False memories prime immune system for future attacks

IN A police line-up, a falsely remembered face is a big problem. But for the body's police force – the immune system – false memories could be a crucial weapon.

When a new bacterium or virus invades the body, the immune system mounts an attack by sending in white blood cells called T-cells that are tailored to the molecular structure of that invader. Defeating the infection can take several weeks. However, once victorious, some T-cells stick around, turning into memory cells that remember the invader, reducing the time taken to kill it the next time it turns up.

Conventional thinking has it that memory cells for a particular microbe only form in response to an infection. "The dogma is that you need to be exposed," says Mark Davis of Stanford University in California, but now he and his colleagues have shown that this is not always the case.

The team took 26 samples from the Stanford Blood Center. All 26 people had been screened for diseases and had never been infected with HIV, herpes simplex virus or cytomegalovirus. Despite this, Davis's team found that all the samples contained T-cells tailored to these viruses, and an average of 50 per cent of these cells were memory cells.

The idea that T-cells don't need to be exposed to the pathogen "is paradigm shifting," says Philip Ashton-Rickardt of Imperial College London, who was not involved in the study. "Not only do they have capacity to remember, they seem to have seen a virus when they haven't."

So how are these false memories created? To a T-cell, each virus is "just a collection of peptides", says Davis. And so different microbes could have structures that are similar enough to confuse the T-cells.

To test this idea, the researchers vaccinated two people with an H1N1 strain of influenza and found that this also stimulated the T-cells to react to two bacteria with a similar peptide structure. Exposing the samples from the blood bank to peptide sequences from certain gut and soil bacteria and a species of ocean algae resulted in an immune response to HIV (Immunology, doi.org/kgg).

The finding could explain why vaccinating children against measles seems to improve mortality rates from other diseases. It also raises the possibility of creating a database of cross-reactive microbes to find new vaccination strategies. "We need to start exploring case by case," says Davis.

"You could find innocuous pathogens that are good at vaccinating against nasty ones," says Ashton-Rickardt. The idea of cross-reactivity is as old as immunology, he says. But he is excited about the potential for finding unexpected correlations. "Who could have predicted that HIV was related to an ocean algae?" he says. "No one's going to make that up!"

This article appeared in print under the headline "False memories prime our defences"

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Australia seeks answers from Israel on 'Prisoner X'

SYDNEY: Canberra said Sunday it was seeking answers from Israel over the death in 2010 of an Australian known as "Prisoner X" in a Tel Aviv jail as part of its own probe into the case.

Foreign Minister Bob Carr said his office was preparing a formal report into the circumstances surrounding the death of the prisoner, identified in Australian media as Ben Zygier, 34, who Israel says committed suicide.

That the detainee, held in a high security prison under continuous surveillance, managed to hang himself has raised questions and fed conspiracy theories that have been reported by the Israeli and Australian media.

Many questions remain unanswered in the mysterious case, with a senior unnamed Israeli official telling The Australian newspaper that Australian officials had interrogated the prisoner on suspicion of spying for Mossad.

Carr said foreign office chief Peter Varghese was preparing a report which would "canvass all the consular contact between Australia and between Israel" including contact between security agencies.

"We have asked the Israeli government for a contribution to that report," Carr told reporters in Sydney.

"We want to give them an opportunity to submit to us an explanation of how this tragic death came about."

If the report showed "any areas where we can improve our contact in consular cases like this", Carr said, "it will have practical effect when there are cases in the future where an Australian citizen is treated in a comparable way."

"I need to know what the contact was between Australian agencies and those of Israel, and I need to see what the Israelis want to tell Australia," he said. "The key is to get all the information."

Carr, foreign minister since early 2012, originally said the Australian government had not been informed of the prisoner's plight.

He later backtracked on this claim, conceding that Canberra was told in February 2010 -- 10 months before the death -- that Israel had detained an Australian-Israeli citizen on national security grounds.

Carr's predecessor Kevin Rudd, foreign minister at the time of the prisoner's death, said Sunday it was important that Australia "get to the bottom of this".

"(I was) deeply surprised to hear not only had this person been incarcerated, but subsequently died in custody," Rudd told Sky News.

"The tradition of this government has to be robust on these matters, even with a country with whom we've had the friendliest of relationships."

- AFP/ir

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Internet rules: More cats. LESS CAPS

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

Our 12 Rules of the Internet

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STORY HIGHLIGHTS

• Yes, there ARE some rules to the Internet, though, for now they're mainly an inside joke


• Some rules based on pop culture, some have become Web memes


• Other rules ominously quote Anonymous


• Is there a need for rules on the vast and wild Web? Depends on where you stand

Editor's note: In the gallery above, we've selected a handful of our favorite Internet rules, or truths. (You might recognize a few.) What are some of yours? Tell us in the comments. We'll feature some of the best on CNN.

(CNN) -- Hello!

Welcome to the Internet. It's a big place, so let me show you around.

You're approaching Oversharing Pass, where residents routinely post too much information. The Facebook Gorge and Twitter Triangle are particularly nefarious time-sucks. Restraint is advised.

Up ahead is Hyperbole Junction, which is the Worst. Spot. Ever. We recommend that you maintain an even keel and stay to the center; the extreme left and right can be dangerous.

And over there is the infamous Lair of Sociopaths, the home of trolls and loners who mercilessly mock everyone who enters their territory. Watch your step: They may trip you up and you'll fall into the Chasm of Lulz.

Our world isn't all dangerous, of course. You may visit Squee City, where images of cute cats and laughing babies fill the landscape. You'll also meet countless kind strangers, hilarious raconteurs and hard-working fact-checkers. They make it all worthwhile.

Hmm. Maybe it would be easier if you had a guide -- you know, some rules to help you find your way.

What, you didn't know there are rules of the Internet?

Of course there are rules. How do you think we maintain order around here?

A parody of rules

That's a joke.

But there really are some rules of the Internet -- even if they, too, began as kind of a joke.

According to the site KnowYourMeme.com, the Rules began around 2006 as a guide for the Internet collective Anonymous and emerged on the old Encyclopedia Dramatica, a bawdy meme catalog. Soon a version emerged on 4chan, an online bulletin board where most users post anonymously, says Jamie Cohen, director of web/digital media at Hofstra University's School of Communication.

"Chris Poole (4chan's founder) kind of designed it, kind of like a Netiquette rules," he says, describing the unspoken code of conduct that lubricates Internet discourse. (Poole has attributed the rules to Gaia Online, a role-playing community.)

But the rules of the Internet deliberately mocked many of those conventions. The self-reflexive parody fit perfectly with its community's attitude, points out Anthony Rotolo, a professor at Syracuse University's School of Information Studies.

"These jokes are meant to comment on something happening in the world," he says. "Later they get accepted as truisms or become a meme."

The absurdity has been reflected even in the supposed number of rules. Though the best-known first version claimed there were 50 rules, only 18 were listed. Number 1 was initially "Do not talk about Rules 2-33"; no Rules 2-33 were on the list.

The sarcastic attitude was reinforced by the kicker found on Encyclopedia Dramatica. It was a parody of Wikipedia's stub language: "This article is crap. You can help by completely re-writing it."

'Fight Club' and Monty Python

Very quickly, the lists started multiplying and expanding, liberally borrowing from comedy, Web culture and math-science tropes. On one list, a few were designated by complex numbers and mathematical symbols. Some were observations; others were directives.

Some have traced the Internet rules to Chris Poole, the founder of 4chan.

Two rules were taken from "Fight Club": "You do not talk about 4chan (or "/b/," 4chan's random, free-wheeling bulletin board) and "You DO NOT talk about 4chan." One version of Rule 6 stated "There is no Rule 6," which is from a Monty Python sketch. Rule 42, "Always bring a towel," was drawn from Douglas Adams' "The Hitchhiker's Guide to the Galaxy" series. (If you have to ask, read the books.) "Profit," Rule 49, came from "South Park."

Other rules went the reverse direction and became part of mainstream culture. Rule 34 -- "If it exists, there is porn of it" -- is likely the most famous. But there's also "Pics or it didn't happen" (Rule 30), "For every given male character, there is a female version of that character; conversely for every given female character, there is a male version of that character" (Rule 63) and, of course, the corollary to Rule 34 -- "If no porn of it exists at the moment, it will be made" (Rule 35).

Most retained a sense of humor, riffing off established rules and occasionally ending with a giggly "No exceptions."

But a handful were, and remain, as serious as a judge -- notably the three directly about Anonymous (commonly Rules 3-5):

- We are Anonymous.

- We are legion.

- We do not forgive, we do not forget.

The overall Internet rules may have started as a joke, but such ominous language from Anonymous speaks to some of the paradoxes of the Web:

Rules? Why do we need some stinkin' rules?

After all, rules can be helpful -- or divisive. They can create community -- or subvert it.

Even Anonymous, the activist group itself, cuts both ways, says Rotolo. When it hacked the extremist Westboro Baptist Church, many people cheered. But when it goes after less unpopular targets, some cry vigilantism.

Cohen says that the rules themselves try to have it both ways. They're funny until someone gets hurt.

They "play more of a game type of role. They can be bent or broken or cheated or moved around, as you would in any game that has no physical reaction," he says. "That doesn't take into account ever the result of real people being affected by this -- such as teenagers, children, anybody who's seeing things that they shouldn't."

He adds, "There's a lot of rules in there that work for (the creators) more than anyone else. Until they become victims of their own thing, they don't know how powerful the rules are."

Evolving from the Wild West

Of course, the Internet isn't that old, and we're still in its Wild West era in many ways. As the technology evolves from a handful of hackers on Usenet bulletin boards to billions of users on officially sponsored sites, the customs -- the rules -- of the Web will evolve with it.

But we're not talking about the kinds of changes that your family makes to the rules of Monopoly (no, Free Parking is NOT for the pool of money acquired via Chance and Community Chest). We're talking something more expansive: All the established customs of our carbon-based life forms, making way for the instantaneous and virtual modes of silicon-based electronics.

Who knows what new rules may be written?

"When you're in the midst of social change, it's impossible to determine where it's going," says Peter S. Vogel, a former programmer who's now a Dallas-based attorney. "And I think we are in the greatest social change in the history of humans, because there are no boundaries of geography or time."

We haven't even sorted out what happens when the differences in local culture meet global technology. Bruce Umbaugh, a philosophy professor at Webster University in St. Louis who teaches a course on philosophy and technology, argues that not all parts of the world are as tolerant or open-minded as Western democracies.

There's a lot of rules in there that work for (the creators) more than anyone else.
Jamie Cohen, Hofstra University

"There are a lot of other places in the world that are actively using the technology of the Internet to control the free communication among citizens, and to identify critics of the government and hurt them," he says. "We need to be mindful in what we advocate from our perspective that the tools that are implemented on the Net are tools for the global Net."

In other words, citizens of other countries already face actual, enforceable rules -- unlike the folkways established by Web users in the West. Witness the frictions of the Arab Spring, or the restrictions of societies such as North Korea.

It's the kind of perspective that provides a different context for the issues raised by a libertarian, anything-goes Internet. It's hard enough to stop "Star Wars" comment boards from devolving into flamebaiting, meme-generating files of NSFW Yodas.

So for now, we're still making our way through the Series of Tubes, and nobody knows where the boundaries lie. We joke, we grimace and we marvel at the creativity of the hive mind. The Internet is a big place, and countless cultures have set up residence. Eventually, what is now humor may lose its zing; what are now customs may become laws.

Will the rules ever become The Rules? Maybe some future generation will figure out the true guideposts of Internet life, and the singularity will be upon us.

Nah. It'll never happen.

What did we miss? Share your rules for the internet below in the comments. We'll feature some of the best on CNN.

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Dozens of pro-Dorner protesters rally at LAPD HQ

LOS ANGELES Dozens of protesters rallied outside Los Angeles police headquarters Saturday in support of Christopher Dorner, the former LAPD officer and suspected killer of four who died after a shootout and fire this week at a mountain cabin following one of the biggest manhunts in recent memory.

Protesters told the Los Angeles Times they didn't support Dorner's deadly methods, but objected to police corruption and brutality, and believed Dorner's claims of racism and unfair treatment by the department. Many said they were angered by the conduct of the manhunt that led to Dorner's death and injuries to innocent bystanders who were mistaken for him.

Play Video

New details of Dorner's final hours

Michael Nam, 30, who held a sign with a flaming tombstone and the inscription "RIP Habeas Corpus," said it was "pretty obvious" police had no intention of bringing Dorner in alive.

"They were the judge, the jury and the executioner," Nam said. "As an American citizen, you have the right to a trial and due process by law."

During the hunt for Dorner, LAPD Chief Charlie Beck called for Dorner's surrender and said he didn't want to see the suspect or anyone else injured.

Dorner was already believed to have killed three people when he was cornered Tuesday at the cabin near Big Bear Lake, and during the standoff shot and killed a San Bernardino County sheriff's deputy, authorities said.

Play Video

Reporter records gunfight in Dorner capture effort

Only after calls for surrender and use of milder tear gas did deputies launch pyrotechnic gas canisters into the cabin, and the subsequent fire was not intentional, the Sheriff's Department said.

Dorner died of a self-inflicted gunshot wound at the end of the standoff, sheriff's officials said.

The 33-year-old has already inspired a burgeoning subculture of followers. While most don't condone killing, they see him as an outlaw hero who raged against powerful forces of authority, and some even question whether he really died.

Tributes include a ballad titled "El Matapolicias," or "The Police Killer," penned by a Mexican crooner with lyrics paying homage to Dorner, and a YouTube clip showing excerpts from a video game titled "Christopher Dorner's Last Stand Survival Game" whose opening frame declares him "A True American Hero."

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Meteor Blast Creates Rush to Cash In

The shattered glass and broken walls caused by the massive explosion of a monstrous meteor over this remote, industrial Russian city is not even cleaned up, and people are already trying to cash in.

Some residents want to turn this city known mostly for its tank factory into a tourist destination, while others from all around the world are determined to find fragments of the meteorite.

Meteor hunters say it's a once in a lifetime opportunity. A small piece of the space rock that exploded over Russia Friday could be worth thousands of dollars, and bigger chunks could fetch hundreds of thousands.

SEE PHOTOS: Meteorite Crashes in Russia

"I haven't been able to sleep for the last two days because of this," said Michael Farmer, who runs the website Meteor Hunter. "This is a once in a lifetime event. We've never seen anything like this in the last hundred years."

He said he started planning a trip to Chelyabinsk as soon as the meteorite exploded.

"The next morning I was on the phone working on visas. I'd like to get a visa and get over to Russia as quickly as possible," he said. "When this type of thing happens, you know hours count so we try to arrange that as fast as possible."

A day after a massive meteor exploded over this city in central Russia, a monumental cleanup effort is under way.

Authorities have deployed around 24,000 troops and emergencies responders to help in the effort.

Officials say more than a million square feet of windows -- the size of about 20 football fields -- were shattered by the shockwave from the meteor's blast. Around 4,000 buildings in the area were damaged.

Nasha gazeta, www.ng.kz/AP Photo

The injury toll climbed steadily on Friday. Authorities said today it now stands at more than 1,200. Most of those injuries were from broken glass, and only a few hundred required hospitalization.

According to NASA, this was the biggest meteor to hit Earth in more than a century. Preliminary figures suggest it was 50 feet wide and weighed more than the Eiffel Tower.

NASA scientists have also estimated the force of the blast that occurred when the meteor fractured upon entering Earth's atmosphere was approximately 470 kilotons -- the equivalent of about 30 Hiroshima bombs, but it did not cause major damage because it occurred so high in the atmosphere.

"This was caused by a small asteroid, about 15 meters in diameter, coming in at around 18 kilometers per second, that's in excess of 40-thousand miles per hour," NASA planetary scientist Paul Abell said. "As the asteroid comes in, it interacts with the atmosphere and effectively it converts all the energy, the kinetic energy of the asteroid, the mass of the asteroid and the velocity and it's actually that velocity, the asteroid just effectively explodes and that creates the pressure wave, the blast wave that comes down."

Treasure hunters hoping to cash in on the bits of space rock aren't the only ones eager to find pieces of the meteor, Abell said. Scientists say the material could offer valuable information.

"One of the things we'd like to learn is first of all, what was the composition of the asteroid, where did it come from," he said. "We know it came from the asteroid belt but can we link it to a bigger asteroid and also, get an idea of the dispersal pattern."

Residents said they still can't believe it happened here.

"It was something we only saw in the movies," one university student said. "We never thought we would see it ourselves."

Throughout the city, the streets are littered with broken glass. Local officials have announced an ambitious pledge to replace all the broken windows within a week. In the early morning hours, however, workers could still be heard drilling new windows into place.

Authorities have sent divers into a frozen lake outside the city, where a large chunk of the meteor is believed to have landed, creating a large hole in the ice. By the end of the day they had not found anything.

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Malaysia detains Australian lawmaker at airport

KUALA LUMPUR: Malaysia detained an Australian lawmaker at Kuala Lumpur airport Saturday and is expected to deport him, an activist said, in a move Canberra described as "disappointing and surprising".

Nick Xenophon, an outspoken independent Senator, was detained at the international airport near the capital Kuala Lumpur upon his arrival from Melbourne.

"He informed me that he is being deported," Ambiga Sreenevasan, a lawyer and co-chair of electoral reform group Bersih, told AFP after she spoke to Xenophon early Saturday.

The Malaysian government is yet to comment on the circumstances surrounding Xenophon's detention but Ambiga said it appeared to be "under the Security Offences Act".

"(Authorities) said he is a security risk," she added.

Xenophon, who has travelled to Malaysia several times, was to meet Bersih members and others including opposition leader Anwar Ibrahim and Election Commission officials next week, Ambiga said.

Australia's Foreign Minister Bob Carr said Australian officials were in touch with Xenophon, as well as Malaysia's foreign and home ministers, and were seeking his "swift release" from custody.

"Senator Xenophon's detention is a surprising and disappointing act from a country with which Australia routinely maintains strong diplomatic relations," he said in a statement.

The Security Offences (Special Measures) Act, or SOSMA, was introduced in Malaysia last year to replace the much-criticised colonial-era Internal Security Act, which allowed indefinite detention without trial.

Prime Minister Najib Razak has touted SOSMA and other reforms to show he is granting more civil liberties, but rights group have criticised the new act, saying it still gives broad powers to detain people for too long.

Malaysia has deported several foreigners in recent years. Among them was a French lawyer representing a human rights group in an inquiry into alleged corruption linked to Najib.

- AFP/ck

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Sen. Rubio drowning in 'water-gate'

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Man arrested in Alaska Coast Guard base deaths

ANCHORAGE, Alaska An Alaska man was arrested Friday in last year's shooting deaths at a Coast Guard air station on Kodiak Island that left two employees dead, the U.S. attorney said.

James Michael Wells of Kodiak is accused in a federal murder complaint of killing Petty Officer 1st Class James Hopkins and retired Chief Boatswain's Mate Richard Belisle on April 12.

Another Coast Guard member found the victims shortly after the two would have arrived for work at the station, which monitors radio traffic from ships and planes and is home to cutters, helicopters and rescue swimmers that aid mariners in the Bering Sea and Pacific Ocean. Their bodies were found in the rigger building, where antennas are repaired.

FBI agents immediately flew to Kodiak Island from Anchorage, about 250 miles away, to investigate the case as a double homicide. Few details were released in the weeks after the deaths.

Wells' arrest came after "an extensive investigation" led by the FBI and the Coast Guard Investigative Service, with help from the Alaska State Troopers, U.S. Attorney Karen Loeffler said in a statement.

Wells is expected to appear in court next week in Anchorage, Loeffler said.

No one was immediately reachable by phone Friday evening at the U.S. attorney's office to provide additional details.

Hopkins, 41, was an electronics technician from Vergennes, Vt. Belisle, 51, was a former chief petty officer who continued service to the Coast Guard as a civilian employee.

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Carnival Cruise Ship Hit With First Lawsuit

The first lawsuit against Carnival Cruise Lines has been filed and it is expected to be the beginning of a wave of lawsuits against the ship's owners.

Cassie Terry, 25, of Brazoria County, Texas, filed a lawsuit today in Miami federal court, calling the disabled Triumph cruise ship "a floating hell."

"Plaintiff was forced to endure unbearable and horrendous odors on the filthy and disabled vessel, and wade through human feces in order to reach food lines where the wait was counted in hours, only to receive rations of spoiled food," according to the lawsuit, obtained by ABCNews.com. "Plaintiff was forced to subsist for days in a floating toilet, a floating Petri dish, a floating hell."

Click Here for Photos of the Stranded Ship at Sea

The filing also said that during the "horrifying and excruciating tow back to the United States," the ship tilted several times "causing human waste to spill out of non-functioning toilets, flood across the vessel's floors and halls, and drip down the vessel's walls."

Terry's attorney Brent Allison told ABCNews.com that Terry knew she wanted to sue before she even got off the boat. When she was able to reach her husband, she told her husband and he contacted the attorneys.

Allison said Terry is thankful to be home with her husband, but is not feeling well and is going to a doctor.

Carnival's Triumph Passengers: 'We Were Homeless' Watch Video

Girl Disembarks Cruise Ship, Kisses the Ground Watch Video

Carnival Cruise Ship Passengers Line Up for Food Watch Video

"She's nauseated and actually has a fever," Allison said.

Terry is suing for breach of maritime contract, negligence, negligent misrepresentation and fraud as a result of the "unseaworthy, unsafe, unsanitary, and generally despicable conditions" on the crippled cruise ship.

"Plaintiff feared for her life and safety, under constant threat of contracting serious illness by the raw sewage filling the vessel, and suffering actual or some bodily injury," the lawsuit says.

Despite having their feet back on solid ground and making their way home, many passengers from the cruise ship are still fuming over their five days of squalor on the stricken ship and the cruise ship company is likely to be hit with a wave of lawsuits.

"I think people are going to file suits and rightly so," maritime trial attorney John Hickey told ABCNews.com. "I think, frankly, that the conduct of Carnival has been outrageous from the get-go."

Hickey, a Miami-based attorney, said his firm has already received "quite a few" inquiries from passengers who just got off the ship early this morning.

"What you have here is a) negligence on the part of Carnival and b) you have them, the passengers, being exposed to the risk of actual physical injury," Hickey said.

The attorney said that whether passengers can recover monetary compensation will depend on maritime law and the 15-pages of legal "gobbledygook," as Hickey described it, that passengers signed before boarding, but "nobody really agrees to."

One of the ticket conditions is that class action lawsuits are not allowed, but Hickey said there is a possibility that could be voided when all the conditions of the situation are taken into account.

One of the passengers already thinking about legal action is Tammy Hilley, a mother of two, who was on a girl's getaway with her two friends when a fire in the ship's engine room disabled the vessel's propulsion system and knocked out most of its power.

"I think that's a direction that our families will talk about, consider and see what's right for us," Hilley told "Good Morning America" when asked if she would be seeking legal action.

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Sand-grain-sized drum extends reach of quantum theory

The banging of a tiny drum heralds the intrusion of the weird world of quantum mechanics into our everyday experience. Though no bigger than a grain of sand, the drum is the largest object ever to have been caught obeying the uncertainty principle, a central idea in quantum theory.

As well as extending the observed reach of quantum theory, the finding could complicate the hunt for elusive gravitational waves : it suggests that the infinitesimal motion caused by these still-hypothetical ripples in spacetime could be overwhelmed by quantum effects.

The uncertainty principle says that you cannot simultaneously determine both a particle's exact position and momentum. For example, bouncing a photon off an electron will tell you where it is, but it will also change the electron's motion, creating fresh uncertainty in its speed.

This idea limits our ability to measure the properties of very small objects, such as electrons and atoms. The principle should also apply to everyday, macroscopic objects, but this has not been tested – for larger objects, the principle's effects tend to be swamped by other uncertainties in measurement, due to random noise, say.

Quantum drum

To extend the known reach of the uncertainty principle, Tom Purdy and colleagues of the University of Colorado, Boulder, created a drum by tightly stretching a 40-nanometre-thick sheet of silicon nitride over a square frame with sides of half a millimetre – about the width of a grain of sand. They placed the drum inside a vacuum chamber cooled to a few degrees above absolute zero, minimising any interference by random noise.

By continuously firing a stream of photons at the drum they were able to get increasingly precise measurements of the position of the skin at any moment. However, this also caused the skin to vibrate at an unknown speed. When they attempted to determine its momentum, the error in their measurement had increased – just as the uncertainty principle predicts.

"You don't usually have to think about quantum mechanics for objects you can hold in your hand," says Purdy.

That the uncertainty principle holds sway at such a large scale could affect the hunt for gravitational waves, which are predicted by Einstein's theory of general relativity but have never been detected.

Mitigation strategy

Gravitational wave detectors look for very slight changes in the distance between two test masses caused by passing spacetime ripples. Purdy says his team's experiment confirms long-held suspicions that quantum uncertainty could overwhelm these very small changes.

Now he and others can use the drum to explore more advanced measurement techniques to mitigate the effects. For example, uncertainty in an object's momentum could lead to future uncertainty in its position and there should be ways to minimise such knock-on effects. "You can't avoid the uncertainty principle, but you can in some clever ways make it [such that] increasing the momentum doesn't add back to the uncertainty in position at a later time," says Purdy.

His experiment is a neat demonstration of the breakdown of the traditional notion that the atomic world is quantum while the macroscopic world is classic, says Gerard Milburn of the University of Queensland in Brisbane, Australia, who was not involved in the work. Previous, attempts to blur the quantum-classical divide have involved entangling diamonds and demonstrating quantum superposition in a strip of metal.

Despite these feats, Milburn doesn't rule out the prospect of a breakdown on really large scales. "Of course maybe one day we will see quantum mechanics fail at some scale. Testing it to destruction is a good motivation for going down this path," he says.

Journal reference: Science, DOI: 10.1126/science.1231282

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

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