# Can you drive fast enough to avoid being clocked by speed cameras?

##### March 25, 2014

Anyone wanting to avoid being caught out by speed cameras can do so very simply - by obeying the speed limits.

But University of Leicester physics students have suggested that - theoretically, at least - there may also be another way of avoiding getting a ticket.

A group of four MPhys students found that drivers could escape detection by driving so fast that their number plates would appear invisible to speed cameras.

But any drivers tempted to give this a try next time they are on the motorway should be warned; the car would need to be travelling at 119 million miles 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.

So – for all concerned – it's still best to stick to the speed limit.

The students 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.

Their 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 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.

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 119 million miles per hour, or one sixth of the speed of light.

Given that the fastest man-made object – the Helios Probe – is only capable of travelling at one five thousandth of the , we clearly have some way to go before we would ever be able to see this effect in action.

Student Dan Worthy, 21, from Chelmsford, Essex, said: "It would be great fun if we could become invisible - but unfortunately our current technology isn't advanced enough to do this.

"I would like to think that in the future, when we can travel between stars, intergalactic would need to look for invisible spaceships too."

"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.

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

Course tutor Dr Mervyn Roy, a lecturer in the University of Leicester's Department of Physics and Astronomy, said: "The aim of the module is for the students to learn about peer review and scientific publishing.

"The students are encouraged to be imaginative with their topics, and find ways to apply basic physics to the weird, the wonderful and the everyday."

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##### verkle
Mar 25, 2014
This comment has been removed by a moderator.
##### Tomator
not rated yet Mar 25, 2014
Those researchers are pretty well candidates to ignoble award by selecting the most stupid way to trick the device. Even much lower speed when passing by the camera in atmosphere would cause a shockwave strong enough to completely destroy the equipment before it could transfer the photo anywhere. Which vehicle could avoid burning in the air, moving so fast? But there are many less self-destructive ways to avoid a photo. My favorite is a HARM missile. Works perfecly against manned patrols too.
##### Jizby
Mar 25, 2014
This comment has been removed by a moderator.
##### indio007
5 / 5 (2) Mar 25, 2014
Know your rights. A speeding ticket camera is not a "witness". It is hearsay evidence.

http://www.thenew...aled.pdf
##### antialias_physorg
not rated yet Mar 25, 2014
Those researchers are pretty well candidates to ignoble award

Chill. These are students publishing in the student paper of their university.
##### fortranfixer
not rated yet Mar 25, 2014
I think the Myth Busters "beat" a radar activated speed camera at a much lower speed with a sports car. The radar could not lock onto the speeding car. I don't remember the vehicle speed.
##### Modernmystic
not rated yet Mar 25, 2014
How about a device that covers your plate when you hit a button and then uncovers it when you hit the button again after you pass the camera?
##### MrVibrating
not rated yet Mar 25, 2014
Just ensure there's another vehicle between you and the camera, time it right and accelerate hard while exploiting the parallax effect...
##### Dichotomy
not rated yet Mar 25, 2014
Furthermore, most cameras don't have the resolution to be able to correctly identify the driver. Since people (and not vehicles) commit crimes, unless the court can show who was driving, they don't have a case against the driver.
##### nkalanaga
not rated yet Mar 25, 2014
But wouldn't reflected UV be red-shifted into the visible range? If the number plate reflects UV, the camera would still get a picture.
##### cryselco
not rated yet Mar 25, 2014
TopGear proved that over 170, they don't work...

http://www.youtub...qv4gYAE8
##### SciAL
2 / 5 (1) Mar 28, 2014
"They found the car would need to be travelling at 53 million metres per second – equal to 119 million miles per hour, or one sixth of the speed of light."

They meant the speed of SOUND! Even after mentioning doppler other news outlets are running with this typo.. Maybe we could time travel in the concord. Maybe thats why they quit flying!?

##### rockwolf1000
3 / 5 (2) Mar 28, 2014
"They found the car would need to be travelling at 53 million metres per second – equal to 119 million miles per hour, or one sixth of the speed of light."

They meant the speed of SOUND! Even after mentioning doppler other news outlets are running with this typo.. Maybe we could time travel in the concord. Maybe thats why they quit flying!?

No. They meant the speed of light. Both sound and electromagnetic (light) waves are subject to the Doppler effect.

The speed of sound is roughly 767 mph and one sixth of that is 128 mph.

128 mph
119,000,000 mph
You see the difference?
##### Nik_2213
not rated yet Mar 29, 2014
May be urban legend, but I've heard of a driver with a high-end sports car that automatically deployed spoilers and wingy-thingies above approx 70 mph. Getting too near the limit of points on his driving license, he had the bright idea of modifying the deployment system so it obscured 'line of sight' from pole and bridge-mounted speed cameras.

Traffic police were fairly sure who he was, as those super-sportsters were few and far between. They just had to grind their teeth and wait for him to make a mistake...

IIRC, he was finally caught zooming through a local motorway's 50 mph 'road works' limit at ~ 65 mph, just below the auto-deployment speed.

The 'aggravated speeding' ticket plus existing points meant a lengthy driving ban. He was also prosecuted for having an un-roadworthy vehicle, due to that obscured number plate. His insurance flagged the unauthorised mods and black-listed him. His car warranty was void...