Universal indicator
Universal indicator is a combination of dyes that is used to indicate the pH of a substance and, therefore, whether it is an acid or an alkali.
![a gif of a space car using indicators](/images/user/base/Chemistry/5. Acids, Alkali, Bases and Salts/2.5.13-Universal-indicator-gif-Resized.gif)
The indicator (universal indicator) of a car in space (universe) is flashing as it turns towards ‘alkali’ or ‘acid’.