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Math Transportation Science

The Laws of Physics Trump Traffic Laws 378

Posted by Soulskill
from the in-this-house-we-obey-the-laws-of-thermodynamics dept.
New submitter HeLLFiRe1151 sends this quote from Physics Central: "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 (PDF) on the arXiv server."
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The Laws of Physics Trump Traffic Laws

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  • by damn_registrars (1103043) <damn.registrars@gmail.com> on Saturday April 14, 2012 @10:08PM (#39690513) Homepage Journal

    As a result of this unfortunate coincidence, the O's perception of reality did not properly re ect reality.

    It's too bad that statement cannot be quickly supported in many other cases.

  • by Anonymous Coward on Saturday April 14, 2012 @10:09PM (#39690517)

    Relative to my car, I was travelling at virtually 0 mph!

  • by WrongSizeGlass (838941) on Saturday April 14, 2012 @10:14PM (#39690541)

    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.

    Physics explained what the officer saw (or thought he saw) but another car explains what the officer didn't see (Krioukov stopping at the stop sign).

    • by jd (1658) <<moc.oohay> <ta> <kapimi>> on Saturday April 14, 2012 @10:27PM (#39690591) Homepage Journal

      We only have his word that he actually stopped. It would be more correct to say that another car explains why there are multiple scenarios explaining what the officer thought he saw. The only way this really relates to traffic (or other) laws is that western law specifically handles multiple scenarios by stating that the burden of proof is on the accuser to show that the scenario they outlined meets a requisite threshold. Physics is not trumping anything, it merely allows one to illustrate in this case some of those alternatives.

      • by Anonymous Coward on Saturday April 14, 2012 @10:40PM (#39690629)

        I swear Judge some where in the multiverse I stopped.

      • by Anonymous Coward on Saturday April 14, 2012 @11:10PM (#39690743)

        by stating that the burden of proof is on the accuser to show that the scenario they outlined meets a requisite threshold

        That threshold, in traffic court, is usually just the officer saying so... not actually proving it. So in this case physics effectively trumped SOP.

        • Indeed. I'm sure the officer's face was red after hearing this explanation.

        • by Belial6 (794905) on Sunday April 15, 2012 @01:40AM (#39691303)
          Yep. I had a pal I was with that was ticketed for not stopping at a stop sign. When asked how he could have seen my pal's car given that there was a field between them where the weeds were 1 1/2 feet higher than the height of my friends car, the cop's answer was "I don't know, but i did." The ticket was upheld, as that was apparently good enough for the judge.
          • by Anonymous Coward on Sunday April 15, 2012 @03:05AM (#39691523)

            I can tell you as a career prosecutor that usually if you want to challenge something in court you need to make sure you imediately ask the court for a jury trial. Otherwise you won't get common citizens to try your case, but just a Judge who has a working relationship with the officers all the time. Experience shows that if a case is tried to a Judge you are most likely to be found guilty. Sadly I once had a Judge say at the end of a morning in court, "If I think they are not guilty, I give them a lower fine." Juries are always willing to let you off if you can give them any excuse to do so.

            • by Anonymous Coward on Sunday April 15, 2012 @04:11AM (#39691655)

              But many of these cases are moving violations and not subject to jury trials. How do would one go about doing what you say in those cases?

            • by wolfgang_spangler (40539) on Sunday April 15, 2012 @10:24AM (#39693309) Homepage

              I tried to use math to defend myself recently when ticketed for using a cel phone in a school zone. As an aside, I was using it legally (hands free) and picked it up after I exited the school zone, the officer said, "you picked it up about 5 feet before the end of the zone."

              It was a very, very interesting experience and I pretty much learned the point you just made AC. At the end of the day, in which I defended myself with math/physics the judge said, "I feel like I just had a college physics class. You know, there are two school zones on that street. You may have been in the zone, you may not have. I don't care, you have no business being on your phone on that street. You are free to appeal my decision.

              The fine was an annoyance (like 150) but I found it a very interesting experience in how small suburbs within cities make money and how a person going in there to defend themselves has basically no chance.

          • by Ferzerp (83619) on Sunday April 15, 2012 @10:11AM (#39693233)

            The problem with his partially blocked view defense is he's claiming that his Yaris, is capable of over 1G accelleration from a stop. (10 m/s^2 is more than 9.8 m/s^2). That is supercar like acceleration, even to maintain only up to 20 MPH.

            His whole paper is based on breaking the laws of physics for his Yaris, and hiding it so that the judge and officer don't notice.

    • by mysidia (191772) on Saturday April 14, 2012 @11:34PM (#39690847)

      Physics explained what the officer saw (or thought he saw) but another car explains what the officer didn't see (Krioukov stopping at the stop sign).

      The officer didn't observe him not stopping at the stop sign. The officer ASSUMED he did not stop based on the state of the car he observed before his was obstructed, and the state of the car he observed after it was no longer obstructed.

      The officer should be disciplined for taking that shortcut and citing based on a supposed occurence that were not actually directly observed.

    • by Essellion (669297) on Sunday April 15, 2012 @01:25AM (#39691243)
      By his graph, it looks like he's saying that he waited until almost at the stop sign, sneezed and slammed on the brakes, came to a stop of zero duration while obscured behind another car stopped at the stop sign, then gunned it to cross the intersection.

      And that the officer totally missed the difference in position between a car that sails through an intersection as opposed to one that both decelerates to a full stop and accelerates fully up to speed over a period of about 3 seconds,

      Hmmm. Maybe...

      But I'd really like to see this demonstrated. It would make an interesting project. Mythbusters?
      • by Mr. Underbridge (666784) on Sunday April 15, 2012 @03:14AM (#39691535)

        And that the officer totally missed the difference in position between a car that sails through an intersection as opposed to one that both decelerates to a full stop and accelerates fully up to speed over a period of about 3 seconds,

        I wondered if someone would bring that up. The angular velocity profiles might look similar during the non-obstructed portions, but their integral will not. Could be that a clever prof just used physics to confuse the crap out of a layperson and get out of a "California stop" (ie, a little flash of red tail light, and proceed on your way) ?

      • by shutdown -p now (807394) on Sunday April 15, 2012 @03:55AM (#39691619) Journal

        And that the officer totally missed the difference in position between a car that sails through an intersection as opposed to one that both decelerates to a full stop and accelerates fully up to speed over a period of about 3 seconds

        His point is that there was no way to not miss the position, because the car that sailed in front was much bigger than his, and had completely occluded his car for a "significant" time (i.e. long enough to make it possible to stop-then-start and end up with the same speed as if he'd slowly cruised through).

  • Years ago I was pulled over by a cop who claimed I was going 45 in a 30, which I knew to be complete bullshit. I was driving a car that could barely produce 70hp under really great conditions, with 500+ pounds of friends in the car (in addition to my own mass) and had just come to a complete stop and made a right-hand turn less than 100 yards prior. In other words, the cop was claiming that my woefully underpowered car from the 70s was accelerating like a modern Porsche.

    He handed me my ticket, and I went to the court hearing at the scheduled time, date, and location. In that county the first meeting is with the DA, you have no option to see a judge that day no matter how much you ask for it. That county was over an hour's drive from work, a place I had never visited prior to the date of the offense. The DA made me an offer; take a plea bargain - which would not be reported to my insurance so long as I was not ticketed in their county again for a year (and carrier a lesser fine) - or come back at a later date to plea my case before a judge.

    I decided my time was worth more than that, and took the plea. I could have taken the second hearing to plead my case before a judge, but the amount it cost me to drive there and back, plus time taken off of work, was likely more than the small fine I paid them that day.

    That said, congrats to the professor for so handily showing the error in the cop's measurement without making them look like a baboon.
    • by PRMan (959735) on Saturday April 14, 2012 @11:01PM (#39690717)

      In other words, the cop was claiming that my woefully underpowered car from the 70s was accelerating like a modern Porsche.

      I had a similar situation where I was stopped going 80 on the freeway. The problem was my Saturn couldn't have accelerated to 80 from the ramp. I presented the mathematical formula to the judge and the officer, showing that there was no way my car could do what he was claiming. They didn't care. I got the ticket anyway.

      • Re: (Score:3, Funny)

        by Anonymous Coward

        You should have appealed to the newspaper. A headline of "xxx Court claims to be Above the Laws of Physics" would have been entertaining.

      • by shentino (1139071) on Saturday April 14, 2012 @11:56PM (#39690937)

        Which just proves that in many cases tickets are more of a revenue source than they are an enforcement mechanism.

        Also the reason why they like to screw with yellow lights to make it harder to stop in time.

        • In my country the green light starts to blink a few seconds before yellow turns on and I start to brake when it does if I see that I won't make it to the intersection before the yellow light.

          Also, the law is that if you are too close to the intersection (so you would need to slam on the brakes to stop before the line as opposed to stopping gradually), you can go even if the light already switched to yellow.

    • Tried it. (Score:5, Informative)

      by tverbeek (457094) on Saturday April 14, 2012 @11:02PM (#39690721) Homepage

      I once used physics to argue that a speeding ticket I received was bogus. I explained that even if I was traveling at the speed the officer claimed (unlikely in the underpowered subcompact I was driving, since I'd just gotten on the freeway), he could not have caught up with me and paced me at that speed in that short distance. I also suggested that a more likely explanation for the ticket was a bumper sticker which identified me as gay, and the fact that I was leaving a (peaceful) civil rights demonstration. (This was in the Midwest, in the 90s.) I was still found guilty, but the full fine and points on my license were not assessed.

      • Wonderous. Proving once again that the US legal system is above the laws of physics.

        Would you happen to have the name of said Judge who committed this gaff?

    • by mysidia (191772) on Saturday April 14, 2012 @11:38PM (#39690861)

      I decided my time was worth more than that, and took the plea. I could have taken the second hearing to plead my case before a judge, but the amount it cost me to drive there and back, plus time taken off of work, was likely more than the small fine I paid them that day.

      What should happen is the county should be required to fairly compensate you for your lost time, driving costs for both trips, and inconvenience (Including the inconvenience of having been pulled over), if you are found not guilty.

      A portion of that should come from the officer's salary / annual bonus. Maybe then they would be more careful about making sure a crime was actually committed before stopping a vehicle and issuing a ticket.

    • by bhcompy (1877290) on Sunday April 15, 2012 @12:11AM (#39691019)
      I successfully tried something similar(explaining my way out of a ticket, not math). Cop pulled me over for a busted taillight, then cited me for driving without a seatbelt because I had undone my seatbelt to get my wallet prior to the officer arriving at my window. Thing is, my car(72 Chevelle) had the most annoying seatbelt warning buzzer in the world and it does not go off automatically after a short duration(like modern cars). I explained what I did to the officer, who didn't believe me, so I asked the officer to put the car in gear and tell me if they can drive with the buzzer from hell buzzing at them in its constant high-pitched whine. Cop relented, gave me my fixit ticket, and let me on my way.
      • Re: (Score:3, Insightful)

        by awall222 (1276148)
        I did the same thing with my seatbelt once. The officer told me "I have no proof you were wearing a seatbelt; I didn't see you wearing one." Apparently he didn't need proof I wasn't... I wasted a day getting it thrown out in court.
    • by Grayhand (2610049)
      I faced something similar except with no ticket. I was driving on a washboard street near my home. If you did more than 20 mph it would tear the undercarriage from your car yet they claimed I was speeding, which was impossible. Turns out there was a drug bust in a nearby apartment and they wanted an excuse to search my vehicle. I was sit on a curb with my hands on my head while they searched my car. They couldn't find anything so I was let go without even a ticket. Sometimes these traffic stops are an excus
      • by Mr. Underbridge (666784) on Sunday April 15, 2012 @03:21AM (#39691553)

        Turns out there was a drug bust in a nearby apartment and they wanted an excuse to search my vehicle. I was sit on a curb with my hands on my head while they searched my car. They couldn't find anything so I was let go without even a ticket.

        Um, since when is simple speeding probable cause for a full search of a vehicle?

        If they don't ticket you there's nothing to fight so they get away with a blatant breech of the law.

        It is even if they do, unless there is something noticeable to justify a search. My guess is they 'asked' you if they could search the vehicle, you were afraid, and you said something that amounted to 'yes'. Should that happen to me, I'll tell them to get a warrant. I'm guessing that if they ask to search the vehicle, they don't have cause and they know it.

    • I had a similar situation where I was pulled over for supposedly doing 50 in a 35 zone. The problem was, it was on a surface street during rush hour, and if anyone there was going over 30 at the time it would have been a miracle (or a flying car). The judge didn't care, and it was the cop's word against mine, so of course I lost.

  • The cop had an obstructed view of his car by a car in front of his, he braked very hard, stopped briefly, and then started again. He then used fancy graphs with the judge. Cool, but according to him he didn't actually break any laws. F'n TFS.

    • Re: (Score:3, Interesting)

      by Anonymous Coward

      tl;dr: Bullshitter claims his $10k Toyota Yaris has better breaking and acceleration than a $60k sports car; court fails to realize that if bullshitter's car were capable of accelerating that fast, then he's guilty of a more expensive ticket for gunning it from the stop sign (display of acceleration is usually a larger fine than running a stop sign).

      Also, I'm pretty sure most places have a minimum prescribed stopping time. Bullshitter's graphs do not have ANY stop time.

      • Re: (Score:3, Informative)

        by jeremy85mai (2520912)
        TL;DR TL;DR: Throw numbers at people who don't understand what the numbers mean, and you can convince anyone of anything
  • April Fools (Score:5, Informative)

    by Anonymous Coward on Saturday April 14, 2012 @10:22PM (#39690573)

    The article was posted on April 1. (Need I say any more?) See the discussion on the PhysicsBuzz blog for details.

    http://physicsbuzz.physicscentral.com/2012/04/physicist-uses-math-to-beat-traffic.html

  • by 1u3hr (530656) on Saturday April 14, 2012 @10:40PM (#39690631)

    http://arxiv.org/abs/1204.0162 [arxiv.org]

    The Proof of Innocence
    Dmitri Krioukov
    (Submitted on 1 Apr 2012)
      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.

    If you think this really happened, find a citation for the case that doesn't end up back at this same article.

    • by mysidia (191772)

      If you think this really happened, find a citation for the case that doesn't end up back at this same article.

      The article is a citation; and it's not particularly newsworthy that someone successfully beat charges of running a stop sign, it's not surprising that there would be one article referring to it.

      You have really shown no evidence that it was actually an April Fools joke. Until you go pull the public records, and find nothing, however, there is no reason to doubt the author's account on the m

    • by spd_rcr (537511) on Sunday April 15, 2012 @12:22AM (#39691047) Homepage

      I tried to argue a reckless driving ticket using math and physics when I was younger. I was in the right and proved it conclusively based on the officers statement, but the back-woods judge just changed the charge to a misdemeanor and fined me anyhow for "anything you might have done in my county". When I asked about appealing his decision, the judge pointed out that it would cost $300 and him being the only judge, he'd probably say the same thing next time. If the court's looking to collect some money, the court's going to collect that money one way or another.

      • by houghi (78078)

        This and other statements I have written here I wonder why people still want to live in the US.

        Running a stop sign would get you a warning if anything here in Belgium. Obviously after more then one warning you will get a ticket. Stop signs are very tricky to give tickets, because it is so hard to prove. So there must be at least two police officers as a witness. Otherwise it is my word against his and that means I win.
        I can appeal if I wanted and would get to a different court, because I should not get the

  • by romit_icarus (613431) on Saturday April 14, 2012 @10:47PM (#39690665) Journal
    Nothing new, I say. I've often seen traffic laws being trumped by nothing less than a generous show of cleavage, which always seemed to defy at least one of the physics laws, namely gravity.
    • by Anonymous Coward on Saturday April 14, 2012 @11:23PM (#39690799)

      I've tried that, but I guess my man-boobs aren't generous enough.

    • by wvmarle (1070040)

      Well considering how it tends to pull DOWN eyes, I'd argue they don't defy but rather enhance gravity. The cleavage-defining objects however do appear to defy gravity, but usually can only do so with the generous help of certain specially designed supports. Without such supports it's generally quite obvious how gravity is not defied at all.

  • Two counter examples (Score:3, Interesting)

    by tipo159 (1151047) on Saturday April 14, 2012 @11:19PM (#39690777)

    a) a physicist professor (postdoc, well-known in his field worldwide) at my university was ticketed for speeding based on a radar gun reading. In court, he presented an analysis that showed that a radar gun reading would be inaccurate under the conditions where used. The judge determined that the analysis was irrelevant and fined the prof.

    b) I was involved in an automobile accident. I was cited for running into the other car. A physicist friend of mine and I put together an analysis based on physics that showed that the other car had to have run into my car. It was pretty cool because it so closely matched what happened (physics works!). However, my insurance company, the prosecutor and my attorney all dismissed the analysis as irrelevant.

  • Utter Sophistry (Score:4, Insightful)

    by ObsessiveMathsFreak (773371) <obsessivemathsfreak@ei r c o m .net> on Saturday April 14, 2012 @11:55PM (#39690931) Homepage Journal

    This argument is a shameless piece of sophistry.

    It's central argument is "I did stop; a car just passed in front of me and you didn't see.". This is then expanded into 4 pages of unnecessary and probably disingenuous over-analysis.

    The entire argument breaks down in FIG 5. Leaving aside this nonsense of measuring angular speed(The human brain interpolates just fine), the author compares two curves in which the equated angular speeds of the car do not translate into the same linear speed. Indeed, at the occlusion point at t~1.5 s, the car corressponding to the blue curve would be travelling at 15m/s, verses the car at constant 8m/s that it is being compared to.

    And this is even before we begin talking about how the author is really comparing a car at constant speed to one which reverses back into the stop sign and then drives forward.

    I think this kind of thing is described as "sophomoric", and in that that word describes a second year student who is full of their own knowledge with no concept of their own ignorance, I would have to label it as such. The cop was right, pay your ticket Mr. Krioukov, and don't darken the door of the maths department for a very long time.

  • "It is widely known that an observer measuring the speed of an object passing by, measures not its actual linear velocity by the angular one."

    I would have found him guilty based on that sentence alone and fined him for gratuitous use of a comma and a blatant misspelling.

  • by Grayhand (2610049) on Sunday April 15, 2012 @12:05AM (#39690987)
    I was always into photography and this was the 70s. My father got ticketed for parking on a cross walk in our small town around midnight. It was the dead of winter and snow covered all the streets. He wanted to fight it so I photographed the place in the middle of the day showing how thoroughly the snow covered the streets making it impossible to see the cross walks. The judge took one look at the photos and motioned for the cop to approach the bench where he chewed him out for wasting his time on such a ridiculous case. It is possible to fight tickets with evidence but so rarely do people have evidence to fight them with.
  • by CanEHdian (1098955) on Sunday April 15, 2012 @12:30AM (#39691075)
    "But officer, since I didn't observe the stop sign, it was both there and not there at the same time. It was there after YOU observed it, but by that time I was already gone!"
  • Me Too! (Score:4, Interesting)

    by Tourney3p0 (772619) on Sunday April 15, 2012 @12:35AM (#39691091)
    Something similar happened to me my freshman year of college. I had an 8am EF exam the following day, so I was up late studying for it. Around 1am or so, my calculator batteries died. I was just about ready to go to bed after studying one or two more problems, so I was quite unhappy about having to go out to get new batteries.

    Speed limit on the main street between myself and the nearest 24-hr convenience store half a mile away was 45 (I know, I should have walked. But all I wanted was to get it over with so I could sleep). I got pulled over for "drag racing" even though the streets were entirely empty other than myself and a cop waiting on a side road. To be fair, I was getting up to speed limit as quickly as possible so I could get it over with. But I was also "paced" at 60, which means he did not clock me but instead estimated my speed based on speeding up to catch up to me after turning off his side street. He included the streets where all this happened, so this gave me all the distances between incidences that I needed.

    I used simple integrals to show the velocity/position relationship, along with the factory specifications of my car. End result is that the judge said he had no idea at all what I was talking about, and the ticket was dismissed because "it sounded right".

  • by nedlohs (1335013) on Sunday April 15, 2012 @01:06AM (#39691191)

    of arguing "I did stop, but the officer's view was obstructed by another vehicle and hence he couldn't have seen whether I did or did not" and having the officer agree that his view was obstructed.

  • Now that he has managed to use physics to get out of a ticket for allegedly running a stop sign, he can use an even simpler argument to get out of a speeding ticket, if he is traveling east to west.

    Let's say he is going from Spokane, Washington to Seattle. Speed limit is 70 mph, and the cop determines he was doing 85.

    All he would have to do is remind the officer that at Seattle's latitude, the Earth rotates west to east at a speed of 707 miles per hour. And since he was moving in the opposite direction of

  • The simple version (Score:5, Insightful)

    by Chrisq (894406) on Sunday April 15, 2012 @02:11AM (#39691387)
    Without the maths, the defence is "I actually did stop briefly, but your view was obscured by another car". I would hope that in the interests of justice the simple version would also lead to an acquittal, the judge realising that if the police couldn't see the car at the time there is reasonable doubt. I expect it was more of a case of "wer'e not going to pay for a mathematician to support the prosecution on a trivial case like this.
  • Yeah... (Score:5, Interesting)

    by abigsmurf (919188) on Sunday April 15, 2012 @05:03AM (#39691809)
    If you go up to a stop/give way sign at a fairly high speed and brake heavily at the last second, you're an arsehole. What people do that fail to realise is that they make people on the road they're joining or turning into nervous as hell. They've no idea if you're a late braker or if you're going to pull out in front of them and potentially cause an accident.

    If he did drive his car as in that graph, I'd hate to be a passenger in his car with those g-forces. Heck even if he took twice as long to slow as in those graphs it would be pretty unpleasant if he did that every time he stopped. Besides which most cars can only manage ~-0.8gs and that's being done by professional drivers in ideal conditions with no regard for tire life. I suspect if you stretched out the graph for a more realistic acceleration of -0.5gs it wouldn't look more damning than supporting of his argument.
  • by fiziko (97143) on Sunday April 15, 2012 @06:32AM (#39692083) Homepage

    The local laws in my area (Alberta, Canada) say you must stop and then *remain* at a complete stop for three seconds before proceeding. A delay that long would have been noticeable in spite of this argument. Are California's laws similar?

    • by swillden (191260)
      No. I don't believe any state in the US requires the driver to remain stationary for any interval. They just require coming to a complete stop.
  • by NicknamesAreStupid (1040118) on Sunday April 15, 2012 @06:58AM (#39692139)
    Laws of Physics were declared unconstitutional by their state supreme court, along with evolution.

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