[b][size=12pt]Neutrinos voltam a ultrapassar a velocidade da luz[/size][/b]As partículas elementares neutrinos voltaram a ultrapassar a velocidade da luz, algo proibido pela teoria de Einstein, na segunda experiência do género realizada por físicos do CERN.
Novos testes realizados sob 730 km entre Suíça e Itália resultaram em valores semelhantes aos obtidos há dois meses, que deixaram perplexa a comunidade científica.
Esta repetição teve como objectivo eliminar um possível erro na medição precedente. Desta vez, a equipa internacional por trás da experiência OPERA, do acelerador de partículas LHC, utilizou um novo feixe de protões para produzir os neutrinos enviados em direção ao laboratório subterrâneo de Gran Sasso, na Itália.
“Com o novo tipo de feixe produzido pelos aceleradores do CERN (Centro Europeu de Pesquisas Nucleares), fomos capazes de medir com precisão o tempo de percurso dos neutrinos”, explicou à AFP Darío Autiero, cientista do Instituto de Física Nuclear de Lyon (França) e responsável de análises de medidas da equipe Ópera.
Na nova experiência, iniciada no final de Outubro, 20 neutrinos puderam ser detectados no laboratório de Gran Sasso, e estas novas medidas “não mudam em nada a conclusão inicial de que os neutrinos parecem viajar mais rápido do que deveriam”, destacou o Centro Nacional Francês de Pesquisa Científica (CNRS).
A 22 de Setembro passado, a equipa do OPERA anunciou que alguns neutrinos tinham percorrido os 730 km superando ligeiramente (por 6 km/s) a velocidade da luz no espaço (cerca de 300.000 km/s), considerada até o momento um “limite insuperável”.
“Os vinte neutrinos que avaliamos forneceram uma precisão comparável aos 15 mil que fundamentaram nossa medição inicial”, assinalou Autiero.
Autiero alerta no entanto que “exames complementares” e “medições independentes” são necessários antes de “a anomalia de tempo de voo” dos neutrinos possa “ser confirmada ou rejeitada”.
Se for confirmada, esta velocidade superior à da luz obrigará a uma revisão da física actual, incluindo a teoria de Einstein.
[size=12pt][b]Second experiment confirms faster-than-light particles[/b][/size]A second experiment at the European facility that reported subatomic particles zooming faster than the speed of light — stunning the world of physics — has reached the same result, scientists said late Thursday.
The “positive outcome of the [second] test makes us more confident in the result,” said Fernando Ferroni, president of the Italian Institute for Nuclear Physics, in a statement released late Thursday. Ferroni is one of 160 physicists involved in the international collaboration known as OPERA (Oscillation Project with Emulsion Tracking Apparatus) that performed the experiment.
While the second experiment “has made an important test of consistency of its result,” Ferroni added, “a final word can only be said by analogous measurements performed elsewhere in the world.”
That is, more tests are needed, and on other experimental setups. There is still a large crowd of skeptical physicists who suspect that the original measurement done in September was an error.
Should the results stand, they would upend more than a century of modern physics.
In the first round of experiments, a massive detector buried in a mountain in Gran Sasso, Italy, recorded neutrinos generated at the CERN particle accelerator on the French-Swiss border arriving 60 nanoseconds sooner than expected. CERN is the French acronym for European Council for Nuclear Research.
A chorus of critiques from physicists soon followed. Among other possible errors, some suggested that the neutrinos generated at CERN were smeared into bunches too wide to measure precisely.
So in recent weeks, the OPERA team tightened the packets of neutrinos that CERN sent sailing toward Italy. Such tightening removed some uncertainty in the neutrinos’ speed.
The detector still saw neutrinos moving faster than light.
“One of the eventual systematic errors is now out of the way,” said Jacques Martino, director of the National Institute of Nuclear and Particle Physics in France, in a statement.
But the faster-than-light drama is far from over, Martino added. The OPERA team is discussing more cross-checks, he added, including possibly running a fiber the 454 miles between the sites.
For more than a century, the speed of light has been locked in as the universe’s ultimate speed limit. No experiment had seen anything moving faster than light, which zips along at 186,000 miles per second.
Much of modern physics — including Albert Einstein’s famous theory of relativity — is built on that ultimate speed limit.
The scientific world stopped and gaped in September when the OPERA team announced it had seen neutrinos moving just a hint faster than light.
“If it’s correct, it’s phenomenal,” said Rob Plunkett, a scientist at Fermilab, the Department of Energy physics laboratory in Illinois, in September. “We’d be looking at a whole new set of rules” for how the universe works.