# Scientists discover how to avoid a speeding ticket

British researchers have found that there may be a way to avoid getting a dreaded speeding ticket - but only if you can travel at a sixth of the speed of light.

PTI| Updated: Apr 26, 2014, 10:14 AM IST

London: British researchers have found that there may be a way to avoid getting a dreaded speeding ticket - but only if you can travel at a sixth of the speed of light.

University of Leicester students found it would be possible to become invisible to speed cameras if you could travel at a sixth of the speed of light.
A group of four students found that drivers could escape detection by driving so fast that their number plates would appear invisible to speed cameras.

But the car would need to be travelling at about 192 million km per hour to make the number plate invisible.

This speed equates to one sixth of the speed of light - and no man-made vehicle is capable of going anywhere near this speed, researchers said.

The researchers made the calculations in their final year paper for the Journal of Physics Special Topics, a peer-reviewed student journal run by the University`s Department of Physics and Astronomy.

The calculation is based on the Doppler Effect - the physical effect where the frequencies of light or sound waves emanating from an object increase or decrease when it moves towards or away from you.
This effect is at work when you hear an ambulance - its siren will appear to lower in pitch as it drives past you.

With light, this process creates `red shift` - where the frequency of light from an object travelling away from the observer is shifted towards the red end of the colour spectrum. The faster an object is travelling, the bigger the shift in frequency.

This means it would theoretically be possible for the light from a fast-moving car number plate to be shifted out of the frequency range which speed cameras are able to detect.

The group assumed the camera would be able to detect a similar frequency range as the human eye - roughly 400 terahertz at the `red` end of the spectrum to 790 terahertz at the violet end.

Car number plates are generally yellow - which has a frequency of around 515 terahertz, researchers said.

To work out the necessary speed of the car for the number plate to be `shifted` past the 400 terahertz boundary of the visible spectrum, the group utilised the equation used by astronomers to calculate how fast stars are travelling away from the Earth.

They found the car would need to be travelling at 53 million metres per second ? equal to one sixth of the speed of light.

"The Doppler Effect is something most people learn in GCSE physics, but we thought it would be good to look at what day-to-day effects it could have," said student Dan Worthy, 21, from Chelmsford, Essex.

"Our message to drivers is that it would be completely pointless to try to use this method to avoid a speeding ticket," Worthy said.