Interview with Klaus Wyrtki
219
During your scientific career the role of models must have changed. I guess, when
you were in Kiel there were no models.
There were of course Stommel’s models. Conceptual models have always been part
of physics. And experimental models also.
Then came computer models and took more and more part of the science. How did
you experience that?
With a certain amount of skepticism, but the same skepticism I would have to an
experiment. That means, I don’t challenge the model, but the conclusions that people
draw from the model.
Go back to basic physics. An astronomer makes an observation, first he speculates what happens. That is the first step, may be right, may be wrong. Then he makes
a theory. Mathematically a model is equivalent to a theory. Then he asks what goes
into the theory? What are the basic assumptions of the model?
I have a question to you. The big ocean circulation models that we are
having today and that show many details of ocean circulation, do they include
tides?
We
25 have in the meantime a circulation model, which includes tides.
For the world ocean? Do the tides interact with the circulation? They must interact.
They cause mixing and will dissipate energy.
Yes, for the world ocean. The tides interact in this model. Normally the circulation
models do not include tides.
When somebody comes with a result on ocean circulation you ask what does it resolve?
What’s the effect of tides? You can put a mixing parameter in your models which
specifies a number. But how good is that? These are the challenges to the models.
But you said you would challenge the modeler, not the models.
The conclusions from the models.
Are there some systematic problems with models?
No, I don’t think so. Models are part of physics, but you have to be skeptical about
the results. Models are as much part of physics as experiments are. They are only a
different way of conducting experiments. Don’t misunderstand that.
Another thing which came up in your career was remote sensing. Suddenly there
were satellites and you could observe the whole world from space. What did they
change?
Well, again a personal approach. If I want my appendix out, I hire a doctor, if I want
to compute I hire a computer programmer, and if I want to do engineering I hire a
competent engineer. I don’t do these things myself. That is simply my approach to
25 Statement by J¨ urgen S¨ undermann.
219
During your scientific career the role of models must have changed. I guess, when
you were in Kiel there were no models.
There were of course Stommel’s models. Conceptual models have always been part
of physics. And experimental models also.
Then came computer models and took more and more part of the science. How did
you experience that?
With a certain amount of skepticism, but the same skepticism I would have to an
experiment. That means, I don’t challenge the model, but the conclusions that people
draw from the model.
Go back to basic physics. An astronomer makes an observation, first he speculates what happens. That is the first step, may be right, may be wrong. Then he makes
a theory. Mathematically a model is equivalent to a theory. Then he asks what goes
into the theory? What are the basic assumptions of the model?
I have a question to you. The big ocean circulation models that we are
having today and that show many details of ocean circulation, do they include
tides?
We
25 have in the meantime a circulation model, which includes tides.
For the world ocean? Do the tides interact with the circulation? They must interact.
They cause mixing and will dissipate energy.
Yes, for the world ocean. The tides interact in this model. Normally the circulation
models do not include tides.
When somebody comes with a result on ocean circulation you ask what does it resolve?
What’s the effect of tides? You can put a mixing parameter in your models which
specifies a number. But how good is that? These are the challenges to the models.
But you said you would challenge the modeler, not the models.
The conclusions from the models.
Are there some systematic problems with models?
No, I don’t think so. Models are part of physics, but you have to be skeptical about
the results. Models are as much part of physics as experiments are. They are only a
different way of conducting experiments. Don’t misunderstand that.
Another thing which came up in your career was remote sensing. Suddenly there
were satellites and you could observe the whole world from space. What did they
change?
Well, again a personal approach. If I want my appendix out, I hire a doctor, if I want
to compute I hire a computer programmer, and if I want to do engineering I hire a
competent engineer. I don’t do these things myself. That is simply my approach to
25 Statement by J¨ urgen S¨ undermann.