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Asked by edwardf to Nazim, Karen, Leila, Catherine, Adam on 14 Mar 2012. This question was also asked by tkidner.
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Adam Stevens answered on 12 Mar 2012:
You may have asked this because of the recent experiment in Italy that thought they had found neutrinos going faster than the speed of light. The results of this experiment aren’t confirmed yet and they think there might have been a timing error, which would explain it without breaking any laws of physics.
However, the restriction on going faster than light comes from Einstein’s theory of Relativity. The first part of the theory made the assumption that particles can’t go faster than light and then looked at the consequences. The second part (general relativity), I think actually gives a some working out for why this speed limit exists.
In fact, only massless particles can go /at/ the speed of light – things like photons. If a particle has mass, then it’s impossible for it to go this fast, and the more mass it has the harder it would be.
So going faster than light would require this law to be broken, which is possible, but not in our current understanding of the universe.
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Leila Battison answered on 12 Mar 2012:
Einstein’s theory set the speed of light (300,000,000 metres per second) as the absolute fastest anything could go, and all of our physics is based on that idea.
Back in September, scientists at CERN (big donut in Swizerland trying to recreate the conditions of the Big Bang) thought they had found neutrinos, which are a tiny part of an atom, going faster than light. If they were right, all of physics would be in serious trouble!
But just a couple of weeks ago, they found the answer to the problem, and it wasn’t because physics was broken! In fact, it was a bit of the machine used to detect the particles, that had some loose wires, so the data was wrong. Physics was saved!!
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Karen Masters answered on 12 Mar 2012:
I don’t think so no. There was a lot of fuss recently about some scientists claiming they saw neutrinos travel faster than light. But I never thought it likely their experimental result was true – I always thought they had missed something, and the last I heard someone suggested they had plugged in a cable wrong. So I think the moral of that story is to be really sure of your evidence before making extraordinary claims!
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Nazim Bharmal answered on 14 Mar 2012:
Yes they can, and they do every day above your heads! The MAGIC telescope on La Palma is designed to measure Cherenkov radiation which occurs when particles travel faster than light.
So far, you might think I’m fibbing because everybody says it isn’t possible, but the important bit is that the speed of light in air is less than the speed of light in a vacuum (like empty space). Some high energy gamma rays from outer space hit the Earth’s atmosphere and produce particles that move more quickly than the speed of light /in air/. The particles then loose energy by emitting Cherenkov radiation, which is a like a sonic boom but made up of light. (And often blue in colour.)
The MAGIC telescope measures this light and can work where the particles came from and from that,
where the gamma rays came from.In deep space or in a vacuum, then you can’t travel faster than the speed of light and even in the atmosphere you can’t travel faster than the speed of light in a vacuum. But in the atmosphere, or in water, or in almost any material, you can go faster than light.
Comments
tkidner commented on :
fantastic question