Do Neutrinos Threaten the Theory of Relativity?

Published on Wednesday, 05 October 2011 15:37

	By Robin Whitlock Follow @RobinWhitlock66

You may have noticed recently a great deal of fuss being made about some small particles called ‘neutrinos’.

Apparently these are sub-atomic particles that can travel faster than light. Such a discovery could force a re-think on the workings of the cosmos, lead to the development of time-travel and enable the discovery of extra-dimensions according to scientists.

Among the scientists working on this is Jeff Forshaw, a professor of particle physics at Manchester University who recently said that in theory this could allow us to send information into the past and possibly lead to time-travel, “though that doesn’t mean we’ll be building time machines any time soon” he told the news agency Reuters.

The discovery was made at Switzerland’s CERN laboratory near Geneva (the home of the Hadron Collider particle accelerator) but it will have to be confirmed by independent scientists.

Meanwhile there has been a great deal of scepticism from the wider, mainstream scientific community with cosmologist and astrophysicist Martin Rees describing the news as ‘an extraordinary claim’.

Professor Stephen Hawking commented that “it is premature to comment on this” and that “further experiments and clarifications are needed.” 

Professor Jenny Thomas from the US physics research centre Fermilab nevertheless commented that the impact of the experiment, if it were to be confirmed, would be huge. A statement from CERN revealed that measurements over three years had shown invisible neutrino particles travelling to a laboratory in Italy, about 730 km away, in about 60 nanoseconds (60 billionths of a second), exceeding the speed of light.

If so, this could prove wrong Einstein’s statement that the speed of light is a ‘cosmic constant’ which nothing can exceed. Einstein’s theory along with his general relativity theory have been cornerstones of the scientific study of the cosmos ever since but there have been some indications recently that the behaviour of some elementary particles might not adhere to it.

Neutrinos are electronically neutral sub-atomic particles with a small, non-zero mass which are normally produced by the decay of nuclear material during the fission process or in natural nuclear reactions such as those that occur on the sun, from which most neutrinos that pass through the Earth emanate.

There are three types of neutrino; muon neutrinos, tau neutrinos and electron neutrinos. Every part of the Earth that faces the sun is subjected to a dense covering of them. Atmospheric neutrinos are created from cosmic rays interacting with atomic nuclei in the Earth’s atmosphere whereas solar neutrinos originate from the fusion process of the sun and other stars.

As such they are part of natural background radiation and were only discovered in 1934. Being electrically neutral they can pass through ordinary matter without any affect including from electromagnetic forces that normally act on electrons. The neutrinos, 15,000 of them to be precise, were pumped to the underground lab at Gran Sasso near Rome where physicists checked and rechecked the results of the experiment before any announcement was released.

A number of science bloggers on the internet have proposed that the neutrinos might be slipping into and out of dimensions besides those that are presently known, length, breadth, depth and time. This is something that has been predicted by string theory.

Before we all get worked up about this, there has been a considerable amount of discussion of the experiment since the results were first announced. For example Geekdad in Wired magazine has some interesting views on the subject. He explains that the team at Gran Sasso, or CNGS as the team is known, were investigating what’s known as ‘neutrino oscillation’, where muon neutrinos turn into tau neutrinos, with a secondary objective of investigating neutrino velocity.

During the experiment the neutrinos were generated in the particle accelerator at CERN and accelerated down a beam line running 732 km straight through the earth to the Gran Sasso laboratory travelling at a depth of up to11.4 km below the surface. At Gran Sasso the neutrinos were detected and measured by a device known as OPERA.

Time was also measured using GPS and a cesium atomic clock. Geekdad points out that a final paragraph in the paper reveals that the CNGS team do not know how they obtained a result showing that neutrinos travel faster than the speed of light and that they do not actually claim this to be the case but only that they discovered something they did not expect. In other words, Geekdad says, it is actually far too early to make definite conclusions.

Alex Knapp, writing in Forbes magazine, also urges caution. “Boston University Physicists Andrew Cohen and Sheldon Glashow have just submitted a paper which casts more doubt on the claims that the OPERA team observed neutrinos that travelled faster than the speed of light” he says, “the paper notes that neutrinos at the recorded energies that were travelling faster than the speed of light should be radiating particles as the neutrinos were travelling.”

He goes on to say that the neutrinos in particular should have been radiating electron-positron pairs, which would have meant that the particles would have been losing substantial amounts of energy. This means that the neutrinos should have arrived at Gran Sasso with most of their energy depleted resulting in a spectral distortion observable by OPERA. No such distortion was observed and on that basis Knapp concludes that until other independent investigations prove otherwise it is most likely that there were measurement errors in the results obtained by CNGS.

Lawrence M. Krauss writing in the Los Angeles Times explains that working with neutrinos is extremely difficult, for a start off you can only ‘see’ them via their interactions with other forms of matter, and those are rare events in themselves. Secondly, if a substantial amount of neutrinos are produced at a given source, they cannot be tracked individually but by ‘probabilistic’ means.

In essence there are a whole load of intrinsic uncertainties to take into account which, if not estimated properly, can lead to an erroneous conclusion. This is even before consideration of the fact that Einstein’s theory has been tested many, many times before and has stood up.

Krauss raises an important note of concern. He states that if CERN has made a dramatic claim that subsequently proves to be false it further erodes science by implying that it is not to be trusted. In essence it gives further ammunition to those who believe that they can simply dismiss scientific conclusions they happen to find inconvient.

At a time when reliable and thoroughly tested climate science is still widely denied by those with an axe to grind, that is something we simply cannot afford.