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--- fermi_estimates [2019/09/09 20:53] – created ethanminot
+++ fermi_estimates [2025/05/18 12:35] (current) – ethanminot
@@ Line 1: / Line 1: @@
 ====== Back of the envelope estimates ======
-The TED talk by Sanjoy Mahajan summarizes the philosophy... striving for too much rigor can stop progress in science and technology. "Perfect" is the enemy of "good enough". These estimates have been given several different names, including Fermi Estimates, Back of the Envelope Estimates and Street Fighting Estimates. Each name has good reason: First, the stamp of approval from a famous physicist who was capable of all levels of rigor. Second, a reminder that all the information you need can be summarized on a small piece of paper. Third, there are no rules about what you can/cannot do when making an estimate.
+The TED talk by Sanjoy Mahajan summarizes the philosophy "striving for too much rigor can stop progress in science and technology". Perfect is the enemy of good enough. When we recognize that we don't need an exact solution, we can do
+  * a Fermi problem,
+  * or a coarse-grained model,
+  * which are both examples of back-of-the-envelope estimates.
+A great video explaining Fermi problems:
+[[https://www.youtube.com/watch?v=KAo6Vn5bDF0|https://www.youtube.com/watch?v=KAo6Vn5bDF0]]
+And a video explaining coarse-grained models (spherical-cow models):
+[[https://www.youtube.com/watch?v=LQR5Us3D_ZA|https://www.youtube.com/watch?v=LQR5Us3D_ZA]]
+**Resources:**
-  *Sanjoy Mahajan's book, "The Art of Insight in Science and Engineering". PDF copy is available for free online.
   *[[http://tedxcaltech.com/speakers/sanjoy-mahajan|TED talk by Sanjoy Mahajan]]
+  *Sanjoy Mahajan's book, "The Art of Insight in Science and Engineering". PDF copy is available for free online.
   *Sanjoy Mahajan has another book called "Street-Fighting Mathematics". Ethan has a copy.
   *Back-of-the-envelope physics by Clifford Swartz. Ethan has a copy.
@@ Line 10: / Line 21: @@
   *{{::weisskopf_simplicity_long.pdf|In Search of Simplicity}} articles by Weisskopf, MIT.
-To be good at making quantitative estimates, you need to know some basic quantities:
+To be good at making such estimates, you need to know some basic quantities:
   *Solar energy flux: ~ 1 kW/m2
   *Energy released by combustion ~ 0.1 eV per bond
@@ Line 18: / Line 29: @@
   *etc.
-It is unfortunate that the United State has not adopted SI units. Physical laws are usually expressed in SI units. To apply these laws to everyday quantities, you need familiarity with mass in kilograms, length in meters, volume in liters (10^-3 cubic meters) etc.
+It is unfortunate that the United State has not adopted SI units. Physical laws are usually expressed in SI units. To apply these laws to everyday quantities, you need familiarity with mass in kilograms, length in meters, volume in cubic meters etc.
 ===No physics required===