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Physicist Uses Math to Beat Traffic Ticket
Here's a practical application for your physics education: using math to successfully beat a traffic ticket in court. Dmitri Krioukov, a physicist based at the University of California San Diego, did just that to avoid paying a fee for (purportedly) running a stop sign.
Krioukov not only proved his innocence, but he also posted a paper detailing his argument online on the arXiv server. The succinct abstract for his paper certainly distinguishes itself from other research papers:
"A way to fight your traffic tickets. The paper was awarded a special prize of $400 that the author did not have to pay to the state of California."
After thinking Krioukov ran through a stop sign, a nearby police officer pulled him over and issued him a citation. According to Krioukov's paper, however, three physical phenomena combined at just the right time and misled the officer.
When Krioukov drove toward the stop sign the police officer was approximating Krioukov's angular velocity instead of his linear velocity. This happens when we try to estimate the speed of a passing object, and the effect is more pronounced for faster objects.
Trains, for instance, appear to be moving very slowly when they are far away, but they speed past when they finally reach us. Despite these two different observations at different distances, the train maintains a roughly constant velocity throughout its trip.
In Krioukov's case, the police cruiser was situated about 100 feet away from a perpendicular intersection with a stop sign. Consequently, a car approaching the intersection with constant linear velocity will rapidly increase in angular velocity from the police officer's perspective.
Similarly, if a car approaches the stop sign with constant velocity but brakes quickly before reaching the sign, the angular velocity will rapidly increase before stopping momentarily. To illustrate this point, Krioukov created two graphs: one for the case of constant linear velocity through a stop sign (illegal) and another for a quick stop at the sign before accelerating back up to speed (legal).
 |  |
If you look at the graph on the right, you'll notice three lines with different colors, and each line corresponds to a different deceleration at the stop sign. The blue line with the biggest spikes represents a 10 m/s^2 deceleration -- about the highest deceleration for the kind of car he was driving.
This line mimics what actually happened best according to Krioukov because he had a terrible cold that day, and one sneaky sneeze caused him to slam on the brakes hard as he approached the stop sign.
The crux of Krioukov's argument is that this rapid, legal deceleration can appear very similar to the case described in the graph on the left. But the left graph actually represents a car cruising through the stop sign at a constant velocity exceeding 20 miles per hour. So surely an officer would still be able to tell the difference, right?
Not when another car partially obstructs his view, according to Krioukov. When another car partially blocked the officer's view of Krioukov's car momentarily, the officer could have missed the brief yet crucial timing of his stop. At least, that's Krioukov's version of the case.
Either way, his argument appeared to work: "The judge was convinced, and the officer was convinced as well," Krioukov told PhysicsCentral.
This physical description swayed the judge, or maybe she was simply impressed by the sheer dedication Krioukov put into avoiding this ticket.
You can peruse the paper here if you want to devise your own plan to get out of traffic tickets. Leniency in court, however, is not nearly as reliable as mathematical proofs.
Now, Krioukov has a challenge for our readers: "I want to ask the readership to please find the flaw in the argument."
165 Comments:
Anonymous said...
i think he never stop, anyway good trick
Wednesday, January 2, 2013 at 11:25 AM
DeadParrot said...
It says April 10th not April 1st.
Friday, December 28, 2012 at 2:24 PM
Anonymous said...
To the Anonymous poster who repeatedly used the word
"paean" Please, look it up. I believe the word you're really reaching for is "peon". Your average citizen is not a "A song of praise or triumph." ;)
Tuesday, December 25, 2012 at 1:12 AM
Charles Ramsey said...
Not all parts of an automobile move at the same speed the top of the wheel moves at twice the speed. Radar detectors are exaggerating the speed of motor cycles which have exposed spokes. Traffic cameras detect cross sectional area motor cycles have to get closer to trip the stoplight this leads to more run red lights because the yellow light has a shorter cycle if no traffic is detected. Sensors in the roads detect metal motorcycles have to get closer to trip the sensor this also leads to more run red lights. Bicycles are generally unable to be detected by all three means this leads cyclist getting speeding tickets because the radar detected an automobile behind it or running red light tickets.
Monday, December 24, 2012 at 6:13 PM
Anonymous said...
This is fantastic!!
Monday, December 24, 2012 at 2:56 PM
Anonymous said...
There is a big hole in this argument. If the car that blocked the Officer's view zoomed through the intercection, without stopping, the Officer will still be able to see Dmitri waiting at the stop sign. On the other hand, if the other driver stopped, the Officer would have noticed Dmitri stopped. A stop at a STOP sign will take a minimum of 1 second, looking left and right before proceeding. A car traveling at 20 mph will travel past the STOP sign in a fraction of a second, still leaving enough time for the Officer to see Dmitri stopping at the STOP sign. The Judge was either confussed or impressed by the law breaker.
Monday, December 24, 2012 at 11:02 AM
A Bocelli, true event said...
Hey I beat a ticket like this also. I had a red light ticket.
I didnt run the light but the officer claimed I did.
I proved 2 things , 1 he could not see the light controlling my direction of travel to testify what color the light was.
2. he information was incorrect about the lane of travel and position of my vehicle. I big work truck.
Dont ever think a ticket means your guilty unless you know your guilty.
Monday, December 24, 2012 at 10:24 AM
Anonymous said...
As it is physically impossible to keep one's eyes open while sneezing, I suggest that he continued his deceleration right on through the stop sign... only to come to a stop after having passed, ever so slowly, through it.
His perception of events may be flawed, just as he suggests, the citation issuing officer's were.
Monday, December 24, 2012 at 9:30 AM
Alissa Banks said...
That's such an amazing way to get out of traffic tickets! I love this guy!
Monday, December 17, 2012 at 4:41 PM
Anonymous said...
I think I've been a passenger in a car with this exact situation 40 years ago. There is no question that a friend of mine made a quick full stop at stop sign, but was issued a citation for running the stop sign. There was an obstruction, and the officer's position was almost exactly as described.
Saturday, June 9, 2012 at 12:40 AM
Anonymous said...
Well, if correct expression is used instead of (8), where initial velocity is not missed, the resulting observed angular rate would never be misinterpreted ...
Saturday, May 5, 2012 at 3:11 AM
Nessanel said...
I believe that one flaw is as follows: police use Doppler radar to measure the speed of their targets. The Doppler shift is proportional to the dot product of the direction of propagation of the radar wave and the direction of travel. Therefore, if the police was perpendicular to the direction of travel, as is the case in the diagrams, then the Doppler shift will be zero and the police will not measure anything.
Tuesday, April 24, 2012 at 9:50 PM
Anonymous said...
I hereby nominate Dmitri Krioukov for the 2012 Ignobel prize in physics
Tuesday, April 24, 2012 at 4:51 PM
Anonymous said...
OK folks - take this as example of how the internet works. HP and many other sites have posted and reposted this story. Check out the link to the original paper - and pay attention to the publication date before you try to wrap your head around the physics. April 1st. Does that date mean anything to you ???? Yes - this was a gag... now picked up and repeated within the echo chamber of the internet. Yes, I do hold several physics degrees.. But really people - you should not need to check the math on this item to understand what's really happening!
Monday, April 23, 2012 at 3:58 AM
Anonymous said...
Date of publication in the UCSD campus newspaper... April 1.... Think about it !!!!!
Monday, April 23, 2012 at 3:55 AM
samhouch said...
Doesn't this presentation presume and require that car #2 (C2) ran the stop sign while blocking the view of car #1 (C1) which was allegedly stopping? Wouldn't the officer therefore have noticed the C2 vehicle as being the primary offender, esp. since it was closest to the officer and in plain view? Furthermore, wouldn't having the two vehicles side by side offer a comparison opportunity, i.e., if car # 2 blows through the stop sign, then car # 1 would appear to stop as it would be lagging behind car #2 (if indeed car#1 stopped). Similarly, if car #2 was directly witnessed to have stopped, then wouldn't that provide a comparitive to determine similar/different behavior of car #1 behind it? I can see this working if car #2 were turning right from the right lane of C1 and C2's shared street, and therefore blocked the view to C1 while failing to give a relative behavior to compare; especially if car #2 had to pause for an oncoming vehicle before completing his turn. But, I don't see it working of C#2 continued to parallel c#1, and thus offering a relative behavior to go compare.
Monday, April 23, 2012 at 2:26 AM
Anonymous said...
Just a correction to the price of the California ticket. The base fine for 21453 is $404, not $235; however, with fees and assessments, the total comes to $480.
Sunday, April 22, 2012 at 11:20 PM
Capo said...
Angular velocity is not the whole story; you must also consider distance. If Krioukov's car accelerated at 10 m/s for the entire 10 sec before and after stopping (Figs 3 and 5), then 10 seconds before and after stopping his car would have been going 100 m/s (224 mph) and would have been 500 m (1640 ft) from where he stopped. If his car had been traveling at a constant 10 m/s speed (22.4 mph) without stopping (Fig 2), then 10 seconds before and after stopping his his car would have been 100 m (328 ft) away from where he should have stopped. A car looks a lot smaller 1640 ft (0.31 miles) away than 328 ft away. The police office could easily have noticed the difference. The numbers would become even more absurd if Krioukov assumed accelerations greater than 10 m/s to shift his double peaked Fig 3 curves closer to the time at which he supposedly stopped in an effort to better mimic the spread in the Fig 2 curve.
Sunday, April 22, 2012 at 7:46 PM
Anonymous said...
Curious... Where does 65 feet come from? Also, how is distance to the intersection irrelevant? Even if R0 is the distance to the defendants' car, the moment of interest occurs when the car is at the intersection. Oh...lane widths? Is that where the 65 is coming from?
Sunday, April 22, 2012 at 6:21 PM
Anonymous said...
For all of you experts the car has to "rock back" at the stop sign to make it obvious to the cop and others that you have stopped. You do not have to launch your car from the stop sign like a Formula 1 car either. Be reasonable. If you sneezed please wipe your nose and be careful so you do not hit the car in front of you. That may require slowing down and even stopping at the STOP sign! For the physics professor please make your car "rock back" (that means zero speed and some negative speed too) so you do not get caught at a weird angle next time.
Sunday, April 22, 2012 at 2:02 PM
Anonymous said...
I thought it might be April fools day joke, but it's been shown not to be
Sunday, April 22, 2012 at 11:34 AM
Phil M said...
What is considered the legal stop position or location of a car on approach to the stop sign and did he stop in that location.
Sunday, April 22, 2012 at 10:25 AM
Anonymous said...
Could it be as simpleas the fact we assumed he was sneezing and assumed the sneezing caused him to press hard on the brake pedal causing an abrupt stop, when infact he may not have sneezed and actually did not stop as described. Furthermore, this is all based on assumption of facts rather than the facts themselves. It boils down to the principal of if you cant dazzle them with brilliance baffle them with bullshit.
Sunday, April 22, 2012 at 9:01 AM
Anonymous said...
(Apologies, for further encouraging something completely off-topic...)
I can tell you where you're wrong: (1) By placing the burden of proof for YOUR argument on those you're challenging; (2) Presenting the false dichotomy that if nobody "shows you where you are wrong", they must be willfully teaching incorrectly.
(P.S. - logic beats Allah: Way to bring some bigotry/religion in on it. Good work.)
Saturday, April 21, 2012 at 9:25 PM
Anonymous said...
Who cares?
Laws are implemented in order to keep the paeans in their place, not to punish the educated elite.
A physicist is not an ignorant paean and should not be bound by the laws which were made to control the ignorant paean masses...We need this in America, or else we would have Presidents labelled as war criminals, Pentagon child-porn-downloading pedophiles filling our prisons, and Rush Limbaughs' convicted of drug offenses. None of which have the slightest chances of ever seeing a court.
As for commenters from other states trying to project their states laws onto Californian jurisdiction: Get a clue! Just because you live in a fascist state doesn't mean that anyone else in the world cares about your states peculiar rules; Running a stop sign may be a capital offense in some third world country, but this event occurred in California, not New Hampshire. What you accept in your state is not what we accept in ours!
In California, the police drive 85 in 25 mph zones, while talking on their cell phones (illegal for the average citizen), completely blowing through stop signs and stop-lights (they just flash their lights and siren). One officer was driving drunk, fell asleep at the wheel, drove across the freeway and crashed into a tree killing himself, and now his wife gets paid $90K a year from the taxpayers because he "died in the line of duty".
Try that as a paean (read: normal citizen).
Saturday, April 21, 2012 at 3:09 PM
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