Einstein, Mileva Maric and Light

''We know from his letters that Einstein, even from the age of 16, was literally obsessed with the nature of light. Everyone he could speak to, his friends, his colleagues, even his then girlfriend, Mileva Maric—who would become his wife—everyone he badgered with the question, "What is light?"

Michio Kaku

EINSTEIN: What would I see if I rode on a beam of light?

MILEVA MARIC: What? A beam of light? By what method do you propose to ride on this beam of light?

EINSTEIN: The method is not important. Let us just imagine we two are young, radical, bohemian experimenters, hand in hand, on a journey to the outer reaches of the universe, and we are riding on the front of a wave of light.

MILEVA MARIC: I really don't know what you are suggesting, Herr Einstein. Do you wish to hold my hand or ridicule me?

EINSTEIN: Ridicule you? No, never. I merely want you to help me to understand. What would we see, do you think, if we were together, and we sped up and up until we caught up to the front of a beam of light? What would we see?

  - Einstein's Big Idea, October 11, 2005