Einstein Was Not Wrong, But Was He Right?

20/06/2012 09:44 BST | Updated 19/08/2012 10:12 BST

Last week, the European Organization for Nuclear Research (CERN) issued a press release regarding the faster-than-light neutrinos that the OPERA collaboration had reported detecting last September, saying that they did, after all, respect the cosmic limit put forward by Einstein in his theory of special relativity. The spurious results were in fact due to a faulty element of the experiment's fibre optic timing system.

The original results in September suggested that neutrinos travelling the 730km from CERN to Gran Sasso were arriving too early, 60 nanoseconds earlier than if they were travelling at the speed of light. This made them 'superluminal'. Confirmation of the anomalous results would have led to a scientific revolution, no less. As CERN Research Director Sergio Bertolucci said, this instantly "captured the public imagination", and news sites worldwide were relating the news that Einstein's theory may be wrong.

The science community, however, reacted which much more moderation. Few physicists believed that the results would stand in light of future experiments, whether internally conducted at OPERA, or at competing collaborations in the US.

Why so much skepticism, amongst a community that might be eager to find a new playing field for fundamental physics? The key reason is that scientists are rarely "surprised" by scientific revolutions (though they may be by discoveries, which is not the same thing). Scientific revolutions often arise after years, if not longer, of mounting evidence of flaws in an underlying theory, acting as signals that a major shift in our understanding of nature is approaching. This is what Thomas Kuhn described in the "Structure of Scientific Revolutions".

As much as scientists would have enjoyed an incredible result regarding the neutrinos, there were no precursor signs to suggest it could be serious. When the news came out that the fault had been found, none were surprised, although a few may have been disappointed.

So Einstein was not wrong, but was he right? Other parts of Einstein's work are currently under intense scrutiny. His theory of general relativity, different from special relativity, explores the laws of gravity on cosmological scales. It explains how the Universe expands and how the largest structures in the Universe, giant filaments of galaxies, form and grow under gravitational collapse.

Yet today, there is much that Einstein's theory of general relativity cannot explain: for example, why is the Universe not only expanding but also accelerating? This was discovered in the 1990s and Perlmutter, Schmidt and Riess were awarded the Nobel Prize in Physics for this last year. This acceleration could be explained by the presence of a mysterious and exotic form of energy dubbed dark energy. But to explain current observations, the dark energy would have to be the dominant form of "stuff" in the Universe today, about 75% of everything in the Universe. Yet there is currently no theory explaining what it could be. Some theorists have postulated that dark energy is not actually required, and that it is the laws of Einstein's general relativity themselves that should be modified. For cosmologists worldwide, a scientific revolution seems close at hand.

In order to reach it, scientists agree that they need to confront their ideas with more observational data. They should be able to construct 3-dimensional maps of galaxies (where galaxies are used merely as points tracing the much larger filamentary structure) and study gravitational lensing over unprecedented large regions of the sky.

There are several competing projects set out to do this. One of them is the European space mission Euclid (of which I am part), the largest existing astronomy collaboration in the world with nearly 1000 scientists from over 100 European laboratories and some US institutes, which has just been adopted today by the European Space Agency (ESA). Launch is planned for 2020 with results from 2025. Many in the field believe that this mission will bring with it a scientific revolution, either through a new understanding of gravity or a new comprehension of the mysterious dark energy.

The best is still to come, because while scientists can predict the arrival of a scientific revolution, they never can predict the advances that will arise from this change of worldview.


Link to ESA Press Release

The Euclid mission was selected in October 2011 alongside Solar Orbiter as one of the first two medium class missions of the Cosmic Vision 2015-2025 plan. On 20th June 2012, Euclid received the final approval necessary from ESA's Science Programme Committee to move the project into the full construction phase, leading to its launch in 2020.