- Today, I need to predict tomorrow’s weather.

- Yesterday I made some measurements of the (temperature, pressure, etc) conditions that I need for today’s prediction.

- Yesterday it was impossible to know what measurements I’d optimally need to take for today’s forecast.

- Today, I can (quantumly, probabilisticly) go back in time and make sure I have the optimal set of measurements for today’s prediction.

- I can’t change anything that happened between yesterday and today, but I now have better information I can use to change tomorrow.