The Science of Can and Can't: A Physicist's Journey through the Land of Counterfactuals

What Darwin discovered, and what Paley could not quite see, is that there is no need for any intentional design process: biological adaptations in animals can be created out of elementary components of matter, such as simple chemicals, via a nonpurposeful process called natural selection.

Any sequence of transformations turning something without energy into something with energy, without depleting any energy supply, is impossible in our universe: it could not be made to happen, because of a fundamental law that physicists call the principle of conservation of energy.

In fact, knowledge is the most resilient stuff that can exist in our universe.

This principle is based on fallibilism, a pillar of Popper’s explanation of rational thinking. Fallibilism makes progress feasible because it allows for further criticism to occur in the future, even when at present we seem to be content with whatever solution we have found.

We can never know whether a physical theory that we have formulated is true; all we can say is that it has so far not been found to be false.

Knowledge in this sense does not have to be known by anyone: the moth does not know its wings are black. ‘Knowledge’ merely denotes a particular kind of information, which has the capacity to perpetuate itself and stay embodied in physical systems—in this case by encoding some facts about the environment.

Something can hold information only if its state could have been otherwise: A computer memory is useless if all the changes in its contents over time are predetermined in the factory. The user could store nothing in it. And the same holds if you replace ‘factory’ with the Big Bang.