4 ms·
They do, but only when they want so, like they want endless exponential growth of economy but not energy consumption.
by anticensor 7y ago
They do, but only when they want so, like they want endless exponential growth of economy but not energy consumption.
- FartyMcFarter 7y agoMost people don't think of 2% annual growth as exponential.
- alasdair_ 7y ago“Most people” could not accurately define the word “exponential” even if they were offered an exponential amount of money every year to do so.
- croon 7y agoTo be fair they'd be incentiviced not to... assuming they understand the exponential nature of the money, which I guess they don't. But as soon as they do learn they won't want to explain.
- TeMPOraL 7y agoAlso, growth narrative is always about adding/subtracting percent points - which makes most people think this is a linear phenomenon, because they don't make the connection that the quantity discussed is a multiplier, and charts they see are on log scale.
- littlestymaar 7y agoAs long as you stay with low percentages, the linear approximation works pretty well: two times 1% lead to a 2.01% increase. But it starts breaking down as soon as you reach 10%. Little trick to know (with some good approximation) the doubling time of some low-percentage growing system: count it linearly up to 10% and then multiply by 7 (which is roughly the doubling time for 10% growth). Example: 2% => 5*7=35 years to double.
- TeMPOraL 7y agoOr, in this context, 20% daily growth of coronavirus cases -> 20% => 0.5*7 = 3.5 days to double.
- bxparks 7y agoThis is identical to the Rule of 72, https://en.m.wikipedia.org/wiki/Rule_of_72 https://en.m.wikipedia.org/wiki/Rule_of_72. Except that you are using 70. The amazing thing about the rule of 72 is that it works pretty well even for rates greater than 10%.
- davidiach 7y agoAnd even fewer realize that a 2.1% growth rate is itself exponentially faster than a 2% growth rate. If something grows by 2% per day, vs 2.1% per day, after a year the second one is >20x bigger.
- algorias 7y agoWhat you say is true in principle, but your numbers are wrong. I got a rather less dramatic 50% difference after a year: >>> 1.02**365 1377.4082919660768 >>> 1.021**365 1969.6808462403098 >>>
- davidiach 7y agoThanks for the correction, I didn't actually do the math for that, just remembered something I've read a while back, but the numbers where different 20% vs 21%. Apparently I don't understand exponential growth either cause I assumed a 5% difference scales linearly (as in the difference between 20% vs 21% growth rates for a given period should be the same as between 2% and 2.1%). Silly me.
- hef19898 7y agoBut a good exmple showing why numbers are so important. A 50% difference is an order of magnitude away from a factor 20. Thing is, once out there the wrong factor 20 is impossible to correct.