[Grammar] Simple present tense — ... along comes Albert Einstein ...

[Xixi Luo]

Think about light. If you look at Huygens, light is a wave as confirmed by double-slit experiments. But then along comes Albert Einstein and discovers that light behaves like particles too. ---extracted from The Big Bang Theory.
Why do the verbs marked use the simple present tense instead of the simple past tense? I think they did happen in the past.

 

[Rover_KE]

Xixi Luo, Please note that I have improved your thread title.

Extract from the Posting Guidelines:

'Thread titles should include all or part of the word/phrase being discussed.'

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The quoted text is written in the historical present or narrative present. [link]

 

[jutfrank]

The first two are in the narrative present but behaves isn't.

... light behaves like particles = This is presented as a fact about nature, not a past action.