Saturday, October 08, 2011

Weekend Post - Faster than light?

There might be a revolution in science any moment now. Or maybe not.

A few weeks ago Italian scientists said that they thought they’d broken one of the fundamental laws of nature. They claimed that they had managed to force a beam of particles to travel faster than the speed of light. Admittedly only very slightly faster than light, but even a little bit would have been enough. Their beam of neutrinos had travelled all the way from the CERN laboratory in Geneva, a trip of 730km, across the border into Italy and they arrived 60 billionths of a second earlier than light would have covered the same distance. If this is true, if something really can travel faster than light, faster than 300,000 kilometers per second, then our understanding of the universe has been incomplete. After the results were announced the international media was full of headlines asking "Was Einstein wrong?"

If true, this won’t be the first time that a revolution like this has occurred in science. When Einstein first proposed his laws of relativity there was an enormous backlash against them because they contradicted the theories of Isaac Newton and the scientific establishment of the time couldn’t accept that. However, a few experiments later it was found that Einstein was right and that Newton was out-dated. Of course that doesn’t mean Newton’s theories and equations aren’t relevant, they still are in almost all circumstances. Engineers building bridges, scientists launching spacecraft, even soldiers firing guns all use Newton’s laws and they work just fine for them. It’s only in extreme circumstances that Newton’s laws stop working and Einstein’s have to be used instead.

What might have happened in Italy is something similar. Nobody is actually saying that Einstein’s theories were wrong, it’s just that they might have been only 99% correct, they might not explain everything, there might be things that his theories don’t predict or explain.

Or, and this is much more likely, the results from Italy might just be wrong. To their credit the Italian scientists have published their results and have given the international scientific community the opportunity to tear them to pieces. That’s the way the scientific process works. You have an idea, you test it, you publish your results and your colleagues do their best to find a flaw in what you’ve done. It’s not a competition, it’s just a rigorous way of testing ideas. Unlike supernatural belief systems, criticism and testing are welcomed as ways to get closer to the truth.

One of the least well understood aspects of the scientific method is that there’s a difference between facts and explanations. Gravity, for instance, is a fact. If you’re unsure, feel free to lean too far out of a top floor window and in the next few seconds you’ll be convinced. Similarly evolution is a fact. It’s been seen in a variety of quickly reproducing animals over several generations. It can be seen in fruit flies, moths and fish. These aren’t denied by anyone who has seen the facts. They don’t need any more proof. Things fall to the ground, planets are attracted to stars, animals gradually change their form to adapt to their environment over time.

What’s differs are the possible explanations. With gravity, Newton just proposed that there was an attraction between bodies but he couldn’t explain how that might happen, he just came up with rather wonderful equations to explain and predict it. But those ideas later turned out to be very slightly imperfect. That’s when Einstein came along with the idea that the structure of space and time was curved by matter. That was a better explanation of everything and filled the gaps in Newton’s explanation. A step forward. Likewise with evolution. Initially we were told that species didn’t naturally change, they were static. Then biologists began to notice what they called “speciation”, that what once identical species seemed to have changed their form to adapt to different environments. Everyone who’s seen the evidence agrees that species adapt over time, the evidence for that is clear. Then Darwin came along with his explanation, natural selection. So far, that’s the best explanation we have for the variety and adaptation of species, humans included. Maybe one day another scientist will come up with an improved explanation. So far there doesn’t seem to be a need, Darwin’s theory appears to be holding out perfectly well, just like Einstein’s.

That’s the wonderful thing about science. Whether the Italian results are right or wrong, scientists will be happy. If Einstein’s ideas continue to adequately explain things then we’re happy. If however, there’s something his theories can’t explain? Fantastic, the universe is even more marvelous and complex than we thought already.


There's a good summary of the experiment in Nature. You can see the reaction to this story by doing a Google search like this.

You can see a summary of Newton and his theories here and of Einstein here. The experiments by Sir Arthur Eddington that provided the first experimental support are discussed in Eddington's biography here.

For a summary of the scientific method see here. If you're feeling a bit more adventurous read this on Karl Popper and "empirical falsification" as the basis of science. Learn that and you understand it all.

For background on Darwin and natural selection as his explanation for evolution see here.

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