Questions

The purpose of these questions is only to suggest games to play with the simulator. Do what's fun.

In the first scenario, "DaisyWorld in 3 species", you'll notice that the living area ("total daisies") doesn't exceed 70%. Look at the Parameters of this scenario. The deathrate is set to 0.3, which may explain the living percentage being no more than 0.7. Play with this parameter. What does the deathrate do to the daisies' ability to control their environment's temperature? To the species mix?

Using a multispecies scenario you like, run the insulation from 0 to 1.0 by .2's. What effect does this have on the daisies' control of the planet temperature? Why? If DaisyWorld had spatial structure, neighboring patches of daisies, and the neighbors were more influential (lower insulation) than the planetary temperature, what might be different?

Another parameter is "max steps per". At each luminosity increment, DaisyWorld runs "to convergence", or a maximum of "max steps per" calculations at that luminosity, before plotting a point. Try setting this down from 1000 to 5. Where does the result differ from the original scenario? Try DaisyWorld in 5 species with max steps set to 1, 2, 3, 4, 5, 20, 50, 100. Speculate on what's going on. (Note: this is a deterministic simulation, no random component. The exact same parameters yield identical results.)

Wanna see something really pretty? If your computer isn't struggling too hard to run the bigger scenarios, try DaisyWorld in 20 species, changing the deathrate to 0.2 and "max steps per" to 2. You could intellectualize about this pattern if you want, or just enjoy it and see if you can come up with others.

Try the next three scenarios (neutral, white, black). They all have barren plus one species of daisy. Pick one and experiment with the albedos from the "Daisies" button. Recall that 0 is a black hole and 1.0 a perfect reflector of incoming light. Play until you can roughly predict what's going to happen with each change. You can play with the temperature ranges on the parameter menu along with this.

Going back to the 3-color base scenario, play around until you can characterize when the living world temperature crosses from above to below the dead world temperature. Does your story have predictive power? Try your predictions on a different scenario.

Some Earth features missing in DaisyWorld are an atmosphere and roundness. Solar input is not the same at all lattitudes or altitudes, the atmosphere serves as a greenhouse, and the neighborhood temperature is definitely more influential than that of the planet as a whole. What might this explain about your results with the Earth albedo values above?

Try the scenario of DaisyWorld in 12 species. Pose an evolutionary argument for species succession in this scenario.

Refute your evolutionary argument above. Having argued both sides, which is "right"? How could you tell?

In the many-color worlds (9 and above), there are sometimes pre-peaks of a color before its decisive succession. Can you come up with a story about that?

Stories like the ones you're inventing here are sometimes called "just-so stories". Do you think you could tell a "just-so story" from a valuable one when reading a scientific paper? How do you think people develop that kind of discernment?

Time-consuming, for the mathematically inclined. Try doing a qualitative analysis of the behavior of the system of equations Under the Hood. This is a feedback loop, so try placing the equations as boxes on a circle, and determine when each has a positive (amplifying) or negative (damping) feedback on the planetary temperature. Note that the authors of this model deemed the system insoluble, so this is only a qualitative analysis. Can you make any predictions and test them out on the simulator?

Ginger Booth, Oct. 19, 1997