어떤 물질도 빛보다 빠를 수 없다는 현대물리학의 근본 가정이 유럽 과학자들의 새로운 발견에 의해 도전 받고 있다.

유럽입자물리연구소(CERN)의 과학자들은 빛보다 빠른 소립자의운동이 관측되었다고 밝혔다.

지난 3년간 스위스 제네바의 실험실에서 732㎞ 떨어진 이탈리아 그란 사소의 실 험실까지 땅속으로 중성미자(뉴트리노)를 보내는 실험을 해 온 과학자들은 뉴트리노 들이 빛의 속도보다 60나노초(0.00000006초) 빨리 목적지에 도착한다는 사실을 발견 했다고 발표했다.

중성미자는 표준모형에서 경입자(輕粒子)에 속하는 소립자의 하나로 질량이사 실상 제로이며 일반 원자와 상호작용하지 않기 때문에 땅속을 진공상태처럼통과한 다.

OPERA(Oscillation Project with Emulsion-tRacking Apparatus) 로 불리는 이 실험에서 연구진은 GPS와 원자시계로 뉴트리노의 속도를 측정했으며 1만5천개의뉴 트리노를 분석해 통계적으로 의미 있는 수준의 수치를 얻었다고 밝혔다.

연구진은 이런 결과에 매우 놀라 온갖 방법으로 오류를 찾으려고 노력했으나 실패했다면서 이런 발견이 가져올 파장을 고려해 23일(현지시간) 논문 초고 온라인 등록 사이트 ArXiv.org에 발표해 다른 학자들의 비판을 수용하겠다고 밝혔다.

OPERA 실험에 참여하지 않은 미국 페르미가속기연구소(페르미랩)의 로버트 플런 킷은 "이것이 사실로 확인된다면 실로 엄청난 일대 혁명이 될 것"이라면서 "바로 그 때문에 이런 주장은 매우 신중하게 다뤄져야 하며 되도록 많은 방법으로 검증돼야 한다"고 강조했다.

스탠퍼드대 선형가속기센터(SLAC)의 이론물리학자 마이클 페스킨은 "빛의속도 는 지금까지 절대적인 속도의 한계로 생각돼 왔다. 입자물리학의 모든 연구가토대 로 삼는 양자장 이론에 따르면 어떤 신호도 빛보다 빠른 속도로 진공상태를 통과할 수는 없다. 이는 불가침의 원리"라고 지적했다.

아인슈타인의 특수상대성 이론은 이런 속도의 한계, 즉 어떤 것도 초당 2억9979 만2천458m보다 빨리 움직일 수 없다는 원칙을 바탕으로 하고 있는데 이런 물리학 법 칙이 바뀐다면 시간여행의 가능성을 비롯한 광범위한 의미가 갖게 된다.

CERN 과학자들의 발견은 기존 가설뿐 아니라 다른 측정치와도 어긋난다.

예를 들어 일본에서 초신성 SN1987A를 대상으로 이루어진 유명한 슈퍼 카미오칸 데 II 실험에서는 지구로부터 16만8천광년 떨어진 이 초신성으로부터 출발한 빛과 뉴트리노가 시차를 두고 지구에 도착한 것으로 나타났다. 뉴트리노는 광속보다1억 분의 1 빠르게 도착했다.

그러나 OPERA 실험에서는 뉴트리노와 빛의 속도 차이가 10만분의 2로 나타났다.

이는 SN1987A 실험 결과보다 2천 배나 빠른 것이다.

이에 대해 펜스테이트 대학의 천체물리학자 데릭 폭스는 "OPERA의 실험결과가 틀렸다는 의미는 아니다. 어쩌면 끈이론 같은 이론적인 해결책이 두 실험 결과의 차 이를 설명해줄 수도 있을 것"이라고 말했다.

연구진은 페르미랩이 진행 중인 유사한 MINOS 실험을 통해 자신들의 실험이입 증되거나 반박될 것을 기대하고 있다.

CERN은 23일 공개 세미나에서 이 문제를 논의할 계획이다. 세미나는 http://web cast.cern.ch를 통해 방영된다

Roll over Einstein: Law of physics challenged

GENEVA (AP) -- One of the very pillars of physics and Einstein's theory of relativity _ that nothing can go faster than the speed of light _ has been rocked by new findings from one of the world's foremost laboratories.

European researchers said Thursday they clocked an oddball type of subatomic particle called a neutrino going faster than the 186,282 miles per second that has long been considered the cosmic speed limit.

The globe of the European Organization for Nuclear Research, CERN, is illuminated outside Geneva, Switzerland. (AP)

The claim was met with skepticism, with one outside physicist calling it the equivalent of saying you have a flying carpet. In fact, the researchers themselves are not ready to proclaim a discovery and are asking other physicists to independently try to verify their findings.

``The feeling that most people have is this can't be right, this can't be real,'' said James Gillies, a spokesman for the European Organization for Nuclear Research, or CERN, which provided the particle accelerator that sent neutrinos on their breakneck 454-mile (730-kilometer) trip underground from Geneva to Italy.

Going faster than light is something that is just not supposed to happen according to Einstein's 1905 special theory of relativity _ the one made famous by the equation E equals mc2. But no one is rushing out to rewrite the science books just yet.

It is ``a revolutionary discovery if confirmed,'' said Indiana University theoretical physicist Alan Kostelecky, who has worked on this concept for a quarter of a century.

Stephen Parke, who is head theoretician at the Fermilab near Chicago and was not part of the research, said: ``It's a shock. It's going to cause us problems, no doubt about that _ if it's true.''

Even if these results are confirmed, they won't change at all the way we live or the way the world works. After all, these particles have presumably been speed demons for billions of years. But the finding will fundamentally alter our understanding of how the universe operates, physicists said.

Einstein's special relativity theory, which says that energy equals mass times the speed of light squared, underlies ``pretty much everything in modern physics,'' said John Ellis, a theoretical physicist at CERN who was not involved in the experiment. ``It has worked perfectly up until now.''

France's National Institute for Nuclear and Particle Physics Research collaborated with Italy's Gran Sasso National Laboratory on the experiment at CERN.

CERN reported that a neutrino beam fired from a particle accelerator near Geneva to a lab 454 miles (730 kilometers) away in Italy traveled 60 nanoseconds faster than the speed of light. Scientists calculated the margin of error at just 10 nanoseconds. (A nanosecond is one-billionth of a second.)

Given the enormous implications of the find, the researchers spent months checking and rechecking their results to make sure there were no flaws in the experiment.

A team at Fermilab had similar faster-than-light results in 2007, but a large margin of error undercut its scientific significance.

If anything is going to throw a cosmic twist into Einstein's theories, it's not surprising that it's the strange particles known as neutrinos. These are odd slivers of an atom that have confounded physicists for about 80 years.

The neutrino has almost no mass, comes in three different ``flavors,'' may have its own antiparticle and has been seen shifting from one flavor to another while shooting out from our sun, said physicist Phillip Schewe, communications director at the Joint Quantum Institute in Maryland.

Columbia University physicist Brian Greene, author of the book ``Fabric of the Cosmos,'' said neutrinos theoretically can travel at different speeds depending on how much energy they have. And some mysterious particles whose existence is still only theorized could be similarly speedy, he said.

Fermilab team spokeswoman Jenny Thomas, a physics professor at the University College of London, said there must be a ``more mundane explanation'' for the European findings. She said Fermilab's experience showed how hard it is to measure accurately the distance, time and angles required for such a claim.

Nevertheless, Fermilab, which shoots neutrinos from Chicago to Minnesota, has already begun working to try to verify or knock down the new findings.

And that's exactly what the team in Geneva wants.

Gillies told The Associated Press that the readings have so astounded researchers that ``they are inviting the broader physics community to look at what they've done and really scrutinize it in great detail, and ideally for someone elsewhere in the world to repeat the measurements.''

Only two labs elsewhere in the world can try to replicate the work: Fermilab and a Japanese installation that has been slowed by the tsunami and earthquake. And Fermilab's measuring systems aren't nearly as precise as the Europeans' and won't be upgraded for a while, said Fermilab scientist Rob Plunkett.

Drew Baden, chairman of the physics department at the University of Maryland, said it is far more likely that the CERN findings are the result of measurement errors or some kind of fluke. Tracking neutrinos is very difficult, he said.

``This is ridiculous what they're putting out,'' Baden said. ``Until this is verified by another group, it's flying carpets. It's cool, but ...''

So if the neutrinos are pulling this fast one on Einstein, how can it happen?

Parke said there could be a cosmic shortcut through another dimension _ physics theory is full of unseen dimensions _ that allows the neutrinos to beat the speed of light.

Indiana's Kostelecky theorizes that there are situations when the background is different in the universe, not perfectly symmetrical as Einstein says. Those changes in background may alter both the speed of light and the speed of neutrinos.

But that doesn't mean Einstein's theory is ready for the trash heap, he said.

``I don't think you're going to ever kill Einstein's theory. You can't. It works,'' Kostelecky said. There are just times when an additional explanation is needed, he said.

If the European findings are correct, ``this would change the idea of how the universe is put together,'' Columbia's Greene said. But he added: ``I would bet just about everything I hold dear that this won't hold up to scrutiny."

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