07.06.2008

Light vs. Sound: Light Wins

Posted by AJ Harbison at 12:19 am

Since most of our ears are still ringing from the fireworks yesterday, here’s a post I wrote on the subject a few weeks ago and haven’t posted yet.

I recently attended a party in Anaheim, at a house just a few miles from Disneyland, and as my girlfriend and I were leaving the party, we saw the fireworks from the nightly show lighting up the sky to the east. We had a pretty good view, so we stood outside for a while and watched. There was a rather long delay between what we saw and what we heard–between the exploding of the fireworks and when we heard the boom. The delay was a little over three seconds, by my count. But it was interesting to note that the ear didn’t want to accept a different timeline for hearing than the eye was getting for seeing: when we heard a boom, we really wanted to associate it with the fireworks that were going off when we heard it, even though we knew it wasn’t. We have a strong desire for our various sensory inputs to line up, even when our brain tells us otherwise. It’s a strange phenomenon that light travels so much faster than sound, and it’s also strange that our brains don’t like to recognize that fact.

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Comments

  1. Gravatar

    Ryan Fleming on 07.07.2008

    Just wanted to point out that the speed of sound is approximately 340m/s while the speed of light is around 300 million meters per second. What our eyes see almost instantly (assuming you are within a few thousand miles from the source), our ears will hear much much much later.

    Based on your 3 second estimate, this puts you guys about 1 kilometer (or 5/8 of a mile) from disneyland. It is also important to note that the speed and direction of sound are somewhat dependent on temperature, wind, pressure, directivity, temperature gradient, absorptivity of the terrain, and other factors.

  2. Gravatar

    Idhrendur on 07.07.2008

    Ah, he beat me to it.

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