Science Forums 2

[sanctus]

Pyro, can you elaborate on "theories are based on evidence"? Because a theory can also be developed on a beginning of the style:"let's assume that" and then see if evidence supporting this can be found.

A best example is inflation, we have an uniform temperature over all the sky (the monopole part of it at least or to fluctuations of order 10^-5). One then looks for a theory which can explain this, what we have now is:"let's assume we had an inflationary era, this explains amongst other the uniform temperature (which is the evidence)".
But there are working alternatives to inflation, but it is still a scientific theory, although not based on direct evidence (inflaton never seen), only indirect (uniform temperature, etc.)