“Karl Popper wrote “A theory is part of empirical science if and only if it conflicts with possible experiences and is therefore in principle falsifiable by experience.” The idea here is that if you can’t prove something wrong, you can’t really prove it right either. Thus, in Popper’s words, science requires testability: “If observation shows that the predicted effect is definitely absent, then the theory is simply refuted.” This means a good theory must have an element of risk to it — namely, it has to risk being wrong. It must be able to be proven wrong under stated conditions. In a true science, as opposed to a pseudo-science, the following statement can be easily made: “If *x* happens, it would show demonstrably that theory *y* is not true.” We can then design an experiment, a physical one or sometimes a thought experiment, to figure out if x actually does happen. Falsification is the opposite of verification; you must try to show the theory is incorrect, and if you fail to do so, you actually strengthen it. To understand how this works in practice, think of evolution. As mutations appear, natural selection eliminated what doesn’t work, thereby strengthening the fitness of the rest of the population.”
— Farnam Street, The Great Mental Models Volume 1: General Thinking Concepts
When our cells are cleaved in two during mitosis, spindles are tiny systems of ‘fibres’ that pull the DNA inside apart. Each daughter cell must be identical, but they also have to fit into the plan for the overall tissue. In these human cells, researchers find a protein in the cell membrane called annexin A1 that juggles these priorities – coordinating the spindles on the inside with chemical cues from neighbouring cells, allowing the DNA (purple) to split to opposite sides of the cell in the top row. The direction or polarity of dividing cells is especially important in the patterning of developing tissues. Losing annexin A1 (lower rows) leaves mitosis struggling, with many of the spindles malformed – in many cases mitosis fails to complete. Investigating other proteins that work towards the ‘big picture’ may help researchers to understand and guide cell division in health and disease.
It is a, uh, bright object And it’s, uh, obviously rotating because it’s flashing It’s, uh, way out in the distance Currently rotating in a very rhythmic fashion Because the, uh, flashes come around, uh, almost on time
