Few scientists are betting against Einstein yet, but the phantom neutrinos of Opera are still eluding explanation.

Two months after scientists reported that they had clocked subatomic particles known as neutrinos going faster than the speed of light, to the astonishment and vocal disbelief of most of the world’s physicists, the same group of scientists, known as Opera, said on Friday that it had performed a second experiment that confirmed its first results and eliminated one possible explanation for how the experiment could have gone wrong.

But the group admitted that many questions remain. “This is not the end of the story,” said Antonio Ereditato of the University of Bern in Switzerland, the spokesman for the collaboration, explaining that physicists would not accept the result that neutrinos could go faster than light until other experiments had come up with the same conclusion. “We are convinced, but that is not enough in science,” he said.

Other physicists said they remained skeptical that the universe was about to be overturned.

The speed of light was established as the cosmic speed limit, at least for ordinary matter in ordinary space, in 1905 by Albert Einstein’s theory of relativity (now known as special relativity), foreclosing the possibility of time travel into the past or of timely travel to other stars.