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Try This Exponential Growth Experiment

On Monday the GrowthBusters project begins a campaign to honor the 40th anniversary of the landmark Limits to Growth study. If you’re not already subscribed to my blog, please do so – you won’t regret it. During March and April I’ll be sharing insights from the leading thinkers in sustainability, economics, population and environment. I’ll also be posting segments from the GrowthBusters movie related to the study. You’ll also be treated to clips that never made the film, including an interview filmed just last week with Jorgen Randers, one of the original MIT team on the study.

As we go along, we’ll also perform a little experiment to demonstrate the power of exponential growth. Now you may think you have a good handle on the mathematics of growth. I feel I certainly do. But I’ll wager that as the experiment proceeds, we may be just as astonished as everyone else. This experiment is also a wonderful way to engage your family (especially your kids), your roommates, or office colleagues. You can have some fun and spark some interesting conversations.

We’ll start the experiment on Monday. Sometime over the next two days please gather the materials you’ll need:

  • At least 3 pounds of grain (wheat or barley)
  • One large, clear container
  • (a beaker, graduated cylinder, large glass measuring cup, jar or pitcher)
  • If you have a kitchen or postal scale, that will come in handy as well.

Instead of going out and purchasing grain for this experiment, you may substitute anything small and numerous you have around the house: rice, pebbles, jelly beans, cheerios, marbles, etc. But only go this route if you have a LOT of these.

As a teaser, I’d like to share a story with you:

Share this video with your lab partners and be ready on Monday to launch our experiment. Be sure to check back tomorrow for some additional information (subscribing to this blog will make that easier), and then on Monday for instructions to begin.

You can also follow along on facebook as we perform this experiment and honor Limits to Growth on its 40th anniversary.

Dave Gardner

Dave Gardner is the director of the new documentary, GrowthBusters: Hooked on Growth, which uncovers the cultural forces that keep us pursuing growth in the face of overwhelming evidence we’ve outgrown the planet.

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Comments (0)

  • Avatar

    Michael Dwyer


    Hi Dave,
    We saw the film last night. Great job, most enjoyable and most pertainant.
    Just one comment. How about a 35 minute version? i could show a 35 minute version to my bike club (who are a bit sceptcal when I talk about the end of the way they live.) I could slip in a 35 minute version during one of our monthly meetings.
    Just a thought.
    Michael, Adelaide, South Australia


  • Avatar

    Dave Gardner


    Thank you for coming out to see the film, Michael, and for your suggestion. We are working on a 50-minute version now, and we’re tinkering with ideas about what we can do in the 15 to 20 minute range. So stay tuned. I might suggest you subscribe to my email updates so you’ll be the first to know when any of these versions are released.


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