Weekend Post - Einstein seems to have been right all along

I don’t know whether to be pleased or disappointed. It looks like Einstein’s theories are still safe. His suggestion that the speed of light can never be exceeded seems still to be true.

Last year, amongst huge fanfare, some Italian scientists published results suggesting they had been able to break 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 across the border into Italy, a trip of 730km, and they had arrived 60 billionths of a second earlier than light would have covered the same distance. If this was true, if something really could travel faster than light, faster than 300,000 kilometers per second, then our understanding of the universe would have been wrong. After the results were announced the international media was full of headlines asking “Was Einstein wrong?” The internet remains full of conspiracy theorists, alien abduction theorists and every single psychotic-with-a-website who thought this vindicated their bizarre theories. This was a great day for them.

However the scientific world was split. A small number of scientists took the results and went on long, fantastic imaginative journeys. If this is true then reverse time travel is possible, we can reach the stars and every science fiction book you’ve ever read could become true. Well, that’s what the newspapers, TV news shows and the internet said.

The better scientists were skeptical. That is, of course, how scientists are MEANT to be. Just because another scientist has suggested something, that doesn’t make it true. The skeptics said that if this was shown to be true then clearly it’s remarkable but, they said, let’s slow down for a moment. Let’s see if these results are true before we jump to any conclusions. The results had to be exposed to the most critical, skeptical and demanding of all of science: peer review.

To their credit the Italian scientists did just that. They published their results and gave the international scientific community the opportunity to tear them to pieces. That’s the nature of the scientific process. 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. Most importantly you give other scientists the opportunity to try and repeat your experiment.

Here’s an experiment I did at home to illustrate this. Three members of my family all measured the height of my youngest son. They all did it in different rooms but using exactly the same technique. He stood against a wall, we rested a book on his head, marked his height against the wall and then measured the distance to the floor. The results were all different. All three measurements were slightly different. He hadn’t grown in between the measurements, gravity hadn’t changed and we all used the same tape measure. This crude experiment demonstrated that there are always tiny variations in experiments, tiny flaws, tiny mistakes that lead to tiny differences in results.

I’m not saying that the Italian scientists were this incompetent in their measurements, I’m just pointing out that experiments have to be repeated many times to be certain they’re measuring things correctly.

That has now happened. A different group of scientists at exactly the same lab in Italy have repeated the experiment. Remember that last time the neutrinos were a mere 60 billionths of a second faster than light. That’s one forty-thousandth faster than expected. This time? They travelled at exactly the same speed as light.

Of course it’s perfectly possible that this repeat of the experiment is wrong and the first one was correct. That’s why they should probably do it again. However, it’s safe to assume for now that Einstein’s theories and propositions are still ok for now. They’ve worked perfectly well for almost a century and they’re no reason to kick them out yet.

A spokesman for the lab, Dr Sandro Centro, sounds like a proper scientist to me. He told the BBC:

"We are completely compatible with the speed of light that we learn at school … In fact I was a little sceptical since the beginning … Now we are 100% sure that the speed of light is the speed of neutrinos."

It looks like the alien, space travel and time travel fantasists will have to wait a little longer before their ideas come true. Perhaps a lot longer.

Weekend Post - Was Einstein right all along?

In September there was a big fuss, reported all over the world, about an experiment conducted in Italy that suggested that Albert Einstein, his Special Theory of Relativity and his notion that nothing can travel faster than light might be wrong.

Almost every newspaper in the world asked “Was Einstein wrong?” The Italian scientists claimed that they had managed to force a beam of neutrinos 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. Clearly something is wrong. Either one of the cornerstones of our understanding of the universe is wrong or there’s been a mistake by the scientists. My money was on the latter.

Obviously the results are interesting. Was Einstein right or wrong? It’s a big question. But I think it’s just as interesting for the public to see how science works. The researchers in Italy went public with their results and said to the entire world (in an Italian accent) “Hey, look at this, can this be right or have we made a mistake?”

The physics community around the world went into overdrive. They thought about repeating the experiment, tried to think of new rules of physics and, most critically, tried to help the Italians discover any mistakes.

It didn’t take long for things to happen. As we speak they’re trying to repeat the experiment in a slightly different way to rule out any systematic errors in their measurements. Just as importantly experts at the University of Groningen in the Netherlands might have come up with an explanation.

This is where it gets complicated. Einstein’s Special Theory of Relativity is simultaneously simple and complex. At it’s simplest he just suggested two things: firstly that it doesn’t matter where you are or what you’re doing, the law of physics remain the same. That’s the easy one. The second is more complicated. It says that wherever you are and whatever you’re doing, the speed of light is always the same. That isn’t as simple as it sounds. Imagine you are the passenger in a car travelling at 50km/h and you lean out of the window and throw a ball ahead of the car at 10 km/h. The speed of the ball will be 60km/h.

But instead imagine now that you lean out of the car window and shine a beam of light from a torch ahead of you. Light travels at roughly a billion km/h. So the light will now be going at a billion plus 50 km/h? No. It still travels at a billion km/h. The speed of light in a specific medium doesn’t change. Not ever. If you travel in a spaceship at half the speed of light and shine that torch forwards the light will still just travel at a billion km/h.

The effect of this is profound. I don’t have the skill or space to explain the steps (I’ll put links on the web site) but it follows from this that as you go faster and faster some pretty strange things happen. The faster you go the greater your mass and the more energy is needed to accelerate further so that actually to get to light speed you would need infinite energy. Most importantly, the closer you get to the speed of light, the slower time itself progresses as seen by an outside observer.

That last element is the critical one for the Italian experimenters. The critics at Groningen noticed that the Italians had used GPS satellites to measure the time the neutrinos were travelling. But GPS satellites are themselves moving, nowhere near light speed but fast enough that their ability to measure time as accurately as the Italians needed was affected. The Groningen scientists did the maths and worked out that this would affect the calculations by, yes, you’ve guessed it, 60 billionths of a second.

The new experiments aren't done yet but we now have a very plausible possible explanation for the effect the Italians saw. Will they be proved right? Only time will tell.

Sources

The original news story can be seen here courtesy of the BBC. The original notice in Nature is here.

For an overview of Special Relativity see How Stuff Works or the Wikipedia page here.

For news on the repeat of the experiment see the BBC story here. For a summary of the Groningen suggestions about GPS satellites and their time dilation see here.

Faster than light? No.

It looks like the the scientists in Italy who thought they found neutrinos travelling faster than light might have made a mistake. The irony is that the theory they thought they might have undermined actually explains the effect they saw.

Speedy neutrino mystery likely solved, relativity safe after all

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.

Sources

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.