the distance from here to the Sun."

And some preparations go further still, with dilutions of '200C' - which means it is effectively diluted by more atoms than there are in the universe, says Goldacre. So even though many homeopathic ingredients do have biological effects (leaving aside imaginative ingredients such as 'lava' and 'moonlight'), they are too dilute to be anything but plain water.

In the face of this reasoning, most homeopaths are happy to admit that the pills and solutions they prescribe contain no molecules of the original substance.

But, they say, the water they sell 'remembers' its medicinal properties. This idea was proposed by French immunologist Jacques Benveniste, who reported that an infinitely diluted solution, which once contained allergens, had a stimulating effect on human white blood cells.

Since "none of the starting molecules [were] present in the dilutions beyond the Avogadro limit … information must have been transmitted during the dilution/ shaking process. Water could act as a 'template' for the molecule," he wrote in a paper that controversially made its way into the British journal Nature in 1988.

Where Benveniste saw proof of a new scientific phenomenon, others saw proof that something had gone amiss with his methods. Criticism was so intense that a Nature team, accompanied by none other than Randi, visited Benveniste's lab to see if his results could be replicated in a properly blinded, controlled experiment.

This failed, and nobody has since been able to replicate the observations. Benveniste persisted, however, later reporting he'd found the memory of water to be stored in electromagnetic waves, which could be captured, transmitted over the Internet and used to 'activate' water on the other side of the world.

Yet, however incredulous all these extreme dilutions and convoluted theories are, the major reason to doubt homeopathy stems from the fact that in large, randomised trials it is no more effective than a placebo.

A placebo is a 'dummy' or control treatment with no medical effect, often used in clinical trials to assess the effect of a new drug. Despite the lack of genuine medical intervention, people taking placebos get better, evidencing the power of our minds over our bodies.

"The totality of the reliable evidence available today tells a clear and simple story: homeopathic remedies are placebos," says Edzard Ernst, professor of complementary medicine at the Peninsula Medical School in Exeter, England. Once a practicing homeopath, Ernst has conducted several random control trials and a dozen systematic reviews of the practice.

But homeopaths claim otherwise, and this, in part, is why the field can be considered classic crank science: they uphold only suggestions of success and ignore the failures. "They are incapable of engaging in any critical appraisal of their ideas," says Goldacre. "While all other medicine welcomes criticism, and thrives on it, homeopathic ideas remain fixed and unchanging."

Though the treatments themselves are unlikely to be actively harmful, there are other risks associated with homeopathy. Several deaths have been linked to cases where patients decided to forgo conventional medical treatment. Homeopaths can also give people false hopes that they will be able to treat incurable diseases, such as terminal cancers.

Homeopaths sell many treatments as alternatives to vaccination, which they call 'homeoprophylaxis', covering everything from meningococcal and whooping cough to avian flu.

At the same time, these practitioners often advise against medically proven vaccinations. "In general, the homeopathic form of the [influenza] vaccine has been shown to be just as effective as the stronger, injectable vaccine," reads one website. "The advantages, however, make the homeopathic remedy much more desirable."

But while homeopathy, like psychic surgery, may appear harmless, there's a real danger to human health through treatment denied. The opportunists who deceive us do so for various reasons, usually connected with money.

"They should be opposed, exposed for what they are, and put out of business - a daunting task, indeed," says Randi. "We should also be able to depend on our media for news of discoveries, statements, opinions and events, without having to allow for hyperbolic intervention and outright falsity."

And just in case you're still not convinced by the evidence debunking the paranormal, the James Randi Educational Foundation is offering a US$1 million dollar prize to anyone who can demonstrate convincing evidence of a paranormal or supernatural power or event. You'd better get moving if you want to claim it, the offer will expire in March 2010.

Follow Cosmos on Twitter!
twitter.com/cosmosmagazine

---