When you drive your car, E = mc2 is at work. As the engine burns gasoline to produce energy in the form of motion, it does so by converting some of the gasoline's mass into energy, in accord with Einstein's formula.

String theory envisions a multiverse in which our universe is one slice of bread in a big cosmic loaf. The other slices would be displaced from ours in some extra dimension of space.

I think the relationship between memory and time is a very deep and tricky one, to tell you the truth. I don't consider memory another sense. I do consider memory that which allows us to think that time flows.

I do feel strongly that string theory is our best hope for making progress at unifying gravity and quantum mechanics.

Science is a way of life. Science is a perspective. Science is the process that takes us from confusion to understanding in a manner that's precise, predictive and reliable - a transformation, for those lucky enough to experience it, that is empowering and emotional.

Science is a way of life. Science is a perspective. Science is the process that takes us from confusion to understanding in a manner that's precise, predictive and reliable - a transformation, for those lucky enough to experience it, that is empowering and emotional.

I believe we owe our young an education that captures the exhilarating drama of science.

When you buy a jacket, you pick the size to ensure it fits. Similarly, we live in a universe in which the amount of dark energy fits our biological make-up. If the amount of dark energy were substantially different from what we've measured, the environmental conditions would be inhospitable to our form of life.

In the far, far future, essentially all matter will have returned to energy. But because of the enormous expansion of space, this energy will be spread so thinly that it will hardly ever convert back to even the lightest particles of matter. Instead, a faint mist of light will fall for eternity through an ever colder and quieter cosmos.

Nature's patterns sometimes reflect two intertwined features: fundamental physical laws and environmental influences. It's nature's version of nature versus nurture.

Intelligence is the ability to take in information from the world and to find patterns in that information that allow you to organize your perceptions and understand the external world.

The melded nature of space and time is intimately woven with properties of light speed. The inviolable nature of the speed of light is actually, in Einstein's hands, talking about the inviolable nature of cause and effect.