Episode 169: Let There Be Light

Air Date: June 22, 2011

A system of mirrors can be used to reflect sunlight into an underground area and illuminate it sufficiently to allow safe passage. (Based on a scene in the film The Mummy.)

plausible (but ridiculous)

Adam and Jamie built an obstacle course in the shop and used it to determine the minimum level of light needed to see. To match the circumstances shown in the movie, Adam went from a brightly lit area into total darkness, then to the course; his goal was to reach the other end without knocking over any glasses. He succeeded at a level of 0.39 lux, while the pair estimated that the movie scene had used roughly 200 lux.

Next, they set up six mirrors to bounce light back and forth down the length of the shop, using a spotlight as the source. Polished metal mirrors gave 1.13 lux, but caused the beam to spread out after only a few reflections. When modern glass mirrors were used instead, the light level registered at 0.49 lux and the beam stayed focused longer. Adam and Jamie realized that the light needed to scatter in order to illuminate the room.

At Treasure Island in San Francisco Bay, they set up a hangar area as a full-scale tomb and brought in six glass mirrors and a 7,000-watt spotlight. After adjusting the mirrors, they measured a light level of 2.3 lux and could easily see their way around. Once the sky cleared, they reflected sunlight into the tomb and found a peak of 2.5 lux until the sun’s position shifted, throwing off the mirrors’ alignment. Finally, Jamie stood in the light beam, which scattered in the air when it hit his white shirt and gave 8.6 lux. The need to keep adjusting the mirrors, and the unlikely prospect of finding several of them ready to use after thousands of years underground, led them to declare the myth “plausible but ridiculous”.

It is possible to safely stop an out-of-control car by pulling in front of it with another car and slowing down.


After taking lessons in stunt driving, Grant, Kari, and Tory tested a scenario in which the runaway car would be coasting without the driver’s foot on the accelerator. As Kari drove without using either the steering wheel or the brake/gas pedals, Grant pulled in front and slowed down until he made contact with her bumper. He was able to stop her from a starting speed of 35 mph and again from 55 mph (56 and 89 km/h). They then tested the possibility of a stuck accelerator and no steering. Kari drove at 75 mph (121 km/h) with her foot on the gas pedal; Tory stopped her with some difficulty, just short of hitting a fence. They declared the myth confirmed at this point.

Next, Grant and Tory tried to sandwich Kari’s car from either side and managed to stop her, though they began to spin out somewhat. The two men then built separate car-stoppers: Grant made side paddles to attach to the two rescue cars’ front bumpers (to block in the runaway car), while Tory made a hood-mounted spear to hook the rescue and runaway cars together so the rescuer can slow them both down. Both rigs were successful.


  1. Huh? says:

    Ok…so when the harpoon hits the back of the car, in one shot it hits high and to the center of the license plate, and in another it hits to the middle and far left. 2 attempts to get a desired result??

  2. Bob Cherney says:

    How do I submit a myth-1957 buick special traveling at 80mph 1:00pm, clear dry straight road (asphalt). The car gets broadsided by a 250 lb. wisc. buck, causing the vehicle to go up on two wheels, is it possible? P.S. the deer was on a full run.

  3. keith jacob markowski says:

    i have a myth can a helicopter blade be fix by a 2 by 4

  4. maki says:

    I have smal myth!
    Can we shoot the gun into the tank of the car that the car explodes?

    • Dan says:

      It’s already been done on Mythbusters and no the fuel tank didn’t explode! Myth BUSTED!!

      • Omen says:

        They revised it, they did a test with a tracer bullet that was conclusive.

  5. Dan says:

    As for the episode using mirrors to reflect sunlight in an unlit area, it is true! I’m an archeologist and have worked in Egypt and occasionally the Egyptians still use polished mirrors to reflect light and illuminate tombs. Myth CONFIRMED!!!

    • T. Rollins says:

      How many mummies did it take to keep readjusting the angles of each mirror?

      • justin says:

        Not mummies, but what do you think they had slaves for? Menial tasks such as making sure the mirrors were always reflecting the light properly.

  6. mark says:

    hi i was watching one off your episoderson doing the burn out and trying to get the tyre arlite you was doing it wrong you have to do are brake brun out with disk brakes it the disk and pads get read hot and the rubber flys off onto the disk/pads and catchers arlite thats how you get the tyre to lite up [catch fire ] ok

  7. Karl Rowe says:

    Adam during your test about bullets and water, all you had to do is watch a real police video and you would have seen that they never shoot straight down but at an ngle 30 to 35 degrees. It would have saved your clear water tank.

  8. sheraz says:

    I i do not know english speking .i just says i like the all tem.i fan u. i like work with u if u want plz….

    • T. Rollins says:

      Not sure if just retarded or a troll… Salam is hardly a Polish word. Lrn2Demograph

  9. LeeJo Rokin says:

    In regards to the following: A system of mirrors can be used to reflect sunlight into an underground area and illuminate it sufficiently to allow safe passage. (Based on a scene in the film The Mummy.)

    Although your testing was excellent, there is a slight problem with your test results.

    You used what I think was similar to an underground car park, with dark coloured walls, a lot of grey etc.

    When it comes to Egyptian buildings, they are built of blocks of sandstone which is often in a shade of yellow. Although yellow will not scatter light as much as Jamie’s white shirt lol, it does add to the scattering of reflected light which you did not get in the facility you used with dark painted walls.

    Although in the end, using the sun to light the underground chamber will have the same result as in the sun will be constantly moving in the sky so you would have to keep re-adjusting the mirrors, it would have helped your test greatly to have used yellow walls to resemble the colour of the inside of most Egyptian structures including underground tombs as you would have had an increase in light scattering due to the yellow walls.

    • Davide says:

      Only one person has to continually adjust the primary mirror the rest can be fixed. So it’s totally plausible. Plus the colour of the sandstone and the slight spill of light off each mirror on to the pale sandstone and you will get a much higher reading especially if the tomb is smaller than a car park!

  10. Graham Redman says:

    Some years ago I actually did stop a runaway car by stopping in front of it. the vehicle was a ford falcon 1970’s and the rear wheel and axle was sliding out from the diff so there were no gears brakes or emergency brake to stop the car. We were going downhill at about 60-70 kph, (35 mph to 40 mph) on a straight between 2 bends and only 200 yards to do it. My passenger needed to tell the driver of the fault and tell him what I was going to do while I was driving alongside of the vehicle. The mythbusters test showed the stopping car pull to the left about 100 yards in front I did it with 20 yards by swerving in, braking hard, allowing the car to hit the rear of my (smaller) car and then I braked hard, no skidding tyres, and we stopped in just over 100 yds just before the final bend approaching a busy intersection, safely, all in the left hand lane. the driver was very appreciative, and no damage to either vehicle.

    • Davide says:

      Was that in Australia? And what car were you in? That took some courage!

  11. Jordan says:

    I liked the success of Tory’s hood-mounted technique, but how did they eventually get the cars apart?

    Also, I’ve got an idea: an air cannon-activated hook mounted under the front bumper of the rescue car, that shoots out and hooks on the other car’s rear axle, pulling it to a stop.

  12. Seth says:

    Just caught this episode on rerun, and while not normally prone to write critiques on your tests, had to mention a missing variable that I think makes a huge difference in the testing results.

    For the mirror test, the testing location in San Fran is much further from the equator than an Egyptian tomb would have been. This distance makes a huge difference not only in the sunlight, but also the movement of the sun. Being further from the equator would cause further movement of the sun, causing the mirrors to have to be adjusted more.

    • Ben says:

      The sun moves just as much at the equator as it does in San Francisco. They would still have to continuously adjust the mirrors to track the sun as it moved across the sky. (Also, you know that the sun is only directly above the equator twice a year, right?)

  13. JP says:

    There is absolutely no need to readjust ALL the mirrors, only the first one which reflects sun to the second one. The second mirror “see” the first one as a light source and only the first mirror has to be tilted so it follows the sun. All other mirrors after the second one can be exactly in their original position all the time.

  14. Cam says:

    i learnt a 1 thing from this episode, first is that Grant, Tory and Kari aren’t very good drivers, blocking the car and then locking the brakes, i am a little surprised it did stop the car, doing it with a car in a controlled stop would have severally reduced the distance and probably would have stayed in the lane, second when they sandwiched the car they weren’t very well lined up, hence one car spinning.
    the mirror myth, wouldn’t they had more success using concave mirrors, or if they wanted to disperse the light more, convex mirrors, just a thought.

  15. PDN says:

    Stopping the car — yeah, seemed as if Kari must have taken her foot off the accelerator at some point. If not, wouldn’t her car’s wheels at least have continued to spin?

  16. curious in missouri says:

    Was it not also a characteristic of the mirrors or polished metal discs found that they were concave (curving inward for better reflection)? Would this not make a significant difference the light dispersal?

Leave a Reply